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Add (updated and general) solve_for functionality for arithmetic, add congruence_explain to API to retrieve explanation for why two terms are congruent Tweak handling of smt.qi.max_instantations

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Add API solve_for(vars).
It takes a list of variables and returns a triangular solved form for the variables.
Currently for arithmetic. The solved form is a list with elements of the form (var, term, guard).
Variables solved in the tail of the list do not occur before in the list.
For example it can return a solution [(x, z, True), (y, x + z, True)] because first x was solved to be z,
then y was solved to be x + z which is the same as 2z.

Add congruent_explain that retuns an explanation for congruent terms.
Terms congruent in the final state after calling SimpleSolver().check() can be queried for
an explanation, i.e., a list of literals that collectively entail the equality under congruence closure.
The literals are asserted in the final state of search.

Adjust smt_context cancellation for the smt.qi.max_instantiations parameter.
It gets checked when qi-queue elements are consumed.
Prior it was checked on insertion time, which didn't allow for processing as many
instantations as there were in the queue. Moreover, it would not cancel the solver.
So it would keep adding instantations to the queue when it was full / depleted the
configuration limit.
This commit is contained in:
Nikolaj Bjorner 2024-12-19 23:26:42 +01:00
parent e4ab2944fe
commit 87f7a20e14
31 changed files with 428 additions and 117 deletions
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145
src/smt/theory_lra.cpp
View file

@ -3169,7 +3169,7 @@ public:
typedef std::pair<lp::constraint_index, rational> constraint_bound;
vector<constraint_bound> m_lower_terms;
vector<constraint_bound> m_upper_terms;
void propagate_eqs(lp::lpvar t, lp::constraint_index ci1, lp::lconstraint_kind k, api_bound& b, rational const& value) {
u_dependency* ci2 = nullptr;
auto pair = [&]() { return lp().dep_manager().mk_join(lp().dep_manager().mk_leaf(ci1), ci2); };
@ -3392,9 +3392,8 @@ public:
}
void set_evidence(lp::constraint_index idx, literal_vector& core, svector<enode_pair>& eqs) {
if (idx == UINT_MAX) {
return;
}
if (idx == UINT_MAX)
return;
switch (m_constraint_sources[idx]) {
case inequality_source: {
literal lit = m_inequalities[idx];
@ -3629,33 +3628,116 @@ public:
return lp().has_upper_bound(vi, dep, val, is_strict);
}
bool solve_for(enode* n, expr_ref& term) {
theory_var v = n->get_th_var(get_id());
if (!is_registered_var(v))
return false;
lpvar vi = get_lpvar(v);
lp::lar_term t;
rational coeff;
if (!lp().solve_for(vi, t, coeff))
return false;
rational lc(1);
if (is_int(v)) {
lc = denominator(coeff);
for (auto const& cv : t)
lc = lcm(denominator(cv.coeff()), lc);
if (lc != 1) {
coeff *= lc;
t *= lc;
}
}
term = mk_term(t, is_int(v));
if (coeff != 0)
term = a.mk_add(a.mk_numeral(coeff, is_int(v)), term);
if (lc != 1)
term = a.mk_idiv(term, a.mk_numeral(lc, true));
return true;
void solve_fixed(enode* n, lpvar j, expr_ref& term, expr_ref& guard) {
term = a.mk_numeral(lp().get_value(j), a.is_int(n->get_expr()));
reset_evidence();
add_explain(j);
guard = extract_explain();
}
void add_explain(unsigned j) {
auto d = lp().get_bound_constraint_witnesses_for_column(j);
set_evidence(d, m_core, m_eqs);
}
expr_ref extract_explain() {
expr_ref_vector es(m);
for (auto [l, r] : m_eqs)
es.push_back(a.mk_eq(l->get_expr(), r->get_expr()));
for (auto l : m_core)
es.push_back(ctx().literal2expr(l));
// remove duplicats from es:
std::stable_sort(es.data(), es.data() + es.size());
unsigned j = 0;
for (unsigned i = 0; i < es.size(); ++i) {
if (i > 0 && es.get(i) == es.get(i - 1))
continue;
es[j++] = es.get(i);
}
es.shrink(j);
return mk_and(es);
}
void solve_term(enode* n, lp::lar_term & lt, expr_ref& term, expr_ref& guard) {
bool is_int = a.is_int(n->get_expr());
bool all_int = is_int;
lp::lar_term t;
rational coeff(0);
expr_ref_vector guards(m);
reset_evidence();
for (auto const& cv : lt) {
if (lp().column_is_fixed(cv.j())) {
coeff += lp().get_value(cv.j()) * cv.coeff();
add_explain(cv.j());
}
else
t.add_monomial(cv.coeff(), cv.j());
}
guards.push_back(extract_explain());
rational lc = denominator(coeff);
for (auto const& cv : t) {
lc = lcm(denominator(cv.coeff()), lc);
all_int &= lp().column_is_int(cv.j());
}
if (lc != 1)
t *= lc, coeff *= lc;
term = mk_term(t, is_int);
if (coeff != 0)
term = a.mk_add(term, a.mk_numeral(coeff, is_int));
if (lc == 1) {
guard = mk_and(guards);
return;
}
expr_ref lce(a.mk_numeral(lc, true), m);
if (all_int)
guards.push_back(m.mk_eq(a.mk_mod(term, lce), a.mk_int(0)));
else if (is_int)
guards.push_back(a.mk_is_int(a.mk_div(term, lce)));
term = a.mk_idiv(term, lce);
guard = mk_and(guards);
}
void solve_for(vector<solution>& solutions) {
unsigned_vector vars;
unsigned j = 0;
for (auto [e, t, g] : solutions) {
auto n = get_enode(e);
if (!n) {
solutions[j++] = { e, t, g };
continue;
}
theory_var v = n->get_th_var(get_id());
if (!is_registered_var(v))
solutions[j++] = { e, t, g };
else
vars.push_back(get_lpvar(v));
}
solutions.shrink(j);
expr_ref term(m), guard(m);
vector<lp::lar_solver::solution> sols;
lp().solve_for(vars, sols);
uint_set seen;
for (auto& s : sols) {
auto n = get_enode(lp().local_to_external(s.j));
if (lp().column_is_fixed(s.j))
solve_fixed(n, s.j, term, guard);
else
solve_term(n, s.t, term, guard);
solutions.push_back({ n->get_expr(), term, guard});
seen.insert(s.j);
}
for (auto j : vars) {
if (seen.contains(j) || !lp().column_is_fixed(j))
continue;
auto n = get_enode(lp().local_to_external(j));
solve_fixed(n, j, term, guard);
solutions.push_back({ n->get_expr(), term, guard });
}
}
bool get_upper(enode* n, expr_ref& r) {
bool is_strict;
rational val;
@ -4166,8 +4248,9 @@ bool theory_lra::get_lower(enode* n, rational& r, bool& is_strict) {
bool theory_lra::get_upper(enode* n, rational& r, bool& is_strict) {
return m_imp->get_upper(n, r, is_strict);
}
bool theory_lra::solve_for(enode* n, expr_ref& r) {
return m_imp->solve_for(n, r);
void theory_lra::solve_for(vector<solution>& sol) {
m_imp->solve_for(sol);
}
void theory_lra::display(std::ostream & out) const {