exatremal polyomino chains with respect to total irregularity

The total irregularity of a given simple graph g is calculated bythe formula irrt(g) =12ófu;vgv (g)j deggu .. deggv j in which deggv isthe degree of a vertex v in g. the aim of this paper is computing the totalirregularity of polyomino chains. upper and lower bounds for the total irreg-ularity of polyomino chains together the st and second extremal polyominochain with respect to this graph invariant will be also presented.