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adding argument restriction to mbqi, fix tracking of m_src/m_dst for expr_safe_replace and avoid resetting the cache.

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This commit is contained in:
Nikolaj Bjorner 2020-10-27 11:41:45 -07:00
parent 24321e311b
commit e2fbd05fe7
6 changed files with 159 additions and 58 deletions
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9
src/ast/rewriter/expr_safe_replace.cpp
View file

@ -27,11 +27,11 @@ Revision History:
void expr_safe_replace::insert(expr* src, expr* dst) {
SASSERT(m.get_sort(src) == m.get_sort(dst));
m_src.push_back(src);
m_dst.push_back(dst);
#if ALIVE_OPT
cache_insert(src, dst);
#else
m_src.push_back(src);
m_dst.push_back(dst);
m_subst.insert(src, dst);
#endif
}
@ -149,14 +149,17 @@ void expr_safe_replace::operator()(expr* e, expr_ref& res) {
m_cache.reset();
m_todo.reset();
m_args.reset();
#if !ALIVE_OPT
m_refs.reset();
#endif
}
void expr_safe_replace::reset() {
m_src.reset();
m_dst.reset();
m_subst.reset();
m_refs.reset();
m_refs.finalize();
m_cache.reset();
}
void expr_safe_replace::apply_substitution(expr* s, expr* def, expr_ref& t) {

11
src/qe/mbp/mbp_plugin.h
View file

@ -114,6 +114,17 @@ namespace mbp {
static void mark_rec(expr_mark& visited, expr* e);
static void mark_rec(expr_mark& visited, expr_ref_vector const& es);
/**
* mark sub-terms in e whether they contain a variable from vars.
*/
void mark_non_ground(app_ref_vector const& vars, expr* e) {
for (app* v : vars)
m_non_ground.mark(v);
mark_non_ground(e);
}
bool is_non_ground(expr* t) const { return m_non_ground.is_marked(t); }
};
}

80
src/sat/smt/q_mbi.cpp
View file

@ -17,6 +17,7 @@ Author:
#include "ast/ast_trail.h"
#include "ast/ast_util.h"
#include "ast/for_each_expr.h"
#include "ast/rewriter/var_subst.h"
#include "ast/rewriter/expr_safe_replace.h"
#include "qe/mbp/mbp_arith.h"
@ -98,7 +99,6 @@ namespace q {
}
lbool mbqi::check_forall(quantifier* q) {
quantifier* q_flat = m_qs.flatten(q);
auto* qb = specialize(q_flat);
if (!qb)
@ -113,18 +113,33 @@ namespace q {
return r;
if (r == l_false)
return l_true;
model_ref mdl0;
model_ref mdl0, mdl1;
expr_ref proj(m);
m_solver->get_model(mdl0);
expr_ref proj = solver_project(*mdl0, *qb);
if (!proj)
return l_undef;
sat::literal qlit = ctx.expr2literal(q);
if (is_exists(q))
qlit.neg();
ctx.get_rewriter()(proj);
TRACE("q", tout << proj << "\n";);
// TODO: add as top-level clause for relevancy
unsigned i = 0;
{
::solver::scoped_push _sp(*m_solver);
restrict_domains(*mdl0, *qb);
for (; i < m_max_cex && l_true == m_solver->check_sat(0, nullptr); ++i) {
m_solver->get_model(mdl1);
proj = solver_project(*mdl1, *qb);
if (!proj)
break;
m_qs.add_clause(~qlit, ~ctx.mk_literal(proj));
m_solver->assert_expr(m.mk_not(proj));
}
}
if (i == 0) {
qb->domain_eqs.reset();
proj = solver_project(*mdl0, *qb);
if (!proj)
return l_undef;
m_qs.add_clause(~qlit, ~ctx.mk_literal(proj));
}
// TODO: add as top-level clause for relevancy
return l_false;
}
@ -146,6 +161,7 @@ namespace q {
restrict_to_universe(vars.get(i), m_model->get_universe(s));
}
expr_ref fml = subst(q->get_expr(), vars);
extract_var_args(q->get_expr(), *result);
if (is_forall(q))
fml = m.mk_not(fml);
flatten_and(fml, result->vbody);
@ -195,6 +211,7 @@ namespace q {
tout << "model of projection\n" << mdl << "\n";);
expr_ref_vector fmls(qb.vbody);
app_ref_vector vars(qb.vars);
fmls.append(qb.domain_eqs);
mbp::project_plugin proj(m);
proj.purify(m_model_fixer, *m_model, vars, fmls);
for (unsigned i = 0; i < vars.size(); ++i) {
@ -203,19 +220,60 @@ namespace q {
if (p)
(*p)(*m_model, vars, fmls);
}
if (!vars.empty()) {
expr_safe_replace esubst(m);
for (app* v : vars) {
for (app* v : qb.vars) {
expr_ref val = assign_value(*m_model, v);
if (!val)
return expr_ref(m);
esubst.insert(v, val);
}
esubst(fmls);
}
return mk_and(fmls);
}
/**
* Add disjunctions to m_solver that restrict the possible values of
* arguments to uninterpreted functions. The disjunctions added to the solver
* are specialized with respect to m_model.
* Add also disjunctions to the quantifier "domain_eqs", to track the constraints
* added to the solver.
*/
void mbqi::restrict_domains(model& mdl, q_body& qb) {
qb.domain_eqs.reset();
var_subst subst(m);
for (auto p : qb.var_args) {
expr_ref bounds = m_model_fixer.restrict_arg(p.first, p.second);
if (m.is_true(bounds))
continue;
expr_ref vbounds = subst(bounds, qb.vars);
expr_ref mbounds(m);
if (!m_model->eval_expr(bounds, mbounds, true))
return;
mbounds = subst(mbounds, qb.vars);
std::cout << "restrict with bounds " << mbounds << " " << vbounds << "\n";
m_solver->assert_expr(mbounds);
qb.domain_eqs.push_back(vbounds);
}
}
/*
* Add domain restrictions for every non-ground arguments to uninterpreted functions.
*/
void mbqi::extract_var_args(expr* _t, q_body& qb) {
expr_ref t(_t, m);
for (expr* s : subterms(t)) {
if (is_ground(s))
continue;
if (is_uninterp(s) && to_app(s)->get_num_args() > 0) {
app* a = to_app(s);
for (unsigned i = 0; i < a->get_num_args(); ++i) {
if (is_ground(a->get_arg(i)))
qb.var_args.push_back(std::make_pair(a, i));
}
}
}
}
expr_ref mbqi::assign_value(model& mdl, app* v) {
func_decl* f = v->get_decl();
expr_ref val(mdl.get_some_const_interp(f), m);

6
src/sat/smt/q_mbi.h
View file

@ -34,7 +34,9 @@ namespace q {
app_ref_vector vars;
expr_ref mbody; // body specialized with respect to model
expr_ref_vector vbody; // (negation of) body specialized with respect to vars
q_body(ast_manager& m) : vars(m), mbody(m), vbody(m) {}
expr_ref_vector domain_eqs; // additional domain restrictions
svector<std::pair<app*, unsigned>> var_args; // (uninterpreted) functions in vbody that contain arguments with variables
q_body(ast_manager& m) : vars(m), mbody(m), vbody(m), domain_eqs(m) {}
};
euf::solver& ctx;
@ -59,6 +61,8 @@ namespace q {
expr_ref basic_project(model& mdl, quantifier* q, app_ref_vector& vars);
expr_ref solver_project(model& mdl, q_body& qb);
expr_ref assign_value(model& mdl, app* v);
void restrict_domains(model& mdl, q_body& qb);
void extract_var_args(expr* t, q_body& qb);
void init_model();
void init_solver();
mbp::project_plugin* get_plugin(app* var);

31
src/sat/smt/q_model_fixer.cpp
View file

@ -21,6 +21,7 @@ Notes:
#include "ast/for_each_expr.h"
#include "ast/ast_util.h"
#include "ast/arith_decl_plugin.h"
#include "ast/bv_decl_plugin.h"
#include "model/model_macro_solver.h"
@ -43,7 +44,7 @@ namespace q {
class arith_projection : public projection_function {
arith_util a;
public:
arith_projection(ast_manager& m): projection_function(m), a(m) {}
arith_projection(ast_manager& m) : projection_function(m), a(m) {}
~arith_projection() override {}
bool operator()(expr* e1, expr* e2) const override { return lt(a, e1, e2); }
expr* mk_lt(expr* x, expr* y) override { return a.mk_lt(x, y); }
@ -52,7 +53,7 @@ namespace q {
class ubv_projection : public projection_function {
bv_util bvu;
public:
ubv_projection(ast_manager& m): projection_function(m), bvu(m) {}
ubv_projection(ast_manager& m) : projection_function(m), bvu(m) {}
~ubv_projection() override {}
bool operator()(expr* e1, expr* e2) const override { return lt(bvu, e1, e2); }
expr* mk_lt(expr* x, expr* y) override { return m.mk_not(bvu.mk_ule(y, x)); }
@ -164,7 +165,7 @@ namespace q {
std::sort(values.c_ptr(), values.c_ptr() + values.size(), _lt);
unsigned j = 0;
for (unsigned i = 0; i < values.size(); ++i)
if (i == 0 || values.get(i-1) != values.get(i))
if (i == 0 || values.get(i - 1) != values.get(i))
values[j++] = values.get(i);
values.shrink(j);
@ -173,14 +174,14 @@ namespace q {
unsigned sz = values.size();
expr_ref var(m.mk_var(0, srt), m);
expr_ref pi(values.get(sz-1), m);
expr_ref pi(values.get(sz - 1), m);
for (unsigned i = sz - 1; i >= 1; i--) {
expr* c = proj->mk_lt(var, values.get(i));
pi = m.mk_ite(c, values.get(i - 1), pi);
}
func_interp* rpi = alloc(func_interp, m, 1);
rpi->set_else(pi);
func_decl * p = m.mk_fresh_func_decl(1, &srt, srt);
func_decl* p = m.mk_fresh_func_decl(1, &srt, srt);
mdl.register_decl(p, rpi);
return expr_ref(m.mk_app(p, m.mk_var(idx, srt)), m);
}
@ -268,6 +269,24 @@ namespace q {
return;
}
lits.push_back(proj->mk_le(term(sz-1), arg));
lits.push_back(proj->mk_le(term(sz - 1), arg));
}
/*
* restrict arg_i of t := f(...,arg_i,...) to be one of terms from the ground instantiations of f.
*/
expr_ref model_fixer::restrict_arg(app* t, unsigned i) {
TRACE("q", tout << "restrict-arg " << mk_pp(t, m) << " " << i << "\n";);
auto const* md = get_projection_data(t->get_decl(), i);
if (!md)
return expr_ref(m.mk_true(), m);
expr* arg = t->get_arg(i);
expr_ref_vector eqs(m);
for (expr* v : md->values)
eqs.push_back(m.mk_eq(arg, md->v2t[v]));
if (eqs.empty())
return expr_ref(m.mk_true(), m);
return mk_or(eqs);
}
}

6
src/sat/smt/q_model_fixer.h
View file

@ -107,6 +107,12 @@ namespace q {
quantifier_macro_info* operator()(quantifier* q) override;
/*
* Create a constraint that restricts the possible values of t to a finite set of values.
* Add value constraints to solver?
*/
expr_ref restrict_arg(app* t, unsigned i);
expr* invert_app(app* t, expr* value) override;
void invert_arg(app* t, unsigned i, expr* value, expr_ref_vector& lits) override;
};