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Bug fix; may not rewrite inequality

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This commit is contained in:
Clemens Eisenhofer 2022-11-21 11:34:23 +01:00
parent 133f3d0a02
commit 7cb87df00c
1 changed files with 47 additions and 42 deletions
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89
src/math/polysat/variable_elimination.cpp
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@ -264,6 +264,10 @@ namespace polysat {
// For now, just restrict to ule_constraint. // For now, just restrict to ule_constraint.
if (!c_target->is_ule()) // TODO: Remove? if (!c_target->is_ule()) // TODO: Remove?
continue; continue;
if (c_target->to_ule().lhs().degree(v) > 1 || // TODO: Invert non-linear parts?
c_target->to_ule().rhs().degree(v) > 1)
continue;
// TODO: Eliminate without inversion? 2x = y && 2x <= z // TODO: Eliminate without inversion? 2x = y && 2x <= z
to_check.push_back(c_target); to_check.push_back(c_target);
@ -291,65 +295,65 @@ namespace polysat {
//pdd rs = rest; //pdd rs = rest;
if (!lc.is_val() && lc.is_var()) if (!lc.is_val() && !lc.is_var())
// TODO: We could introduce a new variable "new_var = lc" and add the valuation for this new variable // TODO: We could introduce a new variable "new_var = lc" and add the valuation for this new variable
return; return;
pdd coeff_odd = get_odd(lc); // a' pdd coeff_odd = get_odd(lc); // a'
optional<pdd> lci = get_inverse(coeff_odd); // a'^-1
if (!lci) LOG("coeff_odd: " << coeff_odd);
optional<pdd> coeff_odd_inv = get_inverse(coeff_odd); // a'^-1
if (!coeff_odd_inv)
return; // For sure not invertible return; // For sure not invertible
LOG("lci: " << lci); LOG("coeff_odd_inv: " << *coeff_odd_inv);
/*assignment_t a;
pdd const lcs = eval(lc, core, a);
LOG("lcs: " << lcs);
pdd lci = m.zero();
if (!inv(lcs, lci))
return;
pdd lci = m.zero();
pdd const rs = s.subst(a, rest);
*/
/*pdd const vs = -rs * lci; // this is the polynomial that computes v
LOG("vs: " << vs);
SASSERT(!vs.free_vars().contains(v));*/
// Find another constraint where we want to substitute v // Find another constraint where we want to substitute v
for (signed_constraint c_target : to_check) { for (signed_constraint c_target : to_check) {
// Move the variable to eliminate to one side // Move the variable to eliminate to one side
pdd fac = m.zero(); pdd fac_lhs = m.zero();
pdd fac2 = m.zero(); pdd fac_rhs = m.zero();
pdd rest2 = m.zero(); pdd rest_lhs = m.zero();
pdd rest3 = m.zero(); pdd rest_rhs = m.zero();
c_target->to_ule().lhs().factor(v, 1, fac, rest2); c_target->to_ule().lhs().factor(v, 1, fac_lhs, rest_lhs);
c_target->to_ule().rhs().factor(v, 1, fac2, rest3); c_target->to_ule().rhs().factor(v, 1, fac_rhs, rest_rhs);
rest2 = rest3 - rest2;
fac = fac - fac2;
LOG("c_target: " << lit_pp(s, c_target)); LOG("c_target: " << lit_pp(s, c_target));
LOG("fac: " << fac); LOG("c_target (lhs): " << c_target->to_ule().lhs());
LOG("rest2: " << rest2); LOG("c_target (rhs): " << c_target->to_ule().rhs());
LOG("fac_lhs: " << fac_lhs);
LOG("rest_lhs: " << rest_lhs);
LOG("fac_rhs: " << fac_rhs);
LOG("rest_rhs: " << rest_rhs);
if (!fac.is_val() && !fac.is_var()) if (!fac_lhs.is_val() && !fac_lhs.is_var())
return; // TODO: Again, we might bind this to a variable return; // TODO: Again, we might bind this to a variable
if (!fac_rhs.is_val() && !fac_rhs.is_var())
return;
// TODO: Maybe only replace one side if the other is not invertible...
pdd pv2 = get_dyadic_valuation(fac).first; pdd pv_equality = get_dyadic_valuation(lc).first;
pdd pv1 = get_dyadic_valuation(lc).first; pdd pv_lhs = get_dyadic_valuation(fac_lhs).first;
pdd odd_fac = get_odd(fac); pdd pv_rhs = get_dyadic_valuation(fac_rhs).first;
pdd power_diff = s.shl(m.one(), pv2 - pv1);
LOG("pv2: " << pv2); pdd odd_fac_lhs = get_odd(fac_lhs);
LOG("pv1: " << pv1); pdd odd_fac_rhs = get_odd(fac_rhs);
LOG("odd_fac: " << odd_fac); pdd power_diff_lhs = s.shl(m.one(), pv_lhs - pv_equality);
LOG("power_diff: " << power_diff); pdd power_diff_rhs = s.shl(m.one(), pv_rhs - pv_equality);
signed_constraint c_new = s.ule(-rest * lci * power_diff * odd_fac, rest2); LOG("pv_equality " << pv_equality);
LOG("pv_lhs: " << pv_lhs);
LOG("odd_fac_lhs: " << odd_fac_lhs);
LOG("power_diff_lhs: " << power_diff_lhs);
LOG("pv_rhs: " << pv_rhs);
LOG("odd_fac_rhs: " << odd_fac_rhs);
LOG("power_diff_rhs: " << power_diff_rhs);
signed_constraint c_new = s.ule(
-rest * *coeff_odd_inv * power_diff_lhs * odd_fac_lhs + rest_lhs,
-rest * *coeff_odd_inv * power_diff_rhs * odd_fac_rhs + rest_rhs);
if (c_target.is_negative()) if (c_target.is_negative())
c_new.negate(); c_new.negate();
LOG("c_new: " << lit_pp(s, c_new)); LOG("c_new: " << lit_pp(s, c_new));
@ -365,7 +369,8 @@ namespace polysat {
cb.push(~s.eq(s.var(w), wv));*/ cb.push(~s.eq(s.var(w), wv));*/
cb.insert(~c); cb.insert(~c);
cb.insert(~c_target); cb.insert(~c_target);
cb.insert(~s.ule(get_dyadic_valuation(lc).first, get_dyadic_valuation(fac).first)); cb.insert(~s.ule(get_dyadic_valuation(lc).first, get_dyadic_valuation(fac_lhs).first));
cb.insert(~s.ule(get_dyadic_valuation(lc).first, get_dyadic_valuation(fac_rhs).first));
cb.insert(c_new); cb.insert(c_new);
ref<clause> c = cb.build(); ref<clause> c = cb.build();
if (c) // Can we get tautologies this way? if (c) // Can we get tautologies this way?