Combinatorics / CONCEPT

Exact stars at a marked packet

Let V be any finite vertex type and H any finite family of subsets of V. Write N(p) for the vertices x outside p such that insert(x,p) belongs to H, K(q) for the two-element sets p with q contained in N(p), and star(c,A) for the edges {c,x} with x in A. A marked triangle packet in a disjoint-union-free family forces two exact common-link stars.