On the Structure of Hamiltonian Graphs with Small Independence Number

Fuente: arXiv
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Autori principali: Jedličková, Nikola, Kratochvíl, Jan
Natura: Preprint
Pubblicazione: 2024
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author Jedličková, Nikola
Kratochvíl, Jan
author_facet Jedličková, Nikola
Kratochvíl, Jan
contents A Hamiltonian path (cycle) in a graph is a path (cycle, respectively) which passes through all of its vertices. The problems of deciding the existence of a Hamiltonian cycle (path) in an input graph are well known to be NP-complete, and restricted classes of graphs which allow for their polynomial-time solutions are intensively investigated. Until very recently the complexity was open even for graphs of independence number at most 3. So far unpublished result of Jedličková and Kratochv\'ıl [arXiv:2309.09228] shows that for every integer $k$, Hamiltonian path and cycle are polynomial-time solvable in graphs of independence number bounded by $k$. As a companion structural result, we determine explicit obstacles for the existence of a Hamiltonian path for small values of $k$, namely for graphs of independence number 2, 3, and 4. Identifying these obstacles in an input graph yields alternative polynomial-time algorithms for Hamiltonian path and cycle with no large hidden multiplicative constants.
format Preprint
id arxiv_https___arxiv_org_abs_2403_03668
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On the Structure of Hamiltonian Graphs with Small Independence Number
Jedličková, Nikola
Kratochvíl, Jan
Combinatorics
Computational Complexity
A Hamiltonian path (cycle) in a graph is a path (cycle, respectively) which passes through all of its vertices. The problems of deciding the existence of a Hamiltonian cycle (path) in an input graph are well known to be NP-complete, and restricted classes of graphs which allow for their polynomial-time solutions are intensively investigated. Until very recently the complexity was open even for graphs of independence number at most 3. So far unpublished result of Jedličková and Kratochv\'ıl [arXiv:2309.09228] shows that for every integer $k$, Hamiltonian path and cycle are polynomial-time solvable in graphs of independence number bounded by $k$. As a companion structural result, we determine explicit obstacles for the existence of a Hamiltonian path for small values of $k$, namely for graphs of independence number 2, 3, and 4. Identifying these obstacles in an input graph yields alternative polynomial-time algorithms for Hamiltonian path and cycle with no large hidden multiplicative constants.
title On the Structure of Hamiltonian Graphs with Small Independence Number
topic Combinatorics
Computational Complexity
url https://arxiv.org/abs/2403.03668