theorem Th46:
   for z holds
   ex r1,r2 be Element of R st r2 in S & z = Class(EqRel(S),[r1,r2])
   proof
     let z;
     consider r be Element of Frac(S)  such that
A1:  z = Class(EqRel(S),r) by Th32;
     consider r1,r2 be Element of R such that
A2:  r1 = r`1 and
A3:  r2 = r`2;
     z = Class(EqRel(S),[r1,r2]) by A1,A2,A3;
     hence thesis by A3,Lm17;
   end;
