The average Steiner [formula omitted]-eccentricity of trees.

The Steiner (k , k ′) -eccentricity of a given k ′ -subset of a graph G is the maximum Steiner distance over all k -subsets of V (G) which contain the given k ′ -subset, an extension of standard Steiner k -eccentricity. In this paper, we mainly study the Steiner (3 , 2) -eccentricity of trees. The σ -transformation which does not increase the average Steiner (3 , 2) -eccentricity is depicted. Using σ -transformation, several lower and upper bounds for the average Steiner (3 , 2) -eccentricity of trees are given. [ABSTRACT FROM AUTHOR]