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add variable minimization

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This commit is contained in:
Nikolaj Bjorner 2021-09-22 14:27:05 -07:00
parent c82bbaad7d
commit e6c413b249
6 changed files with 85 additions and 51 deletions
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36
src/math/polysat/conflict.cpp
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@ -22,6 +22,7 @@ Notes:
It should apply saturation rules currently only available for propagated values.
TODO: dependency tracking for constraints evaluating to false should be minimized.
--*/
#include "math/polysat/conflict.h"
@ -39,9 +40,7 @@ namespace polysat {
conflict::conflict(solver& s):s(s) {
ex_engines.push_back(alloc(ex_polynomial_superposition, s));
ve_engines.push_back(alloc(ve_reduction));
inf_engines.push_back(alloc(inf_saturate));
for (auto* engine : inf_engines)
engine->set_solver(s);
inf_engines.push_back(alloc(inf_saturate, s));
}
conflict::~conflict() {}
@ -218,6 +217,9 @@ namespace polysat {
while (!m_constraints.empty())
keep(m_constraints.back());
for (auto c : *this)
minimize_vars(c);
for (auto c : *this)
lemma.push(~c);
@ -232,6 +234,34 @@ namespace polysat {
return lemma;
}
void conflict::minimize_vars(signed_constraint c) {
if (m_vars.empty())
return;
if (!c.is_currently_false(s))
return;
assignment_t a;
for (auto v : m_vars)
a.push_back(std::make_pair(v, s.get_value(v)));
for (unsigned i = 0; i < a.size(); ++i) {
auto save = a[i];
auto last = a.back();
a[i] = last;
a.pop_back();
if (c.is_currently_false(a))
--i;
else {
a.push_back(last);
a[i] = save;
}
}
if (a.size() == m_vars.num_elems())
return;
m_vars.reset();
for (auto [v, val] : a)
m_vars.insert(v);
LOG("reduced " << m_vars);
}
bool conflict::resolve_value(pvar v, vector<signed_constraint> const& cjust_v) {
// NOTE: