Definition contraTT := contraLR.

(* Specifications: *)
Lemma contraT b : (~~ b -> false) -> b.
Lemma wlog_neg b : (~~ b -> b) -> b.
Lemma contraFT (c b : bool) : (~~ c -> b) -> b = false -> c.
Lemma contraFN (c b : bool) : (c -> b) -> b = false -> ~~ c.
Lemma contraTF (c b : bool) : (c -> ~~ b) -> b -> c = false.
Lemma contraNF (c b : bool) : (c -> b) -> ~~ b -> c = false.
Lemma contraFF (c b : bool) : (c -> b) -> b = false -> c = false.