Questions on Color-Critical Subgraphs

Autor: Nicholas Newman, Matthew Noble
Rok vydání: 2020
Předmět:
Zdroj: Graphs and Combinatorics. 37:313-324
ISSN: 1435-5914
0911-0119
DOI: 10.1007/s00373-020-02243-z
Popis: In our work, we define a k-tuple of positive integers $$(x_1, \ldots , x_k)$$ to be a $$\chi $$ -sequence if there exists a k-chromatic graph G such that for each $$i \in \{1, \ldots , k\}$$ , the order of a minimum i-chromatic subgraph of G is equal to $$x_i$$ . Denote by $$\mathcal {X}_k$$ the set of all $$\chi $$ -sequences of length k. A very difficult question is to determine, for a given $$(x_1, \ldots , x_k) \in \mathcal {X}_k$$ , the set of all integers y such that $$(x_1, \ldots , x_k, y) \in \mathcal {X}_{k+1}$$ . We propose a few variants of this question and elaborate upon a number of partial results along the way.
Databáze: OpenAIRE