Exatremal Polyomino Chains with Respect to Total Irregularity

The total irregularity of a given simple graph G is calculated by the formula irrt(G) = 1 2 Ó fu;vg V (G) j degGu .. degGv j in which degGv is the degree of a vertex v in G. The aim of this paper is computing the total irregularity of polyomino chains. Upper and lower bounds for the total irreg- ularity of polyomino chains together the st and second extremal polyomino chain with respect to this graph invariant will be also presented.