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+;

theorem Th43:
  i,j are_coprime & j <> {} implies numerator (i/j) = i &
  denominator (i/j) = j
proof
  assume i,j are_coprime;
  then RED(i,j) = i & RED(j,i) = j by Th23;
  hence thesis by Th42;
end;
