Assertion: graph's vertex | /r/HasAspect | different colors
Facets:
Source sentences:
text: To explain, if the vertices u and v have different colors, then we might as well consider a graph where u and v are adjacent.
text: In a depth-first search forest, one of the two endpoints of every non-forest edge is an ancestor of the other endpoint, and when the depth first search discovers an edge of this type it should check that these two vertices have different colors.