theorem
  TS is deterministic implies ==>.-relation(TS) is Function-like
proof
  assume TS is deterministic;
  then
  for x, y, z being object
st [x, y] in ==>.-relation(TS) & [x, z] in ==>.-relation(TS)
  holds y = z by Th44;
  hence thesis by FUNCT_1:def 1;
end;
