Home Mathematics Ground states for fractional Kirchhoff double-phase problem with logarithmic nonlinearity
Article Open Access

Ground states for fractional Kirchhoff double-phase problem with logarithmic nonlinearity

  • , EMAIL logo and
Published/Copyright: July 31, 2025
Become an author with De Gruyter Brill

Abstract

Our primary objective is to study the solvability of two kinds of fractional Kirchhoff double-phase problem involving logarithmic nonlinearity in R N via the variational approach. To address the modulation coefficient in fractional double-phase operators, a new functional framework and the corresponding fractional Musielak-Sobolev space are provided. Among others, the completeness, reflexivity, and uniformly convexity of the space are established, and the continuity, boundedness, and ( S + ) -property of the fractional double-phase operator are given.

MSC 2010: 35R11; 35D30; 35J50

1 Introduction and main results

The research on double-phase problems can be traced back to 1986. Zhikov identified a dramatic change in the hardening properties of materials at a specific point, known as Lavrentiev’s phenomenon. For studying the model of strongly anisotropic materials, Zhikov and coworkers [14] employed the homogenization theory to study the functional described by:

u Ω ( u p + η ( x ) u q ) d x ,

with 1 < p < q < N and η ( ) 0 . The modulation coefficient η ( x ) determines the geometry of a composite composed of two distinct materials with hardening indices p and q .

Obviously, the core of double-phase problem is η ( ) . It can switch the elliptic exponent between p and q depending on whether η ( ) exists. On the one hand, the double-phase operator can lower to the p -Laplacian when η = 0 . On the other hand, it declines to the ( p , q ) -Laplacian on the condition of η 1 and p > q .

The working space corresponding to double-phase operators was first given by Colasuonno and Squassina [5] in 2016. They addressed eigenvalue problems involving double-phase variational integrals and established the classical embedding theorem in Musielak-Orlicz-Sobolev space W 0 1 , . In 2018, Liu and Dai [6] furthered this research by examining existence and multiplicity of ground state for the following problem,

(1.1) div ( u p 2 u + η ( x ) u q 2 u ) = g ( x , u ) in Ω .

On the basis of the definitions of double-phase operators and the norm in W 0 1 , , they constructed a modular function and elucidated its properties. Since then, double-phase problems have been extensively analyzed through variational approaches and regularity theory [517].

When Ω = R N in equation (1.1), a significant challenge arises from the absence of compactness in the embeddings. For this, Liu and Dai [7] established a continuous embedding result W 1 , ( R N ) L r ( R N ) , requiring that the nonlinear term g satisfies either a weighted condition or a radially symmetric condition. Through the application of variational methods and critical point theory, they demonstrated the existence of nontrivial solutions. Stegliński [9] ensured compactness by incorporating an unbounded term V ( x ) in W 1 , ( R N ) . Arora et al. [10] examined a class of Choquard double-phase problems in R N . They established compactness by means of the Z N -periodicity of the nonlinear term g .

Some scholars also studied the problem of nonlocal double-phase operators with η 1 [1113]. Such as in 2020, using penalization technique, Nehari approach, and Ljusternik-Schnirelmann theory, Ambrosio and Rǎdulescu [11] considered the following problem:

(1.2) ( Δ ) p s u + ( Δ ) q s u + V ( ε x ) ( u p 2 u + u q 2 u ) = f ( u ) in R N , u W s , p ( R N ) W s , q ( R N ) , u > 0 in R N .

They obtained the existence of multiple positive solutions as ε > 0 sufficiently small, and related concentration properties were established. The operator in (1.2) can be regarded as the fractional double-phase operator corresponding to η 1 , which is also called fractional ( p , q ) -Laplacian. As previously noted, taking into account that the actual physical significance of double-phase problems, it is necessary to consider the cases with modulation coefficients. In this work, we concentrate on the fractional double-phase operator as follows:

(1.3) ( Δ ) p , q , η s u ( x ) ( Δ ) p s u ( x ) + ( Δ ) q , η s u ( x ) = 2 lim ε 0 R N \ B ε ( x ) u ( x ) u ( y ) p 2 ( u ( x ) u ( y ) ) x y N + s p d y + 2 lim ε 0 R N \ B ε ( x ) η ( x , y ) u ( x ) u ( y ) q 2 ( u ( x ) u ( y ) ) x y N + s q d y , for x R N .

Clearly, the operator in (1.3) cannot be addressed under the standard fractional Sobolev spaces.

Hence, it is essential to introduce the definition of fractional Musielak-Sobolev spaces. In 2020, Azroul et al. [18] defined the fractional Musielak-Sobolev space W s , Φ x , y ( Ω ) and its corresponding nonlocal integro-differential operator:

(1.4) ( Δ ) φ x , y s u ( x ) 2 lim ε 0 R N \ B ε ( x ) φ x , y u ( x ) u ( y ) x y s u ( x ) u ( y ) x y s d y x y N + s x R N ,

where s ( 0 , 1 ) and φ : Ω × Ω × ( 0 , + ) [ 0 , + ) is a Carathéodory function. The function Φ x , y ( t ) 0 t λ φ ( x , y , λ ) d λ is required to be a Musielak function, indicating that Φ x , y ( t ) is a function of three variables. Notably, when Φ x , y ( t ) = 1 p t p + η ( x , y ) q t q , the expression (1.4) can represent fractional double-phase operators (Lemma 2.1). To our knowledge, there is relatively little existing literature on fractional Musielak-Sobolev spaces, with only some fundamental properties having been established. For instance, continuous embedding results, uniform convexity, Radon-Riesz property, and Lions-type lemma were presented in [1921].

The correlational research on the Kirchhoff equation can be traced back to 1883, which was treated by German physicist Kirchhoff [22] and embraced by Lions [23]. The initial Kirchhoff equations were first proposed as D’Alembert wave equation, which employed to investigate the transverse oscillations of taut strings, with a specific focus on accounting for the alterations in string length resulting from these oscillations. Lions [23] introduced an abstract functional analysis framework and converted the Kirchhoff equation into the following form:

u t t m 1 + m 2 Ω u 2 d x Δ u = g ( x , u ) in Ω .

Since then, Kirchhoff problem has been studied extensively [1417,2427]. Kirchhoff double-phase problems also have been studied extensively recently [1417], which extend the Kirchhoff operators to the Musielak-Orlicz-Sobolev spaces. In [15,16], Fiscella et al. considered the following Kirchhoff problems in the bounded domain,

Ω u p p + η ( x ) u q q d x div ( u p 2 u + η ( x ) u q 2 u ) = g ( x , u )

and

Ω u p d x Δ p u Ω η ( x ) u q d x div ( η ( x ) u q 2 u ) = g ( x , u ) ,

where represent the Kirchhoff operator. They used the critical point theory, truncation function, and topological tools to demonstrate the existence and multiplicity results under the Dirichlet boundary value condition and the nonlinear boundary value condition, respectively. Arora et al. [17] discussed a class of Kirchhoff double-phase problems with singular and critical terms, and applying the Nehari method to obtain the existence of at least one weak solution.

As far as current literature indicates, most fractional equations only involve power function terms, because logarithmic terms such as u r log u do not satisfy the monotonicity or the Ambrosetti-Rabinowitz condition. Lately, D’Avenia et al. [28] first examined the fractional logarithmic Schrödinger problem:

( Δ ) s u + k u = u log u 2 in R N ,

where k > 0 . By employing the fractional logarithmic Sobolev inequality, they established the existence of infinitely many weak solutions utilizing nonsmooth critical point theory, and also derived the Hölder regularity of weak solutions. Truong [29] addressed the fractional p -Laplacian problem characterized by logarithmic nonlinearity and a sign-changing function. Via the Nehari approach, he obtained existence results for two nontrivial solutions. Most recently, Lv and Zheng [27] explored the following problem:

( u p ) [ ( Δ ) p s u + V ( x ) u p 2 u ] = λ h ( x ) u θ p 2 u ln u + δ u p s * 2 u in R N .

By utilizing the concentration-compactness principle and the critical point theory, the existence of ground state solutions in both critical and subcritical conditions was studied.

As mentioned earlier a natural idea arises, which is whether the fractional Musielak-Sobolev space can be applied to study the solvability for the fractional Kirchhoff double-phase problems with the logarithmic terms. In this article, we first deal with following problem:

(1.5) ( ϱ V ( u ) ) [ ( Δ ) p , q , η s u + V ( x ) ( u p 2 u + η ¯ ( x ) u q 2 u ) ] = ζ ( x ) u γ 2 u log u + λ f ( x , u ) in R N ,

where represents a Kirchhoff coefficient, ( Δ ) p , q , η s has been given in (1.3), s , p , q , γ , λ are positive constants, and ϱ V is the modular in fractional Musielak-Sobolev space, which is given as follow:

ϱ V ( u ) R 2 N u ( x ) u ( y ) p p x y N + s p + η ( x , y ) u ( x ) u ( y ) q q x y N + s q d x d y + R N V ( x ) 1 p u p + 1 q η ¯ ( x ) u q d x .

Let’s start with the following assumptions (for short [ M H ] ):

  1. C ( R 0 + ) and inf t R 0 + ( t ) ϑ > 0 , where ϑ > 0 is a constant;

  2. there exists θ [ 1 , p s * q ) satisfying θ M ( t ) = θ 0 t ( λ ) d λ ( t ) t for every t R 0 + ;

  3. 0 < s < 1 , 1 < p < q < p s * , q < N s , γ ( q θ , p s * ) , where p s * = N p N p s is fractional Sobolev critical exponent;

  4. η L ( R 2 N ) is a non-negative symmetry function, i.e. η ( x , y ) = η ( y , x ) , and η ¯ ( x ) η ( x , x ) .

Specifically, some hypotheses (for short, [ V F ] ) on V and f are given as follows:

  1. V C ( R N ) , and inf x R N V ( x ) υ > 0 for any x R N , where υ > 0 is a constant;

  2. for each L > 0 , set { x R N : V ( x ) < L } has finite Lebesgue measure;

  3. f : R × R R is Carathéodory function, which means, t f ( x , t ) is continuous for a.e. x R , and x f ( x , t ) is Lebesgue measurable for any t R ; ζ L is positive;

  4. there are p < ι q θ and c ˆ > 0 , which ensure that f ( x , s ) c ˆ + s ι 2 s for ( x , s ) R × R ;

  5. lim s 0 f ( x , s ) s q θ 2 s = 0 uniformly for x R ;

  6. for a.e. ( x , t ) R × R , ( x , t ) 1 γ f ( x , t ) t F ( x , t ) 0 .

Theorem 1.1

Assume that λ ( 0 , Λ 1 ) , [ M H ] and [ V F ] hold, where the constant Λ 1 > 0 , then problem (1.5) has a ground state solution.

For the fourth section of this work, the following Kirchhoff double-phase problem is studied,

(1.6) ( ϱ p ( u ) ) [ ( Δ ) p s u + V ( x ) u p 2 u ] + ( ϱ q ( u ) ) [ ( Δ ) η , q s u + V ( x ) η ¯ ( x ) u q 2 u ] = ζ ( x ) u γ 2 u log u + λ f ( x , u ) in R N ,

where

ϱ p ( u ) = R 2 N u ( x ) u ( y ) p p x y N + s p d x d y + R N V ( x ) u p p d x , ϱ q ( u ) = R 2 N η ( x , y ) u ( x ) u ( y ) q q x y N + s q d x d y + R N V ( x ) η ¯ ( x ) u q q d x .

Theorem 1.2

Suppose that λ ( 0 , Λ 2 ) , [ M H ] and [ V F ] hold, where Λ 2 is a positive constant, then problem (1.6) has a ground state solution.

The features of this work are as follows.

First, we introduce fractional double-phase operators in fractional Musielak-Sobolev space, establishing some corresponding embedding results and properties of the modular function. To address the lack of compactness in the embedding, we revisit the conclusions from [21], providing the equivalent norm forms of fractional double-phase operators (Lemmas 2.4 and 2.5). In addition, when examining fractional Musielak-Sobolev spaces in R N and their related nonlocal problems, it is crucial to consider the reflexivity, completeness, and uniform convexity of these spaces, as well as the continuity and ( S + ) properties of the operators. In this work, we offer a detailed proof and supplementation (refer to Theorems 2.7, 3.1, and 3.2), enhancing the properties of the space and laying a foundation for studying fractional double-phase operators. Furthermore, it is particularly noteworthy that previous studies of fractional double-phase problems have only considered the case as η 1 , and this article aims to fill this gap.

Second, unlike [15,16], our consideration is in R N , where the potential function V ( x ) 0 . Consequently, Jensen’s and Simon’s inequalities are essential for ensuring that u n u in X . In (1.6), the presence of two Kirchhoff terms makes the estimation of the convergence of ( P S ) c sequences fine-grained, requiring discussion across multiple situations (see Lemma 5.3).

Third, the coexistence of logarithmic terms u γ 2 u log u and nonlinear terms f ( x , u ) further complicates the analysis of mountain structure. We must construct a new coercive function K to explore the geometry of the energy functional (refer to Lemma 4.2). In addition, logarithmic terms clearly do not satisfy the monotonicity or Ambrosetti-Rabinowitz condition. For this, we establish the relationship between the logarithmic term and the space norm, with the proof of the correlation inequality provided in Lemma 3.5.

The structure of this article is as follows. In Sections 2 and 3, we establish some properties of X and related embedding theorems. The properties of fractional double-phase operators, such as continuity and ( S + ) , are also obtained. In Sections 4 and 5, by utilizing mountain pass theorem, the existence results for (1.5) and (1.6) are obtained.

2 Fractional Musielak-Sobolev spaces framework

In this section, we introduce the fractional Musielak-Sobolev space corresponding to the fractional double-phase operators (1.3), establishing the embedding results and some basic properties.

2.1 Musielak-Orlicz space

For any 1 r < , denote the usual Lebesgue space as L r ( R N ) endowed with the norm r . The weighted Lebesgue space is defined as follows:

L η q ( R N ) = u u : R N R is measurable and R N η ¯ ( x ) u q d x < +

with the seminorm

u q , η = R N η ¯ ( x ) u q d x 1 q .

Let 0 < s < 1 < p < , p s < N be real numbers. The fractional Sobolev space W s , p ( R N ) is a uniformly convex Banach space, and it can be defined by

W s , p ( R N ) = u u L p ( R N ) , R 2 N u ( x ) u ( y ) p x y N + p s d x d y < ,

equipped with the norm

u W s , p = ( u p p + [ u ] s , p p ) 1 p ,

and the seminorm notes as

[ u ] s , p = R 2 N u ( x ) u ( y ) p x y N + p s d x d y 1 p .

Now, we introduce the definition of Musielak-Orlicz space. With regard to double-phase problems, we define

D x , y ( t ) t p p + η ( x , y ) t q q for any ( x , y , t ) R N × R N × [ 0 , + ) ,

where p , q , and η satisfy ( H 1 ) ( H 2 ) . The function D x : R N × R R is given by

D x ( t ) t p p + η ¯ ( x ) t q q for every ( x , t ) R N × [ 0 , + ) .

Then we collect some properties of D x , y ( t ) .

Lemma 2.1

  1. D x , y ( t ) is a generalized N-function;

  2. D x , y ( t ) satisfies ( Δ 2 ) condition;

  3. D x , y ( t ) satisfies fractional boundedness condition.

Proof

For (i), because D x , y ( t ) is even, continuous, increasing and convex in t , and D x , y ( t ) > 0 for all t > 0 . With 1 < p < q < N , we can obtain

lim t 0 D x , y ( t ) t = 0 , lim t D x , y ( t ) t = ,

according to Lemma 3.2.2 in [30], and D x , y ( t ) is a generalized N -function.

For (ii),

D x , y ( x , 2 t ) = ( 2 t ) p p + η ( x , y ) ( 2 t ) q q 2 q p D x , y ( t ) for a.e. ( x , y ) R N × R N , t [ 0 , + ) ,

by Proposition 2.3 in [31], and D x , y ( t ) satisfies ( Δ 2 ) condition.

For (iii), by Definition 2.3 in [20], we can find

0 < 1 p D ( 1 ) = 1 p + η ( x , y ) q 1 p + η q .

The proof is completed.□

On the basis of Lemma 2.1, we define the Musielak-Orlicz space L D x ( R N ) ,

L D x ( R N ) = { u u : R N R measurable , ϱ D x ( λ u ) < , for some λ > 0 } ,

with Luxemburg norm

u D x inf λ > 0 : ϱ D x u λ 1 ,

where ϱ D x : L D x ( R N ) R is the modular function denoted as follows:

ϱ D x ( t ) = R N D x ( t ) d x .

The weighted Musielak-Orlicz space L V D x ( R N ) can be denoted as follows:

L V D x ( R N ) = u u : R N R measurable , R N V ( x ) D x u λ d x < for some λ > 0 ,

with Luxemburg norm

u V , D x inf λ > 0 : R N V ( x ) D x u λ d x 1 .

L D x ( R N ) and L V D x ( R N ) are separable and reflexive Banach spaces.

Proposition 2.2

[32, Theorem 8.5] Let φ and ψ be generalized N-function, with φ ψ . Then

L ψ L φ .

Here, φ ψ means that there exist two positive constants C 1 and C 2 and a nonnegative function h L 1 satisfying φ ( x , t ) C 1 ψ ( x , C 2 t ) + h ( x ) for a.a. x R N and every t [ 0 , ) .

Lemma 2.3

If p , q , η satisfy ( H 1 ) ( H 2 ) , there are some continuous embeddings as follows:

  1. L V D x ( R N ) L D x ( R N ) ;

  2. L V D x ( R N ) L V p ( R N ) , L D x ( R N ) L p ( R N ) , L D x ( R N ) L η q ( R N ) ;

  3. L q ( R N ) L D x ( R N ) .

Proof

For (i), since D x x , t K V ( x ) D x ( x , t ) , where K = υ 1 p as υ 1 or K = υ 1 q as υ 1 . According to Proposition 2.2, we obtain L V D x ( R N ) L D x ( R N ) .

For (ii), set D p ( t ) V ( x ) t p p for each t 0 , x R N . Clearly, D p V ( x ) D x , by Proposition 2.2, we can obtain L V D x ( R N ) L V p ( R N ) and L D x ( R N ) L p ( R N ) . Let u L D x ( R N ) . Then

R N η ¯ ( x ) u q q d x R N u p p + η ¯ ( x ) u q q d x = ϱ D x ( u ) .

Therefore, if u 0 , according to the definition of D x , there is ϱ D x u u D x 1 , which leads to

R N η ¯ ( x ) q u u D x q d x R N u p p u D x p + η ¯ ( x ) q u u D x q d x 1 .

It means that L D x ( R N ) L η q ( R N ) .

For (iii), for each t 0 and a.a. x R N , η ¯ L ( R N ) , it follows that

D x ( t ) = 1 p t p + 1 q η ¯ ( x ) t q 1 p ( 1 + t q ) + 1 q η ¯ ( x ) t q 1 p + 1 p t q + η q t q = 1 p + 1 p + η q t q .

By utilizing Proposition 2.2, we can obtain L q ( R N ) L D x ( R N ) .□

2.2 Fractional Musielak-Sobolev spaces

Then we introduce the fractional Musielak-Sobolev space. By the definition of (1.3), fractional Musielak-Sobolev space associated with D x , y can be defined by

W s , D x , y ( R N ) { u u L D x ( R N ) , ϱ s , D ( λ u ) < + , for some λ > 0 } ,

where

ϱ s , D ( u ) R 2 N u ( x ) u ( y ) p p x y N + s p d x d y + R 2 N η ( x , y ) u ( x ) u ( y ) q q x y N + s q d x d y s ( 0 , 1 ) ,

with norm

u W s , D x , y ( R N ) u D x + [ u ] s , D x , y .

The so-called ( s , D x , y ) -Gagliardo seminorm is

[ u ] s , D x , y inf λ > 0 : ϱ s , D u λ 1 .

W s , D x , y ( R N ) is a reflexive and separable Banach space ([21], Remark 2.9).

The weighted fractional Musielak-Sobolev space is defined by

X { u u W s , D x , y ( R N ) , u L V D x ( R N ) } ,

endowed with norm

u X [ u ] s , D x , y + u V , D x .

We also define the norm

u inf λ > 0 : ϱ V u λ 1 ,

where

ϱ V ( u ) R 2 N u ( x ) u ( y ) p p x y N + s p + η ( x , y ) u ( x ) u ( y ) q q x y N + s q d x d y + R N V ( x ) u p p + η ¯ ( x ) u q q d x for s ( 0 , 1 ) .

Lemma 2.4

Let u X . The ϱ V ( u ) has the following properties:

  1. For u 0 , there is u = θ if and only if ϱ V u θ = 1 ;

  2. u < 1 (resp. = 1 , > 1 ) implies ϱ V ( u ) < 1 (resp. = 1 , > 1 );

  3. u < 1 implies u q ϱ V ( u ) u p , u > 1 implies u p ϱ V ( u ) u q ;

  4. u = 0 ϱ V ( u ) = 0 and u + ϱ V ( u ) + .

Proof

(i) It is clear that the mapping θ ϱ V ( θ u ) is a continuous, convex, even function, and it is strictly increasing on [ 0 , + ) . By the definition of ϱ V and , it implies that

u = θ ϱ V u θ = 1 .

Then (i) and (ii) hold.

To prove (iii), for any constant λ > 0 and u X , combining with the definition of ϱ V ( u ) , it can be obtained

λ p ϱ V ( u ) ϱ V ( λ u ) λ q ϱ V ( u ) , as λ > 1 , λ q ϱ V ( u ) ϱ V ( λ u ) λ p ϱ V ( u ) , as 0 < λ < 1 .

We only prove the case that u < 1 . Let u = θ with 0 < θ < 1 , by (i), we have ϱ V u θ = 1 . Then

ϱ V ( u ) θ p ϱ V u θ = 1 ϱ V ( u ) θ q .

(iii) can be proved. (iv) follows from (iii) is clear.□

Next, we will prove the equivalence of u X and u .

Lemma 2.5

and X are equivalent norms in X, and there is

(2.1) 1 2 u X u 2 u X .

Proof

We first verify that is a norm in X . We will prove that satisfies the three axioms of the norm:

  1. According to the definition of u , it is obvious that if u = 0 , then u 0 .

  2. For each k R , it implies that

    k u = inf λ > 0 : ϱ V k u λ 1 = inf k λ > 0 : ϱ V u λ 1 = k inf λ > 0 : ϱ V u λ 1 = k u .

  3. To prove the triangle inequality, let u 1 , u 2 X , one yields that

    ϱ V u 1 + u 2 u 1 + u 2 = ϱ V u 1 u 1 + u 2 u 1 u 1 + u 2 u 1 + u 2 u 2 u 2 u 1 u 1 + u 2 ϱ V u 1 u 1 + u 2 u 1 + u 2 ϱ V u 2 u 2 1 .

Thus, u 1 + u 2 u 1 + u 2 for all u 1 , u 2 X . is a norm in X .

Next, we verify the inequality (2.1) holds. By combining with the definition of , for each u X , one has ϱ V u u 1 , which means that

R N V ( x ) D x u u d x ϱ V u u 1 and ϱ s , D u u ϱ V u u 1 .

According to the definition of V , D x and [ ] s , D x , y , it can imply

u V , D x u and [ u ] s , D x , y u .

Therefore, we have

1 2 u X u for all u X ,

and

ϱ V u 2 u X 1 2 R N V ( x ) D x u u X d x + 1 2 ϱ s , D u u X 1 2 R N V ( x ) D x u u V , D x d x + 1 2 ϱ s , D u [ u ] s , D x , y 1 2 + 1 2 = 1 .

Thus, u 2 u X for every u X .□

Then, we will give some properties of X .

Lemma 2.6

If ( V 1 ) ( V 2 ) hold, then

  1. X L D x ( R N ) ([21], Theorem 1.3);

  2. X L τ ( R N ) for τ [ p , p s * ] ;

  3. X L τ ( R N ) for τ [ p , p s * ) .

Proof

We first consider the weighted Sobolev space

W V s , p ( R N ) = u W s , p ( R N ) : R N V ( x ) u p d x <

endowed with the norm

u 1 = u p , V + [ u ] p .

Since this norm is equivalent to the norm

u 2 = ( u p , V p + [ u ] p p ) 1 p .

W V s , p ( R N ) is a Banach space, and W V s , p ( R N ) L p ( R N ) ([24]; Theorem 2.1). By Lemma 2.3, X W V s , p ( R N ) and so X L p ( R N ) . The rest of the proof follows from the interpolation argument since X W s , p ( R N ) L p s * ( R N ) .□

Theorem 2.7

( X , X ) is a reflexive, uniformly convex Banach space.

Proof

We first prove X has completeness. Take a Cauchy sequence { u j } X . For every ε > 0 , there is v ε , if i , j v ε , according to Lemma 2.6 (ii), there is a constant C > 0 satisfying

(2.2) ε u i u j C u i u j D x .

Because L D x ( R N ) is a Banach space, there is an element u L D x ( R N ) such that u j u as j + . Thus, there exists a subsequence { u j k } X , satisfying u j k u a.e. in R N . According to Lemma 2.5, Jensen inequality, along with Fatou lemma, it can be obtained

ϱ V ( u ) = R 2 N u ( x ) u ( y ) p p x y N + s p d x d y + R 2 N η ( x , y ) u ( x ) u ( y ) q q x y N + s q d x d y + R N V ( x ) u p p + η ¯ ( x ) q u q d x liminf k + R 2 N u j k ( x ) u j k ( y ) p p x y N + s p d x d y + R 2 N η ( x , y ) u j k ( x ) u j k ( y ) q q x y N + s q d x d y + R N V ( x ) u j k p p + η ¯ ( x ) q u j k q d x = liminf k + R 2 N u j k ( x ) u j k ( y ) [ u v 1 ( x ) u v 1 ( y ) ] + [ u v 1 ( x ) u v 1 ( y ) ] p p x y N + s p d x d y + R 2 N η ( x , y ) u j k ( x ) u j k ( y ) [ u v 1 ( x ) u v 1 ( y ) ] + [ u v 1 ( x ) u v 1 ( y ) ] q q x y N + s q d x d y + liminf k + R N V ( x ) u j k u v 1 + u v 1 p p + η ¯ ( x ) q u j k u v 1 + u v 1 q d x liminf k + R 2 N 2 p 1 u j k ( x ) u j k ( y ) [ u v 1 ( x ) u v 1 ( y ) ] p p x y N + s p + u v 1 ( x ) u v 1 ( y ) p p x y N + s p d x d y + liminf k + R 2 N 2 q 1 η ( x , y ) u j k ( x ) u j k ( y ) [ u v 1 ( x ) u v 1 ( y ) ] q q x y N + s q + u v 1 ( x ) u v 1 ( y ) q q x y N + s p d x d y + liminf k + R N V ( x ) 2 p 1 p ( u j k u v 1 p + u v 1 p ) + 2 q 1 η ¯ ( x ) q ( u j k u v 1 q + u v 1 q ) d x 2 q 1 liminf k + R N u j k ( x ) u j k ( y ) [ u v 1 ( x ) u v 1 ( y ) ] p p x y N + s p + η ( x , y ) u j k ( x ) u j k ( y ) [ u v 1 ( x ) u v 1 ( y ) ] q q x y N + s q d x d y + R N V ( x ) 1 p u j k u v 1 p + η ¯ ( x ) q u j k u v 1 q d x + 2 q 1 liminf k + R 2 N u v 1 ( x ) u v 1 ( y ) p p x y N + s p + η ( x , y ) u v 1 ( x ) u v 1 ( y ) q q x y N + s p d x d y + R N V ( x ) 1 p u v 1 p + η ¯ ( x ) q u v 1 q d x 2 q 1 liminf k + [ ϱ V ( u j k u v 1 ) + ϱ V ( u v 1 ) ] 2 q 1 liminf k + [ u j k u v 1 p + u j k u v 1 q + u v 1 p + u v 1 q ] .

By (2.2) with ε = 1 , we derive

ϱ V ( u ) 2 q 1 ( 2 + u v 1 p + u v 1 q ) < ,

thus u X . Set i v ε . By using (2.2) and Fatou lemma, it leads to

ϱ V ( u i u ) lim k + inf ϱ V ( u i u j k ) ε .

According to Lemma 2.4 (iv), lim i + ϱ V ( u i u ) = 0 . So lim i + u i u = 0 , which means u i u in X as i + . X is complete.

Now, we prove X is a uniform convex space. Let u 1 , u 2 X , fix ε ( 0 , 2 ) , with u 1 = u 2 = 1 and u 1 u 2 ε . For convenience, we note

u 1 ( x ) + u 2 ( x ) 2 = A ( x ) , u 1 ( x ) u 2 ( x ) 2 = ( x ) .

Therefore, we can obtain A ( x ) 1 and ( x ) 1 . Then we break it down into three cases:

Case 1: 2 p < q . Combining with the following inequality [33]

s 1 + s 2 2 p + s 1 s 2 2 p 1 2 ( s 1 p + s 2 p ) s 1 , s 2 R ,

we can arrive that

A q + q ϱ V ( A ) + ϱ V ( ) = [ A ] s , p p + [ ] s , p p + [ A ] η , s , q q + [ ] η , s , q q + A p , V p + p , V p + A q , η V q + q , η V q 1 2 ( [ u 1 ] s , p p + [ u 2 ] s , p p + [ u 1 ] η , s , q q + [ u 2 ] η , s , q q + u 1 p , V p + u 2 p , V p + u 1 q , η V q + u 2 q , η V q ) = ϱ V ( u 1 ) + ϱ V ( u 2 ) 1 2 ( max { u 1 p , u 1 q } + max { u 2 p , u 2 q } ) = 1 .

It can imply that A q 1 ( ε 2 ) q . Let σ = σ ( ε ) such that 1 ( ε 2 ) q = ( 1 σ ) q . Thus, u 1 + u 2 2 1 σ .

Case 2: 1 < p < q < 2 . First, we notice that

[ u 1 ] s , q q = R 2 N u 1 ( x ) u 1 ( y ) x y N + q s q q q 1 d x d y 1 q 1 ,

where q = q q 1 . Applying the reverse Minkowski inequality ([33], Theorem 2.13) and ( V 1 ) , we obtain

(2.3) A ( x ) q + ( x ) q [ ϱ V ( A ) ] 1 q 1 + [ ϱ V ( ) ] 1 q 1 = A ( x ) A ( y ) x y N p s p p L p 1 ( R 2 N ) + η ( x , y ) 1 q A ( x ) A ( y ) x y N q s q q L q 1 ( R 2 N ) + V ( x ) 1 p A ( x ) p L p 1 ( R N ) + ( V ( x ) η ¯ ( x ) ) 1 q A ( x ) q L q 1 ( R N ) + ( x ) ( y ) x y N p s p p L p 1 ( R 2 N ) + η ( x , y ) 1 q ( x ) ( y ) x y N q s q q L q 1 ( R 2 N )

(2.3) + V ( x ) 1 p ( x ) p L p 1 ( R N ) + ( V ( x ) η ¯ ( x ) ) 1 q ( x ) q L q 1 ( R N ) R 2 N A ( x ) A ( y ) x y N p s p p + V ( x ) 1 p A ( x ) p + ( x ) ( y ) x y N p s p p + V ( x ) 1 p ( x ) p p 1 d x d y 1 p 1 + R 2 N η ( x , y ) 1 q A ( x ) A ( y ) x y N q s q q + ( V ( x ) η ¯ ( x ) ) 1 q A ( x ) q + η ( x , y ) 1 q ( x ) ( y ) x y N q s q q + ( V ( x ) η ¯ ( x ) ) 1 q ( x ) q q 1 d x d y 1 q 1 .

By the following inequality [33]

s 1 + s 2 2 q + s 1 s 2 2 q 1 2 ( s 1 q + s 2 q ) 1 q 1 for every s 1 , s 2 R ,

(2.3) implies that,

(2.4) A q + q 1 2 ( max { u 1 p , u 1 q } + max { u 2 p , u 2 q } ) q 1 = 1 .

For 1 < q < 2 , we apply the following inequality:

s 1 1 q 1 + s 2 1 q 1 q 1 s 1 + s 2 for every s 1 , s 2 0 .

By using (2.4), we have

u 1 + u 2 2 q 1 ε 2 q .

Let σ = σ ( ε ) , then 1 ( ε 2 ) q = ( 1 σ ) q , this case is proven.

Case 3: 1 < p < 2 and q 2 . This case can be proved by Cases 1 and 2. We omit the proof.

Thus, X is a uniform convex space. Via Milman-Pettis theorem, the reflexivity of X can be obtained.□

Remark 2.8

In [21], completeness, reflexivity, and uniform convexity with respect to X were directly referenced from the case in the fractional Musielak-Sobolev spaces with a bounded domain. Noting that there remains a distinction due to the presence of the potential function V ( x ) in X . For this, an accurate proof for these properties is necessary. With the help of Jensen’s inequality, Fatou’s Lemma, and other fundamental inequality techniques, we establish the completeness and demonstrate the uniform convexity of X .

3 Functional setting

For convenience, denote

u , v s , p R 2 N u ( x ) u ( y ) p 2 [ u ( x ) u ( y ) ] [ v ( x ) v ( y ) ] x y N + s p d x d y + R N V ( x ) u p 2 u v d x ,

u , v s , q , η R 2 N η ( x , y ) u ( x ) u ( y ) q 2 [ u ( x ) u ( y ) ] [ v ( x ) v ( y ) ] x y N + s q d x d y + R N V ( x ) η ¯ ( x ) u q 2 u v d x , I ( u ) , v ( ϱ V ( u ) ) T ( u ) , v , T ( u ) , v R 2 N u ( x ) u ( y ) p 2 [ u ( x ) u ( y ) ] [ v ( x ) v ( y ) ] x y N + s p d x d y + R 2 N η ( x , y ) u ( x ) u ( y ) q 2 [ u ( x ) u ( y ) ] [ v ( x ) v ( y ) ] x y N + s q d x d y + R N V ( x ) [ u p 2 u v + η ¯ ( x ) u q 2 u v ] d x .

3.1 Fractional double-phase operator

In this subsection, we give the continuity, boundedness, and ( S + ) -property for the fractional double-phase operator.

Theorem 3.1

Let T be a mapping of type ( S + ) , i.e., if u n u in X, and

(3.1) limsup n + T ( u n ) T ( u ) , ω n 0 , where ω n = u n u ,

then u n u in X .

Proof

Let { u n } X satisfy u n u , and (3.1) holds. For every r 1 , s t , s , t R , we have [34]:

(3.2) ( s r 2 s t r 2 t ) ( s t ) > 0 .

By ( V 1 ) and (3.2), it has

liminf n T ( u n ) T ( u ) , ω n 0 .

In consequence,

lim n T ( u n ) T ( u ) , ω n = 0 .

From this and (3.2), one yields that

u n ( x ) u n ( y ) p x y N + p s meas u ( x ) u ( y ) p x y N + p s in R 2 N , V ( x ) u n p meas V ( x ) u p in R N ;

η ( x , y ) u n ( x ) u n ( y ) q x y N + q s meas η ( x , y ) u ( x ) u ( y ) q x y N + q s in R 2 N , V ( x ) η ¯ ( x ) u n q meas V ( x ) η ¯ ( x ) u q in R N .

Therefore, by ([34], Proposition 3.131), we can find subsequences satisfying

(3.3) u n ( x ) u n ( y ) p x y N + p s u ( x ) u ( y ) p x y N + p s a.e. in R 2 N , V ( x ) u n p V ( x ) u p a.e. in R N ; η ( x , y ) u n ( x ) u n ( y ) q x y N + q s η ( x , y ) u ( x ) u ( y ) q x y N + q s a.e. in R 2 N , V ( x ) η ¯ ( x ) u n q V ( x ) η ¯ ( x ) u q a.e. in R N .

For each ( x , y ) R 2 N and x R N , define

g s n ( x , y ) u n ( x ) u n ( y ) p p x y N + s p + η ( x , y ) u n ( x ) u n ( y ) q q x y N + s q , g V n ( x ) V ( x ) 1 p u n p + η ¯ ( x ) q u n q ,

and

g s ( x , y ) u ( x ) u ( y ) p p x y N + s p + η ( x , y ) u ( x ) u ( y ) q q x y N + s q , g V ( x ) V ( x ) 1 p u p + η ¯ ( x ) q u q .

According to (3.3), we have g s n g s a.e. in R 2 N and g V n g V a.e. in R N . Therefore,

lim n T ( u ) , ω n = 0 .

Combining with (3.1), one has

(3.4) limsup n T ( u n ) , ω n 0 .

Applying Young’s inequality, it can obtain

T ( u n ) , ω n = u n , ω n s , p + u n , ω n s , q , η R 2 N u n ( x ) u n ( y ) p 1 [ ω n ( x ) ω n ( y ) ] x y N + s p d x d y + R 2 N η ( x , y ) u n ( x ) u n ( y ) q 1 [ ω n ( x ) ω n ( y ) ] x y N + s q d x d y + R N V ( x ) u n p 1 ω n d x + R N V ( x ) η ¯ ( x ) u n q 1 ω n d x R 2 N u n ( x ) u n ( y ) p x y N + s p + η ( x , y ) u n ( x ) u n ( y ) q x y N + s q d x d y + R N V ( x ) [ u n p + η ¯ ( x ) u n q ] d x 1 p R 2 N u n ( x ) u n ( y ) p x y N + s p d x d y 1 p R 2 N u n ( x ) u n ( y ) p x y N + s p d x d y 1 q R N η ( x , y ) u n ( x ) u n ( y ) q x y N + s q d x d y 1 q R 2 N η ( x , y ) u n ( x ) u n ( y ) q x y N + s q d x d y 1 p R N V ( x ) u n p d x 1 p R N V ( x ) u p d x 1 q R N V ( x ) η ¯ ( x ) u n q d x 1 q R N V ( x ) η ¯ ( x ) u q d x = R 2 N g s n ( x , y ) d x d y + R N g V n ( x ) d x R 2 N g s ( x , y ) d x d y R N g V ( x ) d x .

From this, (3.4) and Fatou’s lemma, one leads to

R 2 N g s ( x , y ) d x d y + R N g V ( x ) d x = R 2 N lim n g s n ( x , y ) d x d y + R N lim n g V n ( x ) d x lim n R 2 N g s n ( x , y ) d x d y + lim n R N g V n ( x ) d x limsup n R 2 N g s n ( x , y ) d x d y + limsup n R N g V n ( x ) d x R 2 N g s ( x , y ) d x d y + R N g V ( x ) d x .

Since g s n , g s , g V n , and g V are nonnegative, one has g s n 1 g s 1 and g V n 1 g V 1 . By Vitali convergence theorem ([34], Theorem 3.128), { g s n } n N and { g V n } n N are uniformly integrable. So, there is C 3 > 0 such that

0 ω n ( x ) ω n ( y ) p x y N + p s + η ( x , y ) ω n ( x ) ω n ( y ) q x y N + q s + V ( x ) ω n p + V ( x ) η ¯ ( x ) ω n q C 3 [ g s n ( x , y ) + g s ( x , y ) + g V n ( x ) + g V ( x ) ] .

Thus,

ω n ( x ) ω n ( y ) p x y N + p s + η ( x , y ) ω n ( x ) ω n ( y ) q x y N + q s n N in R 2 N

and

{ V ( x ) [ ω n p + η ¯ ( x ) ω n q ] } n N in R N

are uniformly integrable. By applying Vitali theorem again, it follows that

lim n R 2 N ω n ( x ) ω n ( y ) p x y N + p s + η ( x , y ) ω n ( x ) ω n ( y ) q x y N + q s d x d y + R N V ( x ) [ ω n p + η ¯ ( x ) ω n q ] d x = 0 ,

which gives u n u in X .□

Theorem 3.2

Suppose that [ M H ] and ( V 1 ) ( V 2 ) exist, then the functional I : X R is C 1 ( X ) and I is bounded.

Proof

We first prove that I is C 1 ( X ) . Let u n u in X . By using Hölder inequality, one has

(3.5) I ( u n ) I ( u ) X * = sup v X , v 1 I ( u n ) I ( u ) , v [ ( ϱ V ( u n ) ) ( ϱ V ( u ) ) ] R 2 N u n ( x ) u n ( y ) p 1 u ( x ) u ( y ) p 1 x y N + p s p d x d y 1 p [ v ] s , p + R 2 N η ( x , y ) u n ( x ) u n ( y ) q 1 u ( x ) u ( y ) q 1 x y N + q s q d x d y 1 q × R 2 N η ( x , y ) v ( x ) v ( y ) q x y N + q s d x d y 1 q + R N ( V ( x ) ( u n p 1 u p 1 ) ) p d x 1 p v p , V + R N ( V ( x ) η ¯ ( x ) ( u n q 1 u q 1 ) ) q d x 1 q v q , V η .

Considering the continuity of Kirchhoff operator , it can be obtained

lim n ( ϱ V ( u n ) ) = ( ϱ V ( u ) ) .

Because of u n u in X , up to a subsequence u n u a.e. in R N . Then

u n ( x ) u n ( y ) p 2 [ u n ( x ) u n ( y ) ] x y N + p s p n N is bounded in L p ( R 2 N )

and

u n ( x ) u n ( y ) p 2 [ u n ( x ) u n ( y ) ] x y N + p s p u ( x ) u ( y ) p 2 [ u ( x ) u ( y ) ] x y N + p s p a.e. in R 2 N .

Hence, by using Brezis-Lieb lemma (see [35]), we derive that

(3.6) lim n R 2 N u n ( x ) u n ( y ) p 2 [ u n ( x ) u n ( y ) ] x y N + p s p u ( x ) u ( y ) p 2 [ u ( x ) u ( y ) ] x y N + p s p p d x d y = lim n R 2 N u n ( x ) u n ( y ) p x y N + p s u ( x ) u ( y ) p x y N + p s d x d y .

Since u n u in X , using Lemma 2.6 (iii), there is

u n u in L r ( R N ) for r [ p , p s * ) , u n u a.e. in R N .

It can be obtained that lim n ϱ V ( u n ) = ϱ V ( u ) , by the definition of ϱ V , we have

lim n R 2 N u n ( x ) u n ( y ) p x y N + p s u ( x ) u ( y ) p x y N + p s d x d y = 0 .

Combining with (3.6), it implies that

lim n R 2 N u n ( x ) u n ( y ) p 1 u ( x ) u ( y ) p 1 x y N + p s p d x d y = 0 .

Similarly, one yields that

lim n R 2 N η ( x , y ) u n ( x ) u n ( y ) q 1 u ( x ) u ( y ) q 1 x y N + q s q d x d y = 0 , lim n R N [ V ( x ) ( u n p 1 u p 1 ) ] p d x = 0 , lim n R N [ V ( x ) η ¯ ( x ) ( u n q 1 u q 1 ) ] q d x = 0 .

Due to Lemma 2.3, there are positive constants C 4 and C 5 , satisfying

v p , V C 4 v D x , v q , η V C 5 v D x ,

by Lemma 2.6, X L D x ( R N ) , so v p , V and v q , η V are bounded. Applying Lemma 2.4, it follows that

R 2 N v ( x ) v ( y ) p x y N + p s d x d y 1 p [ ϱ V ( v ) ] 1 p max { v , v q p } C 6 R 2 N η ( x , y ) v ( x ) v ( y ) q x y N + q s d x d y 1 q [ ϱ V ( v ) ] 1 q max { v , v p q } C 7 .

Based on the aforementioned estimates, we have

I ( u n ) I ( u ) X * 0 , as n .

Therefore, I C 1 ( X , R ) .

Finally, we consider the boundedness of I . Similar to (3.5), by combining with Hölder and Young inequalities, one has

I ( u ) X * = sup v X , v 1 I ( u ) , v ( ϱ V ( u ) ) 1 p R N u ( x ) u ( y ) p 1 x y N + p s d x d y + 1 p R N v ( x ) v ( y ) p 1 x y N + p s d x d y + 1 q R N η ( x , y ) u ( x ) u ( y ) q 1 x y N + q s d x d y + 1 q R N η ( x , y ) v ( x ) v ( y ) q 1 x y N + q s d x d y + 1 p R N V ( x ) u p d x + 1 p R N V ( x ) v p d x + 1 q R N V ( x ) η ¯ ( x ) u q d x + 1 q R N V ( x ) η ¯ ( x ) v q d x ( ϱ V ( u ) ) 1 q ρ V ( u ) + 1 p ρ V ( v ) ( ϱ V ( u ) ) 1 q ( u p + u q ) + 1 p ( v p + v q ) ( ϱ V ( u ) ) 1 q ( u p + u q ) + 2 p .

Therefore, I is bounded.□

Remark 3.3

In [21], the ( S + ) property and continuity of the operator (1.4) were directly referenced from the case in W s , Φ x , y ( Ω ) , where Ω is a bounded domain in R N . However, the effect of the presence of the potential function V ( x ) in the space X must be taken into account. For this purpose, we use the fractional double-phase operator as a specific example to establish these properties, employing fundamental inequality techniques as necessary.

3.2 Logarithmic nonlinearity

In this subsection, we establish the relationship between the logarithmic term and the space norm by proving the correlation inequality.

Lemma 3.4

Let { u n } be bounded in X. There exists a subsequence { u n } such that

lim n R N ζ ( x ) u n γ log u n d x = R N ζ ( x ) u γ log u d x .

Proof

Because ( X , ) is a reflexive Banach space. Let { u n } be bounded in X . By Lemma 2.6 (iii), we can obtain

u n u in X , u n u in L r ( R N ) , r [ p , p s * ) , u n u a.e. in R N .

According to the properties of logarithmic functions, for every t > 0 , there exist some positive constants α , β and C α , β satisfying

log t C α , β ( t α + t β ) .

It follows that

R N ζ ( x ) u n γ log u n d x C p s * θ p , δ ζ R N ( u n p s * + u n γ δ ) d x ,

where δ ( 0 , γ p ] and p γ δ < γ < p s * . Due to the boundedness of { u n } in X , we can obtain

u n C 1 for every n N .

Thus, by Lemma 2.6, there is

R N ζ ( x ) u n γ log u n d x C 2 ζ ( u n p s * + u n γ δ ) C 2 ( C 1 p s * + C 1 γ δ ) ζ L 1 ( R N ) .

By applying Lebesgue dominated convergence theorem, one has

lim n R N ζ ( x ) u n γ log u n d x = R N ζ ( x ) u γ log u d x .

The proof is completed.□

Lemma 3.5

Let u X \ { 0 } . There is

R N ζ ( x ) u γ log u d x C * ζ u γ + log u R N ζ ( x ) u γ d x ,

where C * is a constant independent on ζ and u.

Proof

According to the logarithm algorithm, there is

R N ζ ( x ) u γ log u d x log u R N ζ ( x ) u γ d x = R N ζ ( x ) u γ log u u d x k 1 + k 2 ,

where k 1 and k 2 are defined as follows:

k 1 R u , + N ζ ( x ) u γ log u u d x and k 2 R u , N ζ ( x ) u γ log u u d x ,

and R u , + N and R u , N are denoted as follows:

R u , + N { x R N : u > u } and R u , N { x R N : u u } .

For σ > 0 and t > 0 , there is a constant C σ > 0 , satisfying

(3.7) log t C σ t σ ,

To estimate k 1 and k 2 , using (3.7) with σ ( 0 , p s * γ ) and Lemma 2.6, it has

k 1 ζ R u , + N u γ log u u d x ζ C σ R u , + N u γ u u σ d x C σ ζ u σ u γ + σ γ + σ C * ζ u γ .

Because of k 2 0 , it can be obtained

R N ζ ( x ) u γ log u d x = R N ζ ( x ) u γ log u u d x + log u R N ζ ( x ) u γ d x

C * ζ u γ + log u R N ζ ( x ) u γ d x ,

which completes the proof.□

4 The existence results of Problem (1.5)

In this section, we consider equation (1.5).

Definition 4.1

If u X is a weak solution for (1.5), then for each v X ,

(4.1) ( ϱ V ( u ) ) T ( u ) , v = R N ζ ( x ) u γ 2 u v log u d x + λ R N f ( x , u ) v d x .

The energy functional E λ : X R corresponding to (1.5) is

E λ ( u ) = M ( ρ V ( u ) ) + 1 γ 2 R N ζ ( x ) u γ d x 1 γ R N ζ ( x ) u γ log u d x λ R N F ( x , u ) d x .

Lemma 4.2

Assumptions [ M H ] and [ V F ] are valid, then

  1. there are two constants δ , σ > 0 , satisfying E λ ( u ) δ when u = σ ;

  2. there is κ X with κ > σ , satisfied E λ ( κ ) < 0 .

Proof

For (i), due to ( f 2 ) and ( f 3 ) , fixed ε > 0 , there is C 8 = C 8 ( ε ) > 0 satisfying

(4.2) F ( x , s ) ε q θ s q θ + C 8 s ι , ( x , s ) R × R .

By ( M 2 ), when u 1 , we have

M ( t ) M ( 1 ) t θ .

By Lemma 2.4 (iii), Lemma 2.6, for u X and u 1 , one yields that

E λ ( u ) = M ( ϱ V ( u ) ) + 1 γ 2 R N ζ ( x ) u γ d x 1 γ R N ζ ( x ) u γ log u d x λ R N F ( x , u ) d x M ( 1 ) [ ϱ V ( u ) ] θ + 1 γ 2 R N ζ ( x ) u γ d x 1 γ C 9 ζ u γ 1 γ log u R N ζ ( x ) u γ d x ε λ p u p q θ C 8 λ u ι ι M ( 1 ) u q θ 1 γ C 9 ζ u γ ε λ p u p q θ λ C 8 u ι ι [ M ( 1 ) C 11 ε λ ] u q θ C 9 γ ζ u γ λ C 10 u ι = ( M ( 1 ) C 11 ε λ ) C 9 γ ζ u γ q θ λ C 10 u ι q θ u q θ .

Define

K ( x ) C 9 γ ζ x γ q θ + λ C 10 x ι q θ ,

by ( H 1 ), we have ι q θ < 0 and γ q θ > 0 , we obtain

lim x 0 K ( x ) = lim x K ( x ) = + .

Let

K ( x 0 ) C 9 γ ( γ q θ ) ζ x 0 γ q θ 1 + λ C 10 ( ι q θ ) x 0 ι q θ 1 = 0 ,

there is x 0 = λ C 10 γ ( q θ ι ) C 9 ( γ q θ ) ζ 1 γ ι > 0 and K ( x 0 ) > 0 . Thus, the infimum of K ( x ) can be achieved at x 0 . It means that

K ( x 0 ) = C 9 γ ζ λ C 10 γ ( q θ ι ) C 9 ( γ q θ ) ζ γ q θ γ ι + λ C 10 λ C 10 γ ( q θ ι ) C 9 ( γ q θ ) ζ ι q θ γ ι = C 9 γ λ γ q θ γ ι ζ q θ ι γ ι C 10 γ ( q θ ι ) C 9 ( γ q θ ) γ q θ γ ι + λ γ q θ γ ι C 10 C 10 γ ( q θ ι ) C 9 ( γ q θ ) ζ ι q θ γ ι .

Obviously, K ( x 0 ) 0 as λ 0 + . Therefore, there is a constant Λ 1 > 0 sufficiently small, as λ ( 0 , Λ 1 )

E λ ( u ) δ > 0 when u = x 0 = σ ( 0 , 1 ) .

For (ii), by ( f 4 ), for given ς > 0 , we have constants C 12 = C 12 ( ς ) > 0 , such that

(4.3) F ( x , s ) ς γ s γ C 12 , ( x , s ) R × R .

By ( M 2 ), when u 1 , it implies that

M ( t ) M ( 1 ) t θ .

Take u 1 and t > 1 . It follows that

(4.4) E λ ( t u ) = M ( ϱ V ( t u ) ) + t γ γ 2 R N ζ ( x ) u γ d x t γ γ R N ζ ( x ) u γ log t u d x λ R N F ( x , t u ) d x M ( 1 ) t q θ u p θ + t γ γ 2 R N ζ ( x ) u γ d x t γ γ R N ζ ( x ) u γ log t u d x λ ς t γ γ u γ γ + C 12 M ( 1 ) t q θ u p θ + t γ ζ γ 2 u γ γ λ ς γ u γ γ log t γ R N ζ ( x ) u γ d x 1 γ R N ζ ( x ) u γ log u d x + C 12 .

Since q θ < γ , we obtain

E λ ( t u ) as t .

The proof is completed.□

Next, we prove the ( P S ) b condition for E λ .

Lemma 4.3

If [ M H ] and [ V F ] valid, the functional E λ fulfills ( P S ) b 1 condition, there exists u n u in X .

Proof

We first claim the boundedness of { u n } in X . Suppose by contradiction that u n , as n + . By Lemma 2.4, ( f 4 ), ( M 1 ) ( M 2 ) , we obtain

(4.5) b 1 ( 1 + u ) = E λ ( u n ) 1 γ E ( u n ) , u n M ( ϱ V ( u n ) ) 1 γ ( ϱ V ( u n ) ) T ( u n ) , u n + 1 γ 2 R N ζ ( x ) u n γ d x + λ R N ( x , u n ) d x

(4.5) 1 θ ( ϱ V ( u n ) ) ϱ V ( u n ) q γ ( ϱ V ( u n ) ) ϱ V ( u n ) + 1 γ 2 R N ζ ( x ) u n γ d x + λ R N ( x , u n ) d x 1 θ q γ u n p θ + C 13 ,

Since γ > q θ and p θ > 1 , it is a contradiction, { u n } is bounded in X .

Next, we claim that { u n } has a subsequence that converges in X . Combining with Lemma 2.7 and Lemma 2.6, there are

(4.6) u n u in X , u n u in L ν ( R N ) , ν [ p , p s * ) , ϱ V ( u n ) , u n u a.e. in R N .

Then we have

(4.7) o n ( 1 ) = E λ ( u n ) , ω n = ( ) T ( u n ) , ω n R N ζ ( x ) u n γ 2 u n ω n log u n d x + λ R N f ( x , u n ) ω n d x .

Applying Lemma 3.4, it follows that

(4.8) lim n R N ζ ( x ) u n γ 2 u n log u n ω n d x = 0 .

By ( f 2 ), Hölder inequality and (4.6), we have

(4.9) R N f ( x , u n ) ω n d x R N f ( x , u n ) ω n d x R N c ˆ + u n ι 1 ω n d x c ˆ ω n 1 + u n ι ω n ι 0 , as n .

By ( M 1 ), we have ( ) > 0 . On the basis of (4.7)–(4.9), we have T ( u n ) , ω n 0 as n . Thus, by Lemma 3.1, we have u n u in X .□

Proof of Theorem 1.1

Lemmas 4.2 and 4.3 mean that E λ satisfies the mountain pass geometry structure and ( P S ) b 1 condition. The mountain pass theorem ([36], Theorem 1.15), yields the existence result of Problem (1.5).

To obtain ground state solution, we define K as the critical set of E λ . Set

c 1 inf { E λ ( u ) : u K \ { 0 } } .

For any u K , according to (4.5), we have

E λ ( u ) 1 γ E λ ( u ) , u 1 θ q γ u p θ 0 ,

which means c 1 0 . By Theorem 2.7 and Krein-Šmulian theorem, in X is weak semicontinuity. Along with Fatou lemma, it implies that

c 1 E λ ( u ) = E λ ( u ) 1 γ E λ ( u ) , u = M ( ϱ V ( u ) ) 1 γ ( ϱ V ( u ) ) T ( u ) , u + 1 γ 2 R N ζ ( x ) u γ d x + λ R N ( x , u ) d x liminf n M ( ϱ V ( u n ) ) 1 γ ( ϱ V ( u n ) ) T ( u n ) , u n + liminf n 1 γ 2 R N ζ ( x ) u n γ d x + λ R N ( x , u n ) d x

= liminf n E λ ( u n ) 1 γ E λ ( u n ) , u n = b 1 ,

which implies 0 c 1 b 1 .

Next, let { v k } be a sequence of non-trivial critical points of E λ . Then

E λ ( v k ) c 1 .

By Lemma 4.3, we can see that v k converges to some v 0 . By using the Fatou lemma again, one has

c 1 E λ ( v ) liminf k E λ ( v k ) = c 1 .

Hence, E λ ( v ) = c 1 and E λ ( v ) = 0 .□

5 The existence results of equation (1.6)

In this section, we study the existence results of equation (1.6).

Definition 5.1

If u X is a weak solution for problem (1.6), it means that for every v X , there is

(5.1) ( ϱ p ( u ) ) u , v s , p + ( ϱ q ( u ) ) u , v s , q , η = R N ζ ( x ) u γ 2 u v log u d x + λ R N f ( x , u ) v d x .

The energy functional Φ λ : X R corresponding to (1.6) is

Φ λ ( u ) = M ( ϱ p ( u ) ) + M ( ϱ q ( u ) ) + 1 γ 2 R N ζ ( x ) u γ d x 1 γ R N ζ ( x ) u γ log u d x λ R N F ( x , u ) d x .

Lemma 5.2

Assumptions [ M H ] and [ V F ] are valid, we have

  1. there are two constants δ , σ > 0 , satisfied Φ λ ( u ) δ when u = σ ;

  2. there is κ X with κ > σ , satisfied Φ λ ( κ ) < 0 .

Proof

For (i), due to ( f 2 ) and ( f 3 ) , for fixed ε > 0 , there is C 8 = C 8 ( ε ) > 0 satisfying

(5.2) F ( x , s ) ε q θ s q θ + C 8 s ι , ( x , s ) R × R .

By ( M 1 ) and ( M 2 ) , Lemma 2.4 (iii), Lemma 2.6, and Jensen inequality, for u X , ϱ p ( u ) 1 and ϱ q ( u ) 1 , it can be obtained

Φ λ ( u ) = M ( ϱ p ( u ) ) + M ( ϱ q ( u ) ) + 1 γ 2 R N ζ ( x ) u γ d x 1 γ R N ζ ( x ) u γ log u d x λ R N F ( x , u ) d x M ( 1 ) p [ ϱ p ( u ) ] θ + M ( 1 ) q [ ϱ q ( u ) ] θ + 1 γ 2 R N ζ ( x ) u γ d x 1 γ R N ζ ( x ) u γ log u d x λ R N F ( x , u ) d x M ( 1 ) q 2 θ 1 [ ϱ V ( u ) ] q θ 1 γ C 9 ζ u γ 1 γ log u R N ζ ( x ) u γ d x ε λ p u p q θ C 8 λ u ι ι M ( 1 ) q 2 θ 1 u q θ 1 γ C 9 ζ u γ ε λ p u p q θ λ C 8 u ι ι .

The rest proof can refer to Lemma 4.2 (i). We can obtain (i) hold when λ ( 0 , Λ 2 ) , where Λ 2 > 0 is a constant sufficiently small.

For (ii), by ( f 4 ), for given ς > 0 , we have a constant C 12 = C 12 ( ς ) > 0 , satisfying

(5.3) F ( x , s ) ς γ s γ C 12 , ( x , s ) R × R .

Take ϱ p ( u ) 1 , ϱ q ( u ) 1 and t > 1 . It follows that

Φ λ ( t u ) = M ( ϱ p ( t u ) ) + M ( ϱ q ( t u ) ) + t γ γ 2 R N ζ ( x ) u γ d x t γ γ R N ζ ( x ) u γ log t u d x λ R N F ( x , t u ) d x M ( 1 ) p t p θ [ ϱ p ( u ) ] θ + M ( 1 ) q t q θ [ ϱ q ( u ) ] θ + t γ γ 2 R N ζ ( x ) u γ d x t γ γ R N ζ ( x ) u γ log t u d x λ ς t γ γ u γ γ + C 12 M ( 1 ) p t p θ [ ϱ p ( u ) ] θ + M ( 1 ) q t q θ [ ϱ q ( u ) ] θ + t γ ζ γ 2 u γ γ λ ς γ u γ γ log t γ R N ζ ( x ) u γ d x 1 γ R N ζ ( x ) u γ log u d x + C 12 .

Since q θ < γ , we obtain

Φ λ ( t u ) as t .

The proof is completed.□

Lemma 5.3

If assumptions [ M H ] and [ V F ] hold, the functional Φ λ fulfills the ( P S ) b 2 condition, there exists u n u in X.

Proof

Let { u n } X be a sequence satisfying ( P S ) b 2 , here,

b 2 = inf ς Γ max t [ 0 , 1 ] Φ λ ( ς ( t ) ) with Γ = { ς C 0 ( [ 0 , 1 ] , X ) : ς ( 0 ) = 0 , Φ λ ( ς ( 1 ) ) < 0 } .

We first show the boundedness of { u n } n in X . Suppose by contradiction that there is a subsequence satisfying lim n u n = . By Lemma 2.4 (iv), we have lim n ϱ V ( u n ) = . We break it down into the following two situations.

Case 1: lim n ϱ p ( u n ) = , lim n ϱ q ( u n ) = .

By Lemma 2.4, ( f 4 ) and ( M 1 ) ( M 2 ) , we can obtain

(5.4) b 2 ( 1 + u ) = Φ λ ( u n ) 1 γ Φ λ ( u n ) , u n = M ( ϱ p ( u n ) ) 1 γ ( ϱ p ( u n ) ) u n , u n s , p + M ( ϱ q ( u n ) ) 1 γ ( ϱ q ( u n ) ) u n , u n s , q , η + 1 γ 2 R N ζ ( x ) u n γ d x + λ R N ( x , u n ) d x 1 θ ( ϱ p ( u n ) ) ϱ p ( u n ) p γ ( ϱ p ( u n ) ) ϱ p ( u n ) + 1 θ ( ϱ q ( u n ) ) ϱ q ( u n ) q γ ( ϱ q ( u n ) ) ϱ q ( u n ) + 1 γ 2 R N ζ ( x ) u n γ d x + λ R N ( x , u n ) d x ϑ 1 θ q γ ϱ V ( u n ) + 1 γ 2 R N ζ ( x ) u n γ d x + λ R N ( x , u n ) d x ϑ 1 θ q γ u n p + C 14 .

Since q θ > γ , it is a contradiction. { u n } is bounded in X .

Case 2: One of ϱ p ( u n ) and ϱ q ( u n ) is diverged. We only prove that

lim n ϱ p ( u n ) = , sup n ϱ q ( u n ) < .

Similar to Case 1, we can obtain

b 2 ( 1 + u ) ϑ 1 θ q γ [ ϱ V ( u n ) ] p q C 15 ϑ 1 θ q γ [ ϱ p ( u n ) ] p q C 15 .

By Lemma 2.4, we can obtain

0 < 1 p 2 θ 1 1 θ q γ C 16 [ ϱ p ( u n ) + ϱ q ( u n ) ] 1 p [ ϱ p ( u n ) ] p q C 17 .

Thus, { u n } is bounded in X .

Next, we verify that u n u in X . By the boundedness of { u n } in X , it can be obtained

(5.5) u n u in X , u n u in L D x ( R N ) , ϱ p ( u n ) k p , ϱ q ( u n ) k q , u n u in L ν ( R N ) , u n u a.e. in R N , ν [ p , p s * ) .

Then

(5.6) o n ( 1 ) = Φ λ ( u n ) , ω n = ( ϱ p ( u n ) ) u n , ω n s , p + ( ϱ q ( u n ) ) u n , ω n s , q , η R N ζ ( x ) u n γ 2 u n ω n log u n d x + λ R N f ( x , u n ) ω n d x = ( k p p ) u n , ω n s , p + ( k q q ) u n , ω n s , q , η R N ζ ( x ) u n γ 2 u n ω n log u n d x + λ R N f ( x , u n ) ω n d x .

Next, we will divide two cases to consider the behavior of at zero.

Case 1: ( 0 ) = 0 .

Because of k p 0 and k q 0 in (5.5), we consider the following four subcases.

Subcase 1.1: When k p = 0 and k q = 0 . By means of (5.5), there are ϱ p ( u n ) 0 and ϱ q ( u n ) 0 as n ; thus, u n 0 in X by Lemma 2.4.

Subcase 1.2: When k p = 0 and k q > 0 . We claim that this case do not exist.

By (5.6) and ( M 2 ) , we have

lim n u n , ω n s , q , η = 0 .

By (5.5) and k p = 0 , one yields that

(5.7) lim n u , ω n s , q , η = lim n T ( u ) , ω n = 0 .

Thus,

(5.8) lim n ( u n , ω n s , q , η u , ω n s , q , η ) = 0 .

If q 2 , by using Simon inequality, we can obtain

ϱ q ( ω n ) = R 2 N η ( x , y ) ω n ( x ) ω n ( y ) q q x y N + s q d x d y + R N V ( x ) η ¯ ( x ) ω n q q d x

C 18 R 2 N η ( x , y ) ( u n ( x ) u n ( y ) q 2 [ u n ( x ) u n ( y ) ] u ( x ) u ( y ) q 2 [ u ( x ) u ( y ) ] ) × [ u n ( x ) u n ( y ) u ( x ) + u ( y ) ] x y ( N + s q ) d x d y + C 18 R N V ( x ) η ¯ ( x ) ( u n q 2 u n u q 2 u ) ω n d x = C 18 [ u n , ω n s , q , η u , ω n s , q , η ] .

If 1 < q < 2 , by Simon inequality and Jensen inequality, we have

ϱ q ( ω n ) = R 2 N η ( x , y ) ω n ( x ) ω n ( y ) q q x y N + s q d x d y + R N V ( x ) η ¯ ( x ) ω n q q d x C 19 R 2 N η ( x , y ) ( u n ( x ) u n ( y ) q 2 [ u n ( x ) u n ( y ) ] u ( x ) u ( y ) q 2 [ u ( x ) u ( y ) ] ) q 2 × [ u n ( x ) u n ( y ) u ( x ) + u ( y ) ] q 2 [ u n ( x ) u n ( y ) q + u ( x ) u ( y ) q ] 2 q 2 x y ( N + s q ) d x d y + C 19 R N V ( x ) η ¯ ( x ) ( u n q 2 u n u q 2 u ) q 2 ω n q 2 ( u n q + u q ) ( 2 q ) 2 d x C 19 R 2 N η ( x , y ) u n ( x ) u n ( y ) q 2 [ u n ( x ) u n ( y ) ] [ ω n ( x ) ω n ( y ) ] x y N + s q d x d y R 2 N η ( x , y ) u ( x ) u ( y ) q 2 ( u ( x ) u ( y ) ) ( ω n ( x ) ω n ( y ) ) x y N + s q d x d y q 2 ( [ u n ] s , q , η q + [ u ] s , q , η q ) 2 q 2 + C 19 R N η ¯ ( x ) V ( x ) [ u n q 2 u n u q 2 u ] ω n d x q 2 R N V ( x ) ( u n q + u q ) d x ( 2 q ) 2 C 20 R 2 N η ( x , y ) u n ( x ) u n ( y ) q 2 [ u n ( x ) u n ( y ) ] [ ω n ( x ) ω n ( y ) ] x y N + s q d x d y R 2 N η ( x , y ) u ( x ) u ( y ) q 2 [ u ( x ) u ( y ) ] [ ω n ( x ) ω n ( y ) ] x y N + s q d x d y q 2 + C 20 R N V ( x ) η ¯ ( x ) ( u n q 2 u n u q 2 u ) ω n d x q 2 C 21 2 1 q 2 ( u n , ω n s , q , η u , ω n s , q , η ) q 2 .

Thus, by (5.8), we can obtain ϱ q ( ω n ) = 0 , and ϱ q ( u ) = k q , which implies that

η ( x , y ) 1 q u n ( x ) u n ( y ) x y N + s q q η ( x , y ) 1 q u ( x ) u ( y ) x y N + s q q a.e. in R 2 N , [ V ( x ) η ¯ ( x ) ] 1 q u n [ V ( x ) η ¯ ( x ) ] 1 q u a.e. in R N , as n + .

Denote

ψ s p n ( x , y ) = u n ( x ) u n ( y ) p x y N + s p , ψ p V n ( x ) = V ( x ) u n p , ψ s q n ( x , y ) = η ( x , y ) u n ( x ) u n ( y ) q x y N + s q , ψ q V n ( x ) = V ( x ) η ¯ ( x ) u n q .

On account of k p = 0 , it can imply that ψ s p n ( x , y ) 0 in L p ( R 2 N ) and ψ p V n ( x ) 0 in L p ( R N ) as n , then there exists subsequence ψ s p n ( x , y ) 0 and ψ p V n ( x , y ) 0 , a.e. in R 2 N and R N . Thus, we have ψ s q n ( x , y ) 0 and ψ q V n ( x , y ) 0 , a.e. in R 2 N and R N , so

η ( x , y ) u ( x ) u ( y ) q x y N + s q + V ( x ) η ¯ ( x ) u q = 0 a.e. in R 2 N ,

which is a contraction with ϱ q ( u ) = k q > 0 .

Subcase 1.3: When k p > 0 and k q = 0 . By applying (4.8), (4.9), and (5.6), we have

lim n u n , ω n s , p = 0 .

By (5.5) and k q = 0 , one yields that

(5.9) lim n u , ω n s , p = lim n T ( u ) , ω n = 0 ,

which gives

lim n ( u n , ω n s , p u , ω n s , p ) = 0 .

Similar with subcase 1.2, we obtain that ψ s p n ψ s p in L p ( R 2 N ) and ψ p V n ψ p V in L p ( R N ) as n . Hence, according to ([37], Theorem 4.9), there is a subsequence, such that

(5.10) ψ s p n ( x , y ) ψ s p ( x , y ) a.e. in R 2 N and ψ p V n ( x ) ψ p V ( x ) a.e. in R N as n .

Because ϱ q ( u n ) 0 , which means ψ s q n 0 in L q ( R 2 N ) and ψ q V n 0 in L q ( R N ) as n . Due to ([37], Theorem 4.9), there exists subsequence

ψ s q n 0 a.e. in R 2 N , ψ q V n 0 a.e. in R N as n .

It can ensure that

ψ s p n ( x , y ) 0 a.e. in R 2 N S , ψ p V n ( x ) 0 a.e. in R N \ S ,

where

S { ( x , y ) R 2 N : η ( x , y ) = 0 } , S { x R N : η ¯ ( x ) = 0 } .

Thus, according to (5.10), we have ψ s p ( x , y ) = 0 a.e. in R 2 N \ S and ψ p V ( x ) = 0 a.e. in R N \ S , so we have u = 0 a.e. in R N \ S . Then

ϱ q ( ω n ) = R 2 N \ S η ( x , y ) ω n ( x ) ω n ( y ) q x y N + q s d x d y + R N \ S V ( x ) η ¯ ( x ) ω n q d x = R 2 N \ S η ( x , y ) u n ( x ) u n ( y ) q x y N + q s d x d y + R N \ S V ( x ) η ¯ ( x ) u n q d x = ϱ q ( u n ) 0 , as n .

Hence, by applying Lemma 2.4, we obtain u n u in X .

Subcase 1.4: When k p > 0 and k q > 0 . By using (5.6), we have

o ( 1 ) = ( k p p ) u n , ω n s , p + ( k q q ) u n , ω n s , q , η , as n .

According to the convexity, we can obtain

u n , ω n s , p u , ω n s , p 0 a.e. in R 2 N , u n , ω n s , q , η u , ω n s , q , η 0 a.e. in R 2 N .

Using ( H 2 ), η ( x , y ) 0 a.e. in R 2 N , then it yields

min { ( k p p ) , ( k q q ) } limsup n T ( u n ) T ( u ) , ω n 0 ,

since ( k p p ) > 0 , ( k q q ) > 0 , and ( M 2 ) . By Theorem 3.1, we have u n u in X as n .

Case 2: If ( 0 ) > 0 . Because of ( k p p ) > 0 and ( k q q ) > 0 for k p 0 and k q 0 , using ( M 2 ) , the proof is similar with Subcase 1.4.□

Proof of Theorem 1.2

The functional Φ λ satisfies the mountain pass geometry structure and ( P S ) b 2 condition according to Lemmas 5.2 and 5.3. The mountain pass theorem ([36], Theorem 1.15) yields the existence result of Problem (1.6).

To obtain ground state solution, we denote by K the critical set of Φ λ . Set

c 2 inf { Φ λ ( u ) : u K \ { 0 } } .

For any u K , by (5.4), we have

Φ λ ( u ) 1 γ Φ λ ( u ) , u ϑ 1 θ q θ γ u p θ 0 ,

which means c 2 0 . By Theorem 2.7 and Krein-Šmulian theorem, in X is weak semicontinuity, along with Fatou’s lemma, we have

c 2 Φ λ ( u ) = Φ λ ( u ) 1 γ Φ λ ( u ) , u = M ( ϱ p ( u ) ) 1 γ ( ϱ p ( u ) ) u , u s , p + M ( ϱ q ( u ) ) 1 γ ( ϱ q ( u ) ) u , u s , q , η + 1 γ 2 R N ζ ( x ) u γ d x λ R N ( x , u ) d x liminf n M ( ϱ p ( u n ) ) 1 γ ( ϱ p ( u n ) ) u n , u n s , p + M ( ϱ q ( u n ) ) 1 γ ( ϱ q ( u ) ) u n , u n s , q , η + 1 γ 2 R N ζ ( x ) u n γ d x λ R N ( x , u n ) d x = liminf n Φ λ ( u n ) 1 γ Φ λ ( u n ) , u n = b 2 .

Thus, 0 c 2 b 2 .

Next, let { v k } be a sequence of non-trivial critical points for Φ λ such that

Φ λ ( v k ) c 2 .

By Lemma 4.3, we can see that v k converges to some v 0 . Using Fatou Lemma again, it implies that

c 2 Φ λ ( v ) liminf k Φ λ ( v k ) = c 2 .

Hence, Φ λ ( v ) = c 2 and Φ λ ( v ) = 0 .□

Acknowledgments

The authors express their sincere gratitude to the anonymous referees for their careful reading of the manuscript and valuable comments.

  1. Funding information: This work was supported by the National Natural Science Foundation of China (12371173), the Shandong Natural Science Foundation of China (ZR2023QA025 and ZR2021MA064), and the Taishan Scholar project of China.

  2. Author contributions: All authors contributed equally to this work.

  3. Conflict of interest: The authors declare that there is no conflict of interest.

  4. Ethical approval: Not applicable.

  5. Data availability statement: No data was used for the research described in the article.

References

[1] V. Zhikov, S. Kozlov, O. Oleinik, Homogenization of Differential Operators and Integral Functionals, Springer-Verlag, Berlin, 1994. 10.1007/978-3-642-84659-5Search in Google Scholar

[2] V. Zhikov, Averaging of functional of the calculus of variations and elasticity theory, Izv. Akad. Nauk SSSR, Ser. Mat. 50 (1986), 675–710, DOI: https://doi.org/10.1070/IM1987v029n01ABEH000958. 10.1070/IM1987v029n01ABEH000958Search in Google Scholar

[3] V. Zhikov, On Lavrentiev’s phenomenon, Russ. J. Math. Phys. 3 (1995), 249–269, DOI: https://doi.org/10.1007/s00205-022-01816-x. 10.1007/s00205-022-01816-xSearch in Google Scholar

[4] V. Zhikov, On some variational problems, Russ. J. Math. Phys. 5 (1997), 105–116. Search in Google Scholar

[5] F. Colasuonno and M. Squassina, Eigenvalues for double-phase variational integrals, Ann. Mat. Pura Appl. 195 (2016), no. 6, 61917–1959, DOI: https://doi.org/10.1007/s10231-015-0542-7. 10.1007/s10231-015-0542-7Search in Google Scholar

[6] W. Liu and G. Dai, Existence and multiplicity results for double-phase problem, J. Differential Equations 265 (2018), no. 9, 4311–4334, DOI: https://doi.org/10.1016/j.jde.2018.06.006. 10.1016/j.jde.2018.06.006Search in Google Scholar

[7] W. Liu, G. Dai, Three ground state solutions for double-phase problem, J. Math. Phys. 59 (2018), 121503, DOI: https://doi.org/10.1063/1.5055300. 10.1063/1.5055300Search in Google Scholar

[8] S. Zeng, V. Rǎdulescu, P. Winkert, Double phase implicit obstacle problems with convection and multivalued mixed boundary value conditions, SIAM J. Math. Anal. 54 (2022), no. 2, 1898–1926, DOI: https://doi.org/10.1137/21M1441195. 10.1137/21M1441195Search in Google Scholar

[9] R. Stegliński, Infinitely many solutions for double-phase problem with unbounded potential in RN, Nonlinear Anal. 214 (2022), 112580, DOI: https://doi.org/10.1016/j.na.2021.112580. 10.1016/j.na.2021.112580Search in Google Scholar

[10] R. Arora, A. Fiscella, T. Mukherjee, P. Winkert, Existence of ground state solutions for a Choquard double-phase problem, Nonlinear Anal.-Real World Appl. 73 (2023), 103914, DOI: https://doi.org/10.1016/j.nonrwa.2023.103914. 10.1016/j.nonrwa.2023.103914Search in Google Scholar

[11] V. Ambrosio, V. Rǎdulescu, Fractional double-phase patterns: concentration and multiplicity of solutions, J. Math. Pures Appl. 142 (2020), 101–145, DOI: https://doi.org/10.1016/j.matpur.2020.08.011. 10.1016/j.matpur.2020.08.011Search in Google Scholar

[12] Y. Zhang, X. Tang, V. Rǎdulescu, Concentration of solutions for fractional double-phase problems: critical and supercritical cases, J. Differential Equations 302 (2021), 139–184, DOI: https://doi.org/10.1016/j.jde.2021.08.038. 10.1016/j.jde.2021.08.038Search in Google Scholar

[13] R. Biswas, S. Bahrouni, M. Carvalho, Fractional double-phase Robin problem involving variable order-exponents without Ambrosetti-Rabinowitz condition, Z. Angew. Math. Phys. 73 (2022), Art. No. 99, DOI: https://doi.org/10.1007/s00033-022-01724-w. 10.1007/s00033-022-01724-wSearch in Google Scholar

[14] Y. Cheng, Z. Bai, Existence and multiplicity results for parameter Kirchhoff double-phase problem with Hardy-Sobolev exponents, J. Math. Phys. 65 (2024), 011506, DOI: https://doi.org/10.1063/5.0169972. 10.1063/5.0169972Search in Google Scholar

[15] A. Fiscella, A. Pinamonti, Existence and multiplicity results for Kirchhoff-type problems on a double-phase setting, Mediterr. J. Math. 20 (2023), Art. No. 33, DOI: https://doi.org/10.1007/s00009-022-02245-6. 10.1007/s00009-022-02245-6Search in Google Scholar

[16] A. Fiscella, G. Marino, A. Pinamonti, Multiple solutions for nonlinear boundary value problems of Kirchhoff type on a double-phase setting, Rev. Mat. Complut. 37 (2024), 205–236, DOI: https://doi.org/10.1007/s13163-022-00453-y. 10.1007/s13163-022-00453-ySearch in Google Scholar

[17] R. Arora, A. Fiscella, T. Mukherjee, P. Winkert, On critical double-phase Kirchhoff problems with singular nonlinearity, Rend. Circ. Mat. Palerm. 71 (2022), 1079–1106, DOI: https://doi.org/10.1007/s12215-022-00762-7. 10.1007/s12215-022-00762-7Search in Google Scholar

[18] E. Azroul, A. Benkirane, M. Shimi, M. Srati, On a class of nonlocal problems in new fractional Musielak-Sobolev spaces, Appl. Anal. 101 (2020), 1933–1952, DOI: https://doi.org/10.1080/00036811.2020.1789601. 10.1080/00036811.2020.1789601Search in Google Scholar

[19] E. Azroul, A. Benkirane, M. Shimi, M. Srati, Embedding and extension results in fractional Musielak-Sobolev spaces, Appl. Anal. 102 (2021), 195–219, DOI: https://doi.org/10.1080/00036811.2021.1948019. 10.1080/00036811.2021.1948019Search in Google Scholar

[20] J. Albuquerque, J. Assis, L. Carvalho, M. Carvalho, A. Salort, On fractional Musielak-Sobolev spaces and applications to nonlocal problems, J. Geom. Anal. 33 (2023), Art. No. 130, DOI: https://doi.org/10.1007/s12220-023-01211-2. 10.1007/s12220-023-01211-2Search in Google Scholar

[21] A. Bahrouni, H. Missaoui, H. Ounaies, On the fractional Musielak-Sobolev spaces in Rd: Embedding results and applications, J. Math. Anal. Appl. 537 (2024), 128284, DOI: https://doi.org/10.1016/j.jmaa.2024.128284. 10.1016/j.jmaa.2024.128284Search in Google Scholar

[22] G. Kirchhoff, Mechanik, Teubner, Leipzig, 1883. Search in Google Scholar

[23] J. Lions, On some questions in boundary value problems of mathematical physics, in: Contemporary Development in Continuum Mechanics and Partial Differential Equations, North-Holland Mathematical Studies, vol. 30, North-Holland, Amsterdam, New York, pp. 284–346, 1978. 10.1016/S0304-0208(08)70870-3Search in Google Scholar

[24] K. Perera, Z. Zhang, Nontrivial solutions of Kirchhoff-type problems via the Yang index, J. Differential Equations 221 (2006), 246–255, DOI: https://doi.org/10.1016/j.jde.2005.03.006. 10.1016/j.jde.2005.03.006Search in Google Scholar

[25] X. He, W. Zou, Infinitely many positive solutions for Kirchhoff type problems, Nonlinear Anal. 70 (2009), 1407–1414, DOI: https://doi.org/10.1016/j.na.2008.02.021. 10.1016/j.na.2008.02.021Search in Google Scholar

[26] G. Autuori, A. Fiscella, P. Pucci, Stationary Kirchhoff problems involving a fractional elliptic operator and a critical nonlinearity, Nonlinear Anal. 125 (2015), 699–714, DOI: https://doi.org/10.1016/j.na.2015.06.014. 10.1016/j.na.2015.06.014Search in Google Scholar

[27] H. Lv, S. Zheng, Ground states for Schrödinger-Kirchhoff equations of fractional p-Laplacian involving logarithmic and critical nonlinearity, Commun. Nonlinear Sci. Numer. Simul. 111 (2022), 106438, DOI: https://doi.org/10.1016/j.cnsns.2022.106438. 10.1016/j.cnsns.2022.106438Search in Google Scholar

[28] P. d’Avenia, M. Squassina, M. Zenari, Fractional logarithmic Schrödinger equations, Math. Methods Appl. Sci. 38 (2015), 5207–5216, DOI: https://doi.org/10.1002/mma.3449. 10.1002/mma.3449Search in Google Scholar

[29] L. Truong, The Nehari manifold for fractional p-Laplacian equation with logarithmic nonlinearity on whole space, Comput. Math. Appl. 78 (2019), 3931–3940, DOI: https://doi.org/10.1016/j.camwa.2019.06.024. 10.1016/j.camwa.2019.06.024Search in Google Scholar

[30] A. Kufner, O. John, S. Fučík, Function Spaces, Noordhoff, Leyden, 1977. Search in Google Scholar

[31] M. Mihăilescu, V. Rǎdulescu, Neumann problems associated to nonhomogeneous differential operators in Orlicz-Sobolev spaces, Ann. I. Fourier 58 (2008), no. 6, 2087–2111, DOI: https://doi.org/10.5802/aif.2407. 10.5802/aif.2407Search in Google Scholar

[32] J. Musielak, Orlicz spaces and modular spaces, Lecture Notes in Mathematics, vol. 1034, Springer, Berlin, 1983. 10.1007/BFb0072210Search in Google Scholar

[33] R. Adams, J. Fournier, Sobolev Spaces, 2nd edn., Academic Press, New York, 2003. Search in Google Scholar

[34] P. Lindqvist, Notes on the stationary p-Laplace equation, Springer Briefs in Mathematics, Springer, Cham, 2019, xi+104. 10.1007/978-3-030-14501-9Search in Google Scholar

[35] B. Barrios, E. Colorado, A. De Pablo, and U. Sanchez, On some critical problems for the fractional Laplacian operator, J. Differential Equations 252 (2012), 6133–6162, DOI: https://doi.org/10.1016/j.jde.2012.02.023. 10.1016/j.jde.2012.02.023Search in Google Scholar

[36] M. Willem, Minimax Theorems, Birkhäuser, Boston, 1996. 10.1007/978-1-4612-4146-1Search in Google Scholar

[37] H. Brézis, Functional Analysis, Sobolev Spaces and Partial Differential Equations, Universitext, Springer, New York, 2011. 10.1007/978-0-387-70914-7Search in Google Scholar

Received: 2025-01-18
Revised: 2025-03-20
Accepted: 2025-04-29
Published Online: 2025-07-31

© 2025 the author(s), published by De Gruyter

This work is licensed under the Creative Commons Attribution 4.0 International License.

Articles in the same Issue

  1. Research Articles
  2. On approximation by Stancu variant of Bernstein-Durrmeyer-type operators in movable compact disks
  3. Circular n,m-rung orthopair fuzzy sets and their applications in multicriteria decision-making
  4. Grand Triebel-Lizorkin-Morrey spaces
  5. Coefficient estimates and Fekete-Szegö problem for some classes of univalent functions generalized to a complex order
  6. Proofs of two conjectures involving sums of normalized Narayana numbers
  7. On the Laguerre polynomial approximation errors and lower type of entire functions of irregular growth
  8. New convolutions for the Hartley integral transform imbedded in the Banach algebras and convolution-type integral equations
  9. Some inequalities for rational function with prescribed poles and restricted zeros
  10. Lucas difference sequence spaces defined by Orlicz function in 2-normed spaces
  11. Evaluating the efficacy of fuzzy Bayesian networks for financial risk assessment
  12. Fixed point results for contractions of polynomial type
  13. Estimation for spatial semi-functional partial linear regression model with missing response at random
  14. Investigating the controllability of differential systems with nonlinear fractional delays, characterized by the order 0 < η ≤ 1 < ζ ≤ 2
  15. New forms of bilateral inequalities for K-g-frames
  16. Rate of pole detection using Padé approximants to polynomial expansions
  17. Existence results for nonhomogeneous Choquard equation involving p-biharmonic operator and critical growth
  18. Note on the shape-preservation of a new class of Kantorovich-type operators via divided differences
  19. Geršhgorin-type theorems for Z1-eigenvalues of tensors with applications
  20. New topologies derived from the old one via operators
  21. Blow up solutions for two-dimensional semilinear elliptic problem of Liouville type with nonlinear gradient terms
  22. Infinitely many normalized solutions for Schrödinger equations with local sublinear nonlinearity
  23. Nonparametric expectile shortfall regression for functional data
  24. Advancing analytical solutions: Novel wave insights and methodologies for beta fractional Kuralay-II equations
  25. A generalized p-Laplacian problem with parameters
  26. A study of solutions for several classes of systems of complex nonlinear partial differential difference equations in ℂ2
  27. Towards finding equalities involving mixed products of the Moore-Penrose and group inverses by matrix rank methodology
  28. ω -biprojective and ω ¯ -contractible Banach algebras
  29. Coefficient functionals for Sakaguchi-type-Starlike functions subordinated to the three-leaf function
  30. Solutions of several general quadratic partial differential-difference equations in ℂ2
  31. Inequalities for the generalized trigonometric functions with respect to weighted power mean
  32. Optimization of Lagrange problem with higher-order differential inclusion and special boundary-value conditions
  33. Hankel determinants for q-starlike functions connected with q-sine function
  34. System of partial differential hemivariational inequalities involving nonlocal boundary conditions
  35. A new family of multivalent functions defined by certain forms of the quantum integral operator
  36. A matrix approach to compare BLUEs under a linear regression model and its two competing restricted models with applications
  37. Weighted composition operators on bicomplex Lorentz spaces with their characterization and properties
  38. Behavior of spatial curves under different transformations in Euclidean 4-space
  39. Commutators for the maximal and sharp functions with weighted Lipschitz functions on weighted Morrey spaces
  40. A new kind of Durrmeyer-Stancu-type operators
  41. A study of generalized Mittag-Leffler-type function of arbitrary order
  42. On the approximation of Kantorovich-type Szàsz-Charlier operators
  43. Split quaternion Fourier transforms for two-dimensional real invariant field
  44. Quantum injectivity of G-frames in Hilbert spaces
  45. Some results on disjointly weakly compact sets
  46. On Motzkin sequence spaces via q-analog and compact operators
  47. Existence and multiplicity of nontrivial solutions for Schrödinger-Bopp-Podolsky systems with critical nonlinearity in ℝ3
  48. Stability analysis of linear time-invariant difference-differential system with constant and distributed delays
  49. The discriminant of quasi m-boundary singularities
  50. Norm constrained empirical portfolio optimization with stochastic dominance: Robust optimization non-asymptotics
  51. Fuzzy stability of multi-additive mappings
  52. On inequalities involving n-polynomial exponential-type convex functions
  53. Singularities of multiplicative spherical Darboux image and multiplicative rectifying developable surface
  54. A golden ratio technique for equilibrium problem in reflexive Banach spaces
  55. A parallel inertial three-step iteration monotone hybrid algorithm for a finite family of G-nonexpansive mappings in Hilbert spaces endowed with graphs applicable to signal recovery problems
  56. Multiple and unique nontrivial solutions for fractional differential equations with singular property and derivatives contained in the nonlinear term
  57. New soliton solutions for a nonlinear complex hyperbolic Schrödinger dynamical equation with a truncated M-fractional derivative
  58. On a generalization of derangement polynomials and numbers
  59. The description of entire solutions of complex PDEs and PDDEs
  60. A modified RMIL conjugate gradient-based projection algorithm for constrained nonlinear equations: application to image denoising
  61. Fast solution strategies for time-space fractional linear complementarity problems governing American options pricing
  62. Existence results for Robin problems involving p(x)-Laplacian-like operators with convection term
  63. On asymptotic behaviors of a specific cubic functional equation and its hyperstability
  64. The description of entire solutions for some class of complex nonlinear partial differential equation (systems) in C 2
  65. Variations in the geometry of the basins of escape in a modified Hénon–Heiles potential
  66. A Rothe method for a viscoelastic contact problem involving time-fractional derivatives in locking materials
  67. Upper and lower solution method for a higher order ϕ-Laplacian BVPs on an infinite interval
  68. Weyl almost periodic functions on time scales and their Fourier series
  69. Integrable system of null curve and Betchov-Da Rios equation
  70. Fekete–Szegö problems for (β, Φ)-spirllike mapping of complex order γ in Banach space
  71. Modulated convergence: a deferred approach
  72. Infinitely many solutions for an instantaneous and non-instantaneous fourth-order differential system with local assumptions
  73. Existence and nonexistence of normalized solutions for the Biharmonic equation with combined nonlinearities
  74. Ekeland’s variational principle for interval-valued functions with an α-level set in Kaleva-Seikkala’s type fuzzy metric spaces
  75. On Kurzweil integral of fuzzy number valued functions with two variables
  76. On split common null point and common fixed point problems for multivalued demicontractive mappings
  77. Approximation by weighted Durrmeyer-type max-product neural network operators
  78. A new predictor-corrector interior-point algorithm for semidefinite optimization
  79. Densities of measures: fine properties and examples
  80. Review Articles
  81. Characterization generalized derivations of tensor products of nonassociative algebras
  82. On the performance of the new minimax shrinkage estimators for a normal mean vector
  83. Special Issue on Differential Equations and Numerical Analysis - Part II
  84. Existence and optimal control of Hilfer fractional evolution equations
  85. Persistence of a unique periodic wave train in convecting shallow water fluid
  86. Existence results for critical growth Kohn-Laplace equations with jumping nonlinearities
  87. Monotonicity and oscillation for fractional differential equations with Riemann-Liouville derivatives
  88. Nontrivial solutions for a generalized poly-Laplacian system on finite graphs
  89. Stability and bifurcation analysis of a modified chemostat model
  90. Some new quantum derivatives and integrals with their applications in integral error bounds
  91. Special Issue on Nonlinear Evolution Equations and Their Applications - Part II
  92. Analytic solutions of a generalized complex multi-dimensional system with fractional order
  93. Extraction of soliton solutions and Painlevé test for fractional Peyrard-Bishop DNA model
  94. Special Issue on Recent Developments in Fixed-Point Theory and Applications - Part II
  95. Some fixed point results with the vector degree of nondensifiability in generalized Banach spaces and application on coupled Caputo fractional delay differential equations
  96. On the sum form functional equation related to diversity index
  97. Special Issue on International E-Conference on Mathematical and Statistical Sciences - Part II
  98. Simpson, midpoint, and trapezoid-type inequalities for multiplicatively s-convex functions
  99. Converses of nabla Pachpatte-type dynamic inequalities on arbitrary time scales
  100. Special Issue on Blow-up Phenomena in Nonlinear Equations of Mathematical Physics - Part II
  101. Energy decay of a coupled system involving a biharmonic Schrödinger equation with an internal fractional damping
  102. Special Issue on Some Integral Inequalities, Integral Equations, and Applications - Part II
  103. Nonlinear heat equation with viscoelastic term: Global existence and blowup in finite time
  104. New Jensen's bounds for HA-convex mappings with applications to Shannon entropy
  105. Special Issue on Approximation Theory and Special Functions 2024 conference
  106. Ulam-type stability for Caputo-type fractional delay differential equations
  107. Faster approximation to multivariate functions by combined Bernstein-Taylor operators
  108. (λ, ψ)-Bernstein-Kantorovich operators
  109. Some special functions and cylindrical diffusion equation on α-time scale
  110. (q, p)-Mixing Bloch maps
  111. Orthogonalizing q-Bernoulli polynomials
  112. On better approximation order for the max-product Meyer-König and Zeller operator
  113. Moment-based approximation for a renewal reward process with generalized gamma-distributed interference of chance
  114. A note on linear compositions of the Mellin convolution operators in the weighted Mellin-Lebesgue spaces
  115. A new perspective on generalized Laguerre polynomials
  116. Global existence of semilinear system of Klein-Gordon equations in anti-de Sitter spacetime
  117. Estimates for Durrmeyer-type exponential sampling series in Mellin-Orlicz spaces
  118. -αβ-statistical relative uniform convergence for double sequences and its applications
  119. New developments for the Jacobi polynomials
  120. Generalization of Sheffer-λ polynomials
  121. Fractional calculus containing certain bivariate Mittag-Leffler kernel with respect to function
  122. A new type of soft multi rough sets
  123. Special Issue on Variational Methods and Nonlinear PDEs
  124. A note on mean field type equations
  125. Ground states for fractional Kirchhoff double-phase problem with logarithmic nonlinearity
  126. Solution of nonlinear Langevin equations involving Hilfer-Hadamard fractional order derivatives and variable coefficients
  127. Bifurcation, quasi-periodic, and wave solutions to the fractional model of optical fibers in communication systems
  128. Multiplicity and concentration behavior of solutions for the generalized quasilinear Schrödinger equation with critical growth
  129. Ground state solutions to singularly perturbed Chern-Simons-Schrödinger systems with a neutral scalar field
  130. Weak solutions to an asymptotic equation of the variational sine-Gordon equation
  131. Multiplicity of positive solutions for a concave-convex fractional elliptic system with critical growth
Downloaded on 27.3.2026 from https://www.degruyterbrill.com/document/doi/10.1515/dema-2025-0137/html
Scroll to top button