On Bounds for the Product Irregularity Strength of Graphs.

For a graph $$X$$ with at most one isolated vertex and without isolated edges, a product-irregular labeling $$\omega :E(X)\rightarrow \{1,2,\ldots ,s\}$$ , first defined by Anholcer in 2009, is a labeling of the edges of $$X$$ such that for any two distinct vertices $$u$$ and $$v$$ of $$X$$ the product of labels of the edges incident with $$u$$ is different from the product of labels of the edges incident with $$v$$ . The minimal $$s$$ for which there exist a product irregular labeling is called the product irregularity strength of $$X$$ and is denoted by $$ps(X)$$ . In this paper it is proved that $$ps(X)\le |V(X)|-1$$ for any graph $$X$$ with more than $$3$$ vertices. Moreover, the connection between the product irregularity strength and the multidimensional multiplication table problem is given, which is especially expressed in the case of the complete multipartite graphs. [ABSTRACT FROM AUTHOR]