reserve i,j,k,x for object;

theorem Th19:
  for A being non empty set, o being Object of DiscrCat A holds (
  the Comp of DiscrCat A).(o,o,o) = (id o,id o) :-> id o
proof
  let A be non empty set, o be Object of DiscrCat A;
  <^o,o^> = {id o} by Def20;
  hence thesis by FUNCOP_1:def 10;
end;
