Topological minors of cover graphs and dimension

Piotr Micek, Veit Wiechert

Published 2015-04-28Version 1

We introduce new tools to tackle problems involving upper bounds on poset dimension. Using these tools we prove two results: (1) Posets of bounded height whose cover graphs exclude a fixed graph as a topological minor have bounded dimension; (2) The $(k+k)$-free posets whose cover graphs exclude a fixed graph as a topological minor contain only standard examples of size bounded in terms of $k$. The first result was already given by Walczak. Our argument is very different, elementary, and in particular does not rely on structural decomposition theorems. The second result supports a conjectured generalization of the first result for $(k+k)$-free posets.