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wip: conflicts for pruning branches with too many unrollings

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use the local assumption on depth to ensure the conflict clause is valid
This commit is contained in:
Simon Cruanes 2017-12-06 14:05:14 +01:00
parent 06e0b12700
commit 7b1e1d52e7
3 changed files with 85 additions and 36 deletions
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81
src/smt/theory_recfun.cpp
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@ -4,10 +4,18 @@
#include "smt/theory_recfun.h"
#include "smt/params/smt_params_helper.hpp"
#define DEBUG(x) \
do { \
TRACE("recfun", tout << x << '\n';); \
auto& out = std::cout; out << "recfun: "; out << x; out << '\n' << std::flush; } while(0)
#define DEBUG(x) TRACE("recfun", tout << x << '\n';)
struct pp_lit {
smt::context & ctx;
smt::literal lit;
pp_lit(smt::context & ctx, smt::literal lit) : ctx(ctx), lit(lit) {}
};
std::ostream & operator<<(std::ostream & out, pp_lit const & pp) {
pp.ctx.display_detailed_literal(out, pp.lit);
return out;
}
// NOTE: debug
struct pp_lits {
@ -76,7 +84,6 @@ namespace smt {
}
bool theory_recfun::internalize_term(app * term) {
DEBUG("internalizing term: " << mk_pp(term, m()));
context & ctx = get_context();
for (expr* e : *term) ctx.internalize(e, false);
// the internalization of the arguments may have triggered the internalization of term.
@ -112,11 +119,13 @@ namespace smt {
}
void theory_recfun::push_scope_eh() {
DEBUG("push_scope");
theory::push_scope_eh();
m_trail.push_scope();
}
void theory_recfun::pop_scope_eh(unsigned num_scopes) {
DEBUG("pop_scope");
m_trail.pop_scope(num_scopes);
theory::pop_scope_eh(num_scopes);
reset_queues();
@ -151,20 +160,64 @@ namespace smt {
m_q_body_expand.clear();
}
class depth_conflict_justification : public justification {
literal_vector lits;
theory_recfun * th;
ast_manager & m() const { return th->get_manager(); }
public:
depth_conflict_justification(theory_recfun * th, region & r, literal_vector const & lits)
: lits(lits), th(th) {}
depth_conflict_justification(depth_conflict_justification const & from)
: lits(from.lits), th(from.th) {}
depth_conflict_justification(depth_conflict_justification && from)
: lits(std::move(from.lits)), th(from.th) {}
char const * get_name() const override { return "depth-conflict"; }
theory_id get_from_theory() const override { return th->get_id(); }
void get_antecedents(conflict_resolution & cr) override {
auto & ctx = cr.get_context();
for (unsigned i=0; i < lits.size(); ++i) {
DEBUG("mark literal " << pp_lit(ctx, lits[i]));
cr.mark_literal(lits[i]);
}
}
proof * mk_proof(conflict_resolution & cr) override {
UNREACHABLE();
/* FIXME: actual proof
app * lemma = m().mk_or(c.size(), c.c_ptr());
return m().mk_lemma(m().mk_false(), lemma);
*/
}
};
void theory_recfun::max_depth_conflict() {
DEBUG("max-depth conflict");
// TODO: build clause from `m_guards`
/*
context & ctx = get_context();
region & r = ctx.get_region();
ctx.set_conflict(
*/
literal_vector c;
// make clause `depth_limit => V_{g : guards} ~ g`
{
// first literal must be the depth limit one
app_ref dlimit = m_util->mk_depth_limit_pred(get_max_depth());
ctx.internalize(dlimit, false);
c.push_back(~ ctx.get_literal(dlimit));
SASSERT(ctx.get_assignment(ctx.get_literal(dlimit)) == l_true);
}
for (auto& kv : m_guards) {
expr * g = & kv.get_key();
c.push_back(~ ctx.get_literal(g));
}
DEBUG("max-depth conflict: add clause " << pp_lits(ctx, c.size(), c.c_ptr()));
SASSERT(std::all_of(c.begin(), c.end(), [&](literal & l) { return ctx.get_assignment(l) == l_false; })); // conflict
region r;
depth_conflict_justification js(this, r, c);
ctx.set_conflict(ctx.mk_justification(js));
}
// if `is_true` and `v = C_f_i(t1…tn)`, then body-expand i-th case of `f(t1…tn)`
void theory_recfun::assign_eh(bool_var v, bool is_true) {
expr* e = get_context().bool_var2expr(v);
DEBUG("assign_eh "<< mk_pp(e,m()));
if (!is_true) return;
if (!is_app(e)) return;
app* a = to_app(e);
@ -256,7 +309,6 @@ namespace smt {
}
// assert `p(args) <=> And(guards)` (with CNF on the fly)
ctx.internalize(pred_applied, false);
// FIXME: we need to be informed wen `pred_applied` is true!!
ctx.mark_as_relevant(ctx.get_bool_var(pred_applied));
literal concl = ctx.get_literal(pred_applied);
{
@ -335,8 +387,9 @@ namespace smt {
}
void theory_recfun::add_theory_assumptions(expr_ref_vector & assumptions) {
DEBUG("add_theory_assumptions");
// TODO: add depth-limit assumptions?
app_ref dlimit = m_util->mk_depth_limit_pred(get_max_depth());
DEBUG("add_theory_assumption " << mk_pp(dlimit.get(), m()));
assumptions.push_back(dlimit);
}
void theory_recfun::display(std::ostream & out) const {