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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2021-11-18 15:53:51 -08:00
commit 6bf4f001d9
6 changed files with 51 additions and 49 deletions
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78
src/math/polysat/solver.cpp
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@ -134,13 +134,15 @@ namespace polysat {
m_constraints.ensure_bvar(c.get());
sat::literal lit = c.blit();
LOG("New constraint: " << c);
if (m_bvars.is_false(lit) || c.is_currently_false(*this)) {
set_conflict(c /*, dep */);
return;
if (m_bvars.is_false(lit))
set_conflict(c);
else {
m_bvars.asserted(lit, m_level, dep);
m_trail.push_back(trail_instr_t::assign_bool_i);
m_search.push_boolean(lit);
if (c.is_currently_false(*this))
set_conflict(c);
}
m_bvars.asserted(lit, m_level, dep);
m_trail.push_back(trail_instr_t::assign_bool_i);
m_search.push_boolean(lit);
#if ENABLE_LINEAR_SOLVER
m_linear_solver.new_constraint(*c.get());
@ -582,38 +584,43 @@ namespace polysat {
return;
case l_false:
break;
case l_undef:
num_choices++;
case l_undef:
if (lit2cnstr(lit).is_currently_false(*this)) {
unsigned level = m_level; // TODO
assign_eval(level, lit);
}
else
else {
num_choices++;
choice = lit;
}
break;
}
}
LOG_V("num_choices: " << num_choices);
if (choice == sat::null_literal) {
// This case may happen when all undefined literals are false under the current variable assignment.
// TODO: The question is whether such lemmas should be generated? Check test_monot() for such a case.
switch (num_choices) {
case 0:
set_conflict(lemma);
return;
}
signed_constraint c = lit2cnstr(choice);
if (num_choices > 1)
push_level();
if (num_choices == 1)
break;
case 1:
assign_propagate(choice, lemma);
else
break;
default:
push_level();
assign_decision(choice, &lemma);
break;
}
}
/**
* Revert a decision that caused a conflict.
* Variable v was assigned by a decision at position i in the search stack.
*
* C & v = val is conflict.
*
* C => v != val
*
* l1 \/ l2 \/ ... \/ lk \/ v != val
*
*/
void solver::revert_decision(pvar v) {
rational val = m_value[v];
@ -621,21 +628,14 @@ namespace polysat {
SASSERT(m_justification[v].is_decision());
clause_ref lemma = m_conflict.build_lemma().build();
if (lemma->empty()) {
if (lemma->empty())
report_unsat();
return;
}
m_conflict.reset();
backjump(get_level(v) - 1);
// The justification for this restriction is the guessed constraint from the lemma.
// cjust[v] will be updated accordingly by decide_bool.
// m_viable.add_non_viable(v, val);
learn_lemma(*lemma);
if (!is_conflict())
else {
m_conflict.reset();
backjump(get_level(v) - 1);
learn_lemma(*lemma);
narrow(v);
}
}
bool solver::is_decision(search_item const& item) const {
@ -685,11 +685,8 @@ namespace polysat {
backjump(m_bvars.level(var) - 1);
add_lemma(*reason);
if (is_conflict()) {
LOG_H1("Conflict during revert_bool_decision/propagate_bool!");
return;
}
if (lemma)
if (!is_conflict() && lemma)
decide_bool(*lemma);
}
@ -763,7 +760,8 @@ namespace polysat {
* placeholder for factoring/gcd common factors
*/
void solver::narrow(pvar v) {
if (is_conflict())
return;
}
// Add lemma to storage