`hooo_dual_rev_neq` should require excluded middle for `A, B`
bvssvni opened this issue · comments
See #620
Since hooo_dual_eq
is too strong, a new constructive proof is desirable for hooo_dual_rev_neq
.
A such proof exists if excluded middle is required for A, B
.
This is required due to or::from_de_morgan
being used in the proof.
I think this proof is acceptable, given that the only reference to hooo_dual_rev_neq
is in tauto_from_para_transitivity
which requires excluded middle.
This can be also used to prove tauto_hooo_dual_rev_neq
when A, B
uses excluded middle.