
theorem
  for x,y being Element of BOOLEAN holds or2.<*x,y*> = x 'or' y & or2a.
  <*x,y*> = 'not' x 'or' y & nand2.<*x,y*> = 'not' x 'or' 'not' y
   by FACIRC_1:def 5,Def4
