Partial k-tree

Partial [math]\displaystyle{ k }[/math]-tree --- частичное [math]\displaystyle{ k }[/math]-дерево.

A partial [math]\displaystyle{ k }[/math]-tree is a subgraph of a [math]\displaystyle{ k }[/math]-tree. The class of partial [math]\displaystyle{ k }[/math]-trees is exactly the class of graphs with a treewidth at most [math]\displaystyle{ k }[/math]. Note that, for each constant [math]\displaystyle{ k }[/math], the class of partial [math]\displaystyle{ k }[/math]-trees is minor-closed.