theorem
  H is conditional implies H is negative & the_argument_of H is
  conjunctive & the_right_argument_of the_argument_of H is negative
proof
  given F,G such that
A1: H = F => G;
  the_argument_of 'not'(F '&' 'not' G) = F '&' 'not' G &
  the_right_argument_of (F '&' 'not' G) = 'not' G by Th1,Th4;
  hence thesis by A1;
end;
