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update viable

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2021-12-03 17:57:08 -08:00
parent a81a00a93c
commit 4d0f55febd
2 changed files with 18 additions and 120 deletions
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24
src/math/polysat/viable.cpp
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@ -163,14 +163,20 @@ namespace polysat {
/**
* Traverse all interval constraints with coefficients to check whether current value 'val' for
* 'v' is feasible. If not, extract a (maximal) interval to block 'v' from being assigned val.
*
* To investigate:
* - side conditions are stronger than for unit intervals. They constrain the lower and upper bounds to
* be precisely the assigned values. This is to ensure that lo/hi that are computed based on lo_val
* and division with coeff are valid. Is there a more relaxed scheme?
*/
bool viable::refine_viable(pvar v, rational const& val) {
auto* e = m_non_units[v];
if (!e)
return true;
entry* first = e;
rational const& max_value = s.var2pdd(v).max_value();
do {
rational coeff_val = mod(e->coeff * val, s.var2pdd(v).max_value() + 1);
rational coeff_val = mod(e->coeff * val, max_value + 1);
if (e->interval.currently_contains(coeff_val)) {
rational delta_l = floor((coeff_val - e->interval.lo_val()) / e->coeff);
rational delta_u = floor((e->interval.hi_val() - coeff_val - 1) / e->coeff);
@ -181,21 +187,25 @@ namespace polysat {
// pass
}
else if (e->interval.lo_val() <= coeff_val) {
hi = val + 1;
if (hi > s.var2pdd(v).max_value())
rational lambda_u = floor((max_value - coeff_val - 1) / e->coeff);
hi = val + lambda_u + 1;
if (hi > max_value)
hi = 0;
}
else {
SASSERT(coeff_val < e->interval.hi_val());
lo = val;
rational lambda_l = floor(coeff_val / e->coeff);
lo = val - lambda_l;
}
SASSERT(hi <= s.var2pdd(v).max_value());
LOG("forbidden interval [" << lo << ", " << hi << "[\n");
LOG("forbidden interval " << e->interval << " [" << lo << ", " << hi << "[");
entry* ne = alloc_entry();
ne->src = e->src;
ne->side_cond = e->side_cond;
ne->side_cond.push_back(s.eq(e->interval.hi(), e->interval.hi_val()));
ne->side_cond.push_back(s.eq(e->interval.lo(), e->interval.lo_val()));
ne->coeff = 1;
pdd lop = s.var2pdd(v).mk_val(lo); // TODO?
pdd lop = s.var2pdd(v).mk_val(lo);
pdd hip = s.var2pdd(v).mk_val(hi);
ne->interval = eval_interval::proper(lop, lo, hip, hi);
intersect(v, ne);
@ -435,7 +445,7 @@ namespace polysat {
do {
if (e->coeff != 1)
out << e->coeff << " * v" << v << " ";
out << e->interval << " " << e->side_cond << " " << e->src << " ";
out << e->interval << " " << e->side_cond << " " << e->src << "; ";
e = e->next();
}
while (e != first);