reserve X,Y for set, x,y,z for object, i,j,n for natural number;
reserve
  n for non empty Nat,
  S for non empty non void n PC-correct PCLangSignature,
  L for language MSAlgebra over S,
  F for PC-theory of L,
  A,B,C,D for Formula of L;

theorem :: Modus ponendo ponens
  B\imp((B\impA)\impA) in F
  proof
A1: ((B\impA)\imp(B\impA))\imp(B\imp((B\impA)\impA)) in F by Th41;
    (B\impA)\imp(B\impA) in F by Th34;
    hence thesis by A1,Def38;
  end;
