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Polysat: first pass at forbidden intervals (not yet fully integrated into solver) (#5227)

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* Add interval class

* Take dependency as const reference

* Compute forbidden intervals for ule-constraints

* Add class for evaluated interval

* We need the evaluated bounds as well

* Don't add constraint to cjust multiple times (hack, to be improved later)

* typo

* More interval helpers

* Add constraint::ult factory function

* Fix forbidden interval condition

* Add solver::has_viable

* Add conflict explanation using forbidden intervals (not yet fully integrated into solver)
This commit is contained in:
Jakob Rath 2021-04-29 19:12:54 +02:00 • committed by GitHub
parent 60972de562
commit f83705bf9f
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14 changed files with 501 additions and 13 deletions
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29
src/math/polysat/solver.cpp
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@ -19,6 +19,7 @@ Author:
#include "math/polysat/solver.h"
#include "math/polysat/log.h"
#include "math/polysat/fixplex_def.h"
#include "math/polysat/forbidden_intervals.h"
namespace polysat {
@ -40,6 +41,10 @@ namespace polysat {
return *bits;
}
bool solver::has_viable(pvar v) {
return !m_viable[v].is_false();
}
bool solver::is_viable(pvar v, rational const& val) {
return var2bits(v).contains(m_viable[v], val);
}
@ -421,17 +426,39 @@ namespace polysat {
return;
}
pvar conflict_var = null_var;
scoped_ptr<constraint> lemma;
reset_marks();
for (constraint* c : m_conflict)
for (auto v : c->vars())
for (auto v : c->vars()) {
set_mark(v);
if (!has_viable(v)) {
SASSERT(conflict_var == null_var || conflict_var == v); // at most one variable can be empty
conflict_var = v;
}
}
if (conflict_var != null_var) {
LOG_H2("Conflict due to empty viable set for pvar " << conflict_var);
scoped_ptr_vector<constraint> disjunctive_lemma;
if (forbidden_intervals::explain(*this, m_conflict, conflict_var, disjunctive_lemma)) {
LOG_H3("Learning disjunctive lemma"); // << disjunctive_lemma);
SASSERT(disjunctive_lemma.size() > 0);
if (disjunctive_lemma.size() == 1) {
// TODO: continue normally?
} else {
// TODO: solver needs to return l_undef and allow external handling of disjunctive lemma
}
}
}
for (unsigned i = m_search.size(); i-- > 0; ) {
pvar v = m_search[i].first;
LOG_H2("Working on pvar " << v);
if (!is_marked(v))
continue;
justification& j = m_justification[v];
LOG("Justification: " << j);
if (j.level() <= base_level()) {
report_unsat();
return;