Pathway XIX

ΓSimple graphs

Vertices and undirected edges, no loops or doubles. The skeleton of combinatorics.

1. 01Simple graphsA simple graph is a vertex set and a set of unordered pairs. Degrees count incident edges.4 min
2. 02TreesA tree is a connected graph with no cycles. Equivalently: |E| = |V| − 1, and unique paths.4 min