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
  assume H is conditional;
  then
A1: H = (the_antecedent_of H) => (the_consequent_of H) by ZF_LANG:47;
  hence H is negative;
A2: the_argument_of H = (the_antecedent_of H) '&' 'not'(the_consequent_of H)
  by A1,Th3;
  hence the_argument_of H is conjunctive;
  the_right_argument_of the_argument_of H = 'not' (the_consequent_of H) by A2
,Th4;
  hence thesis;
end;
