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wip - add xor and non-bool ite tseitin rules

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This commit is contained in:
Nikolaj Bjorner 2022-10-11 09:15:18 +02:00
parent cd8b8b603a
commit 62438da0f5
2 changed files with 57 additions and 19 deletions
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64
src/sat/smt/tseitin_proof_checker.cpp
View file

@ -13,7 +13,17 @@ Author:
Nikolaj Bjorner (nbjorner) 2022-10-07
TODOs:
- handle distinct
- handle other internalization from euf_internalize
- equiv should be modulo commutativity (the E-graph indexes expressions modulo commutativity of top-level operator)
- should we log rules for root clauses too? Root clauses should follow from input.
They may be simplified using Tseitin transformation. For example, (and a b) is clausified into
two clauses a, b.
- Tesitin checking could also be performed by depth-bounded SAT (e.g., using BDDs)
--*/
#include "ast/ast_pp.h"
@ -44,7 +54,7 @@ namespace tseitin {
if (!main_expr)
return false;
expr* a, * x, * y, *z;
expr* a, * x, * y, *z, *u, *v;
// (or (and a b) (not a) (not b))
// (or (and (not a) b) a (not b))
@ -53,10 +63,10 @@ namespace tseitin {
for (expr* arg : *jst)
complement_mark(arg);
for (expr* arg : *to_app(main_expr)) {
for (expr* arg : *to_app(main_expr))
if (!is_complement(arg))
return false;
}
return true;
}
@ -83,6 +93,16 @@ namespace tseitin {
return true;
}
if (m.is_eq(main_expr, x, y) && m.is_ite(x, z, u, v)) {
scoped_mark sm(*this);
for (expr* arg : *jst)
complement_mark(arg);
if (is_marked(z) && equiv(y, v))
return true;
if (is_complement(z) && equiv(y, u))
return true;
}
// (or (if a b c) (not b) (not c))
// (or (if a b c) a (not c))
// (or (if a b c) (not a) (not b))
@ -112,6 +132,21 @@ namespace tseitin {
return true;
}
// (or (xor a b c d) a b (not c) (not d))
if (m.is_xor(main_expr)) {
scoped_mark sm(*this);
for (expr* arg : *jst)
complement_mark(arg);
int parity = 0;
for (expr* arg : *to_app(main_expr))
if (is_marked(arg))
parity++;
else if (is_complement(arg))
parity--;
if ((parity % 2) == 0)
return true;
}
if (m.is_not(main_expr, a)) {
// (or (not a) a')
@ -174,17 +209,24 @@ namespace tseitin {
return true;
}
// (or (not (xor a b c d)) a b c (not d))
if (m.is_xor(a)) {
scoped_mark sm(*this);
for (expr* arg : *jst)
complement_mark(arg);
int parity = 1;
for (expr* arg : *to_app(main_expr))
if (is_marked(arg))
parity++;
else if (is_complement(arg))
parity--;
if ((parity % 2) == 0)
return true;
}
IF_VERBOSE(0, verbose_stream() << "miss " << mk_pp(main_expr, m) << "\n");
#if 0
if (m.is_implies(a))
return false;
if (m.is_ite(a))
return false;
if (m.is_distinct(a))
return false;
#endif
}
return false;
}

12
src/sat/tactic/goal2sat.cpp
View file

@ -142,23 +142,19 @@ struct goal2sat::imp : public sat::sat_internalizer {
bool top_level_relevant() {
return m_top_level && relevancy_enabled();
}
void mk_clause(sat::literal l) {
mk_clause(1, &l);
}
}
void mk_clause(sat::literal l1, sat::literal l2, euf::th_proof_hint* ph = nullptr) {
void mk_clause(sat::literal l1, sat::literal l2, euf::th_proof_hint* ph) {
sat::literal lits[2] = { l1, l2 };
mk_clause(2, lits, ph);
}
void mk_clause(sat::literal l1, sat::literal l2, sat::literal l3, euf::th_proof_hint* ph = nullptr) {
void mk_clause(sat::literal l1, sat::literal l2, sat::literal l3, euf::th_proof_hint* ph) {
sat::literal lits[3] = { l1, l2, l3 };
mk_clause(3, lits, ph);
}
void mk_clause(unsigned n, sat::literal * lits, euf::th_proof_hint* ph = nullptr) {
void mk_clause(unsigned n, sat::literal * lits, euf::th_proof_hint* ph) {
TRACE("goal2sat", tout << "mk_clause: "; for (unsigned i = 0; i < n; i++) tout << lits[i] << " "; tout << "\n";);
if (relevancy_enabled())
ensure_euf()->add_aux(n, lits);