mirrors/z3
3
0
Fork 0
mirror of https://github.com/Z3Prover/z3 synced 2025-04-08 18:31:49 +00:00
Code Activity

remove watch, hoist orbit to track used variables

Browse source 
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2020-01-02 00:39:50 -08:00
parent 1d0572354b
commit c1032c3403
6 changed files with 46 additions and 117 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

7
src/math/dd/dd_pdd.cpp
View file

@ -285,7 +285,12 @@ namespace dd {
if (level_p > level_q) {
push(apply_rec(lo(p), q, op));
push(apply_rec(hi(p), q, op));
r = make_node(level_p, read(2), read(1));
if (read(2) == lo(p) && read(1) == hi(p)) {
r = p;
}
else {
r = make_node(level_p, read(2), read(1));
}
}
else {
SASSERT(level_p == level_q);

51
src/math/grobner/pdd_simplifier.cpp
View file

@ -56,7 +56,6 @@
#include "math/grobner/pdd_simplifier.h"
#include "math/simplex/bit_matrix.h"
#include "util/uint_set.h"
namespace dd {
@ -395,34 +394,42 @@ namespace dd {
vector<pdd> eqs, simp_eqs;
for (auto* e : s.m_to_simplify) if (!e->dep()) eqs.push_back(e->poly());
for (auto* e : s.m_processed) if (!e->dep()) eqs.push_back(e->poly());
exlin_augment(eqs);
simplify_exlin(eqs, simp_eqs);
vector<uint_set> orbits(s.m.num_vars());
init_orbits(eqs, orbits);
exlin_augment(orbits, eqs);
simplify_exlin(orbits, eqs, simp_eqs);
for (pdd const& p : simp_eqs) {
s.add(p);
}
return !simp_eqs.empty() && simplify_linear_step(false);
}
/**
augment set of equations by multiplying with selected variables.
Uses orbits to prune which variables are multiplied.
TBD: could also prune added polynomials based on a maximal degree.
*/
void simplifier::exlin_augment(vector<pdd>& eqs) {
unsigned nv = s.m.num_vars();
vector<uint_set> orbits(nv);
random_gen rand(s.m_config.m_random_seed);
unsigned modest_num_eqs = std::min(eqs.size(), 500u);
unsigned max_xlin_eqs = modest_num_eqs*modest_num_eqs + eqs.size();
for (pdd p : eqs) {
void simplifier::init_orbits(vector<pdd> const& eqs, vector<uint_set>& orbits) {
for (pdd const& p : eqs) {
auto const& fv = p.free_vars();
for (unsigned i = fv.size(); i-- > 0; ) {
orbits[fv[i]].insert(fv[i]); // if v is used, it is in its own orbit.
for (unsigned j = i; j-- > 0; ) {
orbits[fv[i]].insert(fv[j]);
orbits[fv[j]].insert(fv[i]);
}
}
}
}
/**
augment set of equations by multiplying with selected variables.
Uses orbits to prune which variables are multiplied.
TBD: could also prune added polynomials based on a maximal degree.
TBD: for large systems, extract cluster of polynomials based on sampling orbits
*/
void simplifier::exlin_augment(vector<uint_set> const& orbits, vector<pdd>& eqs) {
unsigned nv = s.m.num_vars();
random_gen rand(s.m_config.m_random_seed);
unsigned modest_num_eqs = std::min(eqs.size(), 500u);
unsigned max_xlin_eqs = modest_num_eqs*modest_num_eqs + eqs.size();
TRACE("dd.solver", tout << "augment " << nv << "\n";
for (auto const& o : orbits) tout << o.num_elems() << "\n";
);
@ -435,7 +442,7 @@ namespace dd {
pdd pv = s.m.mk_var(v);
for (pdd p : eqs) {
for (unsigned w : p.free_vars()) {
if (orbitv.contains(w)) {
if (v != w && orbitv.contains(w)) {
n_eqs.push_back(pv * p);
break;
}
@ -453,7 +460,7 @@ namespace dd {
if (orbitv.empty()) continue;
pdd pv = s.m.mk_var(v);
for (unsigned w : orbitv) {
if (v > w) continue;
if (v >= w) continue;
pdd pw = s.m.mk_var(w);
for (pdd p : eqs) {
if (n_eqs.size() > max_xlin_eqs) {
@ -474,7 +481,7 @@ namespace dd {
TRACE("dd.solver", for (pdd const& p : eqs) tout << p << "\n";);
}
void simplifier::simplify_exlin(vector<pdd> const& eqs, vector<pdd>& simp_eqs) {
void simplifier::simplify_exlin(vector<uint_set> const& orbits, vector<pdd> const& eqs, vector<pdd>& simp_eqs) {
// create variables for each non-constant monomial.
u_map<unsigned> mon2idx;
@ -497,9 +504,11 @@ namespace dd {
// insert variables last.
unsigned nv = s.m.num_vars();
for (unsigned v = 0; v < nv; ++v) {
pdd r = s.m.mk_var(v);
mon2idx.insert(r.index(), idx2mon.size());
idx2mon.push_back(r);
if (!orbits[v].empty()) { // not all variables are used.
pdd r = s.m.mk_var(v);
mon2idx.insert(r.index(), idx2mon.size());
idx2mon.push_back(r);
}
}
bit_matrix bm;

6
src/math/grobner/pdd_simplifier.h
View file

@ -13,6 +13,7 @@
--*/
#pragma once
#include "util/uint_set.h"
#include "math/grobner/pdd_solver.h"
namespace dd {
@ -46,8 +47,9 @@ private:
bool simplify_elim_dual_step();
bool simplify_leaf_step();
bool simplify_exlin();
void exlin_augment(vector<pdd>& eqs);
void simplify_exlin(vector<pdd> const& eqs, vector<pdd>& simp_eqs);
void init_orbits(vector<pdd> const& eqs, vector<uint_set>& orbits);
void exlin_augment(vector<uint_set> const& orbits, vector<pdd>& eqs);
void simplify_exlin(vector<uint_set> const& orbits, vector<pdd> const& eqs, vector<pdd>& simp_eqs);
};

95
src/math/grobner/pdd_solver.cpp
View file

@ -47,18 +47,6 @@ namespace dd {
- add a to S
- simplify A using a
Apply a watch list to filter out relevant elements of S
Index leading_term_watch: Var -> Equation*
Only need to simplify equations that contain eliminated variable.
The watch list can be used to index into equations that are useful to simplify.
A Bloom filter on leading term could further speed up test whether reduction applies.
For p in A:
populate watch list by maxvar(p) |-> p
For p in S:
do not occur in watch list
- the variable ordering should be chosen from a candidate model M,
in a way that is compatible with weights that draw on the number of occurrences
in polynomials with violated evaluations and with the maximal slack (degree of freedom).
@ -67,12 +55,6 @@ namespace dd {
slack is computed from interval assignments to variables, and is an interval in which x can possibly move
(an over-approximation).
The alternative version maintains the following invariant:
- polynomials not in the watch list cannot be simplified using a
Justification:
- elements in S have no variables watched
- elements in A are always reduced modulo all variables above the current x_i.
*/
@ -99,7 +81,6 @@ namespace dd {
DEBUG_CODE(invariant(););
}
catch (pdd_manager::mem_out) {
m_watch.reset();
IF_VERBOSE(2, verbose_stream() << "mem-out\n");
// don't reduce further
}
@ -161,8 +142,7 @@ namespace dd {
/*
Use the given equation to simplify equations in set
*/
void solver::simplify_using(equation_vector& set, equation const& eq) {
void solver::simplify_using(equation_vector& set, equation const& eq) {
struct scoped_update {
equation_vector& set;
unsigned i, j, sz;
@ -195,9 +175,8 @@ namespace dd {
else if (simplified && changed_leading_term) {
SASSERT(target.state() == processed);
push_equation(to_simplify, target);
if (!m_watch.empty()) {
if (!m_var2level.empty()) {
m_levelp1 = std::max(m_var2level[target.poly().var()]+1, m_levelp1);
add_to_watch(target);
}
}
else {
@ -276,7 +255,6 @@ namespace dd {
if (!e) return false;
scoped_process sd(*this, e);
equation& eq = *e;
SASSERT(!m_watch[eq.poly().var()].contains(e));
SASSERT(eq.state() == to_simplify);
simplify_using(eq, m_processed);
if (is_trivial(eq)) { sd.e = nullptr; retire(e); return true; }
@ -286,7 +264,7 @@ namespace dd {
if (done()) return false;
TRACE("dd.solver", display(tout << "eq = ", eq););
superpose(eq);
simplify_watch(eq);
simplify_using(m_to_simplify, eq);
if (done()) return false;
if (!m_too_complex) sd.done();
return true;
@ -300,58 +278,14 @@ namespace dd {
m_level2var[i] = l2v[i];
m_var2level[l2v[i]] = i;
}
m_watch.reset();
m_watch.reserve(m_level2var.size());
m_levelp1 = m_level2var.size();
for (equation* eq : m_to_simplify) add_to_watch(*eq);
}
void solver::add_to_watch(equation& eq) {
SASSERT(eq.state() == to_simplify);
pdd const& p = eq.poly();
if (!p.is_val()) {
m_watch[p.var()].push_back(&eq);
}
}
void solver::simplify_watch(equation const& eq) {
unsigned v = eq.poly().var();
auto& watch = m_watch[v];
unsigned j = 0;
for (equation* _target : watch) {
equation& target = *_target;
SASSERT(target.state() == to_simplify);
SASSERT(target.poly().var() == v);
bool changed_leading_term = false;
if (!done()) {
try_simplify_using(target, eq, changed_leading_term);
}
if (is_trivial(target)) {
pop_equation(target);
retire(&target);
}
else if (is_conflict(target)) {
pop_equation(target);
set_conflict(target);
}
else if (target.poly().var() != v) {
// move to other watch list
m_watch[target.poly().var()].push_back(_target);
}
else {
// keep watching same variable
watch[j++] = _target;
}
}
watch.shrink(j);
}
solver::equation* solver::pick_next() {
while (m_levelp1 > 0) {
unsigned v = m_level2var[m_levelp1-1];
equation_vector const& watch = m_watch[v];
equation* eq = nullptr;
for (equation* curr : watch) {
for (equation* curr : m_to_simplify) {
pdd const& p = curr->poly();
if (curr->state() == to_simplify && p.var() == v) {
if (!eq || is_simpler(*curr, *eq))
@ -360,7 +294,6 @@ namespace dd {
}
if (eq) {
pop_equation(eq);
m_watch[eq->poly().var()].erase(eq);
return eq;
}
--m_levelp1;
@ -384,7 +317,6 @@ namespace dd {
m_processed.reset();
m_to_simplify.reset();
m_stats.reset();
m_watch.reset();
m_level2var.reset();
m_var2level.reset();
m_conflict = nullptr;
@ -398,9 +330,8 @@ namespace dd {
}
push_equation(to_simplify, eq);
if (!m_watch.empty()) {
if (!m_var2level.empty()) {
m_levelp1 = std::max(m_var2level[p.var()]+1, m_levelp1);
add_to_watch(*eq);
}
update_stats_max_degree_and_size(*eq);
}
@ -524,28 +455,12 @@ namespace dd {
// equations in to_simplify have correct indices
// they are labeled as non-processed
// their top-most variable is watched
i = 0;
for (auto* e : m_to_simplify) {
VERIFY(e->idx() == i);
VERIFY(e->state() == to_simplify);
pdd const& p = e->poly();
VERIFY(!p.is_val());
CTRACE("dd.solver", !m_watch.empty() && !m_watch[p.var()].contains(e),
display(tout << "not watched: ", *e) << "\n";);
VERIFY(m_watch.empty() || m_watch[p.var()].contains(e));
++i;
}
// the watch list consists of equations in to_simplify
// they watch the top most variable in poly
i = 0;
for (auto const& w : m_watch) {
for (equation* e : w) {
VERIFY(!e->poly().is_val());
VERIFY(e->poly().var() == i);
VERIFY(e->state() == to_simplify);
VERIFY(m_to_simplify.contains(e));
}
++i;
}
}

3
src/math/grobner/pdd_solver.h
View file

@ -147,14 +147,11 @@ private:
bool is_too_complex(const equation& eq) const { return is_too_complex(eq.poly()); }
bool is_too_complex(const pdd& p) const { return p.tree_size() > m_config.m_expr_size_limit; }
vector<equation_vector> m_watch; // watch list mapping variables to vector of equations where they occur (generally a subset)
unsigned m_levelp1; // index into level+1
unsigned_vector m_level2var; // level -> var
unsigned_vector m_var2level; // var -> level
void init_saturate();
void simplify_watch(equation const& eq);
void add_to_watch(equation& eq);
void del_equation(equation& eq) { del_equation(&eq); }
void del_equation(equation* eq);

1
src/math/simplex/bit_matrix.cpp
View file

@ -49,6 +49,7 @@ std::ostream& bit_matrix::row::display(std::ostream& out) const {
void bit_matrix::reset(unsigned num_columns) {
m_region.reset();
m_rows.reset();
m_num_columns = num_columns;
m_num_chunks = (num_columns + 63)/64;
}