Yehuda Roditty

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An edge-colored graph G is rainbow connected if any two vertices are connected by a path whose edges have distinct colors. The rainbow connection number of a connected graph G, denoted rc(G), is the smallest number of colors that are needed in order to make G rainbow connected. In this paper we prove several non-trivial upper bounds for rc(G), as well as(More)
An antimagic labeling of a graph with m edges and n vertices is a bijection from the set of edges to the integers 1, . . . ,m such that all n vertex sums are pairwise distinct, where a vertex sum is the sum of labels of all edges incident with the same vertex. A graph is called antimagic if it has an antimagic labeling. A conjecture of Ringel (see [4])(More)
Let X be a (finite or infinite) set and let G be a (finite or infinite) group of automorphisms of X. Thus G acts on X and for every g E G the sequence k&x is a permutation of X. For every subset Y of X and every g E G, let g Y be the set of all elements gy, for y E Y. Clearly 1 g Y 1 = 1 Y 1 for every finite Y, and this defines an action of the group G on(More)
The sequence of graphs { G1, G2, . . . , G,} is said to be packed into a graph G if G has edge disjoint subgraphs HI, Hz, . . . , H, such that Hi G Gj, j = 1, . . . , t. We say that a graph G is m-panarboreal if each tree on m vertices, T,, can be packed into G. Gyarfas and Lehel [3] conjectured that if z is any tree of order i then the sequence of trees(More)