reserve T, X, Y for Subset of HP-WFF;
reserve p, q, r, s for Element of HP-WFF;

theorem Th36:
  ( (p => q) '&' p ) => q in HP_TAUT
proof
  set P = p => q;
A1: P => P in HP_TAUT by Th14;
  ( P => P ) => (( P '&' p ) => q ) in HP_TAUT by Th34;
  hence thesis by A1,Def10;
end;
