A non-hereditary Pollyanna class that is not strongly Pollyanna
Combinatorics
2026-05-15 v1
Abstract
Chudnovsky, Cook, Davies, and Oum introduced the notion of Pollyanna graph classes: a class is Pollyanna if for every -bounded class , the intersection is polynomially -bounded. They further defined to be strongly Pollyanna if it is -strongly Pollyanna for some integer , meaning that is polynomially -bounded for every -good class . They asked whether there are Pollyanna graph classes that are not strongly Pollyanna. In this note we answer this question affirmatively, under the literal interpretation that graph classes are not required to be hereditary. We construct a class that is Pollyanna but, for every , is not -strongly Pollyanna; in particular is not strongly Pollyanna.
Cite
@article{arxiv.2605.14547,
title = {A non-hereditary Pollyanna class that is not strongly Pollyanna},
author = {Hongzhang Chen and Kaiyang Lan},
journal= {arXiv preprint arXiv:2605.14547},
year = {2026}
}
Comments
7 pages. Any comments and suggestions are welcome