reserve L for satisfying_Sh_1 non empty ShefferStr;
reserve L for satisfying_Sheffer_1 satisfying_Sheffer_2 satisfying_Sheffer_3
  non empty ShefferStr;
reserve v,q,p,w,z,y,x for Element of L;

theorem Th112:
  for w,y,p holds (w | p) | (w | (p | (y | (y | y)))) = w
proof
  let w,y,p;
  p | p = p | (y | (y | y)) by SHEFFER1:def 14;
  hence thesis by Th107;
end;
