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fix #5560 - add a throttle on maximal size of bignums created for propagate-value lemmas

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2021-09-21 08:55:28 -07:00
parent 2c266a96c8
commit 2e96557827
3 changed files with 32 additions and 2 deletions
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20
src/ast/rewriter/bool_rewriter.cpp
View file

@ -905,7 +905,26 @@ br_status bool_rewriter::mk_ite_core(expr * c, expr * t, expr * e, expr_ref & re
}
}
#if 0
expr* t1, *t2;
// (ite c (not (= t1 t2)) t1) ==> (not (= t1 (and c t2)))
if (m().is_not(t, t1) && m().is_eq(t1, t1, t2) && e == t1) {
expr_ref a(m());
mk_and(c, t2, a);
result = m().mk_not(m().mk_eq(t1, a));
return BR_REWRITE2;
}
if (m().is_not(t, t1) && m().is_eq(t1, t2, t1) && e == t1) {
expr_ref a(m());
mk_and(c, t2, a);
result = m().mk_eq(t1, a);
return BR_REWRITE2;
}
#endif
if (m().is_ite(t) && m_ite_extra_rules && m_elim_ite) {
std::cout << "extra rules\n";
// (ite c1 (ite c2 t1 t2) t1) ==> (ite (and c1 (not c2)) t2 t1)
if (e == to_app(t)->get_arg(1)) {
expr_ref not_c2(m());
@ -923,6 +942,7 @@ br_status bool_rewriter::mk_ite_core(expr * c, expr * t, expr * e, expr_ref & re
return BR_REWRITE1;
}
if (m().is_ite(e)) {
// (ite c1 (ite c2 t1 t2) (ite c3 t1 t2)) ==> (ite (or (and c1 c2) (and (not c1) c3)) t1 t2)
if (to_app(t)->get_arg(1) == to_app(e)->get_arg(1) &&

13
src/math/lp/monomial_bounds.cpp
View file

@ -24,6 +24,11 @@ namespace nla {
}
}
bool monomial_bounds::is_too_big(mpq const& q) const {
return rational(q).bitsize() > 256;
}
/**
* Accumulate product of variables in monomial starting at position 'start'
*/
@ -51,6 +56,8 @@ namespace nla {
lp::explanation ex;
dep.get_upper_dep(range, ex);
auto const& upper = dep.upper(range);
if (is_too_big(upper))
return false;
auto cmp = dep.upper_is_open(range) ? llc::LT : llc::LE;
new_lemma lemma(c(), "propagate value - upper bound of range is below value");
lemma &= ex;
@ -62,6 +69,8 @@ namespace nla {
lp::explanation ex;
dep.get_lower_dep(range, ex);
auto const& lower = dep.lower(range);
if (is_too_big(lower))
return false;
auto cmp = dep.lower_is_open(range) ? llc::GT : llc::GE;
new_lemma lemma(c(), "propagate value - lower bound of range is above value");
lemma &= ex;
@ -106,7 +115,7 @@ namespace nla {
auto le = dep.upper_is_open(range) ? llc::LT : llc::LE;
new_lemma lemma(c(), "propagate value - root case - upper bound of range is below value");
lemma &= ex;
lemma |= ineq(v, le, r);
lemma |= ineq(v, le, r);
return true;
}
if (p % 2 == 0 && val_v.is_neg()) {
@ -114,7 +123,7 @@ namespace nla {
auto ge = dep.upper_is_open(range) ? llc::GT : llc::GE;
new_lemma lemma(c(), "propagate value - root case - upper bound of range is below negative value");
lemma &= ex;
lemma |= ineq(v, ge, -r);
lemma |= ineq(v, ge, -r);
return true;
}
}

1
src/math/lp/monomial_bounds.h
View file

@ -17,6 +17,7 @@ namespace nla {
class monomial_bounds : common {
dep_intervals& dep;
void var2interval(lpvar v, scoped_dep_interval& i);
bool is_too_big(mpq const& q) const;
bool propagate_down(monic const& m, lpvar u);
bool propagate_value(dep_interval& range, lpvar v);
bool propagate_value(dep_interval& range, lpvar v, unsigned power);