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Readded variable evaluation as fallback for variable elimination

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Clemens Eisenhofer 2022-12-07 16:54:39 +01:00
parent 47cb83f578
commit c088eb4a26
1 changed files with 68 additions and 47 deletions
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115
src/math/polysat/variable_elimination.cpp
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@ -316,55 +316,74 @@ namespace polysat {
bool is_multiple1 = is_multiple(fac_lhs, fac, new_lhs);
bool is_multiple2 = is_multiple(fac_rhs, fac, new_rhs);
bool evaluated = false;
substitution sub(m);
if (!is_multiple1 || !is_multiple2) {
if (!fac.is_val() && !fac.is_var())
if (
(!fac.is_val() && !fac.is_var()) ||
(!fac_lhs.is_val() && !fac_lhs.is_var()) ||
(!fac_rhs.is_val() && !fac_rhs.is_var())) {
// TODO: We could introduce a new variable "new_var = lc" and add the valuation for this new variable
continue;
if (!fac_lhs.is_val() && !fac_lhs.is_var())
continue;
if (!fac_rhs.is_val() && !fac_rhs.is_var())
continue;
pv_equality = get_dyadic_valuation(fac).first;
LOG("pv_equality " << pv_equality);
coeff_odd = get_odd(fac); // a'
LOG("coeff_odd: " << coeff_odd);
fac_odd_inv = get_inverse(coeff_odd); // a'^-1
if (!fac_odd_inv)
continue; // factor is for sure not invertible
LOG("coeff_odd_inv: " << *fac_odd_inv);
pdd const fac_eval = eval(fac, core, sub);
LOG("lcs: " << fac_eval);
pdd fac_eval_inv = m.zero();
if (!inv(fac_eval, fac_eval_inv))
return;
pdd const rest_eval = sub.apply_to(rest);
pdd const vs = -rest_eval * fac_eval_inv; // this is the polynomial that computes v
LOG("vs: " << vs);
SASSERT(!vs.free_vars().contains(v));
new_lhs = c_target->to_ule().lhs().subst_pdd(v, vs);
new_rhs = c_target->to_ule().rhs().subst_pdd(v, vs);
evaluated = true;
}
else {
pv_equality = get_dyadic_valuation(fac).first;
LOG("pv_equality " << pv_equality);
coeff_odd = get_odd(fac); // a'
LOG("coeff_odd: " << coeff_odd);
fac_odd_inv = get_inverse(coeff_odd); // a'^-1
if (!fac_odd_inv)
continue; // factor is for sure not invertible
LOG("coeff_odd_inv: " << *fac_odd_inv);
}
}
if (!evaluated) {
if (!is_multiple1) { // Sometimes we can simply unify the two equations
pdd pv_lhs = get_dyadic_valuation(fac_lhs).first;
pdd odd_fac_lhs = get_odd(fac_lhs);
pdd power_diff_lhs = s.shl(m.one(), pv_lhs - pv_equality);
LOG("pv_lhs: " << pv_lhs);
LOG("odd_fac_lhs: " << odd_fac_lhs);
LOG("power_diff_lhs: " << power_diff_lhs);
new_lhs = -rest * *fac_odd_inv * power_diff_lhs * odd_fac_lhs + rest_rhs;
p1 = s.ule(get_dyadic_valuation(fac).first, get_dyadic_valuation(fac_lhs).first);
}
else
new_lhs = -rest * new_lhs + rest_lhs;
if (!is_multiple2) {
pdd pv_rhs = get_dyadic_valuation(fac_rhs).first;
pdd odd_fac_rhs = get_odd(fac_rhs);
pdd power_diff_rhs = s.shl(m.one(), pv_rhs - pv_equality);
LOG("pv_rhs: " << pv_rhs);
LOG("odd_fac_rhs: " << odd_fac_rhs);
LOG("power_diff_rhs: " << power_diff_rhs);
new_rhs = -rest * *fac_odd_inv * power_diff_rhs * odd_fac_rhs + rest_rhs;
p2 = s.ule(get_dyadic_valuation(fac).first, get_dyadic_valuation(fac_rhs).first);
}
else
new_rhs = -rest * new_rhs + rest_rhs;
}
if (!is_multiple1) { // Sometimes we can simply unify the two equations
pdd pv_lhs = get_dyadic_valuation(fac_lhs).first;
pdd odd_fac_lhs = get_odd(fac_lhs);
pdd power_diff_lhs = s.shl(m.one(), pv_lhs - pv_equality);
LOG("pv_lhs: " << pv_lhs);
LOG("odd_fac_lhs: " << odd_fac_lhs);
LOG("power_diff_lhs: " << power_diff_lhs);
new_lhs = -rest * *fac_odd_inv * power_diff_lhs * odd_fac_lhs + rest_rhs;
p1 = s.ule(get_dyadic_valuation(fac).first, get_dyadic_valuation(fac_lhs).first);
}
else
new_lhs = -rest * new_lhs + rest_lhs;
if (!is_multiple2) {
pdd pv_rhs = get_dyadic_valuation(fac_rhs).first;
pdd odd_fac_rhs = get_odd(fac_rhs);
pdd power_diff_rhs = s.shl(m.one(), pv_rhs - pv_equality);
LOG("pv_rhs: " << pv_rhs);
LOG("odd_fac_rhs: " << odd_fac_rhs);
LOG("power_diff_rhs: " << power_diff_rhs);
new_rhs = -rest * *fac_odd_inv * power_diff_rhs * odd_fac_rhs + rest_rhs;
p2 = s.ule(get_dyadic_valuation(fac).first, get_dyadic_valuation(fac_rhs).first);
}
else
new_rhs = -rest * new_rhs + rest_rhs;
signed_constraint c_new = s.ule(new_lhs , new_rhs );
signed_constraint c_new = s.ule(new_lhs , new_rhs);
if (c_target.is_negative())
c_new.negate();
@ -381,8 +400,10 @@ namespace polysat {
clause_builder cb(s);
/*for (auto [w, wv] : a)
cb.push(~s.eq(s.var(w), wv));*/
if (evaluated) {
for (auto [w, wv] : sub)
cb.insert(~s.eq(s.var(w), wv));
}
cb.insert(~c);
cb.insert(~c_target);
cb.insert(~p1);