The poset of morphism-extension classes of countable graphs
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Andrés Aranda
Abstract
Let XYL,T consist of all countable L-structures M that satisfy the axioms T and in which all homomorphisms of type X (these could be plain homomorphisms, monomorphisms, or isomorphisms) between finite substructures of M are restrictions of an endomorphism of M of type Y (for example, an automorphism or a surjective endomorphism). Lockett and Truss introduced 18 such classes for relational structures. For a given pair L, T however, two or more morphism-extension properties may define the same class of structures.
In this paper, we establish all equalities and inequalities between morphism-extension classes of countable graphs.
The research presented here was completed while I was a postdoctoral researcher at the Institute for Algebra of Dresden Technical University (funded by the ERC under the European Union’s Horizon 2020 Research and Innovation Programme, grant agreement No. 681988, CSP-Infinity). Editing and corrections were made at my current position in Charles University Prague, funded by the Czech Science Foundation (GAČR), grant 21-10775S
Acknowledgements
I thank Thomas D. H. Coleman for the fruitful correspondence of 2018, and the anonymous referee for suggestions that helped improve the presentation of this paper.
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(Communicated by Anatolij Dvurečenskij)
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Artikel in diesem Heft
- Regular Papers
- The poset of morphism-extension classes of countable graphs
- Characterization of monadic BL-algebras by state operators
- Comments on efficient batch verification test for digital signatures based on elliptic curves
- On necessary and sufficient conditions for the monogeneity of a certain class of polynomials
- An exponential Diophantine equation involving the sum or difference of powers of two Pell numbers
- Some results on certain types of Putcha semigroups
- Inner functions in QK spaces and multipliers
- Certain subclasses of meromorphic multivalent q-starlike and q-convex functions
- Algebraic dependences of meromorphic mappings into a projective space sharing few hyperplanes
- Unbounded oscillation criteria for fourth order neutral differential equations of non-canonical type
- Existence of radial solutions for a weighted p-biharmonic problem with navier boundary condition on the Heisenberg group
- Intuitionistic fuzzy Tribonacci I-convergent sequence spaces
- Lipschitz class functions and their general Fourier coefficients
-
Spectra and fine spectra of the generalized upper difference operator with triple repetition
- A Topological sphere theorem for contact CR-warped product submanifolds of an odd-dimensional unit sphere
- An extended type I half-logistic family of distributions: Properties, applications and different method of estimations
- On the Unit-Chen distribution with associated quantile regression and applications
- A note on Lévy subordinators in cones of fuzzy sets in Banach spaces
- Uniformly asymptotic normality of the weighted estimator in nonparametric regression model with φ-mixing errors
- Upper bound for variance of finite mixtures of power exponential distributions
- The dimension Dind of finite topological T0-spaces
