let n be set ; for L being non empty right_zeroed addLoopStr
for p being Series of n,L holds p + (0_ n,L) = p
let L be non empty right_zeroed addLoopStr ; for p being Series of n,L holds p + (0_ n,L) = p
let p be Series of n,L; p + (0_ n,L) = p
reconsider ls = p + (0_ n,L), p' = p as Function of Bags n,the carrier of L ;
hence
p + (0_ n,L) = p
by FUNCT_2:113; verum