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dtrim

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This commit is contained in:
Jakob Rath 2023-11-09 16:40:47 +01:00
parent fc676e235f
commit b7ee4b0d63
1 changed files with 52 additions and 13 deletions
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65
src/math/polysat/viable.cpp
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@ -273,20 +273,59 @@ namespace polysat {
return true;
}
else {
unsigned const v_bits = s.size(v);
unsigned const coeff_parity = ne->coeff.parity(v_bits);
unsigned const lo_parity = ne->interval.lo_val().parity(v_bits);
unsigned const hi_parity = ne->interval.hi_val().parity(v_bits);
if (coeff_parity <= lo_parity && coeff_parity <= hi_parity && ne->coeff.is_power_of_two()) {
unsigned const w = s.size(v);
unsigned const k = ne->coeff.parity(w);
// unsigned const lo_parity = ne->interval.lo_val().parity(w);
// unsigned const hi_parity = ne->interval.hi_val().parity(w);
// display_one(std::cerr << "try to reduce entry: ", v, ne) << "\n";
// std::cerr << "coeff_parity " << k << " lo_parity " << lo_parity << " hi_parity " << hi_parity << "\n";
if (k > 0 && ne->coeff.is_power_of_two()) {
// reduction of coeff gives us a unit entry
ne->coeff = 1;
ne->interval = eval_interval::proper(
ne->interval.lo(),
machine_div2k(ne->interval.lo_val(), coeff_parity),
ne->interval.hi(),
machine_div2k(ne->interval.hi_val(), coeff_parity)
);
ne->bit_width -= coeff_parity;
//
// 2^k a x \not\in [ lo ; hi [
//
// new_lo = lo[w-1:k] if lo[k-1:0] = 0
// lo[w-1:k] + 1 otherwise
//
// new_hi = hi[w-1:k] if hi[k-1:0] = 0
// hi[w-1:k] + 1 otherwise
//
pdd const& pdd_lo = ne->interval.lo();
pdd const& pdd_hi = ne->interval.hi();
rational const& lo = ne->interval.lo_val();
rational const& hi = ne->interval.hi_val();
rational new_lo = machine_div2k(lo, k);
if (mod2k(lo, k).is_zero())
ne->side_cond.push_back( s.eq(pdd_lo * rational::power_of_two(w - k)) );
else {
new_lo += 1;
ne->side_cond.push_back( ~s.eq(pdd_lo * rational::power_of_two(w - k)) );
}
rational new_hi = machine_div2k(hi, k);
if (mod2k(hi, k).is_zero())
ne->side_cond.push_back( s.eq(pdd_hi * rational::power_of_two(w - k)) );
else {
new_hi += 1;
ne->side_cond.push_back( ~s.eq(pdd_hi * rational::power_of_two(w - k)) );
}
// we have to update also the pdd bounds accordingly, but it seems not worth introducing new variables for this eagerly
// new_lo = lo[:k] etc.
// TODO: for now just disable the FI-lemma if this case occurs
if (new_lo == new_hi) {
// empty or full
// if (ne->interval.currently_contains(rational::zero()))
NOT_IMPLEMENTED_YET();
}
ne->coeff = machine_div2k(ne->coeff, k);
ne->interval = eval_interval::proper(pdd_lo, new_lo, pdd_hi, new_hi);
ne->bit_width -= k;
LOG("reduced entry to unit in width " << ne->bit_width);
return intersect(v, ne);
}