theorem Th53:
  x*'one = x
proof
  set y = one;
A1: (numerator x)*^1 = numerator x & (denominator x)*^1 = denominator x by
ORDINAL2:39;
  numerator y = 1 & denominator y = 1 by Def8,Def9;
  hence thesis by A1,Th39;
end;
