Flowers in graph-like spaces

Abstract

One perspective on tree decompositions is that they display (low-order) separations of the underlying graph or matroid. The separations displayed by a tree decomposition are necessarily nested. In 2013, Clark and Whittle proved the existence of tree decompositions with flowers added in which, up to a natural equivalence, all low-order separations are displayed. An important step in that proof is to show that flowers can be extended to maximal flowers. In this paper we generalise the notion of a flower to pseudoflowers in graph-like spaces and show for our generalisation, flowers can be extended to maximal flowers.