A graph class is hereditary if it is closed under vertex deletion. We give examples of NP-hard, PSPACE-complete and NEXPTIME-complete problems that become constant-time solvable for every hereditary graph class that is not equal to the class of all graphs.
@article{arxiv.2012.09770,
title = {Hard Problems That Quickly Become Very Easy},
author = {Barnaby Martin and Daniël Paulusma and Siani Smith},
journal= {arXiv preprint arXiv:2012.09770},
year = {2021}
}