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trying trim

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2022-10-04 16:25:40 +02:00
parent d22c86f9fe
commit c1c659dc93
4 changed files with 457 additions and 196 deletions
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247
src/cmd_context/extra_cmds/proof_cmds.cpp
View file

@ -45,6 +45,7 @@ Proof checker for clauses created during search.
#include "smt/smt_solver.h"
#include "sat/sat_solver.h"
#include "sat/sat_drat.h"
#include "sat/sat_proof_trim.h"
#include "sat/smt/euf_proof_checker.h"
#include "cmd_context/cmd_context.h"
#include "params/solver_params.hpp"
@ -181,203 +182,57 @@ public:
};
namespace sat {
/**
* Replay proof entierly, then walk backwards extracting reduced proof.
*/
class proof_trim {
cmd_context& ctx;
ast_manager& m;
solver s;
literal_vector m_clause;
vector<std::tuple<literal_vector, clause*, bool, bool>> m_trail;
/**
* Replay proof entierly, then walk backwards extracting reduced proof.
*/
class proof_trim {
cmd_context& ctx;
ast_manager& m;
sat::proof_trim trim;
struct hash {
unsigned operator()(literal_vector const& v) const {
return string_hash((char const*)v.begin(), v.size()*sizeof(literal), 3);
}
};
struct eq {
bool operator()(literal_vector const& a, literal_vector const& b) const {
return a == b;
}
};
map<literal_vector, clause_vector, hash, eq> m_clauses;
void mk_clause(expr_ref_vector const& clause) {
trim.init_clause();
for (expr* arg: clause)
add_literal(arg);
}
void mk_clause(expr_ref_vector const& clause) {
m_clause.reset();
for (expr* arg: clause)
add_literal(arg);
std::sort(m_clause.begin(), m_clause.end());
}
sat::bool_var mk_var(expr* arg) {
while (arg->get_id() >= trim.num_vars())
trim.mk_var();
return arg->get_id();
}
bool_var mk_var(expr* arg) {
while (arg->get_id() >= s.num_vars())
s.mk_var(true, true);
return arg->get_id();
}
void add_literal(expr* arg) {
bool sign = m.is_not(arg, arg);
m_clause.push_back(literal(mk_var(arg), sign));
}
/**
Pseudo-code from Gurfinkel, Vizel, FMCAD 2014
Input: trail (a0,d0), ..., (an,dn) = ({},bot)
Output: reduced trail - result
result = []
C = { an }
for i = n to 0 do
if s.is_deleted(ai) then s.revive(ai)
else
if s.isontrail(ai) then
s.undotrailcore(ai,C)
s.delete(ai)
if ai in C then
if ai is not initial then
s.savetrail()
s.enqueue(not ai)
c = s.propagate()
s.conflictanalysiscore(c, C)
s.restoretrail()
result += [ai]
reverse(result)
is_deleted(ai):
clause was detached
revive(ai):
attach clause ai
isontrail(ai):
some literal on the current trail in s is justified by ai
undotrailcore(ai, C):
pop the trail until dependencies on ai are gone
savetrail:
store current trail so it can be restored
enqueue(not ai):
assert negations of ai at a new decision level
conflictanalysiscore(c, C):
?
restoretrail:
restore the trail to the position before enqueue
*/
void trim() {
vector<literal_vector> result, clauses;
clauses.push_back(literal_vector());
for (unsigned i = m_trail.size(); i-- > 0; ) {
auto const& [cl, clp, is_add, is_initial] = m_trail[i];
if (!is_add) {
revive(cl, clp);
continue;
}
prune_trail(cl, clp);
del(cl, clp);
if (!clauses.contains(cl))
continue;
if (!is_initial) {
s.push();
unsigned lvl = s.scope_lvl();
for (auto lit : cl)
s.assign(~lit, justification(lvl));
s.propagate(false);
SASSERT(s.inconsistent());
conflict_analysis(clauses);
s.pop(1);
}
result.push_back(cl);
}
result.reverse();
}
void del(literal_vector const& cl, clause* cp) {
if (cp)
s.detach_clause(*cp);
else
del(cl);
}
void prune_trail(literal_vector const& cl, clause* cp) {
}
void conflict_analysis(vector<literal_vector> const& clauses) {
}
void revive(literal_vector const& cl, clause* cp) {
if (cp)
s.attach_clause(*cp);
else
s.mk_clause(cl, status::redundant());
}
clause* del(literal_vector const& cl) {
clause* cp = nullptr;
IF_VERBOSE(3, verbose_stream() << "del: " << cl << "\n");
if (m_clause.size() == 2) {
s.detach_bin_clause(cl[0], cl[1], true);
return cp;
}
auto* e = m_clauses.find_core(cl);
if (!e)
return cp;
auto& v = e->get_data().m_value;
if (!v.empty()) {
cp = v.back();
IF_VERBOSE(3, verbose_stream() << "del: " << *cp << "\n");
s.detach_clause(*cp);
v.pop_back();
}
return cp;
}
void save(literal_vector const& lits, clause* cl) {
if (!cl)
return;
IF_VERBOSE(3, verbose_stream() << "add: " << *cl << "\n");
auto& v = m_clauses.insert_if_not_there(lits, clause_vector());
v.push_back(cl);
}
public:
proof_trim(cmd_context& ctx):
ctx(ctx),
m(ctx.m()),
s(gparams::get_module("sat"), m.limit()) {
}
void assume(expr_ref_vector const& _clause, bool is_initial = true) {
mk_clause(_clause);
IF_VERBOSE(3, verbose_stream() << "add: " << m_clause << "\n");
auto* cl = s.mk_clause(m_clause, status::redundant());
m_trail.push_back({ m_clause, cl, true, is_initial });
s.propagate(false);
save(m_clause, cl);
}
void del(expr_ref_vector const& _clause) {
mk_clause(_clause);
clause* cp = del(m_clause);
m_trail.push_back({ m_clause, cp, false, true });
}
void infer(expr_ref_vector const& _clause, app*) {
assume(_clause, false);
}
void updt_params(params_ref const& p) {
s.updt_params(p);
}
};
}
void add_literal(expr* arg) {
bool sign = m.is_not(arg, arg);
trim.add_literal(mk_var(arg), sign);
}
public:
proof_trim(cmd_context& ctx):
ctx(ctx),
m(ctx.m()),
trim(gparams::get_module("sat"), m.limit()) {
}
void assume(expr_ref_vector const& _clause, bool is_initial = true) {
mk_clause(_clause);
trim.assume(true);
}
void del(expr_ref_vector const& _clause) {
mk_clause(_clause);
trim.del();
}
void infer(expr_ref_vector const& _clause, app*) {
mk_clause(_clause);
trim.infer();
}
void updt_params(params_ref const& p) {
trim.updt_params(p);
}
};
class proof_saver {
cmd_context& ctx;
@ -415,11 +270,11 @@ class proof_cmds_imp : public proof_cmds {
bool m_trim = false;
scoped_ptr<smt_checker> m_checker;
scoped_ptr<proof_saver> m_saver;
scoped_ptr<sat::proof_trim> m_trimmer;
scoped_ptr<proof_trim> m_trimmer;
smt_checker& checker() { if (!m_checker) m_checker = alloc(smt_checker, m); return *m_checker; }
proof_saver& saver() { if (!m_saver) m_saver = alloc(proof_saver, ctx); return *m_saver; }
sat::proof_trim& trim() { if (!m_trimmer) m_trimmer = alloc(sat::proof_trim, ctx); return *m_trimmer; }
proof_trim& trim() { if (!m_trimmer) m_trimmer = alloc(proof_trim, ctx); return *m_trimmer; }
public:
proof_cmds_imp(cmd_context& ctx): ctx(ctx), m(ctx.m()), m_lits(m), m_proof_hint(m) {

1
src/sat/CMakeLists.txt
View file

@ -30,6 +30,7 @@ z3_add_component(sat
sat_parallel.cpp
sat_prob.cpp
sat_probing.cpp
sat_proof_trim.cpp
sat_scc.cpp
sat_simplifier.cpp
sat_solver.cpp

326
src/sat/sat_proof_trim.cpp Normal file
View file

@ -0,0 +1,326 @@
/*++
Copyright (c) 2020 Microsoft Corporation
Module Name:
sat_proof_trim.cpp
Abstract:
proof replay and trim
Author:
Nikolaj Bjorner 2023-10-04
Notes:
--*/
#include "sat/sat_proof_trim.h"
namespace sat {
/**
Pseudo-code from Gurfinkel, Vizel, FMCAD 2014
Input: trail (a0,d0), ..., (an,dn) = ({},bot)
Output: reduced trail - result
result = []
C = { an }
for i = n to 0 do
if s.is_deleted(ai) then s.revive(ai)
else
if s.isontrail(ai) then
s.undotrailcore(ai,C)
s.delete(ai)
if ai in C then
if ai is not initial then
s.savetrail()
s.enqueue(not ai)
c = s.propagate()
s.conflictanalysiscore(c, C)
s.restoretrail()
result += [ai]
reverse(result)
is_deleted(ai):
clause was detached
revive(ai):
attach clause ai
isontrail(ai):
some literal on the current trail in s is justified by ai
undotrailcore(ai, C):
pop the trail until dependencies on ai are gone
savetrail:
store current trail so it can be restored
enqueue(not ai):
assert negations of ai at a new decision level
conflictanalysiscore(c, C):
?
restoretrail:
restore the trail to the position before enqueue
*/
void proof_trim::trim() {
vector<literal_vector> result, clauses;
clauses.push_back(literal_vector());
for (unsigned i = m_trail.size(); i-- > 0; ) {
auto const& [cl, clp, is_add, is_initial] = m_trail[i];
if (!is_add) {
revive(cl, clp);
continue;
}
prune_trail(cl, clp);
del(cl, clp);
if (!clauses.contains(cl))
continue;
result.push_back(cl);
if (is_initial)
continue;
s.push();
unsigned init_sz = s.m_trail.size();
unsigned lvl = s.scope_lvl();
for (auto lit : cl)
s.assign(~lit, justification(lvl));
s.propagate(false);
SASSERT(s.inconsistent());
conflict_analysis_core(init_sz, clauses);
s.pop(1);
}
result.reverse();
}
void proof_trim::del(literal_vector const& cl, clause* cp) {
if (cp)
s.detach_clause(*cp);
else
del(cl);
}
bool proof_trim::match_clause(literal_vector const& cl, literal l1, literal l2) const {
return cl.size() == 2 && ((l1 == cl[0] && l2 == cl[1]) || (l1 == cl[1] && l2 == cl[0]));
}
bool proof_trim::match_clause(literal_vector const& cl, literal l1, literal l2, literal l3) const {
return cl.size() == 3 &&
((l1 == cl[0] && l2 == cl[1] && l3 == cl[2]) ||
(l1 == cl[0] && l2 == cl[2] && l3 == cl[1]) ||
(l1 == cl[1] && l2 == cl[0] && l3 == cl[2]) ||
(l1 == cl[1] && l2 == cl[2] && l3 == cl[0]) ||
(l1 == cl[2] && l2 == cl[1] && l3 == cl[0]) ||
(l1 == cl[2] && l2 == cl[0] && l3 == cl[1]));
}
/**
* cl is on the trail if there is some literal l that is implied by cl
* Remove all clauses after cl that are in the cone of influence of cl.
* The coi is defined inductively: C is in coi of cl if it contains ~l
* or it contains ~l' where l' is implied by a clause in the coi of cl.
* Possible optimization:
* - check if clause contains a literal that is on implied on the trail
* if it doesn't contain any such literal, bypass the trail adjustment.
*/
void proof_trim::prune_trail(literal_vector const& cl, clause* cp) {
m_in_clause.reset();
m_in_coi.reset();
for (literal lit : cl)
m_in_clause.insert(lit.index());
bool on_trail = false;
unsigned j = 0;
for (unsigned i = 0; i < s.trail_size(); ++i) {
literal l = s.trail_literal(i);
if (m_in_clause.contains(l.index())) {
SASSERT(!on_trail);
on_trail = true;
m_in_coi.insert((~l).index());
s.m_assignment[l.index()] = l_undef;
s.m_assignment[(~l).index()] = l_undef;
continue;
}
if (!on_trail) {
s.m_trail[j++] = s.m_trail[i];
continue;
}
auto js = s.get_justification(l);
bool in_coi = false;
if (js.is_clause())
for (literal lit : s.get_clause(j))
in_coi |= m_in_coi.contains(lit.index());
else if (js.is_binary_clause())
in_coi = m_in_coi.contains(js.get_literal().index());
else if (js.is_ternary_clause())
in_coi = m_in_coi.contains(js.get_literal1().index()) || m_in_coi.contains(js.get_literal2().index());
else
UNREACHABLE(); // approach does not work for external justifications
if (in_coi) {
m_in_coi.insert((~l).index());
s.m_assignment[l.index()] = l_undef;
s.m_assignment[(~l).index()] = l_undef;
}
else
s.m_trail[j++] = s.m_trail[i];
}
s.m_trail.shrink(j);
}
/**
The current state is in conflict.
Chase justifications for conflict to extract clauses that are in coi of conflict.
Assume:
F | G, ~C |- []
Let T (trail) be the extension of G, ~C that derives the empty clause.
T := G, ~C, l1:j1, l2:j2, ..., lk:jk
The goal is to extract clauses in T that are used to derive C.
- some of the literals in ~C that are not set to true already (they must be unassigned relative)
are used to derive the empty clause.
- some literals in ~C that are assigned to true may also be used to derive the empty clause.
Example:
C = c or d or e
G = a
F = { ~a or ~b, c or d or b, ... }
T = ~b : ~a or ~b, ~c: D ~d : D , ~e : D, b : c or d or b
where D is a decision marker (justification::NONE)
The conflict depends on the first two clauses in F.
All literals that are are used in clauses leading to the conflict are
queried for their explanation. Their explanation is added to the clauses.
*/
void proof_trim::conflict_analysis_core(unsigned init_sz, vector<literal_vector>& clauses) {
justification j = s.m_conflict;
literal consequent = null_literal;
unsigned idx = s.m_trail.size() - 1;
unsigned old_sz = s.m_unmark.size();
bool_var c_var;
auto add_dependency = [&](bool_var v) {
auto j = s.m_justification[v];
literal lit = literal(v, s.value(v) == l_false);
add_core(lit, j, clauses);
};
if (s.m_not_l != null_literal) {
s.process_antecedent_for_unsat_core(s.m_not_l);
add_core(s.m_not_l, s.m_justification[s.m_not_l.var()], clauses);
add_core(~s.m_not_l, j, clauses);
consequent = ~s.m_not_l;
}
while (true) {
s.process_consequent_for_unsat_core(consequent, j);
while (idx >= init_sz) {
consequent = s.m_trail[idx];
c_var = consequent.var();
if (s.is_marked(c_var))
break;
--idx;
}
if (idx < init_sz)
break;
j = s.m_justification[c_var];
--idx;
}
for (unsigned i = s.m_mark.size(); i-- > old_sz; )
add_dependency(s.m_unmark[i]);
s.reset_unmark(old_sz);
}
void proof_trim::add_core(literal l, justification j, vector<literal_vector>& clauses) {
m_clause.reset();
switch (j.get_kind()) {
case justification::NONE:
return;
case justification::BINARY:
m_clause.push_back(l);
m_clause.push_back(j.get_literal());
break;
case justification::TERNARY:
m_clause.push_back(l);
m_clause.push_back(j.get_literal1());
m_clause.push_back(j.get_literal2());
break;
case justification::CLAUSE:
for (auto lit : s.get_clause(j))
m_clause.push_back(lit);
break;
default:
UNREACHABLE();
break;
}
std::sort(m_clause.begin(), m_clause.end());
clauses.insert(m_clause);
}
void proof_trim::revive(literal_vector const& cl, clause* cp) {
if (cp)
s.attach_clause(*cp);
else
s.mk_clause(cl, status::redundant());
}
clause* proof_trim::del(literal_vector const& cl) {
clause* cp = nullptr;
IF_VERBOSE(3, verbose_stream() << "del: " << cl << "\n");
if (m_clause.size() == 2) {
s.detach_bin_clause(cl[0], cl[1], true);
return cp;
}
auto* e = m_clauses.find_core(cl);
if (!e)
return cp;
auto& v = e->get_data().m_value;
if (!v.empty()) {
cp = v.back();
IF_VERBOSE(3, verbose_stream() << "del: " << *cp << "\n");
s.detach_clause(*cp);
v.pop_back();
}
return cp;
}
void proof_trim::save(literal_vector const& lits, clause* cl) {
if (!cl)
return;
IF_VERBOSE(3, verbose_stream() << "add: " << *cl << "\n");
auto& v = m_clauses.insert_if_not_there(lits, clause_vector());
v.push_back(cl);
}
proof_trim::proof_trim(params_ref const& p, reslimit& lim):
s(p, lim)
{}
void proof_trim::assume(bool is_initial) {
std::sort(m_clause.begin(), m_clause.end());
IF_VERBOSE(3, verbose_stream() << "add: " << m_clause << "\n");
auto* cl = s.mk_clause(m_clause, status::redundant());
m_trail.push_back({ m_clause, cl, true, is_initial });
s.propagate(false);
save(m_clause, cl);
}
void proof_trim::del() {
std::sort(m_clause.begin(), m_clause.end());
clause* cp = del(m_clause);
m_trail.push_back({ m_clause, cp, false, true });
}
void proof_trim::infer() {
assume(false);
}
}

79
src/sat/sat_proof_trim.h Normal file
View file

@ -0,0 +1,79 @@
/*++
Copyright (c) 2020 Microsoft Corporation
Module Name:
sat_trim.h
Abstract:
proof replay and trim
Author:
Nikolaj Bjorner 2023-10-04
Notes:
--*/
#pragma once
#include "util/params.h"
#include "util/statistics.h"
#include "sat/sat_clause.h"
#include "sat/sat_types.h"
#include "sat/sat_solver.h"
namespace sat {
class proof_trim {
solver s;
literal_vector m_clause;
uint_set m_in_clause;
uint_set m_in_coi;
vector<std::tuple<literal_vector, clause*, bool, bool>> m_trail;
struct hash {
unsigned operator()(literal_vector const& v) const {
return string_hash((char const*)v.begin(), v.size()*sizeof(literal), 3);
}
};
struct eq {
bool operator()(literal_vector const& a, literal_vector const& b) const {
return a == b;
}
};
map<literal_vector, clause_vector, hash, eq> m_clauses;
void del(literal_vector const& cl, clause* cp);
bool match_clause(literal_vector const& cl, literal l1, literal l2) const;
bool match_clause(literal_vector const& cl, literal l1, literal l2, literal l3) const;
void prune_trail(literal_vector const& cl, clause* cp);
void conflict_analysis_core(unsigned init_sz, vector<literal_vector>& clauses);
void add_core(literal l, justification j, vector<literal_vector>& clauses);
void revive(literal_vector const& cl, clause* cp);
clause* del(literal_vector const& cl);
void save(literal_vector const& lits, clause* cl);
public:
proof_trim(params_ref const& p, reslimit& lim);
bool_var mk_var() { return s.mk_var(true, true); }
void init_clause() { m_clause.reset(); }
void add_literal(bool_var v, bool sign) { m_clause.push_back(literal(v, sign)); }
unsigned num_vars() { return s.num_vars(); }
void assume(bool is_initial = true);
void del();
void infer();
void updt_params(params_ref const& p) { s.updt_params(p); }
void trim();
};
}