reserve X,X1,X2,Y,Y1,Y2 for set, p,x,x1,x2,y,y1,y2,z,z1,z2 for object;
reserve f,g,g1,g2,h for Function,
  R,S for Relation;

theorem Th36:
  f is one-to-one implies dom(f*f") = rng f & rng(f*f") = rng f
proof
  assume
A1: f is one-to-one;
  then
A2: rng(f") = dom f by Th32;
  then dom(f*f") = dom(f") by RELAT_1:27;
  hence thesis by A1,A2,Th32,RELAT_1:28;
end;
