theorem
  f1 is total & f2^ is total implies (f1/f2)/.c = ((f1/.c)) *(((f2/.c))) "
proof
  assume that
A1: f1 is total and
A2: f2^ is total;
  f2"{0c} = {} & f2 is total by A2,Th61;
  then f1/f2 is total by A1,Th62;
  then dom (f1/f2) = C;
  hence thesis by Def1;
end;
