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First version of refine_disequal_lin

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This commit is contained in:
Jakob Rath 2021-12-23 18:36:27 +01:00
parent eb9bfbb3d8
commit 28864e563c
5 changed files with 103 additions and 8 deletions
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38
src/math/polysat/forbidden_intervals.cpp
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@ -47,17 +47,15 @@ namespace polysat {
fi.coeff = 1;
fi.src = c;
// eval(lhs) = a1*v + eval(e1) = a1*v + b1
// eval(rhs) = a2*v + eval(e2) = a2*v + b2
// We keep the e1, e2 around in case we need side conditions such as e1=b1, e2=b2.
auto [ok1, a1, e1, b1] = linear_decompose(v, c->to_ule().lhs(), fi.side_cond);
auto [ok2, a2, e2, b2] = linear_decompose(v, c->to_ule().rhs(), fi.side_cond);
if (!ok1 || !ok2 || (a1.is_zero() && a2.is_zero()))
return false;
SASSERT(b1.is_val());
SASSERT(b2.is_val());
// TBD: use fi.coeff = -1 to tell caller to treat it as a diseq_lin.
// record a1, a2, b1, b2 for fast access, add non_unit side conditions on b1 = e1, b2 = e2?
if (a1 != a2 && !a1.is_zero() && !a2.is_zero())
return false;
_backtrack.released = true;
@ -67,6 +65,8 @@ namespace polysat {
return true;
if (match_linear3(c, a1, b1, e1, a2, b2, e2, fi))
return true;
if (match_linear4(c, a1, b1, e1, a2, b2, e2, fi))
return true;
_backtrack.released = false;
return false;
@ -88,12 +88,16 @@ namespace polysat {
pdd e = m.zero();
unsigned const deg = p.degree(v);
if (deg == 0)
// p = 0*v + e
e = p;
else if (deg == 1)
// p = q*v + e
p.factor(v, 1, q, e);
else
return std::tuple(false, rational(0), q, e);
// r := eval(q)
// Add side constraint q = r.
if (!q.is_val()) {
pdd r = q.subst_val(s.assignment());
if (!r.is_val())
@ -221,6 +225,30 @@ namespace polysat {
return false;
}
/**
* e1 + t <= e2 + t', with t = a1*y, t' = a2*y, a1 != a2, a1, a2 non-zero
*/
bool forbidden_intervals::match_linear4(signed_constraint const& c,
rational const & a1, pdd const& b1, pdd const& e1,
rational const & a2, pdd const& b2, pdd const& e2,
fi_record& fi) {
if (a1 != a2 && !a1.is_zero() && !a2.is_zero()) {
// NOTE: we don't have an interval here in the same sense as in the other cases.
// We use the interval to smuggle out the values a1,b1,a2,b2 without adding additional fields.
// to_interval flips a1,b1 with a2,b2 for negative constraints, which we also need for this case.
auto lo = b1;
rational lo_val = a1;
auto hi = b2;
rational hi_val = a2;
// We use fi.coeff = -1 to tell the caller to treat it as a diseq_lin.
fi.coeff = -1;
fi.interval = to_interval(c, false, fi.coeff, lo_val, lo, hi_val, hi);
add_non_unit_side_conds(fi, b1, e1, b2, e2);
return true;
}
return false;
}
void forbidden_intervals::add_non_unit_side_conds(fi_record& fi, pdd const& b1, pdd const& e1, pdd const& b2, pdd const& e2) {
if (fi.coeff == 1)
return;