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review and fix soundness bug in band rule

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2022-12-02 19:04:23 -08:00
parent 2704626a5d
commit 215a4e9bad
4 changed files with 21 additions and 17 deletions
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27
src/math/polysat/op_constraint.cpp
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@ -37,17 +37,12 @@ namespace polysat {
switch (c) {
case code::and_op:
case code::or_op:
case code::xor_op:
if (p.index() > q.index())
std::swap(m_p, m_q);
break;
default:
break;
}
// The following can currently not be used as standalone constraints
SASSERT(c != code::or_op);
SASSERT(c != code::xor_op);
}
lbool op_constraint::eval() const {
@ -89,10 +84,6 @@ namespace polysat {
return out << "<<";
case op_constraint::code::and_op:
return out << "&";
case op_constraint::code::or_op:
return out << "|";
case op_constraint::code::xor_op:
return out << "^";
default:
UNREACHABLE();
return out;
@ -333,8 +324,8 @@ namespace polysat {
* p[i] && q[i] = r[i]
* p = 2^K - 1 => q = r
* q = 2^K - 1 => p = r
* r = 0 && p = 2^k - 1 => q >= 2^k (or: q > p)
* r = 0 && q = 2^k - 1 => p >= 2^k (or: p > q)
* r = 0 && q != 0 & p = 2^k - 1 => q >= 2^k
* r = 0 && p != 0 & q = 2^k - 1 => p >= 2^k
*/
clause_ref op_constraint::lemma_and(solver& s, assignment const& a) {
auto& m = p().manager();
@ -344,21 +335,29 @@ namespace polysat {
signed_constraint const andc(this, true);
// r <= p
if (pv.is_val() && rv.is_val() && rv.val() > pv.val())
return s.mk_clause(~andc, s.ule(r(), p()), true);
// r <= q
if (qv.is_val() && rv.is_val() && rv.val() > qv.val())
return s.mk_clause(~andc, s.ule(r(), q()), true);
// p = q => r = p
if (pv.is_val() && qv.is_val() && rv.is_val() && pv == qv && rv != pv)
return s.mk_clause(~andc, ~s.eq(p(), q()), s.eq(r(), p()), true);
if (pv.is_val() && qv.is_val() && rv.is_val()) {
// p = -1 => r = q
if (pv.val() == m.max_value() && qv != rv)
return s.mk_clause(~andc, ~s.eq(p(), m.max_value()), s.eq(q(), r()), true);
// q = -1 => r = p
if (qv.val() == m.max_value() && pv != rv)
return s.mk_clause(~andc, ~s.eq(q(), m.max_value()), s.eq(p(), r()), true);
if (rv.is_zero() && (pv.val() + 1).is_power_of_two() && qv.val() <= pv.val())
return s.mk_clause(~andc, ~s.eq(r()), ~s.eq(p(), pv.val()), s.ult(q(), p()), true);
// r = 0 && q != 0 & p = 2^k - 1 => q >= 2^k
if ((pv.val() + 1).is_power_of_two() && rv.val() > pv.val())
return s.mk_clause(~andc, ~s.eq(r()), ~s.eq(p(), pv.val()), s.eq(q()), s.ult(p(), q()), true);
// r = 0 && p != 0 & q = 2^k - 1 => p >= 2^k
if (rv.is_zero() && (qv.val() + 1).is_power_of_two() && pv.val() <= qv.val())
return s.mk_clause(~andc, ~s.eq(r()), ~s.eq(q(), qv.val()), s.ult(p(), q()), true);
return s.mk_clause(~andc, ~s.eq(r()), ~s.eq(q(), qv.val()), s.eq(p()),s.ult(q(), p()), true);
unsigned K = p().manager().power_of_2();
for (unsigned i = 0; i < K; ++i) {
bool pb = pv.val().get_bit(i);