Which of the various properties of relations does the isasub

Solution

Clearly every graph is a subgraph of itself, so the relation is reflexive.

Transitivity is also clear : If K is a subgraph of H , and H is a subgraph of G, then the vertex set of K and the edge set of K , being subsets of the vertex set and edge set of H, are also subsets of the vertex and the edge set of G.

It is defnitely not symmetric: Let G be the complete graph on 2 vertices and H be the subgraph of G with the same vertex set (of two points) and no edges. G is not a subgraph of H.