On graphs whose maximal subgraphs have at most two orbits

Graphs whose positive semi-definite matr

Graphs whose positive semi-definite matrices have nullity at most two

✍ Hein van der Holst 📂 Article 📅 2003 🏛 Elsevier Science 🌐 English ⚖ 202 KB

Let G = (V , E) be a undirected graph containing n vertices, and let M G be the set of all Hermitian n × n matrices M = (m i,j ) with m i,j / = 0 if i and j are connected by one edge of G, with m i,j ∈ C if i and j are connected by at least two edges, with m i,j = 0 if i / = j , and i and j are not