Lemma sqrrB1 x :

(* Specifications: *)
Lemma subr_sqr_1 x : x ^+ 2 -
Proof. by rewrite subrX1 !bi
Qed.
Proof. by move=> lt0kp; apply/e
rewrite subn0 mulr1 mul1r bin0 binn big1 ?ad
have charRp: p \in [char R] by r
elim: e => // e IHe; rewrite
Lemma addrr_char2 x : x + x = 0. Proof. b