update in ground_2 and basic_2

[helm.git] / matita / matita / contribs / lambdadelta / ground_2 / lib / arith.ma

diff --git a/matita/matita/contribs/lambdadelta/ground_2/lib/arith.ma b/matita/matita/contribs/lambdadelta/ground_2/lib/arith.ma
index 932f95de21eb441d4897083156538eb71c282a67..dfc61de151fa83e058f234f30fdc0f2438d0dd1b 100644 (file)
--- a/matita/matita/contribs/lambdadelta/ground_2/lib/arith.ma
+++ b/matita/matita/contribs/lambdadelta/ground_2/lib/arith.ma
@@ -60,9 +60,11 @@ lemma minus_plus_m_m_commutative: ∀n,m:nat. n = m + n - m.
 lemma plus_n_2: ∀n. n + 2 = n + 1 + 1.
 // qed.
 
-lemma arith_l: ∀x. 1 = 1-x+(x-(x-1)).
-* // #x >minus_S_S >minus_S_S <minus_O_n <minus_n_O //
-qed.
+lemma arith_l (n1) (n2): ↑n2-n1 = 1-n1+(n2-(n1-1)).
+* // qed.
+
+lemma arith_l_eq: ∀x. 1 = 1-x+(x-(x-1)).
+// qed.
 
 (* Note: uses minus_minus_comm, minus_plus_m_m, commutative_plus, plus_minus *)
 lemma plus_minus_minus_be: ∀x,y,z. y ≤ z → z ≤ x → (x - z) + (z - y) = x - y.
@@ -147,6 +149,9 @@ fact le_repl_sn_trans_aux: ∀x,y,z:nat. x ≤ z → y = x → y ≤ z.
 lemma monotonic_le_minus_l2: ∀x1,x2,y,z. x1 ≤ x2 → x1 - y - z ≤ x2 - y - z.
 /3 width=1 by monotonic_le_minus_l/ qed.
 
+lemma minus_le_trans_sn: ∀x1,x2. x1 ≤ x2 → ∀x. x1-x ≤ x2.
+/2 width=3 by transitive_le/ qed.
+
 (* Note: this might interfere with nat.ma *)
 lemma monotonic_lt_pred: ∀m,n. m < n → 0 < m → pred m < pred n.
 #m #n #Hmn #Hm whd >(S_pred … Hm)