(*** le_or_ge *)
lemma nle_ge_dis (m) (n): ∨∨ m ≤ n | n ≤ m.
-#m #n @(nat_ind_succ_2 … m n) -m -n
+#m #n @(nat_ind_2_succ … m n) -m -n
[ /2 width=1 by or_introl/
| /2 width=1 by or_intror/
| #m #n * /3 width=2 by nle_succ_bi, or_introl, or_intror/
]
qed-.
-(* Basic inversions *********************************************************)
+(* Basic destructions *******************************************************)
-lemma nle_inv_succ_sn (m) (n): ↑m ≤ n → m ≤ n.
+lemma nle_des_succ_sn (m) (n): ↑m ≤ n → m ≤ n.
#m #n #H elim H -n /2 width=1 by nle_succ_dx/
qed-.
+(* Basic inversions *********************************************************)
+
(*** le_S_S_to_le *)
lemma nle_inv_succ_bi (m) (n): ↑m ≤ ↑n → m ≤ n.
#m #n @(insert_eq_0 … (↑n))
-#y * -y
-[ #H <(eq_inv_nsucc_bi … H) -m //
-| #y #Hy #H >(eq_inv_nsucc_bi … H) -n /2 width=1 by nle_inv_succ_sn/
+#x * -x
+[ #H >(eq_inv_nsucc_bi … H) -n //
+| #o #Ho #H >(eq_inv_nsucc_bi … H) -n
+ /2 width=1 by nle_des_succ_sn/
]
qed-.
#m @(insert_eq_0 … (𝟎))
#y * -y
[ #H destruct //
-| #y #_ #H elim (eq_inv_nzero_succ … H)
+| #y #_ #H elim (eq_inv_zero_nsucc … H)
]
qed-.
(* Advanced inversions ******************************************************)
+(*** le_plus_xSy_O_false *)
lemma nle_inv_succ_zero (m): ↑m ≤ 𝟎 → ⊥.
-/3 width=2 by nle_inv_zero_dx, eq_inv_nzero_succ/ qed-.
+/3 width=2 by nle_inv_zero_dx, eq_inv_zero_nsucc/ qed-.
lemma nle_inv_succ_sn_refl (m): ↑m ≤ m → ⊥.
#m @(nat_ind_succ … m) -m [| #m #IH ] #H
-[ /3 width=2 by nle_inv_zero_dx, eq_inv_nzero_succ/
+[ /3 width=2 by nle_inv_zero_dx, eq_inv_zero_nsucc/
| /3 width=1 by nle_inv_succ_bi/
]
qed-.
theorem nle_antisym (m) (n): m ≤ n → n ≤ m → m = n.
#m #n #H elim H -n //
#n #_ #IH #Hn
-lapply (nle_inv_succ_sn … Hn) #H
+lapply (nle_des_succ_sn … Hn) #H
lapply (IH H) -IH -H #H destruct
elim (nle_inv_succ_sn_refl … Hn)
qed-.
(∀n. Q (𝟎) (n)) →
(∀m,n. m ≤ n → Q m n → Q (↑m) (↑n)) →
∀m,n. m ≤ n → Q m n.
-#Q #IH1 #IH2 #m #n @(nat_ind_succ_2 … m n) -m -n //
+#Q #IH1 #IH2 #m #n @(nat_ind_2_succ … m n) -m -n //
[ #m #H elim (nle_inv_succ_zero … H)
| /4 width=1 by nle_inv_succ_bi/
]
(*** transitive_le *)
theorem nle_trans: Transitive … nle.
-#m #n #H elim H -n /3 width=1 by nle_inv_succ_sn/
+#m #n #H elim H -n /3 width=1 by nle_des_succ_sn/
qed-.
-(*** decidable_le *)
+(*** decidable_le le_dec *)
lemma nle_dec (m) (n): Decidable … (m ≤ n).
#m #n elim (nle_ge_dis m n) [ /2 width=1 by or_introl/ ]
#Hnm elim (eq_nat_dec m n) [ #H destruct /2 width=1 by nle_refl, or_introl/ ]