The Structure of Delta-Matroids with Width One Twists
Keywords: Delta-matroid, Matroid, Partial dual, Excluded minor, Twist, Width
The width of a delta-matroid is the difference in size between a maximal and minimal feasible set. We give a Rough Structure Theorem for delta-matroids that admit a twist of width one. We apply this theorem to give an excluded minor characterisation of delta-matroids that admit a twist of width at most one.