theorem Th36:
  still_not-bound_in X is finite implies
  still_not-bound_in (X \/ {p}) is finite
proof
  assume
A1: still_not-bound_in X is finite;
  still_not-bound_in p is finite by CQC_SIM1:19;
  then still_not-bound_in {p} is finite by Th26;
  then still_not-bound_in X \/ still_not-bound_in {p} is finite by A1;
  hence thesis by Th27;
end;
