reserve A,B,C for Ordinal;
reserve a,b,c,d for natural Ordinal;
reserve l,m,n for natural Ordinal;
reserve i,j,k for Element of omega;
reserve x,y,z for Element of RAT+;
reserve i,j,k for natural Ordinal;

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;
