symbolic n,m;
R1 := {[x,y] -> [x,y+1] : 1 <= x,y <= 10};
R2 := {[x,y] -> [x+1,y] : 1 <= x <= 20 && 5 <= y <= 15};
R12 := R1 union R2;
R12c := R12+;
R12c;
(R12c compose R12c) - R12c;
(R12c compose R12) - R12c;