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better encodings for at-most-1, #755

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2016-10-10 23:46:03 -07:00
parent 5d9820f3e2
commit 8d2b70a5e2
17 changed files with 232 additions and 253 deletions
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57
src/solver/solver.cpp
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@ -138,63 +138,6 @@ lbool solver::get_consequences_core(expr_ref_vector const& asms, expr_ref_vector
lbool solver::find_mutexes(expr_ref_vector const& vars, vector<expr_ref_vector>& mutexes) {
return l_true;
#if 0
// complete for literals, but inefficient.
// see more efficient (incomplete) version in sat_solver
mutexes.reset();
ast_manager& m = vars.get_manager();
typedef obj_hashtable<expr> expr_set;
expr_set A, P;
for (unsigned i = 0; i < vars.size(); ++i) {
A.insert(vars[i]);
}
while (!A.empty()) {
P = A;
expr_ref_vector mutex(m);
while (!P.empty()) {
expr_ref_vector asms(m);
expr* p = *P.begin();
P.remove(p);
if (!is_literal(m, p)) {
break;
}
mutex.push_back(p);
asms.push_back(p);
expr_set Q;
expr_set::iterator it = P.begin(), end = P.end();
for (; it != end; ++it) {
expr* q = *it;
scoped_assumption_push _scoped_push(asms, q);
if (is_literal(m, q)) {
lbool is_sat = check_sat(asms);
switch (is_sat) {
case l_false:
Q.insert(q);
break;
case l_true:
break;
case l_undef:
return l_undef;
}
}
}
P = Q;
}
if (mutex.size() > 1) {
mutexes.push_back(mutex);
}
for (unsigned i = 0; i < mutex.size(); ++i) {
A.remove(mutex[i].get());
}
}
return l_true;
#endif
}
bool solver::is_literal(ast_manager& m, expr* e) {