Reconsideration of Tangle and Ultrafilter using Separation and Partition

Abstract

Tangle is a concept in graph theory that has a dual relationship with branch-width which is well-known graph width parameter. Ultrafilter, a fundamental notion in mathematics, is similarly known to have a dual relationship with branch-width when extended to a connectivity system (X, f). We will reconsider these concepts using separation and partition.

8 pages