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resolve

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2019-12-26 02:30:12 -08:00
parent d13f1310a7
commit 2c6e6b1fdb
4 changed files with 75 additions and 9 deletions
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51
src/math/grobner/pdd_grobner.cpp
View file

@ -189,7 +189,8 @@ namespace dd {
while (simplify_linear_step(true) ||
simplify_elim_pure_step() ||
simplify_linear_step(false) ||
simplify_cc_step() ||
simplify_cc_step() ||
simplify_leaf_step() ||
/*simplify_elim_dual_step() ||*/
false) {
DEBUG_CODE(invariant(););
@ -304,6 +305,43 @@ namespace dd {
return reduced;
}
/**
\brief remove ax+b from p if x occurs as a leaf in p and a is a constant.
*/
bool grobner::simplify_leaf_step() {
use_list_t use_list = get_use_list();
bool reduced = false;
equation_vector leaves;
for (unsigned i = 0; i < m_to_simplify.size(); ++i) {
equation* e = m_to_simplify[i];
pdd p = e->poly();
if (!p.hi().is_val()) {
continue;
}
leaves.reset();
for (equation* e2 : use_list[p.var()]) {
if (e != e2 && e2->poly().var_is_leaf(p.var())) {
leaves.push_back(e2);
}
}
for (equation* e2 : leaves) {
bool changed_leading_term;
remove_from_use(e2, use_list);
simplify_using(*e2, *e, changed_leading_term);
add_to_use(e2, use_list);
if (check_conflict(*e2)) {
return false;
}
else if (changed_leading_term) {
pop_equation(e2);
push_equation(to_simplify, e2);
}
reduced = true;
}
}
return reduced;
}
/**
\brief treat equations as processed if top variable occurs only once.
*/
@ -334,12 +372,13 @@ namespace dd {
bool grobner::simplify_elim_dual_step() {
use_list_t use_list = get_use_list();
unsigned j = 0;
bool reduced = false;
for (unsigned i = 0; i < m_to_simplify.size(); ++i) {
equation* e = m_to_simplify[i];
pdd p = e->poly();
// check that e is linear in top variable.
if (e->state() != to_simplify) {
// this was moved before this pass
reduced = true;
}
else if (!done() && !is_trivial(*e) && p.hi().is_val() && use_list[p.var()].size() == 2) {
for (equation* e2 : use_list[p.var()]) {
@ -351,9 +390,8 @@ namespace dd {
if (check_conflict(*e2)) {
break;
}
if (is_trivial(*e2)) {
break;
}
// when e2 is trivial, leading term is changed
SASSERT(!is_trivial(*e2) || changed_leading_term);
if (changed_leading_term) {
pop_equation(e2);
push_equation(to_simplify, e2);
@ -361,6 +399,7 @@ namespace dd {
add_to_use(e2, use_list);
break;
}
reduced = true;
push_equation(solved, e);
}
else {
@ -368,7 +407,7 @@ namespace dd {
e->set_index(j++);
}
}
if (j != m_to_simplify.size()) {
if (reduced) {
// clean up elements in m_to_simplify
// they may have moved.
m_to_simplify.shrink(j);

1
src/math/grobner/pdd_grobner.h
View file

@ -170,6 +170,7 @@ private:
bool simplify_cc_step();
bool simplify_elim_pure_step();
bool simplify_elim_dual_step();
bool simplify_leaf_step();
void invariant() const;
struct scoped_process {