令G是一個圖且包含點和邊,l為將圖G的點集合和邊集合對應到一個整數集{0,…,λ}使得(1)相鄰的點不能標記相同的整數,(2)相鄰的邊不能標記相同的整數,(3)相鄰的點和邊標號差值的絕對值必須大於等於2,則稱 l為圖G的一個(2,1)-全標號。在一個(2,1)-全標號中,兩個標記整數之間最大的差值稱為跨度。在圖 的(2,1)-全標號中,最小的跨度我們稱之為圖G的(2,1)-全標號數。
Let G be a graph. A (2,1)-total labeling of G is a mapping from VUE into {0,…, λ} for some integer λ such that: (i) if x and y are adjacent vertices, then l(x) =/=l(y) ;(ii) if e and f are adjacent edges, then l(e)=/=l(f) ;(iii) if an edge e is incident to a vertex x, then |l(e)-l(x)|>=2 . The span of a (2,1)-total labeling is the maximum difference between two labels. The (2,1)-total number of a graph G is the minimum span of a (2,1)-total labeling of G.