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Lower bounds for regular genus and gem-complexity of PL 4-manifolds with boundary

  • Biplab Basak ORCID logo EMAIL logo and Manisha Binjola ORCID logo
Published/Copyright: November 26, 2020

Abstract

Let 𝑀 be a connected compact PL 4-manifold with boundary. In this article, we give several lower bounds for regular genus and gem-complexity of the manifold 𝑀. In particular, we prove that if 𝑀 is a connected compact 4-manifold with ℎ boundary components, then its gem-complexity k(M) satisfies the inequalities k(M)3χ(M)+7m+7h-10 and k(M)k(M)+3χ(M)+4m+6h-9, and its regular genus G(M) satisfies the inequalities G(M)2χ(M)+3m+2h-4 and G(M)G(M)+2χ(M)+2m+2h-4, where 𝑚 is the rank of the fundamental group of the manifold 𝑀. These lower bounds enable to strictly improve previously known estimations for regular genus and gem-complexity of a PL 4-manifold with boundary. Further, the sharpness of these bounds is also shown for a large class of PL 4-manifolds with boundary.

MSC 2010: 57Q15; 57Q05; 57K41; 05C15

Award Identifier / Grant number: DST/INSPIRE/04/2017/002471

Funding statement: The first author is supported by DST INSPIRE Faculty Research Grant (DST/INSPIRE/04/2017/002471).

Acknowledgements

The authors would like to thank the anonymous referees for many useful comments and suggestions.

  1. Communicated by: Frederick R. Cohen

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Received: 2020-04-15
Revised: 2020-09-06
Published Online: 2020-11-26
Published in Print: 2021-03-01

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