reserve Y for non empty set,
  a,b,c,d for Function of Y,BOOLEAN;
reserve Y for non empty set,
  a,b,c for Function of Y,BOOLEAN;

theorem Th36:
  a 'nor' (b 'imp' c) = 'not' a '&' b '&' 'not' c
proof
  thus a 'nor' (b 'imp' c) = 'not' (a 'or' (b 'imp' c)) by Th2
    .= ('not' a) '&' ('not' (b 'imp' c)) by BVFUNC_1:13
    .= ('not' a) '&' (b '&' 'not' c) by Th1
    .= 'not' a '&' b '&' 'not' c by BVFUNC_1:4;
end;
