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Polysat: check test results, forbidden intervals for coefficient -1 (#5241)

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* Use scoped_ptr for condition

* Check solver result in unit tests

* Add test for unusual cjust

* Add solver::get_value

* Broken assertion

* Support forbidden interval for coefficient -1
This commit is contained in:
Jakob Rath 2021-05-04 18:33:55 +02:00 • committed by GitHub
parent 5791b41133
commit fd1758ffab
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8 changed files with 164 additions and 58 deletions
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46
src/math/polysat/ule_constraint.cpp
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@ -118,7 +118,7 @@ namespace polysat {
return p.is_val() && q.is_val() && p.val() > q.val();
}
bool ule_constraint::forbidden_interval(solver& s, pvar v, eval_interval& i, constraint*& neg_condition)
bool ule_constraint::forbidden_interval(solver& s, pvar v, eval_interval& out_interval, scoped_ptr<constraint>& out_neg_cond)
{
SASSERT(!is_undef());
@ -136,6 +136,8 @@ namespace polysat {
unsigned const sz = s.size(v);
dd::pdd_manager& m = s.sz2pdd(sz);
rational const pow2 = rational::power_of_two(sz);
rational const minus_one = pow2 - 1;
pdd p1 = m.zero();
pdd e1 = m.zero();
@ -163,10 +165,10 @@ namespace polysat {
rational a1 = p1.val();
rational a2 = p2.val();
// TODO: to express the interval for coefficient 2^i symbolically, we need right-shift/upper-bits-extract in the language.
// So currently we can only do it if the coefficient is 1.
if (!a1.is_zero() && !a1.is_one())
// So currently we can only do it if the coefficient is 1 or -1.
if (!a1.is_zero() && !a1.is_one() && a1 != minus_one)
return false;
if (!a2.is_zero() && !a2.is_one())
if (!a2.is_zero() && !a2.is_one() && a2 != minus_one)
return false;
/*
unsigned j1 = 0;
@ -177,6 +179,9 @@ namespace polysat {
return false;
*/
rational const y_coeff = a1.is_zero() ? a2 : a1;
SASSERT(!y_coeff.is_zero());
// Concrete values of evaluable terms
auto e1s = e1.subst_val(s.m_search);
auto e2s = e2.subst_val(s.m_search);
@ -219,6 +224,7 @@ namespace polysat {
else {
SASSERT(!a1.is_zero());
SASSERT(!a2.is_zero());
SASSERT_EQ(a1, a2);
// e1 + t <= e2 + t, with t = 2^j1*y = 2^j2*y
// condition for empty/full: e1 == e2
is_trivial = e1s.val() == e2s.val();
@ -234,22 +240,44 @@ namespace polysat {
if (condition_body.is_val()) {
// Condition is trivial; no need to create a constraint for that.
SASSERT(is_trivial == condition_body.is_zero());
neg_condition = nullptr;
out_neg_cond = nullptr;
}
else
neg_condition = constraint::eq(level(), s.m_next_bvar++, is_trivial ? neg_t : pos_t, condition_body, m_dep);
out_neg_cond = constraint::eq(level(), s.m_next_bvar++, is_trivial ? neg_t : pos_t, condition_body, m_dep);
if (is_trivial) {
if (is_positive())
i = eval_interval::empty(m);
// TODO: we cannot use empty intervals for interpolation. So we
// can remove the empty case (make it represent 'full' instead),
// and return 'false' here. Then we do not need the proper/full
// tag on intervals.
out_interval = eval_interval::empty(m);
else
i = eval_interval::full();
out_interval = eval_interval::full();
} else {
if (y_coeff == minus_one) {
// Transform according to: y \in [l;u[ <=> -y \in [1-u;1-l[
// -y \in [1-u;1-l[
// <=> -y - (1 - u) < (1 - l) - (1 - u) { by: y \in [l;u[ <=> y - l < u - l }
// <=> u - y - 1 < u - l { simplified }
// <=> (u-l) - (u-y-1) - 1 < u-l { by: a < b <=> b - a - 1 < b }
// <=> y - l < u - l { simplified }
// <=> y \in [l;u[.
lo = 1 - lo;
hi = 1 - hi;
swap(lo, hi);
lo_val = mod(1 - lo_val, pow2);
hi_val = mod(1 - hi_val, pow2);
lo_val.swap(hi_val);
}
else
SASSERT(y_coeff.is_one());
if (is_negative()) {
swap(lo, hi);
lo_val.swap(hi_val);
}
i = eval_interval::proper(lo, lo_val, hi, hi_val);
out_interval = eval_interval::proper(lo, lo_val, hi, hi_val);
}
return true;