Minimal imperfect graph

Minimal imperfect graph --- минимальный несовершенный граф.

A graph is called minimal imperfect graph if it is not perfect but every its proper induced subgraph is. The strong perfect graph conjecture made by C. Berge states that the only minimal imperfect graphs are the chordless odd cycles of length at least five and their complements. The chordless odd cycles of length five and their complements are often referred to as the odd holes and odd antiholes, respectively. Until now, the strong perfect graph conjecture is unsettled.