theorem eqb_to_Prop: \forall n,m:nat.
match (eqb n m) with
[ true \Rightarrow n = m
-| false \Rightarrow \lnot (n = m)].
+| false \Rightarrow n \neq m].
intros.
apply nat_elim2
(\lambda n,m:nat.match (eqb n m) with
[ true \Rightarrow n = m
-| false \Rightarrow \lnot (n = m)]).
+| false \Rightarrow n \neq m]).
intro.elim n1.
simplify.reflexivity.
simplify.apply not_eq_O_S.
qed.
theorem eqb_elim : \forall n,m:nat.\forall P:bool \to Prop.
-(n=m \to (P true)) \to (\lnot n=m \to (P false)) \to (P (eqb n m)).
+(n=m \to (P true)) \to (n \neq m \to (P false)) \to (P (eqb n m)).
intros.
cut
match (eqb n m) with
[ true \Rightarrow n = m
-| false \Rightarrow \lnot (n = m)] \to (P (eqb n m)).
+| false \Rightarrow n \neq m] \to (P (eqb n m)).
apply Hcut.apply eqb_to_Prop.
elim eqb n m.
apply (H H2).
theorem leb_to_Prop: \forall n,m:nat.
match (leb n m) with
[ true \Rightarrow n \leq m
-| false \Rightarrow \lnot (n \leq m)].
+| false \Rightarrow n \nleq m].
intros.
apply nat_elim2
(\lambda n,m:nat.match (leb n m) with
[ true \Rightarrow n \leq m
-| false \Rightarrow \lnot (n \leq m)]).
+| false \Rightarrow n \nleq m]).
simplify.exact le_O_n.
simplify.exact not_le_Sn_O.
intros 2.simplify.elim (leb n1 m1).
qed.
theorem leb_elim: \forall n,m:nat. \forall P:bool \to Prop.
-(n \leq m \to (P true)) \to (\lnot (n \leq m) \to (P false)) \to
+(n \leq m \to (P true)) \to (n \nleq m \to (P false)) \to
P (leb n m).
intros.
cut
match (leb n m) with
[ true \Rightarrow n \leq m
-| false \Rightarrow \lnot (n \leq m)] \to (P (leb n m)).
+| false \Rightarrow n \nleq m] \to (P (leb n m)).
apply Hcut.apply leb_to_Prop.
elim leb n m.
apply (H H2).