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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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40
src/tactic/arith/card2bv_tactic.cpp
View file

@ -168,13 +168,39 @@ namespace pb {
return BR_FAILED;
}
expr_ref card2bv_rewriter::mk_atmost1(unsigned sz, expr * const* args) {
expr_ref f1(m), f2(m), f3(m), result(m);
f1 = bv.mk_bv(sz, args);
f2 = bv.mk_bv_sub(f1, bv.mk_numeral(rational(1), sz));
f3 = m.mk_app(bv.get_fid(), OP_BAND, f1, f2);
result = m.mk_eq(f3, bv.mk_numeral(rational(0), sz));
return result;
expr_ref card2bv_rewriter::mk_atmost1(unsigned n, expr * const* xs) {
expr_ref_vector result(m), in(m);
in.append(n, xs);
unsigned inc_size = 4;
while (!in.empty()) {
expr_ref_vector ors(m);
unsigned i = 0;
unsigned n = in.size();
bool last = n <= inc_size;
for (; i + inc_size < n; i += inc_size) {
mk_at_most_1_small(last, inc_size, in.c_ptr() + i, result, ors);
}
if (i < n) {
mk_at_most_1_small(last, n - i, in.c_ptr() + i, result, ors);
}
if (last) {
break;
}
in.reset();
in.append(ors);
}
return mk_and(result);
}
void card2bv_rewriter::mk_at_most_1_small(bool last, unsigned n, literal const* xs, expr_ref_vector& result, expr_ref_vector& ors) {
if (!last) {
ors.push_back(m.mk_or(n, xs));
}
for (unsigned i = 0; i < n; ++i) {
for (unsigned j = i + 1; j < n; ++j) {
result.push_back(m.mk_not(m.mk_and(xs[i], xs[j])));
}
}
}
bool card2bv_rewriter::is_atmost1(func_decl* f, unsigned sz, expr * const* args, expr_ref& result) {

1
src/tactic/arith/card2bv_tactic.h
View file

@ -54,6 +54,7 @@ namespace pb {
bool is_and(func_decl* f);
bool is_atmost1(func_decl* f, unsigned sz, expr * const* args, expr_ref& result);
expr_ref mk_atmost1(unsigned sz, expr * const* args);
void mk_at_most_1_small(bool last, unsigned n, literal const* xs, expr_ref_vector& result, expr_ref_vector& ors);
public:
card2bv_rewriter(ast_manager& m);