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Linear rankwidth meets stability

Publikace na Matematicko-fyzikální fakulta |
2020

Tento text není v aktuálním jazyce dostupný. Zobrazuje se verze "en".Abstrakt

Classes with bounded rankwidth are MSO-transductions of trees and classes with bounded linear rankwidth are MSO-transductions of paths. These results show a strong link between the properties of these graph classes considered from the point of view of structural graph theory and from the point of view of finite model theory.

We take both views on classes with bounded linear rankwidth and prove structural and model theoretic properties of these classes: 1) Graphs with linear rankwidth at most r are linearly chi-bounded. Actually, they have bounded c-chromatic number, meaning that they can be colored with f(r) colors, each color inducing a cograph. 2) Based on a Ramsey-like argument, we prove for every proper hereditary family F of graphs (like cographs) that there is a class with bounded rankwidth that does not have the property that graphs in it can be colored by a bounded number of colors, each inducing a subgraph in 3) For C class with bounded linear rankwidth the following conditions are equivalent: a) C is stable, b) C excludes some half-graph as a semi-induced subgraph, c) C is a first-order transduction of a class with bounded pathwidth.

These results open the perspective to study classes admitting low linear rankwidth covers.