From 019d78e2194277fb38e8635ed33960cecfa812f2 Mon Sep 17 00:00:00 2001
From: Nikolaj Bjorner <nbjorner@microsoft.com>
Date: Wed, 24 Jul 2019 09:47:25 -0700
Subject: [PATCH] fix #2422
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
---
src/smt/theory_seq.cpp | 26 +++++++++++++-------------
1 file changed, 13 insertions(+), 13 deletions(-)
diff --git a/src/smt/theory_seq.cpp b/src/smt/theory_seq.cpp
index ede98c783..e27b5f8ce 100644
--- a/src/smt/theory_seq.cpp
+++ b/src/smt/theory_seq.cpp
@@ -4998,10 +4998,7 @@ this translates to:
0 <= i <= |s| -> len(x) = i
0 <= i <= |s| & 0 <= l <= |s| - i -> |e| = l
0 <= i <= |s| & |s| < l + i -> |e| = |s| - i
- i >= |s| => |e| = 0
- i < 0 => |e| = 0
- l <= 0 => |e| = 0
- |e| = 0 => i < 0 | l <= 0 | i >= |s|
+ |e| = 0 <=> i < 0 | |s| <= i | l <= 0 | |s| <= 0
It follows that:
|e| = min(l, |s| - i) for 0 <= i < |s| and 0 < |l|
@@ -5040,21 +5037,24 @@ void theory_seq::add_extract_axiom(expr* e) {
expr_ref zero(m_autil.mk_int(0), m);
literal i_ge_0 = mk_simplified_literal(m_autil.mk_ge(i, zero));
- literal ls_le_i = mk_simplified_literal(m_autil.mk_le(mk_sub(i, ls), zero));
+ literal i_le_ls = mk_simplified_literal(m_autil.mk_le(mk_sub(i, ls), zero));
+ literal ls_le_i = mk_simplified_literal(m_autil.mk_le(mk_sub(ls, i), zero));
literal li_ge_ls = mk_simplified_literal(m_autil.mk_ge(ls_minus_i_l, zero));
- literal l_ge_zero = mk_simplified_literal(m_autil.mk_ge(l, zero));
+ literal l_ge_0 = mk_simplified_literal(m_autil.mk_ge(l, zero));
+ literal l_le_0 = mk_simplified_literal(m_autil.mk_le(l, zero));
literal ls_le_0 = mk_simplified_literal(m_autil.mk_le(ls, zero));
literal le_is_0 = mk_eq(le, zero, false);
- add_axiom(~i_ge_0, ~ls_le_i, mk_seq_eq(xey, s));
- add_axiom(~i_ge_0, ~ls_le_i, mk_eq(lx, i, false));
- add_axiom(~i_ge_0, ~ls_le_i, ~l_ge_zero, ~li_ge_ls, mk_eq(le, l, false));
- add_axiom(~i_ge_0, ~ls_le_i, li_ge_ls, mk_eq(le, mk_sub(ls, i), false));
- add_axiom(~i_ge_0, ~ls_le_i, l_ge_zero, mk_eq(le, zero, false));
+ add_axiom(~i_ge_0, ~i_le_ls, mk_seq_eq(xey, s));
+ add_axiom(~i_ge_0, ~i_le_ls, mk_eq(lx, i, false));
+ add_axiom(~i_ge_0, ~i_le_ls, ~l_ge_0, ~li_ge_ls, mk_eq(le, l, false));
+ add_axiom(~i_ge_0, ~i_le_ls, li_ge_ls, mk_eq(le, mk_sub(ls, i), false));
+ add_axiom(~i_ge_0, ~i_le_ls, l_ge_0, mk_eq(le, zero, false));
add_axiom(i_ge_0, le_is_0);
- add_axiom(ls_le_i, le_is_0);
+ add_axiom(~ls_le_i, le_is_0);
add_axiom(~ls_le_0, le_is_0);
- add_axiom(~le_is_0, ~i_ge_0, ~ls_le_i, ls_le_0);
+ add_axiom(~l_le_0, le_is_0);
+ add_axiom(~le_is_0, ~i_ge_0, ls_le_i, ls_le_0, l_le_0);
}
void theory_seq::add_tail_axiom(expr* e, expr* s) {