KnowraHandshaking lemmaLinked fromLinked fromThe 6 pages that link to Handshaking lemma, each with the reason it gives.All 6Related 6Graph theoryRelated: Euler's bridge analysis uses the parity principle behind this fundamental degree relation.Complete graphRelated: It gives the edge count from the uniform degree n−1.Degree (graph theory)Related: It follows by counting each edge through its two ends.Simple graphRelated: It links local degrees to the total edge count in simple graphs.Regular graphRelated: It gives the edge count of a finite k-regular graph as k times the vertex count divided by two.Erdős–Gallai theorem (degree sequences)Related: It yields the theorem’s necessary even-sum condition.