theorem
  for f being Function, a,b,c being object st a <> c holds (f +* (a .-->b))
  .c = f.c
proof
  let f be Function, a,b,c be object such that
A1: a <> c;
  set g = a .-->b;
  not c in dom g by A1,TARSKI:def 1;
  hence thesis by Th11;
end;
