
theorem
  for x,y being Element of BOOLEAN holds nand2.<*x,y*> = 'not' (x '&' y)
& nand2a.<*x,y*> = 'not' ('not' x '&' y) & or2.<*x,y*> = 'not' ('not' x '&'
  'not' y) by Def2,Def3,Lm1;
