On Graceful Spider Graphs with at Most Four Legs of Lengths Greater than One

Abstract

A graceful labeling of a tree T with n edges is a bijection f:V(T)→{0,1,2,…,n} such that {|f(u)-f(v)|:uv∈E(T)} equal to {1,2,…,n}. A spider graph is a tree with at most one vertex of degree greater than 2. We show that all spider graphs with at most four legs of lengths greater than one admit graceful labeling.