reserve a,x,y for object, A,B for set,
  l,m,n for Nat;
reserve X,Y for set, x for object,
  p,q for Function-yielding FinSequence,
  f,g,h for Function;
reserve m,n,k for Nat, R for Relation;

theorem Th67:
  iter (R,0) = id(field R)
proof
  ex p being sequence of  bool [:field R,field R:] st iter
(R,0) = p.0 & p.0 = id(field R) & for k being Nat holds p.(k+1) = R*p.k
by Def10;
  hence thesis;
end;
