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add interpretations when there are ranges

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2025-10-20 23:21:30 +02:00
parent 65f38eac16
commit 2e4402c8f3
8 changed files with 427 additions and 158 deletions
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12
src/smt/smt_context.cpp
View file

@ -1525,16 +1525,24 @@ namespace smt {
}
lbool context::find_assignment(expr * n) const {
if (m.is_false(n))
return l_false;
expr* arg = nullptr;
if (m.is_not(n, arg)) {
if (b_internalized(arg))
return ~get_assignment_core(arg);
if (m.is_false(arg))
return l_true;
if (m.is_true(arg))
return l_false;
return l_undef;
}
if (b_internalized(n))
return get_assignment(n);
if (m.is_false(n))
return l_false;
if (m.is_true(n))
return l_true;
return l_undef;
}

268
src/smt/theory_finite_set.cpp
View file

@ -15,6 +15,7 @@ Abstract:
#include "smt/theory_finite_set.h"
#include "smt/smt_context.h"
#include "smt/smt_model_generator.h"
#include "smt/smt_arith_value.h"
#include "ast/ast_pp.h"
namespace smt {
@ -29,8 +30,8 @@ namespace smt {
m_axioms(m), m_find(*this)
{
// Setup the add_clause callback for axioms
std::function<void(theory_axiom const &)> add_clause_fn =
[this](theory_axiom const &ax) {
std::function<void(theory_axiom *)> add_clause_fn =
[this](theory_axiom* ax) {
this->add_clause(ax);
};
m_axioms.set_add_clause(add_clause_fn);
@ -67,7 +68,7 @@ namespace smt {
theory_var r = theory::mk_var(n);
VERIFY(r == static_cast<theory_var>(m_find.mk_var()));
SASSERT(r == static_cast<int>(m_var_data.size()));
m_var_data.push_back(alloc(var_data));
m_var_data.push_back(alloc(var_data, m));
ctx.push_trail(push_back_vector<ptr_vector<var_data>>(m_var_data));
ctx.push_trail(new_obj_trail(m_var_data.back()));
expr *e = n->get_expr();
@ -90,7 +91,8 @@ namespace smt {
m_var_data[r]->m_setops.push_back(n);
ctx.push_trail(push_back_trail(m_var_data[r]->m_setops));
for (auto arg : enode::args(n)) {
if (!u.is_finite_set(arg->get_expr()))
expr *e = arg->get_expr();
if (!u.is_finite_set(e))
continue;
auto v = arg->get_root()->get_th_var(get_id());
SASSERT(v != null_theory_var);
@ -103,6 +105,9 @@ namespace smt {
}
else if (u.is_map(e) || u.is_filter(e)) {
NOT_IMPLEMENTED_YET();
}
else if (u.is_range(e)) {
}
return r;
}
@ -157,6 +162,7 @@ namespace smt {
* for each T := (set.op U V) in d2->setops
* then S ~ T by construction
* add axioms for (set.in x T)
*
*/
void theory_finite_set::add_in_axioms(enode *in, var_data *d) {
@ -276,6 +282,9 @@ namespace smt {
if (activate_unasserted_clause())
return FC_CONTINUE;
if (false && activate_range_local_axioms())
return FC_CONTINUE;
if (assume_eqs())
return FC_CONTINUE;
@ -293,20 +302,38 @@ namespace smt {
* - (set.singleton x) -> (set.in x (set.singleton x))
* - (set.singleton x) -> (set.size (set.singleton x)) = 1
* - (set.empty) -> (set.size (set.empty)) = 0
* - (set.range lo hi) -> lo-1,hi+1 not in range, lo, hi in range
*/
void theory_finite_set::add_immediate_axioms(app* term) {
expr *elem = nullptr, *set = nullptr;
expr *lo = nullptr, *hi = nullptr;
unsigned sz = m_clauses.axioms.size();
if (u.is_in(term, elem, set) && u.is_empty(set))
add_membership_axioms(elem, set);
else if (u.is_subset(term))
m_axioms.subset_axiom(term);
else if (u.is_singleton(term, elem))
m_axioms.in_singleton_axiom(elem, term);
else if (u.is_singleton(term))
m_axioms.in_singleton_axiom(term);
else if (u.is_range(term, lo, hi)) {
m_axioms.in_range_axiom(term);
auto range = ctx.get_enode(term);
auto v = range->get_th_var(get_id());
// declare lo-1, lo, hi, hi+1 as range local.
// we don't have to add additional range local variables for them.
auto &range_local = m_var_data[v]->m_range_local;
ctx.push_trail(push_back_vector(range_local));
arith_util a(m);
range_local.push_back(lo);
range_local.push_back(hi);
range_local.push_back(a.mk_add(lo, a.mk_int(-1)));
range_local.push_back(a.mk_add(hi, a.mk_int(1)));
}
// Assert all new lemmas as clauses
for (unsigned i = sz; i < m_clauses.axioms.size(); ++i)
for (unsigned i = sz; i < m_clauses.axioms.size(); ++i) {
m_clauses.squeue.push_back(i);
ctx.push_trail(push_back_vector(m_clauses.squeue));
}
}
void theory_finite_set::assign_eh(bool_var v, bool is_true) {
@ -322,8 +349,8 @@ namespace smt {
for (unsigned i = 0; i < m_clauses.watch[idx].size(); ++i) {
TRACE(finite_set, tout << " watch[" << i << "] size: " << m_clauses.watch[i].size() << "\n";);
auto clause_idx = m_clauses.watch[idx][i];
auto &ax = m_clauses.axioms[clause_idx];
auto &clause = ax.clause;
auto* ax = m_clauses.axioms[clause_idx];
auto &clause = ax->clause;
if (any_of(clause, [&](expr *lit) { return ctx.find_assignment(lit) == l_true; })) {
TRACE(finite_set, tout << " satisfied\n";);
m_clauses.watch[idx][j++] = clause_idx;
@ -365,6 +392,7 @@ namespace smt {
continue; // the clause is removed from this watch list
// either all literals are false, or the other watch literal is propagating.
m_clauses.squeue.push_back(clause_idx);
ctx.push_trail(push_back_vector(m_clauses.squeue));
TRACE(finite_set, tout << " propagate clause\n";);
m_clauses.watch[idx][j++] = clause_idx;
++i;
@ -390,21 +418,22 @@ namespace smt {
// empty the propagation queue of clauses to assert
while (m_clauses.sqhead < m_clauses.squeue.size() && !ctx.inconsistent()) {
auto index = m_clauses.squeue[m_clauses.sqhead++];
auto const &clause = m_clauses.axioms[index];
assert_clause(clause);
auto clause_idx = m_clauses.squeue[m_clauses.sqhead++];
auto ax = m_clauses.axioms[clause_idx];
assert_clause(ax);
}
}
}
void theory_finite_set::activate_clause(unsigned clause_idx) {
TRACE(finite_set, tout << "activate_clause: " << clause_idx << "\n";);
auto &ax = m_clauses.axioms[clause_idx];
auto &clause = ax.clause;
auto* ax = m_clauses.axioms[clause_idx];
auto &clause = ax->clause;
if (any_of(clause, [&](expr *e) { return ctx.find_assignment(e) == l_true; }))
return;
if (clause.size() <= 1) {
m_clauses.squeue.push_back(clause_idx);
ctx.push_trail(push_back_vector(m_clauses.squeue));
return;
}
expr *w1 = nullptr, *w2 = nullptr;
@ -430,6 +459,7 @@ namespace smt {
}
if (!w2) {
m_clauses.squeue.push_back(clause_idx);
ctx.push_trail(push_back_vector(m_clauses.squeue));
return;
}
bool w1neg = m.is_not(w1, w1);
@ -446,8 +476,8 @@ namespace smt {
unsigned index;
unwatch_clause(theory_finite_set &th, unsigned index) : th(th), index(index) {}
void undo() override {
auto &ax = th.m_clauses.axioms[index];
auto &clause = ax.clause;
auto* ax = th.m_clauses.axioms[index];
auto &clause = ax->clause;
expr *w1 = clause.get(0);
expr *w2 = clause.get(1);
bool w1neg = th.m.is_not(w1, w1);
@ -487,8 +517,9 @@ namespace smt {
// Create a union expression that is canonical (sorted)
auto& set = *m_set_members[r];
ptr_vector<expr> elems;
for (auto e : set)
elems.push_back(e->get_expr());
for (auto [e,b] : set)
if (b)
elems.push_back(e->get_expr());
std::sort(elems.begin(), elems.end(), [](expr *a, expr *b) { return a->get_id() < b->get_id(); });
expr *s = mk_union(elems.size(), elems.data(), n->get_expr()->get_sort());
trail.push_back(s);
@ -569,9 +600,10 @@ namespace smt {
}
}
void theory_finite_set::add_clause(theory_axiom const& ax) {
void theory_finite_set::add_clause(theory_axiom* ax) {
TRACE(finite_set, tout << "add_clause: " << ax << "\n");
ctx.push_trail(push_back_vector(m_clauses.axioms));
ctx.push_trail(new_obj_trail(ax));
m_clauses.axioms.push_back(ax);
m_stats.m_num_axioms_created++;
}
@ -601,19 +633,19 @@ namespace smt {
mg.register_factory(m_factory);
collect_members();
}
void theory_finite_set::collect_members() {
// This method can be used to collect all elements that are members of sets
// and ensure that the model factory has values for them.
// For now, we rely on the default model construction.
reset_set_members();
for (auto f : m_set_in_decls) {
for (auto n : ctx.enodes_of(f)) {
SASSERT(u.is_in(n->get_expr()));
auto x = n->get_arg(0);
if (!ctx.is_relevant(x))
if (!ctx.is_relevant(n))
continue;
x = x->get_root();
SASSERT(u.is_in(n->get_expr()));
auto x = n->get_arg(0)->get_root();
if (x->is_marked())
continue;
x->set_mark(); // make sure we only do this once per element
@ -622,61 +654,139 @@ namespace smt {
continue;
if (!u.is_in(p->get_expr()))
continue;
if (ctx.get_assignment(p->get_expr()) != l_true)
continue;
bool b = ctx.find_assignment(p->get_expr()) == l_true;
auto set = p->get_arg(1)->get_root();
auto elem = p->get_arg(0)->get_root();
if (elem != x)
continue;
if (!m_set_members.contains(set))
m_set_members.insert(set, alloc(obj_hashtable<enode>));
m_set_members.find(set)->insert(x);
if (!m_set_members.contains(set)) {
using om = obj_map<enode, bool>;
auto m = alloc(om);
m_set_members.insert(set, m);
}
m_set_members.find(set)->insert(x, b);
}
}
}
for (auto f : m_set_in_decls) {
for (auto n : ctx.enodes_of(f)) {
SASSERT(u.is_in(n->get_expr()));
auto x = n->get_arg(0);
x = x->get_root();
auto x = n->get_arg(0)->get_root();
if (x->is_marked())
x->unset_mark();
}
}
}
// to collect range interpretations for S:
// walk parents of S that are (set.in x S)
// evaluate truth value of (set.in x S), evaluate x
// add (eval(x), eval(set.in x S)) into a vector.
// sort the vector by eval(x)
// [(v1, b1), (v2, b2), ..., (vn, bn)]
// for the first i, with b_i true, add the range [vi, v_{i+1}-1].
// the last bn should be false by construction.
void theory_finite_set::add_range_interpretation(enode* s) {
vector<std::tuple<rational, enode *, bool>> elements;
arith_value av(m);
av.init(&ctx);
for (auto p : enode::parents(s)) {
if (!ctx.is_relevant(p))
continue;
if (u.is_in(p->get_expr())) {
rational val;
auto x = p->get_arg(0)->get_root();
VERIFY(av.get_value_equiv(x->get_expr(), val) && val.is_int());
elements.push_back({val, x, ctx.find_assignment(p->get_expr()) == l_true});
}
}
std::stable_sort(elements.begin(), elements.end(),
[](auto const &a, auto const &b) { return std::get<0>(a) < std::get<0>(b); });
}
struct finite_set_value_proc : model_value_proc {
theory_finite_set &th;
sort *s = nullptr;
obj_hashtable<enode>* m_elements = nullptr;
enode *n = nullptr;
obj_map<enode, bool>* m_elements = nullptr;
finite_set_value_proc(theory_finite_set &th, sort *s, obj_hashtable<enode> *elements)
: th(th), s(s), m_elements(elements) {}
// use range interpretations if there is a range constraint and the base sort is integer
bool use_range() {
auto &m = th.m;
sort *base_s = nullptr;
VERIFY(th.u.is_finite_set(n->get_expr()->get_sort(), base_s));
arith_util a(m);
if (!a.is_int(base_s))
return false;
func_decl_ref range_fn(th.u.mk_range_decl(), m);
return th.ctx.get_num_enodes_of(range_fn.get()) > 0;
}
finite_set_value_proc(theory_finite_set &th, enode *n, obj_map<enode, bool> *elements)
: th(th), n(n), m_elements(elements) {}
void get_dependencies(buffer<model_value_dependency> &result) override {
if (!m_elements)
return;
for (auto v : *m_elements)
result.push_back(model_value_dependency(v));
bool ur = use_range();
for (auto [n, b] : *m_elements)
if (!ur || b)
result.push_back(model_value_dependency(n));
}
app *mk_value(model_generator &mg, expr_ref_vector const &values) override {
SASSERT(values.empty() == !m_elements);
if (values.empty())
auto s = n->get_sort();
if (values.empty())
return th.u.mk_empty(s);
SASSERT(m_elements);
SASSERT(values.size() == m_elements->size());
return th.mk_union(values.size(), values.data(), s);
SASSERT(m_elements);
if (use_range())
return mk_range_value(mg, values);
else
return th.mk_union(values.size(), values.data(), s);
}
app *mk_range_value(model_generator &mg, expr_ref_vector const &values) {
unsigned i = 0;
arith_value av(th.m);
av.init(&th.ctx);
vector<std::tuple<rational, enode *, bool>> elems;
for (auto [n, b] : *m_elements) {
rational r;
av.get_value(n->get_expr(), r);
elems.push_back({r, n, b});
}
std::stable_sort(elems.begin(), elems.end(),
[](auto const &a, auto const &b) { return std::get<0>(a) < std::get<0>(b); });
app *range = nullptr;
arith_util a(th.m);
for (unsigned j = 0; j < elems.size(); ++j) {
auto [r, n, b] = elems[j];
if (!b)
continue;
rational lo = r;
rational hi = j + 1 < elems.size() ? std::get<0>(elems[j + 1]) - rational(1) : r;
while (j + 1 < elems.size() && std::get<0>(elems[j + 1]) == hi + rational(1) && std::get<2>(elems[j + 1])) {
hi = std::get<0>(elems[j + 1]);
++j;
}
auto new_range = th.u.mk_range(a.mk_int(lo), a.mk_int(hi));
range = range ? th.u.mk_union(range, new_range) : new_range;
}
return range ? range : th.u.mk_empty(n->get_sort());
}
};
model_value_proc * theory_finite_set::mk_value(enode * n, model_generator & mg) {
TRACE(finite_set, tout << "mk_value: " << mk_pp(n->get_expr(), m) << "\n";);
obj_hashtable<enode>*elements = nullptr;
sort *s = n->get_expr()->get_sort();
m_set_members.find(n->get_root(), elements);
return alloc(finite_set_value_proc, *this, s, elements);
TRACE(finite_set, tout << "mk_value: " << mk_pp(n->get_expr(), m) << "\n";);
obj_map<enode, bool>*elements = nullptr;
n = n->get_root();
m_set_members.find(n, elements);
return alloc(finite_set_value_proc, *this, n, elements);
}
@ -692,10 +802,62 @@ namespace smt {
return false;
}
bool theory_finite_set::assert_clause(theory_axiom const &ax) {
auto const &clause = ax.clause;
/*
* Add x-1, x+1 in range axioms for every x in setop(range, S)
* then x-1, x+1 will also propagate against setop(range, S).
*/
bool theory_finite_set::activate_range_local_axioms() {
bool new_axiom = false;
func_decl_ref range_fn(u.mk_range_decl(), m);
for (auto range : ctx.enodes_of(range_fn.get())) {
SASSERT(u.is_range(range->get_expr()));
auto v = range->get_th_var(get_id());
for (auto p : m_var_data[v]->m_parent_setops) {
auto w = p->get_th_var(get_id());
for (auto in : m_var_data[w]->m_parent_in) {
if (activate_range_local_axioms(in->get_arg(0)->get_expr(), range))
new_axiom = true;
}
}
}
return new_axiom;
}
bool theory_finite_set::activate_range_local_axioms(expr* elem, enode* range) {
auto v = range->get_th_var(get_id());
auto &range_local = m_var_data[v]->m_range_local;
auto &parent_in = m_var_data[v]->m_parent_in;
if (range_local.contains(elem))
return false;
arith_util a(m);
expr_ref lo(a.mk_add(elem, a.mk_int(-1)), m);
expr_ref hi(a.mk_add(elem, a.mk_int(1)), m);
bool new_axiom = false;
if (!range_local.contains(lo) && all_of(parent_in, [lo](enode* in) { return in->get_arg(0)->get_expr() != lo; })) {
// lo is not range local and lo is not already in an expression (lo in range)
// checking that lo is not in range_local is actually redundant because we will instantiate
// membership expressions for every range local expression.
// but we keep this set and check for now in case we want to change the saturation strategy.
ctx.push_trail(push_back_vector(range_local));
range_local.push_back(lo);
m_axioms.in_range_axiom(lo, range->get_expr());
new_axiom = true;
}
if (!range_local.contains(hi) &&
all_of(parent_in, [&hi](enode *in) { return in->get_arg(0)->get_expr() != hi; })) {
ctx.push_trail(push_back_vector(range_local));
range_local.push_back(hi);
m_axioms.in_range_axiom(hi, range->get_expr());
new_axiom = true;
}
return new_axiom;
}
bool theory_finite_set::assert_clause(theory_axiom const *ax) {
expr *unit = nullptr;
unsigned undef_count = 0;
auto &clause = ax->clause;
for (auto e : clause) {
switch (ctx.find_assignment(e)) {
case l_true:
@ -719,8 +881,8 @@ namespace smt {
}
m_stats.m_num_axioms_propagated++;
enode_pair_vector eqs;
auto just = ext_theory_propagation_justification(get_id(), ctx, antecedent.size(), antecedent.data(), eqs.size(), eqs.data(), lit, ax.params.size(),
ax.params.data());
auto just = ext_theory_propagation_justification(get_id(), ctx, antecedent.size(), antecedent.data(), eqs.size(), eqs.data(),
lit, ax->params.size(), ax->params.data());
auto bjust = ctx.mk_justification(just);
if (ctx.clause_proof_active()) {
// assume all justifications is a non-empty list of symbol parameters
@ -729,8 +891,8 @@ namespace smt {
// this misses conflicts at base level.
proof_ref pr(m);
expr_ref_vector args(m);
for (auto const& p : ax.params)
args.push_back(m.mk_const(p.get_symbol(), m.mk_proof_sort()));
for (auto const& p : ax->params)
args.push_back(m.mk_const(p.get_symbol(), m.mk_proof_sort()));
pr = m.mk_app(m.get_family_name(get_family_id()), args.size(), args.data(), m.mk_proof_sort());
justification_proof_wrapper jp(ctx, pr.get(), false);
ctx.get_clause_proof().propagate(lit, &jp, antecedent);
@ -748,7 +910,7 @@ namespace smt {
literal_vector lclause;
for (auto e : clause)
lclause.push_back(mk_literal(e));
ctx.mk_th_axiom(get_id(), lclause, ax.params.size(), ax.params.data());
ctx.mk_th_axiom(get_id(), lclause, ax->params.size(), ax->params.data());
return true;
}

23
src/smt/theory_finite_set.h
View file

@ -101,13 +101,15 @@ namespace smt {
friend struct finite_set_value_proc;
struct var_data {
ptr_vector<enode> m_setops;
ptr_vector<enode> m_parent_in;
ptr_vector<enode> m_parent_setops;
ptr_vector<enode> m_setops; // set operations equivalent to this
ptr_vector<enode> m_parent_in; // x in A expressions
ptr_vector<enode> m_parent_setops; // set of set expressions where this appears as sub-expression
expr_ref_vector m_range_local; // set of range local variables associated with range
var_data(ast_manager &m) : m_range_local(m) {}
};
struct theory_clauses {
vector<theory_axiom> axioms; // vector of created theory axioms
ptr_vector<theory_axiom> axioms; // vector of created theory axioms
unsigned aqhead = 0; // queue head of created axioms
unsigned_vector squeue; // propagation queue of axioms to be added to the solver
unsigned sqhead = 0; // head into propagation queue axioms to be added to solver
@ -133,12 +135,16 @@ namespace smt {
}
};
struct range {
rational lo, hi;
};
finite_set_util u;
finite_set_axioms m_axioms;
th_union_find m_find;
theory_clauses m_clauses;
finite_set_factory *m_factory = nullptr;
obj_map<enode, obj_hashtable<enode> *> m_set_members;
obj_map<enode, obj_map<enode, bool> *> m_set_members;
ptr_vector<func_decl> m_set_in_decls;
ptr_vector<var_data> m_var_data;
stats m_stats;
@ -172,11 +178,13 @@ namespace smt {
// Helper methods for axiom instantiation
void add_membership_axioms(expr* elem, expr* set);
void add_clause(theory_axiom const& ax);
bool assert_clause(theory_axiom const &ax);
void add_clause(theory_axiom * ax);
bool assert_clause(theory_axiom const *ax);
void activate_clause(unsigned index);
bool activate_unasserted_clause();
void add_immediate_axioms(app *atom);
bool activate_range_local_axioms();
bool activate_range_local_axioms(expr *elem, enode *range);
bool assume_eqs();
bool is_new_axiom(expr *a, expr *b);
app *mk_union(unsigned num_elems, expr *const *elems, sort* set_sort);
@ -184,6 +192,7 @@ namespace smt {
// model construction
void collect_members();
void reset_set_members();
void add_range_interpretation(enode *s);
// manage union-find of theory variables
theory_var find(theory_var v) const { return m_find.find(v); }