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reviewing seq_nielsen, detect repeated final-check to avoid rebuilding nielsen graph

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2026-03-30 00:01:24 -07:00
parent a79a48ed2a
commit 9aceaf3cac
3 changed files with 34 additions and 87 deletions
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30
src/smt/theory_nseq.cpp
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@ -537,6 +537,14 @@ namespace smt {
return FC_DONE;
}
// All literals that were needed to build a model could be assigned to true.
// There is an existing nielsen graph with a satisfying assignment.
if (!m_nielsen_literals.empty() &&
all_of(m_nielsen_literals, [&](auto lit) { return l_true == ctx.get_assignment(lit); })) {
IF_VERBOSE(1, verbose_stream() << "nseq final_check: satifiable state revisited\n");
return FC_DONE;
}
// unfold higher-order terms when sequence structure is known
if (unfold_ho_terms()) {
IF_VERBOSE(1, verbose_stream() << "nseq final_check: unfolded ho_terms, FC_CONTINUE\n";);
@ -625,12 +633,20 @@ namespace smt {
}
bool theory_nseq::add_nielsen_assumptions() {
// return true;
bool theory_nseq::add_nielsen_assumptions() {
bool has_undef = false;
bool has_false = false;
m_nielsen_literals.reset();
struct reset_vector : public trail {
sat::literal_vector &v;
reset_vector(sat::literal_vector &v) : v(v) {}
void undo() override {
v.reset();
}
};
ctx.push_trail(reset_vector(m_nielsen_literals));
for (auto const& c : m_nielsen.sat_node()->constraints()) {
auto lit = mk_literal(c.fml);
m_nielsen_literals.push_back(lit);
switch (ctx.get_assignment(lit)) {
case l_true:
break;
@ -642,8 +658,7 @@ namespace smt {
TRACE(seq, tout << "assign: " << c.fml << "\n");
break;
case l_false:
// do we really expect this to happen?
has_false = true;
// this should not happen because nielsen checks for this before returning a satisfying path.
IF_VERBOSE(0, verbose_stream()
<< "nseq final_check: nielsen assumption " << c.fml << " is false\n";);
ctx.force_phase(lit);
@ -654,11 +669,6 @@ namespace smt {
}
if (has_undef)
return false;
if (has_false) {
IF_VERBOSE(0, verbose_stream() << "has false\n");
// fishy case.
return false;
}
return true;
}