We describe a family of graphs with queue-number at most 4 but unbounded stack-number. This resolves open problems of Heath, Leighton and Rosenberg (1992) and Blankenship and Oporowski (1999).
@article{arxiv.2011.04195,
title = {Stack-number is not bounded by queue-number},
author = {Vida Dujmović and David Eppstein and Robert Hickingbotham and Pat Morin and David R. Wood},
journal= {arXiv preprint arXiv:2011.04195},
year = {2022}
}