From e167bc0b0d1e770cdd5994ade002335b88f87b65 Mon Sep 17 00:00:00 2001 From: Ferruccio Guidi Date: Wed, 2 May 2007 09:53:20 +0000 Subject: [PATCH] some improvements --- matita/contribs/RELATIONAL/NPlus/monoid.ma | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/matita/contribs/RELATIONAL/NPlus/monoid.ma b/matita/contribs/RELATIONAL/NPlus/monoid.ma index 4d1705b90..368396a77 100644 --- a/matita/contribs/RELATIONAL/NPlus/monoid.ma +++ b/matita/contribs/RELATIONAL/NPlus/monoid.ma @@ -39,6 +39,19 @@ theorem nplus_comm_rew: \forall p,q,r. (p + q == r) \to q + p == r. intros. elim H; clear H q r; auto. qed. +theorem nplus_ass: \forall p1, p2, r1. (p1 + p2 == r1) \to + \forall p3, s1. (r1 + p3 == s1) \to + \forall r3. (p2 + p3 == r3) \to + \forall s3. (p1 + r3 == s3) \to s1 = s3. + intros 4. elim H; clear H p2 r1; + [ lapply linear nplus_inv_zero_1 to H2. subst. + lapply nplus_mono to H1, H3. subst. auto + | lapply linear nplus_inv_succ_1 to H3. decompose. subst. + lapply linear nplus_inv_succ_1 to H4. decompose. subst. + lapply linear nplus_inv_succ_2 to H5. decompose. subst. auto + ]. +qed. + (* Corollaries of functional properties **************************************) theorem nplus_inj_2: \forall p, q1, r. (p + q1 == r) \to -- 2.39.2