theorem Th32:
  for T,V,Q for F being Formula of Q st F is T-headed
    holds Polish-ext-head F = T-head F
proof
  let T,V,Q;
  let F be Formula of Q;
  assume A1: F is T-headed;
  T c= Polish-ext-domain Q by Def9;
  hence thesis by A1, POLNOT_1:55;
end;
