theorem Th76:
  for f being PartFunc of X,Y st Y = {} implies X = {} ex g being
  Function of X,Y st f tolerates g
proof
  let f be PartFunc of X,Y;
  assume
A1: Y = {} implies X = {};
  then consider g being Function of X,Y such that
A2: for x being object st x in dom f holds g.x = f.x by Th70;
  take g;
  thus thesis by A1,A2,Th74;
end;
