The PI(Padmakar-Ivan) Index of Polyominoes

The Padmakar – Ivan (PI) index of polyominoes is examined.Efficient calculations of formulas for PI index for the polyominoes are put forward. In chemical graph theory, the PI index is a topological indexof a graph G is defined as , where for edge e = xy, n1 (e) is the number of edges of G lying closer to x than y, n2 (e) is the number of edges of G lying closer to y than x and summation goes over all edges of G. The edges equidistant from x and y are not considered for the calculation of PI index. In this paper, we calculated the PI index of polyominoes like square Polyomino, L-Polyomino,T-Polyomino, Straight-Polyomino and Skew-Polyomino.