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fix proof generation for euf-solver

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2023-07-23 14:31:44 -07:00
parent e64bab4bb8
commit 48deb4d3e0
6 changed files with 108 additions and 49 deletions
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84
src/sat/smt/euf_proof.cpp
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@ -44,17 +44,73 @@ namespace euf {
}
/**
* \brief logs antecedents to a proof trail.
*
* NB with theories, this is not a pure EUF justification,
* It is true modulo EUF and previously logged certificates
* so it isn't necessarily an axiom over EUF,
* We will here leave it to the EUF checker to perform resolution steps.
*/
* Log justifications.
* is_euf - true if l is justified by congruence closure. In this case create a congruence closure proof.
* explain_size - the relevant portion of premises for the congruence closure proof.
* The EUF solver manages equality propagation. Each propagated equality is justified by a congruence closure.
*/
void solver::log_justifications(literal l, unsigned explain_size, bool is_euf) {
unsigned nv = s().num_vars();
expr_ref_vector eqs(m);
auto add_hint_literals = [&](unsigned sz) {
eqs.reset();
m_hint_lits.reset();
nv = s().num_vars();
for (unsigned i = 0; i < sz; ++i) {
size_t* e = m_explain[i];
if (is_literal(e))
m_hint_lits.push_back(get_literal(e));
else {
auto [x, y] = th_explain::from_index(get_justification(e)).eq_consequent();
eqs.push_back(m.mk_eq(x->get_expr(), y->get_expr()));
set_tmp_bool_var(nv, eqs.back());
m_hint_lits.push_back(literal(nv, false));
++nv;
}
}
};
auto clear_hint_literals = [&]() {
for (unsigned v = s().num_vars(); v < nv; ++v)
set_tmp_bool_var(v, nullptr);
};
// log EUF justifications
if (is_euf) {
add_hint_literals(explain_size);
auto* hint = mk_hint(m_euf, l);
log_antecedents(l, m_hint_lits, hint);
clear_hint_literals();
}
// explain equalities
for (auto const& [a, b] : m_hint_eqs) {
m_egraph.begin_explain();
m_explain.reset();
m_egraph.explain_eq<size_t>(m_explain, &m_explain_cc, a, b);
m_egraph.end_explain();
// Detect shortcut if equality is explained directly by a theory
if (m_explain.size() == 1 && !is_literal(m_explain[0])) {
auto const& [x, y] = th_explain::from_index(get_justification(m_explain[0])).eq_consequent();
if (x == a && y == b)
continue;
}
add_hint_literals(m_explain.size());
eqs.push_back(m.mk_eq(a->get_expr(), b->get_expr()));
set_tmp_bool_var(nv, eqs.back());
sat::literal eql = literal(nv, false);
++nv;
auto* hint = mk_hint(m_euf, eql);
log_antecedents(eql, m_hint_lits, hint);
clear_hint_literals();
}
}
void solver::log_antecedents(literal l, literal_vector const& r, th_proof_hint* hint) {
SASSERT(hint && use_drat());
TRACE("euf", log_antecedents(tout, l, r); tout << mk_pp(hint->get_hint(*this), m) << "\n");
if (!use_drat())
return;
literal_vector lits;
for (literal lit : r)
lits.push_back(~lit);
@ -63,6 +119,15 @@ namespace euf {
get_drat().add(lits, sat::status::th(true, get_id(), hint));
}
void solver::log_rup(literal l, literal_vector const& r) {
literal_vector lits;
for (literal lit : r)
lits.push_back(~lit);
if (l != sat::null_literal)
lits.push_back(l);
get_drat().add(lits, sat::status::redundant());
}
void solver::log_antecedents(std::ostream& out, literal l, literal_vector const& r) {
for (sat::literal l : r) {
expr* n = m_bool_var2expr[l.var()];
@ -159,6 +224,7 @@ namespace euf {
};
for (unsigned i = m_lit_head; i < m_lit_tail; ++i)
args.push_back(s.literal2expr(s.m_proof_literals[i]));
std::sort(s.m_explain_cc.data() + m_cc_head, s.m_explain_cc.data() + m_cc_tail, compare_ts);
for (unsigned i = m_cc_head; i < m_cc_tail; ++i) {
auto const& [a, b, ts, comm] = s.m_explain_cc[i];