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This commit is contained in:
Jakob Rath 2022-08-04 11:51:25 +02:00
parent 4282cfa148
commit a3e8124245
1 changed files with 70 additions and 64 deletions
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134
src/math/polysat/solver.cpp
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@ -273,7 +273,10 @@ namespace polysat {
DEBUG_CODE(m_locked_wlist = std::nullopt;);
}
/** Return true if a new watch was found; or false to keep the existing one. */
/**
* Propagate assignment to variable v into constraint c.
* Return true if a new watch was found; or false to keep the existing one.
*/
bool solver::propagate(pvar v, constraint* c) {
LOG_H3("Propagate " << m_vars[v] << " in " << constraint_pp(c, m_bvars.value(c->bvar())));
SASSERT(is_assigned(v));
@ -288,16 +291,9 @@ namespace polysat {
if (!is_assigned(other_v)) {
add_pwatch(c, other_v);
std::swap(c->vars()[idx], c->vars()[i]);
// if (!is_assigned(c->var(1 - idx))) // TODO: why this check? if the other watch is already assigned (because e.g. all other variables have been propagated from other constraints first), then we end up with 3 watches on c
return true;
return true;
}
}
// TODO: aren't we visiting many constraints twice here?
// first, when one variable is unassigned -> intersect viable with constraint
// second, when all variables are assigned -> check if there's a conflict.
// maybe not really a problem.
// at most one poly variable remains unassigned.
if (m_bvars.is_assigned(c->bvar())) {
// constraint is active, propagate it
@ -314,10 +310,10 @@ namespace polysat {
SASSERT(!c->is_active());
if (c->vars().size() >= 2) {
unsigned other_v = c->var(1 - idx);
if (!is_assigned(other_v)) {
// wait for the remaining variable to be assigned (might not be necessary in all cases)
// Wait for the remaining variable to be assigned
// (although sometimes we would be able to evaluate constraints earlier)
if (!is_assigned(other_v))
return false;
}
}
// Evaluate constraint
signed_constraint sc(c, true);
@ -331,19 +327,26 @@ namespace polysat {
return false;
}
/**
* Propagate boolean assignment of literal lit into clause cl.
* Return true if a new watch was found; or false to keep the existing one.
*/
bool solver::propagate(sat::literal lit, clause& cl) {
SASSERT(m_bvars.is_true(lit));
SASSERT(cl.size() >= 2);
unsigned idx = cl[0] == ~lit ? 1 : 0;
unsigned idx = (cl[0] == ~lit) ? 1 : 0;
SASSERT(cl[1 - idx] == ~lit);
if (m_bvars.is_true(cl[idx]))
return false;
unsigned i = 2;
for (; i < cl.size() && m_bvars.is_false(cl[i]); ++i);
if (i < cl.size()) {
// found non-false literal in cl; watch it instead
m_bvars.watch(cl[i]).push_back(&cl);
std::swap(cl[1 - idx], cl[i]);
return true;
}
// all literals in cl are false, except possibly the other watch cl[idx]
if (m_bvars.is_false(cl[idx]))
set_conflict(cl);
else
@ -363,6 +366,60 @@ namespace polysat {
#endif
}
void solver::add_pwatch(constraint* c) {
SASSERT(c);
if (c->is_pwatched())
return;
auto& vars = c->vars();
unsigned i = 0, j = 0, sz = vars.size();
for (; i < sz && j < 2; ++i)
if (!is_assigned(vars[i]))
std::swap(vars[i], vars[j++]);
if (vars.size() > 0)
add_pwatch(c, vars[0]);
if (vars.size() > 1)
add_pwatch(c, vars[1]);
c->set_pwatched(true);
m_pwatch_trail.push_back(c);
m_trail.push_back(trail_instr_t::pwatch_i);
}
void solver::add_pwatch(constraint* c, pvar v) {
SASSERT(m_locked_wlist != v); // the propagate loop will not discover the new size
LOG("Watching v" << v << " in constraint " << show_deref(c));
m_pwatch[v].push_back(c);
}
void solver::erase_pwatch(constraint* c) {
if (!c->is_pwatched())
return;
auto const& vars = c->vars();
if (vars.size() > 0)
erase_pwatch(vars[0], c);
if (vars.size() > 1)
erase_pwatch(vars[1], c);
c->set_pwatched(false);
}
void solver::erase_pwatch(pvar v, constraint* c) {
if (v == null_var)
return;
SASSERT(m_locked_wlist != v);
LOG("Unwatching v" << v << " in constraint " << show_deref(c));
auto& wlist = m_pwatch[v];
unsigned sz = wlist.size();
for (unsigned i = 0; i < sz; ++i) {
if (c == wlist[i]) {
wlist[i] = wlist.back();
wlist.pop_back();
return;
}
}
}
// TODO: get rid of this or at least rename it
void solver::propagate(pvar v, rational const& val, signed_constraint c) {
// this looks weird... mixing propagation and conflict with c? also, the conflict should not be c but the whole of viable+c.
LOG("Propagation: " << assignment_pp(*this, v, val) << ", due to " << c);
@ -466,57 +523,6 @@ namespace polysat {
}
}
void solver::add_pwatch(constraint* c) {
SASSERT(c);
if (c->is_pwatched())
return;
auto& vars = c->vars();
unsigned i = 0, j = 0, sz = vars.size();
for (; i < sz && j < 2; ++i)
if (!is_assigned(vars[i]))
std::swap(vars[i], vars[j++]);
if (vars.size() > 0)
add_pwatch(c, vars[0]);
if (vars.size() > 1)
add_pwatch(c, vars[1]);
c->set_pwatched(true);
m_pwatch_trail.push_back(c);
m_trail.push_back(trail_instr_t::pwatch_i);
}
void solver::add_pwatch(constraint* c, pvar v) {
// SASSERT(m_locked_wlist != v); // appending doesn't interfere with propagation, so it should be fine
LOG("Watching v" << v << " in constraint " << show_deref(c));
m_pwatch[v].push_back(c);
}
void solver::erase_pwatch(constraint* c) {
if (!c->is_pwatched())
return;
auto const& vars = c->vars();
if (vars.size() > 0)
erase_pwatch(vars[0], c);
if (vars.size() > 1)
erase_pwatch(vars[1], c);
c->set_pwatched(false);
}
void solver::erase_pwatch(pvar v, constraint* c) {
if (v == null_var)
return;
SASSERT(m_locked_wlist != v);
LOG("Unwatching v" << v << " in constraint " << show_deref(c));
auto& wlist = m_pwatch[v];
unsigned sz = wlist.size();
for (unsigned i = 0; i < sz; ++i) {
if (c == wlist[i]) {
wlist[i] = wlist.back();
wlist.pop_back();
return;
}
}
}
void solver::decide() {
LOG_H2("Decide");
SASSERT(can_decide());