theorem Th2:
i <= j implies ((0*j) | (i-'1)) = 0*((i-'1))
proof
   assume  i <= j;
then A1: i-1 <= j-1 by XREAL_1:9;
     j-1 <= j by XREAL_1:43;
    then i-1 <= j by A1,XXREAL_0:2;
    then i-'1 <= j by XREAL_0:def 2;
    hence thesis by Th1;
end;
