reserve p,p1,p2,q,r,F,G,G1,G2,H,H1,H2 for ZF-formula,
  x,x1,x2,y,y1,y2,z,z1,z2,s,t for Variable,
  a,X for set;

theorem
  not (H is being_equality & (H is being_membership or H is negative or
  H is conjunctive or H is universal)) & not (H is being_membership & (H is
  negative or H is conjunctive or H is universal)) & not (H is negative & (H is
  conjunctive or H is universal)) & not (H is conjunctive & H is universal)
proof
  H.1 = 0 or H.1 = 1 or H.1 = 2 or H.1 = 3 or H.1 = 4 by ZF_LANG:23;
  hence thesis by ZF_LANG:18,19,20,21,22;
end;
