theorem Th85:
  for L, E for F being Polish-WFF of L, E st F in Polish-atoms(L, E) holds
    Polish-WFF-head F = F & L-head F = F & Polish-WFF-args F = {}
proof
  let L, E;
  let F be Polish-WFF of L, E;
  assume A1: F in Polish-atoms(L, E);
  then F in L by Def7;
  hence Polish-WFF-head F = F & L-head F = F by Th53;
  then Polish-arity F = 0 by A1, Def7;
  hence Polish-WFF-args F = {} by Th61;
end;
