 reserve i,j,n,k,l for Nat;
 reserve T,S,X,Y,Z for Subset of MC-wff;
 reserve p,q,r,t,F,H,G for Element of MC-wff;
 reserve s,U,V for MC-formula;

theorem Th1:
  0 in Proof_Step_Kinds_IPC & ... & 10 in Proof_Step_Kinds_IPC;
