Minor of a graph
Minor of a graph --- минор графа.
A graph obtained from by a series of vertex deletions, edge deletions and contractions of an edge. A class of graphs is called minor-closed if for every graph in , every minor of is also a member of . For a class of graphs , a finite obstruction set is a finite set of minors such that a graph is a member of if and only if it does not contain an element of as a minor.
The graphs in every minor-closed class of graphs are recognizable in time.