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add Horner saturation to Grobner conflict detection

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- throttle Grobner
- add (disabled) propagate_linear_equation to prepare for additional propagation.
- add validation code is_nla_conflict/add_nla_conflict to establish missed conflicts
This commit is contained in:
Nikolaj Bjorner 2023-10-17 21:19:57 -07:00
parent 0a1cc4c054
commit 37fe9cc764
3 changed files with 167 additions and 38 deletions
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172
src/math/lp/nla_grobner.cpp
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@ -13,7 +13,6 @@ Author:
#include "util/uint_set.h"
#include "math/lp/nla_core.h"
#include "math/lp/factorization_factory_imp.h"
#include "math/lp/nex.h"
#include "math/grobner/pdd_solver.h"
#include "math/dd/pdd_interval.h"
#include "math/dd/pdd_eval.h"
@ -33,17 +32,33 @@ namespace nla {
}
void grobner::operator()() {
if (lra.column_count() > 5000)
return;
if (m_quota == 0)
m_quota = c().params().arith_nl_gr_q();
if (m_quota == 1)
if (m_quota == 1) {
m_delay_base++;
m_delay = m_delay_base;
m_quota = c().params().arith_nl_gr_q();
}
if (m_delay > 0) {
--m_delay;
return;
}
lp_settings().stats().m_grobner_calls++;
find_nl_cluster();
configure();
m_solver.saturate();
if (m_delay_base > 0)
--m_delay_base;
if (is_conflicting())
return;
@ -56,6 +71,9 @@ namespace nla {
if (propagate_factorization())
return;
if (false && propagate_linear_equations())
return;
}
catch (...) {
@ -63,15 +81,14 @@ namespace nla {
// DEBUG_CODE(for (auto e : m_solver.equations()) check_missing_propagation(*e););
++m_delay_base;
if (m_quota > 0)
--m_quota;
IF_VERBOSE(2, verbose_stream() << "grobner miss, quota " << m_quota << "\n");
IF_VERBOSE(3, verbose_stream() << "grobner miss, quota " << m_quota << "\n");
IF_VERBOSE(4, diagnose_pdd_miss(verbose_stream()));
#if 0
// diagnostics: did we miss something
vector<dd::pdd> eqs;
@ -82,18 +99,16 @@ namespace nla {
}
bool grobner::is_conflicting() {
unsigned conflicts = 0;
for (auto eq : m_solver.equations())
if (is_conflicting(*eq) && ++conflicts >= m_solver.number_of_conflicts_to_report())
break;
if (conflicts > 0)
lp_settings().stats().m_grobner_conflicts++;
TRACE("grobner", m_solver.display(tout));
IF_VERBOSE(2, if (conflicts > 0) verbose_stream() << "grobner conflict\n");
return conflicts > 0;
bool is_conflict = false;
for (auto eq : m_solver.equations()) {
if (is_conflicting(*eq)) {
lp_settings().stats().m_grobner_conflicts++;
TRACE("grobner", m_solver.display(tout));
IF_VERBOSE(3, verbose_stream() << "grobner conflict\n");
return true;
}
}
return false;
}
bool grobner::propagate_bounds() {
@ -293,22 +308,29 @@ namespace nla {
return out;
}
bool grobner::is_conflicting(const dd::solver::equation& e) {
for (auto j : e.poly().free_vars())
if (lra.column_is_free(j))
return false;
bool grobner::equation_is_true(dd::solver::equation const& eq) {
if (any_of(eq.poly().free_vars(), [&](unsigned j) { return lra.column_is_free(j); }))
return true;
dd::pdd_eval eval;
eval.var2val() = [&](unsigned j){ return val(j); };
return eval(eq.poly()) == 0;
}
bool grobner::is_conflicting(const dd::solver::equation& e) {
if (equation_is_true(e))
return false;
auto& di = c().m_intervals.get_dep_intervals();
dd::pdd_interval eval(di);
eval.var2interval() = [this](lpvar j, bool deps, scoped_dep_interval& a) {
dd::pdd_interval evali(di);
evali.var2interval() = [this](lpvar j, bool deps, scoped_dep_interval& a) {
if (deps) c().m_intervals.set_var_interval<dd::w_dep::with_deps>(j, a);
else c().m_intervals.set_var_interval<dd::w_dep::without_deps>(j, a);
};
scoped_dep_interval i(di), i_wd(di);
eval.get_interval<dd::w_dep::without_deps>(e.poly(), i);
evali.get_interval<dd::w_dep::without_deps>(e.poly(), i);
if (!di.separated_from_zero(i)) {
TRACE("grobner", m_solver.display(tout << "not separated from 0 ", e) << "\n";
eval.get_interval_distributed<dd::w_dep::without_deps>(e.poly(), i);
evali.get_interval_distributed<dd::w_dep::without_deps>(e.poly(), i);
tout << "separated from 0: " << di.separated_from_zero(i) << "\n";
for (auto j : e.poly().free_vars()) {
scoped_dep_interval a(di);
@ -316,14 +338,17 @@ namespace nla {
c().m_intervals.display(tout << "j" << j << " ", a); tout << " ";
}
tout << "\n");
if (add_horner_conflict(e))
return true;
#if 0
if (add_nla_conflict(e))
return true;
#endif
return false;
}
eval.get_interval<dd::w_dep::with_deps>(e.poly(), i_wd);
evali.get_interval<dd::w_dep::with_deps>(e.poly(), i_wd);
std::function<void (const lp::explanation&)> f = [this](const lp::explanation& e) {
new_lemma lemma(m_core, "pdd");
lemma &= e;
@ -356,6 +381,57 @@ namespace nla {
return false;
}
bool grobner::propagate_linear_equations() {
unsigned changed = 0;
for (auto eq : m_solver.equations())
if (propagate_linear_equations(*eq) && ++changed >= m_solver.number_of_conflicts_to_report())
return true;
return changed > 0;
}
bool grobner::propagate_linear_equations(dd::solver::equation const& e) {
if (equation_is_true(e))
return false;
if (!e.poly().is_linear())
return false;
rational lc(1);
for (auto const& [coeff, vars] : e.poly())
lc = lcm(denominator(coeff), lc);
auto q = e.poly();
#if 0
// TODO: instead add a row to lra solver, make sure that make_feasible
// gets invoked (for example, bail out of final check).
vector<std::pair<lp::mpq, unsigned>> coeffs;
while (!q.is_val()) {
coeffs.push_back({lc*q.hi().val(), q.var()});
q = q.lo();
}
lp::lpvar term_index = c().lra.add_term(coeffs, UINT_MAX);
term_index = c().lra.map_term_index_to_column_index(term_index);
c().lra.update_column_type_and_bound(term_index, lp::lconstraint_kind::EQ, -lc*q.val(), e.dep());
#else
new_lemma lemma(m_core,"nla-linear");
lp::explanation exp;
explain(e, exp);
lemma &= exp;
term t;
while (!q.is_val()) {
t.add_monomial(lc*q.hi().val(), q.var());
q = q.lo();
}
lemma |= ineq(t, llc::EQ, -lc*q.val());
#endif
return true;
}
void grobner::add_var_and_its_factors_to_q_and_collect_new_rows(lpvar j, svector<lpvar> & q) {
if (c().active_var_set_contains(j))
return;
@ -581,6 +657,50 @@ namespace nla {
return l_false == c().m_nra.check(eqs);
}
bool grobner::add_horner_conflict(const dd::solver::equation& eq) {
nex_creator& nc = m_nex_creator;
nc.pop(0);
nex_creator::sum_factory sum(nc);
unsigned row_index = 0;
u_map<nex_var*> var2nex;
for (auto v : eq.poly().free_vars())
var2nex.insert(v, nc.mk_var(v));
unsigned mx = 0;
for (auto v : eq.poly().free_vars())
mx = std::max(v, mx);
nc.set_number_of_vars(mx + 1);
for (auto const& [coeff, vars] : eq.poly()) {
switch (vars.size()) {
case 0:
sum += nc.mk_scalar(coeff);
break;
case 1:
sum += nc.mk_mul(coeff, var2nex[vars[0]]);
break;
default:
nc.m_mk_mul.reset();
nc.m_mk_mul *= coeff;
for (auto v : vars)
nc.m_mk_mul *= var2nex[v];
sum += nc.m_mk_mul.mk();
break;
}
}
nex* e = nc.simplify(sum.mk());
if (e->get_degree() < 2 || !e->is_sum())
return false;
auto dep = eq.dep();
cross_nested cn(
[this, dep](const nex* n) { bool r = c().m_intervals.check_nex(n, dep); TRACE("grobner", tout << "check " << r << " " << *n << "\n"); return r; },
[this](unsigned j) { return c().var_is_fixed(j); },
[this]() { return c().random(); }, nc);
cn.run(to_sum(e));
bool ret = cn.done();
TRACE("grobner", tout << "Horner " << ret << " " << eq.poly() << "\n");
return ret;
}
bool grobner::add_nla_conflict(const dd::solver::equation& eq) {
if (is_nla_conflict(eq)) {
new_lemma lemma(m_core,"nla-conflict");