theorem Th61:
  p in rng(f:-p)
proof
  rng<*p*> = {p} by FINSEQ_1:39;
  then
A1: p in rng<*p*> by TARSKI:def 1;
  f:-p = <*p*>^(f/^p..f) by FINSEQ_5:def 2;
  then rng(f:-p) = rng<*p*> \/ rng(f/^p..f) by FINSEQ_1:31;
  hence thesis by A1,XBOOLE_0:def 3;
end;
