
theorem
  for x,y being Element of BOOLEAN holds and2.<*x,y*> = x '&' y & and2a.
<*x,y*> = 'not' x '&' y & nor2.<*x,y*> = 'not' x '&' 'not' y
   by FACIRC_1:def 6,Def1,Lm3;
