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implemented basics

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Tom
2019-02-15 21:28:37 +01:00
parent 4f9ae6c67d
commit 9346bcdf63
3473 changed files with 504669 additions and 0 deletions
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89
contrib/minisat/src/core/Dimacs.h Normal file
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/****************************************************************************************[Dimacs.h]
Copyright (c) 2003-2006, Niklas Een, Niklas Sorensson
Copyright (c) 2007-2010, Niklas Sorensson
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
associated documentation files (the "Software"), to deal in the Software without restriction,
including without limitation the rights to use, copy, modify, merge, publish, distribute,
sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or
substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT
OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
**************************************************************************************************/
#ifndef Minisat_Dimacs_h
#define Minisat_Dimacs_h
#include <stdio.h>
#include "utils/ParseUtils.h"
#include "core/SolverTypes.h"
namespace Minisat {
//=================================================================================================
// DIMACS Parser:
template<class B, class Solver>
static void readClause(B& in, Solver& S, vec<Lit>& lits) {
int parsed_lit, var;
lits.clear();
for (;;){
parsed_lit = parseInt(in);
if (parsed_lit == 0) break;
var = abs(parsed_lit)-1;
while (var >= S.nVars()) S.newVar();
lits.push( (parsed_lit > 0) ? mkLit(var) : ~mkLit(var) );
}
}
template<class B, class Solver>
static void parse_DIMACS_main(B& in, Solver& S) {
vec<Lit> lits;
int vars = 0;
int clauses = 0;
int cnt = 0;
for (;;){
skipWhitespace(in);
if (*in == EOF) break;
else if (*in == 'p'){
if (eagerMatch(in, "p cnf")){
vars = parseInt(in);
clauses = parseInt(in);
// SATRACE'06 hack
// if (clauses > 4000000)
// S.eliminate(true);
}else{
printf("PARSE ERROR! Unexpected char: %c\n", *in), exit(3);
}
} else if (*in == 'c' || *in == 'p')
skipLine(in);
else{
cnt++;
readClause(in, S, lits);
S.addClause_(lits); }
}
if (vars != S.nVars())
fprintf(stderr, "WARNING! DIMACS header mismatch: wrong number of variables.\n");
if (cnt != clauses)
fprintf(stderr, "WARNING! DIMACS header mismatch: wrong number of clauses.\n");
}
// Inserts problem into solver.
//
template<class Solver>
static void parse_DIMACS(gzFile input_stream, Solver& S) {
StreamBuffer in(input_stream);
parse_DIMACS_main(in, S); }
//=================================================================================================
}
#endif

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contrib/minisat/src/core/Main.cc Normal file
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/*****************************************************************************************[Main.cc]
Copyright (c) 2003-2006, Niklas Een, Niklas Sorensson
Copyright (c) 2007-2010, Niklas Sorensson
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
associated documentation files (the "Software"), to deal in the Software without restriction,
including without limitation the rights to use, copy, modify, merge, publish, distribute,
sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or
substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT
OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
**************************************************************************************************/
#include <errno.h>
#include <signal.h>
#include <zlib.h>
#include "utils/System.h"
#include "utils/ParseUtils.h"
#include "utils/Options.h"
#include "core/Dimacs.h"
#include "core/Solver.h"
using namespace Minisat;
//=================================================================================================
void printStats(Solver& solver)
{
double cpu_time = cpuTime();
double mem_used = memUsedPeak();
printf("restarts : %"PRIu64"\n", solver.starts);
printf("conflicts : %-12"PRIu64" (%.0f /sec)\n", solver.conflicts , solver.conflicts /cpu_time);
printf("decisions : %-12"PRIu64" (%4.2f %% random) (%.0f /sec)\n", solver.decisions, (float)solver.rnd_decisions*100 / (float)solver.decisions, solver.decisions /cpu_time);
printf("propagations : %-12"PRIu64" (%.0f /sec)\n", solver.propagations, solver.propagations/cpu_time);
printf("conflict literals : %-12"PRIu64" (%4.2f %% deleted)\n", solver.tot_literals, (solver.max_literals - solver.tot_literals)*100 / (double)solver.max_literals);
if (mem_used != 0) printf("Memory used : %.2f MB\n", mem_used);
printf("CPU time : %g s\n", cpu_time);
}
static Solver* solver;
// Terminate by notifying the solver and back out gracefully. This is mainly to have a test-case
// for this feature of the Solver as it may take longer than an immediate call to '_exit()'.
static void SIGINT_interrupt(int signum) { solver->interrupt(); }
// Note that '_exit()' rather than 'exit()' has to be used. The reason is that 'exit()' calls
// destructors and may cause deadlocks if a malloc/free function happens to be running (these
// functions are guarded by locks for multithreaded use).
static void SIGINT_exit(int signum) {
printf("\n"); printf("*** INTERRUPTED ***\n");
if (solver->verbosity > 0){
printStats(*solver);
printf("\n"); printf("*** INTERRUPTED ***\n"); }
_exit(1); }
//=================================================================================================
// Main:
int main(int argc, char** argv)
{
try {
setUsageHelp("USAGE: %s [options] <input-file> <result-output-file>\n\n where input may be either in plain or gzipped DIMACS.\n");
// printf("This is MiniSat 2.0 beta\n");
#if defined(__linux__)
fpu_control_t oldcw, newcw;
_FPU_GETCW(oldcw); newcw = (oldcw & ~_FPU_EXTENDED) | _FPU_DOUBLE; _FPU_SETCW(newcw);
printf("WARNING: for repeatability, setting FPU to use double precision\n");
#endif
// Extra options:
//
IntOption verb ("MAIN", "verb", "Verbosity level (0=silent, 1=some, 2=more).", 1, IntRange(0, 2));
IntOption cpu_lim("MAIN", "cpu-lim","Limit on CPU time allowed in seconds.\n", INT32_MAX, IntRange(0, INT32_MAX));
IntOption mem_lim("MAIN", "mem-lim","Limit on memory usage in megabytes.\n", INT32_MAX, IntRange(0, INT32_MAX));
parseOptions(argc, argv, true);
Solver S;
double initial_time = cpuTime();
S.verbosity = verb;
solver = &S;
// Use signal handlers that forcibly quit until the solver will be able to respond to
// interrupts:
signal(SIGINT, SIGINT_exit);
signal(SIGXCPU,SIGINT_exit);
// Set limit on CPU-time:
if (cpu_lim != INT32_MAX){
rlimit rl;
getrlimit(RLIMIT_CPU, &rl);
if (rl.rlim_max == RLIM_INFINITY || (rlim_t)cpu_lim < rl.rlim_max){
rl.rlim_cur = cpu_lim;
if (setrlimit(RLIMIT_CPU, &rl) == -1)
printf("WARNING! Could not set resource limit: CPU-time.\n");
} }
// Set limit on virtual memory:
if (mem_lim != INT32_MAX){
rlim_t new_mem_lim = (rlim_t)mem_lim * 1024*1024;
rlimit rl;
getrlimit(RLIMIT_AS, &rl);
if (rl.rlim_max == RLIM_INFINITY || new_mem_lim < rl.rlim_max){
rl.rlim_cur = new_mem_lim;
if (setrlimit(RLIMIT_AS, &rl) == -1)
printf("WARNING! Could not set resource limit: Virtual memory.\n");
} }
if (argc == 1)
printf("Reading from standard input... Use '--help' for help.\n");
gzFile in = (argc == 1) ? gzdopen(0, "rb") : gzopen(argv[1], "rb");
if (in == NULL)
printf("ERROR! Could not open file: %s\n", argc == 1 ? "<stdin>" : argv[1]), exit(1);
if (S.verbosity > 0){
printf("============================[ Problem Statistics ]=============================\n");
printf("| |\n"); }
parse_DIMACS(in, S);
gzclose(in);
FILE* res = (argc >= 3) ? fopen(argv[2], "wb") : NULL;
if (S.verbosity > 0){
printf("| Number of variables: %12d |\n", S.nVars());
printf("| Number of clauses: %12d |\n", S.nClauses()); }
double parsed_time = cpuTime();
if (S.verbosity > 0){
printf("| Parse time: %12.2f s |\n", parsed_time - initial_time);
printf("| |\n"); }
// Change to signal-handlers that will only notify the solver and allow it to terminate
// voluntarily:
signal(SIGINT, SIGINT_interrupt);
signal(SIGXCPU,SIGINT_interrupt);
if (!S.simplify()){
if (res != NULL) fprintf(res, "UNSAT\n"), fclose(res);
if (S.verbosity > 0){
printf("===============================================================================\n");
printf("Solved by unit propagation\n");
printStats(S);
printf("\n"); }
printf("UNSATISFIABLE\n");
exit(20);
}
vec<Lit> dummy;
lbool ret = S.solveLimited(dummy);
if (S.verbosity > 0){
printStats(S);
printf("\n"); }
printf(ret == l_True ? "SATISFIABLE\n" : ret == l_False ? "UNSATISFIABLE\n" : "INDETERMINATE\n");
if (res != NULL){
if (ret == l_True){
fprintf(res, "SAT\n");
for (int i = 0; i < S.nVars(); i++)
if (S.model[i] != l_Undef)
fprintf(res, "%s%s%d", (i==0)?"":" ", (S.model[i]==l_True)?"":"-", i+1);
fprintf(res, " 0\n");
}else if (ret == l_False)
fprintf(res, "UNSAT\n");
else
fprintf(res, "INDET\n");
fclose(res);
}
#ifdef NDEBUG
exit(ret == l_True ? 10 : ret == l_False ? 20 : 0); // (faster than "return", which will invoke the destructor for 'Solver')
#else
return (ret == l_True ? 10 : ret == l_False ? 20 : 0);
#endif
} catch (OutOfMemoryException&){
printf("===============================================================================\n");
printf("INDETERMINATE\n");
exit(0);
}
}

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contrib/minisat/src/core/Makefile Normal file
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EXEC = minisat
DEPDIR = mtl utils
include $(MROOT)/mtl/template.mk

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contrib/minisat/src/core/Solver.cc Normal file
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/***************************************************************************************[Solver.cc]
Copyright (c) 2003-2006, Niklas Een, Niklas Sorensson
Copyright (c) 2007-2010, Niklas Sorensson
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
associated documentation files (the "Software"), to deal in the Software without restriction,
including without limitation the rights to use, copy, modify, merge, publish, distribute,
sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or
substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT
OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
**************************************************************************************************/
#include <math.h>
#include "mtl/Sort.h"
#include "core/Solver.h"
using namespace Minisat;
//=================================================================================================
// Options:
static const char* _cat = "CORE";
static DoubleOption opt_var_decay (_cat, "var-decay", "The variable activity decay factor", 0.95, DoubleRange(0, false, 1, false));
static DoubleOption opt_clause_decay (_cat, "cla-decay", "The clause activity decay factor", 0.999, DoubleRange(0, false, 1, false));
static DoubleOption opt_random_var_freq (_cat, "rnd-freq", "The frequency with which the decision heuristic tries to choose a random variable", 0, DoubleRange(0, true, 1, true));
static DoubleOption opt_random_seed (_cat, "rnd-seed", "Used by the random variable selection", 91648253, DoubleRange(0, false, HUGE_VAL, false));
static IntOption opt_ccmin_mode (_cat, "ccmin-mode", "Controls conflict clause minimization (0=none, 1=basic, 2=deep)", 2, IntRange(0, 2));
static IntOption opt_phase_saving (_cat, "phase-saving", "Controls the level of phase saving (0=none, 1=limited, 2=full)", 2, IntRange(0, 2));
static BoolOption opt_rnd_init_act (_cat, "rnd-init", "Randomize the initial activity", false);
static BoolOption opt_luby_restart (_cat, "luby", "Use the Luby restart sequence", true);
static IntOption opt_restart_first (_cat, "rfirst", "The base restart interval", 100, IntRange(1, INT32_MAX));
static DoubleOption opt_restart_inc (_cat, "rinc", "Restart interval increase factor", 2, DoubleRange(1, false, HUGE_VAL, false));
static DoubleOption opt_garbage_frac (_cat, "gc-frac", "The fraction of wasted memory allowed before a garbage collection is triggered", 0.20, DoubleRange(0, false, HUGE_VAL, false));
//=================================================================================================
// Constructor/Destructor:
Solver::Solver() :
// Parameters (user settable):
//
verbosity (0)
, var_decay (opt_var_decay)
, clause_decay (opt_clause_decay)
, random_var_freq (opt_random_var_freq)
, random_seed (opt_random_seed)
, luby_restart (opt_luby_restart)
, ccmin_mode (opt_ccmin_mode)
, phase_saving (opt_phase_saving)
, rnd_pol (false)
, rnd_init_act (opt_rnd_init_act)
, garbage_frac (opt_garbage_frac)
, restart_first (opt_restart_first)
, restart_inc (opt_restart_inc)
// Parameters (the rest):
//
, learntsize_factor((double)1/(double)3), learntsize_inc(1.1)
// Parameters (experimental):
//
, learntsize_adjust_start_confl (100)
, learntsize_adjust_inc (1.5)
// Statistics: (formerly in 'SolverStats')
//
, solves(0), starts(0), decisions(0), rnd_decisions(0), propagations(0), conflicts(0)
, dec_vars(0), clauses_literals(0), learnts_literals(0), max_literals(0), tot_literals(0)
, ok (true)
, cla_inc (1)
, var_inc (1)
, watches (WatcherDeleted(ca))
, qhead (0)
, simpDB_assigns (-1)
, simpDB_props (0)
, order_heap (VarOrderLt(activity))
, progress_estimate (0)
, remove_satisfied (true)
// Resource constraints:
//
, conflict_budget (-1)
, propagation_budget (-1)
, asynch_interrupt (false)
{}
Solver::~Solver()
{
}
//=================================================================================================
// Minor methods:
// Creates a new SAT variable in the solver. If 'decision' is cleared, variable will not be
// used as a decision variable (NOTE! This has effects on the meaning of a SATISFIABLE result).
//
Var Solver::newVar(bool sign, bool dvar)
{
int v = nVars();
watches .init(mkLit(v, false));
watches .init(mkLit(v, true ));
assigns .push(l_Undef);
vardata .push(mkVarData(CRef_Undef, 0));
//activity .push(0);
activity .push(rnd_init_act ? drand(random_seed) * 0.00001 : 0);
seen .push(0);
polarity .push(sign);
decision .push();
trail .capacity(v+1);
setDecisionVar(v, dvar);
return v;
}
bool Solver::addClause_(vec<Lit>& ps)
{
assert(decisionLevel() == 0);
if (!ok) return false;
// Check if clause is satisfied and remove false/duplicate literals:
sort(ps);
Lit p; int i, j;
for (i = j = 0, p = lit_Undef; i < ps.size(); i++)
if (value(ps[i]) == l_True || ps[i] == ~p)
return true;
else if (value(ps[i]) != l_False && ps[i] != p)
ps[j++] = p = ps[i];
ps.shrink(i - j);
if (ps.size() == 0)
return ok = false;
else if (ps.size() == 1){
uncheckedEnqueue(ps[0]);
return ok = (propagate() == CRef_Undef);
}else{
CRef cr = ca.alloc(ps, false);
clauses.push(cr);
attachClause(cr);
}
return true;
}
void Solver::attachClause(CRef cr) {
const Clause& c = ca[cr];
assert(c.size() > 1);
watches[~c[0]].push(Watcher(cr, c[1]));
watches[~c[1]].push(Watcher(cr, c[0]));
if (c.learnt()) learnts_literals += c.size();
else clauses_literals += c.size(); }
void Solver::detachClause(CRef cr, bool strict) {
const Clause& c = ca[cr];
assert(c.size() > 1);
if (strict){
remove(watches[~c[0]], Watcher(cr, c[1]));
remove(watches[~c[1]], Watcher(cr, c[0]));
}else{
// Lazy detaching: (NOTE! Must clean all watcher lists before garbage collecting this clause)
watches.smudge(~c[0]);
watches.smudge(~c[1]);
}
if (c.learnt()) learnts_literals -= c.size();
else clauses_literals -= c.size(); }
void Solver::removeClause(CRef cr) {
Clause& c = ca[cr];
detachClause(cr);
// Don't leave pointers to free'd memory!
if (locked(c)) vardata[var(c[0])].reason = CRef_Undef;
c.mark(1);
ca.free(cr);
}
bool Solver::satisfied(const Clause& c) const {
for (int i = 0; i < c.size(); i++)
if (value(c[i]) == l_True)
return true;
return false; }
// Revert to the state at given level (keeping all assignment at 'level' but not beyond).
//
void Solver::cancelUntil(int level) {
if (decisionLevel() > level){
for (int c = trail.size()-1; c >= trail_lim[level]; c--){
Var x = var(trail[c]);
assigns [x] = l_Undef;
if (phase_saving > 1 || (phase_saving == 1) && c > trail_lim.last())
polarity[x] = sign(trail[c]);
insertVarOrder(x); }
qhead = trail_lim[level];
trail.shrink(trail.size() - trail_lim[level]);
trail_lim.shrink(trail_lim.size() - level);
} }
//=================================================================================================
// Major methods:
Lit Solver::pickBranchLit()
{
Var next = var_Undef;
// Random decision:
if (drand(random_seed) < random_var_freq && !order_heap.empty()){
next = order_heap[irand(random_seed,order_heap.size())];
if (value(next) == l_Undef && decision[next])
rnd_decisions++; }
// Activity based decision:
while (next == var_Undef || value(next) != l_Undef || !decision[next])
if (order_heap.empty()){
next = var_Undef;
break;
}else
next = order_heap.removeMin();
return next == var_Undef ? lit_Undef : mkLit(next, rnd_pol ? drand(random_seed) < 0.5 : polarity[next]);
}
/*_________________________________________________________________________________________________
|
| analyze : (confl : Clause*) (out_learnt : vec<Lit>&) (out_btlevel : int&) -> [void]
|
| Description:
| Analyze conflict and produce a reason clause.
|
| Pre-conditions:
| * 'out_learnt' is assumed to be cleared.
| * Current decision level must be greater than root level.
|
| Post-conditions:
| * 'out_learnt[0]' is the asserting literal at level 'out_btlevel'.
| * If out_learnt.size() > 1 then 'out_learnt[1]' has the greatest decision level of the
| rest of literals. There may be others from the same level though.
|
|________________________________________________________________________________________________@*/
void Solver::analyze(CRef confl, vec<Lit>& out_learnt, int& out_btlevel)
{
int pathC = 0;
Lit p = lit_Undef;
// Generate conflict clause:
//
out_learnt.push(); // (leave room for the asserting literal)
int index = trail.size() - 1;
do{
assert(confl != CRef_Undef); // (otherwise should be UIP)
Clause& c = ca[confl];
if (c.learnt())
claBumpActivity(c);
for (int j = (p == lit_Undef) ? 0 : 1; j < c.size(); j++){
Lit q = c[j];
if (!seen[var(q)] && level(var(q)) > 0){
varBumpActivity(var(q));
seen[var(q)] = 1;
if (level(var(q)) >= decisionLevel())
pathC++;
else
out_learnt.push(q);
}
}
// Select next clause to look at:
while (!seen[var(trail[index--])]);
p = trail[index+1];
confl = reason(var(p));
seen[var(p)] = 0;
pathC--;
}while (pathC > 0);
out_learnt[0] = ~p;
// Simplify conflict clause:
//
int i, j;
out_learnt.copyTo(analyze_toclear);
if (ccmin_mode == 2){
uint32_t abstract_level = 0;
for (i = 1; i < out_learnt.size(); i++)
abstract_level |= abstractLevel(var(out_learnt[i])); // (maintain an abstraction of levels involved in conflict)
for (i = j = 1; i < out_learnt.size(); i++)
if (reason(var(out_learnt[i])) == CRef_Undef || !litRedundant(out_learnt[i], abstract_level))
out_learnt[j++] = out_learnt[i];
}else if (ccmin_mode == 1){
for (i = j = 1; i < out_learnt.size(); i++){
Var x = var(out_learnt[i]);
if (reason(x) == CRef_Undef)
out_learnt[j++] = out_learnt[i];
else{
Clause& c = ca[reason(var(out_learnt[i]))];
for (int k = 1; k < c.size(); k++)
if (!seen[var(c[k])] && level(var(c[k])) > 0){
out_learnt[j++] = out_learnt[i];
break; }
}
}
}else
i = j = out_learnt.size();
max_literals += out_learnt.size();
out_learnt.shrink(i - j);
tot_literals += out_learnt.size();
// Find correct backtrack level:
//
if (out_learnt.size() == 1)
out_btlevel = 0;
else{
int max_i = 1;
// Find the first literal assigned at the next-highest level:
for (int i = 2; i < out_learnt.size(); i++)
if (level(var(out_learnt[i])) > level(var(out_learnt[max_i])))
max_i = i;
// Swap-in this literal at index 1:
Lit p = out_learnt[max_i];
out_learnt[max_i] = out_learnt[1];
out_learnt[1] = p;
out_btlevel = level(var(p));
}
for (int j = 0; j < analyze_toclear.size(); j++) seen[var(analyze_toclear[j])] = 0; // ('seen[]' is now cleared)
}
// Check if 'p' can be removed. 'abstract_levels' is used to abort early if the algorithm is
// visiting literals at levels that cannot be removed later.
bool Solver::litRedundant(Lit p, uint32_t abstract_levels)
{
analyze_stack.clear(); analyze_stack.push(p);
int top = analyze_toclear.size();
while (analyze_stack.size() > 0){
assert(reason(var(analyze_stack.last())) != CRef_Undef);
Clause& c = ca[reason(var(analyze_stack.last()))]; analyze_stack.pop();
for (int i = 1; i < c.size(); i++){
Lit p = c[i];
if (!seen[var(p)] && level(var(p)) > 0){
if (reason(var(p)) != CRef_Undef && (abstractLevel(var(p)) & abstract_levels) != 0){
seen[var(p)] = 1;
analyze_stack.push(p);
analyze_toclear.push(p);
}else{
for (int j = top; j < analyze_toclear.size(); j++)
seen[var(analyze_toclear[j])] = 0;
analyze_toclear.shrink(analyze_toclear.size() - top);
return false;
}
}
}
}
return true;
}
/*_________________________________________________________________________________________________
|
| analyzeFinal : (p : Lit) -> [void]
|
| Description:
| Specialized analysis procedure to express the final conflict in terms of assumptions.
| Calculates the (possibly empty) set of assumptions that led to the assignment of 'p', and
| stores the result in 'out_conflict'.
|________________________________________________________________________________________________@*/
void Solver::analyzeFinal(Lit p, vec<Lit>& out_conflict)
{
out_conflict.clear();
out_conflict.push(p);
if (decisionLevel() == 0)
return;
seen[var(p)] = 1;
for (int i = trail.size()-1; i >= trail_lim[0]; i--){
Var x = var(trail[i]);
if (seen[x]){
if (reason(x) == CRef_Undef){
assert(level(x) > 0);
out_conflict.push(~trail[i]);
}else{
Clause& c = ca[reason(x)];
for (int j = 1; j < c.size(); j++)
if (level(var(c[j])) > 0)
seen[var(c[j])] = 1;
}
seen[x] = 0;
}
}
seen[var(p)] = 0;
}
void Solver::uncheckedEnqueue(Lit p, CRef from)
{
assert(value(p) == l_Undef);
assigns[var(p)] = lbool(!sign(p));
vardata[var(p)] = mkVarData(from, decisionLevel());
trail.push_(p);
}
/*_________________________________________________________________________________________________
|
| propagate : [void] -> [Clause*]
|
| Description:
| Propagates all enqueued facts. If a conflict arises, the conflicting clause is returned,
| otherwise CRef_Undef.
|
| Post-conditions:
| * the propagation queue is empty, even if there was a conflict.
|________________________________________________________________________________________________@*/
CRef Solver::propagate()
{
CRef confl = CRef_Undef;
int num_props = 0;
watches.cleanAll();
while (qhead < trail.size()){
Lit p = trail[qhead++]; // 'p' is enqueued fact to propagate.
vec<Watcher>& ws = watches[p];
Watcher *i, *j, *end;
num_props++;
for (i = j = (Watcher*)ws, end = i + ws.size(); i != end;){
// Try to avoid inspecting the clause:
Lit blocker = i->blocker;
if (value(blocker) == l_True){
*j++ = *i++; continue; }
// Make sure the false literal is data[1]:
CRef cr = i->cref;
Clause& c = ca[cr];
Lit false_lit = ~p;
if (c[0] == false_lit)
c[0] = c[1], c[1] = false_lit;
assert(c[1] == false_lit);
i++;
// If 0th watch is true, then clause is already satisfied.
Lit first = c[0];
Watcher w = Watcher(cr, first);
if (first != blocker && value(first) == l_True){
*j++ = w; continue; }
// Look for new watch:
for (int k = 2; k < c.size(); k++)
if (value(c[k]) != l_False){
c[1] = c[k]; c[k] = false_lit;
watches[~c[1]].push(w);
goto NextClause; }
// Did not find watch -- clause is unit under assignment:
*j++ = w;
if (value(first) == l_False){
confl = cr;
qhead = trail.size();
// Copy the remaining watches:
while (i < end)
*j++ = *i++;
}else
uncheckedEnqueue(first, cr);
NextClause:;
}
ws.shrink(i - j);
}
propagations += num_props;
simpDB_props -= num_props;
return confl;
}
/*_________________________________________________________________________________________________
|
| reduceDB : () -> [void]
|
| Description:
| Remove half of the learnt clauses, minus the clauses locked by the current assignment. Locked
| clauses are clauses that are reason to some assignment. Binary clauses are never removed.
|________________________________________________________________________________________________@*/
struct reduceDB_lt {
ClauseAllocator& ca;
reduceDB_lt(ClauseAllocator& ca_) : ca(ca_) {}
bool operator () (CRef x, CRef y) {
return ca[x].size() > 2 && (ca[y].size() == 2 || ca[x].activity() < ca[y].activity()); }
};
void Solver::reduceDB()
{
int i, j;
double extra_lim = cla_inc / learnts.size(); // Remove any clause below this activity
sort(learnts, reduceDB_lt(ca));
// Don't delete binary or locked clauses. From the rest, delete clauses from the first half
// and clauses with activity smaller than 'extra_lim':
for (i = j = 0; i < learnts.size(); i++){
Clause& c = ca[learnts[i]];
if (c.size() > 2 && !locked(c) && (i < learnts.size() / 2 || c.activity() < extra_lim))
removeClause(learnts[i]);
else
learnts[j++] = learnts[i];
}
learnts.shrink(i - j);
checkGarbage();
}
void Solver::removeSatisfied(vec<CRef>& cs)
{
int i, j;
for (i = j = 0; i < cs.size(); i++){
Clause& c = ca[cs[i]];
if (satisfied(c))
removeClause(cs[i]);
else
cs[j++] = cs[i];
}
cs.shrink(i - j);
}
void Solver::rebuildOrderHeap()
{
vec<Var> vs;
for (Var v = 0; v < nVars(); v++)
if (decision[v] && value(v) == l_Undef)
vs.push(v);
order_heap.build(vs);
}
/*_________________________________________________________________________________________________
|
| simplify : [void] -> [bool]
|
| Description:
| Simplify the clause database according to the current top-level assigment. Currently, the only
| thing done here is the removal of satisfied clauses, but more things can be put here.
|________________________________________________________________________________________________@*/
bool Solver::simplify()
{
assert(decisionLevel() == 0);
if (!ok || propagate() != CRef_Undef)
return ok = false;
if (nAssigns() == simpDB_assigns || (simpDB_props > 0))
return true;
// Remove satisfied clauses:
removeSatisfied(learnts);
if (remove_satisfied) // Can be turned off.
removeSatisfied(clauses);
checkGarbage();
rebuildOrderHeap();
simpDB_assigns = nAssigns();
simpDB_props = clauses_literals + learnts_literals; // (shouldn't depend on stats really, but it will do for now)
return true;
}
/*_________________________________________________________________________________________________
|
| search : (nof_conflicts : int) (params : const SearchParams&) -> [lbool]
|
| Description:
| Search for a model the specified number of conflicts.
| NOTE! Use negative value for 'nof_conflicts' indicate infinity.
|
| Output:
| 'l_True' if a partial assigment that is consistent with respect to the clauseset is found. If
| all variables are decision variables, this means that the clause set is satisfiable. 'l_False'
| if the clause set is unsatisfiable. 'l_Undef' if the bound on number of conflicts is reached.
|________________________________________________________________________________________________@*/
lbool Solver::search(int nof_conflicts)
{
assert(ok);
int backtrack_level;
int conflictC = 0;
vec<Lit> learnt_clause;
starts++;
for (;;){
CRef confl = propagate();
if (confl != CRef_Undef){
// CONFLICT
conflicts++; conflictC++;
if (decisionLevel() == 0) return l_False;
learnt_clause.clear();
analyze(confl, learnt_clause, backtrack_level);
cancelUntil(backtrack_level);
if (learnt_clause.size() == 1){
uncheckedEnqueue(learnt_clause[0]);
}else{
CRef cr = ca.alloc(learnt_clause, true);
learnts.push(cr);
attachClause(cr);
claBumpActivity(ca[cr]);
uncheckedEnqueue(learnt_clause[0], cr);
}
varDecayActivity();
claDecayActivity();
if (--learntsize_adjust_cnt == 0){
learntsize_adjust_confl *= learntsize_adjust_inc;
learntsize_adjust_cnt = (int)learntsize_adjust_confl;
max_learnts *= learntsize_inc;
if (verbosity >= 1)
printf("| %9d | %7d %8d %8d | %8d %8d %6.0f | %6.3f %% |\n",
(int)conflicts,
(int)dec_vars - (trail_lim.size() == 0 ? trail.size() : trail_lim[0]), nClauses(), (int)clauses_literals,
(int)max_learnts, nLearnts(), (double)learnts_literals/nLearnts(), progressEstimate()*100);
}
}else{
// NO CONFLICT
if (nof_conflicts >= 0 && conflictC >= nof_conflicts || !withinBudget()){
// Reached bound on number of conflicts:
progress_estimate = progressEstimate();
cancelUntil(0);
return l_Undef; }
// Simplify the set of problem clauses:
if (decisionLevel() == 0 && !simplify())
return l_False;
if (learnts.size()-nAssigns() >= max_learnts)
// Reduce the set of learnt clauses:
reduceDB();
Lit next = lit_Undef;
while (decisionLevel() < assumptions.size()){
// Perform user provided assumption:
Lit p = assumptions[decisionLevel()];
if (value(p) == l_True){
// Dummy decision level:
newDecisionLevel();
}else if (value(p) == l_False){
analyzeFinal(~p, conflict);
return l_False;
}else{
next = p;
break;
}
}
if (next == lit_Undef){
// New variable decision:
decisions++;
next = pickBranchLit();
if (next == lit_Undef)
// Model found:
return l_True;
}
// Increase decision level and enqueue 'next'
newDecisionLevel();
uncheckedEnqueue(next);
}
}
}
double Solver::progressEstimate() const
{
double progress = 0;
double F = 1.0 / nVars();
for (int i = 0; i <= decisionLevel(); i++){
int beg = i == 0 ? 0 : trail_lim[i - 1];
int end = i == decisionLevel() ? trail.size() : trail_lim[i];
progress += pow(F, i) * (end - beg);
}
return progress / nVars();
}
/*
Finite subsequences of the Luby-sequence:
0: 1
1: 1 1 2
2: 1 1 2 1 1 2 4
3: 1 1 2 1 1 2 4 1 1 2 1 1 2 4 8
...
*/
static double luby(double y, int x){
// Find the finite subsequence that contains index 'x', and the
// size of that subsequence:
int size, seq;
for (size = 1, seq = 0; size < x+1; seq++, size = 2*size+1);
while (size-1 != x){
size = (size-1)>>1;
seq--;
x = x % size;
}
return pow(y, seq);
}
// NOTE: assumptions passed in member-variable 'assumptions'.
lbool Solver::solve_()
{
model.clear();
conflict.clear();
if (!ok) return l_False;
solves++;
max_learnts = nClauses() * learntsize_factor;
learntsize_adjust_confl = learntsize_adjust_start_confl;
learntsize_adjust_cnt = (int)learntsize_adjust_confl;
lbool status = l_Undef;
if (verbosity >= 1){
printf("============================[ Search Statistics ]==============================\n");
printf("| Conflicts | ORIGINAL | LEARNT | Progress |\n");
printf("| | Vars Clauses Literals | Limit Clauses Lit/Cl | |\n");
printf("===============================================================================\n");
}
// Search:
int curr_restarts = 0;
while (status == l_Undef){
double rest_base = luby_restart ? luby(restart_inc, curr_restarts) : pow(restart_inc, curr_restarts);
status = search(rest_base * restart_first);
if (!withinBudget()) break;
curr_restarts++;
}
if (verbosity >= 1)
printf("===============================================================================\n");
if (status == l_True){
// Extend & copy model:
model.growTo(nVars());
for (int i = 0; i < nVars(); i++) model[i] = value(i);
}else if (status == l_False && conflict.size() == 0)
ok = false;
cancelUntil(0);
return status;
}
//=================================================================================================
// Writing CNF to DIMACS:
//
// FIXME: this needs to be rewritten completely.
static Var mapVar(Var x, vec<Var>& map, Var& max)
{
if (map.size() <= x || map[x] == -1){
map.growTo(x+1, -1);
map[x] = max++;
}
return map[x];
}
void Solver::toDimacs(FILE* f, Clause& c, vec<Var>& map, Var& max)
{
if (satisfied(c)) return;
for (int i = 0; i < c.size(); i++)
if (value(c[i]) != l_False)
fprintf(f, "%s%d ", sign(c[i]) ? "-" : "", mapVar(var(c[i]), map, max)+1);
fprintf(f, "0\n");
}
void Solver::toDimacs(const char *file, const vec<Lit>& assumps)
{
FILE* f = fopen(file, "wr");
if (f == NULL)
fprintf(stderr, "could not open file %s\n", file), exit(1);
toDimacs(f, assumps);
fclose(f);
}
void Solver::toDimacs(FILE* f, const vec<Lit>& assumps)
{
// Handle case when solver is in contradictory state:
if (!ok){
fprintf(f, "p cnf 1 2\n1 0\n-1 0\n");
return; }
vec<Var> map; Var max = 0;
// Cannot use removeClauses here because it is not safe
// to deallocate them at this point. Could be improved.
int cnt = 0;
for (int i = 0; i < clauses.size(); i++)
if (!satisfied(ca[clauses[i]]))
cnt++;
for (int i = 0; i < clauses.size(); i++)
if (!satisfied(ca[clauses[i]])){
Clause& c = ca[clauses[i]];
for (int j = 0; j < c.size(); j++)
if (value(c[j]) != l_False)
mapVar(var(c[j]), map, max);
}
// Assumptions are added as unit clauses:
cnt += assumptions.size();
fprintf(f, "p cnf %d %d\n", max, cnt);
for (int i = 0; i < assumptions.size(); i++){
assert(value(assumptions[i]) != l_False);
fprintf(f, "%s%d 0\n", sign(assumptions[i]) ? "-" : "", mapVar(var(assumptions[i]), map, max)+1);
}
for (int i = 0; i < clauses.size(); i++)
toDimacs(f, ca[clauses[i]], map, max);
if (verbosity > 0)
printf("Wrote %d clauses with %d variables.\n", cnt, max);
}
//=================================================================================================
// Garbage Collection methods:
void Solver::relocAll(ClauseAllocator& to)
{
// All watchers:
//
// for (int i = 0; i < watches.size(); i++)
watches.cleanAll();
for (int v = 0; v < nVars(); v++)
for (int s = 0; s < 2; s++){
Lit p = mkLit(v, s);
// printf(" >>> RELOCING: %s%d\n", sign(p)?"-":"", var(p)+1);
vec<Watcher>& ws = watches[p];
for (int j = 0; j < ws.size(); j++)
ca.reloc(ws[j].cref, to);
}
// All reasons:
//
for (int i = 0; i < trail.size(); i++){
Var v = var(trail[i]);
if (reason(v) != CRef_Undef && (ca[reason(v)].reloced() || locked(ca[reason(v)])))
ca.reloc(vardata[v].reason, to);
}
// All learnt:
//
for (int i = 0; i < learnts.size(); i++)
ca.reloc(learnts[i], to);
// All original:
//
for (int i = 0; i < clauses.size(); i++)
ca.reloc(clauses[i], to);
}
void Solver::garbageCollect()
{
// Initialize the next region to a size corresponding to the estimated utilization degree. This
// is not precise but should avoid some unnecessary reallocations for the new region:
ClauseAllocator to(ca.size() - ca.wasted());
relocAll(to);
if (verbosity >= 2)
printf("| Garbage collection: %12d bytes => %12d bytes |\n",
ca.size()*ClauseAllocator::Unit_Size, to.size()*ClauseAllocator::Unit_Size);
to.moveTo(ca);
}

373
contrib/minisat/src/core/Solver.h Normal file
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/****************************************************************************************[Solver.h]
Copyright (c) 2003-2006, Niklas Een, Niklas Sorensson
Copyright (c) 2007-2010, Niklas Sorensson
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
associated documentation files (the "Software"), to deal in the Software without restriction,
including without limitation the rights to use, copy, modify, merge, publish, distribute,
sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or
substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT
OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
**************************************************************************************************/
#ifndef Minisat_Solver_h
#define Minisat_Solver_h
#include "mtl/Vec.h"
#include "mtl/Heap.h"
#include "mtl/Alg.h"
#include "utils/Options.h"
#include "core/SolverTypes.h"
namespace Minisat {
//=================================================================================================
// Solver -- the main class:
class Solver {
public:
// Constructor/Destructor:
//
Solver();
virtual ~Solver();
// Problem specification:
//
Var newVar (bool polarity = true, bool dvar = true); // Add a new variable with parameters specifying variable mode.
bool addClause (const vec<Lit>& ps); // Add a clause to the solver.
bool addEmptyClause(); // Add the empty clause, making the solver contradictory.
bool addClause (Lit p); // Add a unit clause to the solver.
bool addClause (Lit p, Lit q); // Add a binary clause to the solver.
bool addClause (Lit p, Lit q, Lit r); // Add a ternary clause to the solver.
bool addClause_( vec<Lit>& ps); // Add a clause to the solver without making superflous internal copy. Will
// change the passed vector 'ps'.
// Solving:
//
bool simplify (); // Removes already satisfied clauses.
bool solve (const vec<Lit>& assumps); // Search for a model that respects a given set of assumptions.
lbool solveLimited (const vec<Lit>& assumps); // Search for a model that respects a given set of assumptions (With resource constraints).
bool solve (); // Search without assumptions.
bool solve (Lit p); // Search for a model that respects a single assumption.
bool solve (Lit p, Lit q); // Search for a model that respects two assumptions.
bool solve (Lit p, Lit q, Lit r); // Search for a model that respects three assumptions.
bool okay () const; // FALSE means solver is in a conflicting state
void toDimacs (FILE* f, const vec<Lit>& assumps); // Write CNF to file in DIMACS-format.
void toDimacs (const char *file, const vec<Lit>& assumps);
void toDimacs (FILE* f, Clause& c, vec<Var>& map, Var& max);
// Convenience versions of 'toDimacs()':
void toDimacs (const char* file);
void toDimacs (const char* file, Lit p);
void toDimacs (const char* file, Lit p, Lit q);
void toDimacs (const char* file, Lit p, Lit q, Lit r);
// Variable mode:
//
void setPolarity (Var v, bool b); // Declare which polarity the decision heuristic should use for a variable. Requires mode 'polarity_user'.
void setDecisionVar (Var v, bool b); // Declare if a variable should be eligible for selection in the decision heuristic.
// Read state:
//
lbool value (Var x) const; // The current value of a variable.
lbool value (Lit p) const; // The current value of a literal.
lbool modelValue (Var x) const; // The value of a variable in the last model. The last call to solve must have been satisfiable.
lbool modelValue (Lit p) const; // The value of a literal in the last model. The last call to solve must have been satisfiable.
int nAssigns () const; // The current number of assigned literals.
int nClauses () const; // The current number of original clauses.
int nLearnts () const; // The current number of learnt clauses.
int nVars () const; // The current number of variables.
int nFreeVars () const;
// Resource contraints:
//
void setConfBudget(int64_t x);
void setPropBudget(int64_t x);
void budgetOff();
void interrupt(); // Trigger a (potentially asynchronous) interruption of the solver.
void clearInterrupt(); // Clear interrupt indicator flag.
// Memory managment:
//
virtual void garbageCollect();
void checkGarbage(double gf);
void checkGarbage();
// Extra results: (read-only member variable)
//
vec<lbool> model; // If problem is satisfiable, this vector contains the model (if any).
vec<Lit> conflict; // If problem is unsatisfiable (possibly under assumptions),
// this vector represent the final conflict clause expressed in the assumptions.
// Mode of operation:
//
int verbosity;
double var_decay;
double clause_decay;
double random_var_freq;
double random_seed;
bool luby_restart;
int ccmin_mode; // Controls conflict clause minimization (0=none, 1=basic, 2=deep).
int phase_saving; // Controls the level of phase saving (0=none, 1=limited, 2=full).
bool rnd_pol; // Use random polarities for branching heuristics.
bool rnd_init_act; // Initialize variable activities with a small random value.
double garbage_frac; // The fraction of wasted memory allowed before a garbage collection is triggered.
int restart_first; // The initial restart limit. (default 100)
double restart_inc; // The factor with which the restart limit is multiplied in each restart. (default 1.5)
double learntsize_factor; // The intitial limit for learnt clauses is a factor of the original clauses. (default 1 / 3)
double learntsize_inc; // The limit for learnt clauses is multiplied with this factor each restart. (default 1.1)
int learntsize_adjust_start_confl;
double learntsize_adjust_inc;
// Statistics: (read-only member variable)
//
uint64_t solves, starts, decisions, rnd_decisions, propagations, conflicts;
uint64_t dec_vars, clauses_literals, learnts_literals, max_literals, tot_literals;
protected:
// Helper structures:
//
struct VarData { CRef reason; int level; };
static inline VarData mkVarData(CRef cr, int l){ VarData d = {cr, l}; return d; }
struct Watcher {
CRef cref;
Lit blocker;
Watcher(CRef cr, Lit p) : cref(cr), blocker(p) {}
bool operator==(const Watcher& w) const { return cref == w.cref; }
bool operator!=(const Watcher& w) const { return cref != w.cref; }
};
struct WatcherDeleted
{
const ClauseAllocator& ca;
WatcherDeleted(const ClauseAllocator& _ca) : ca(_ca) {}
bool operator()(const Watcher& w) const { return ca[w.cref].mark() == 1; }
};
struct VarOrderLt {
const vec<double>& activity;
bool operator () (Var x, Var y) const { return activity[x] > activity[y]; }
VarOrderLt(const vec<double>& act) : activity(act) { }
};
// Solver state:
//
bool ok; // If FALSE, the constraints are already unsatisfiable. No part of the solver state may be used!
vec<CRef> clauses; // List of problem clauses.
vec<CRef> learnts; // List of learnt clauses.
double cla_inc; // Amount to bump next clause with.
vec<double> activity; // A heuristic measurement of the activity of a variable.
double var_inc; // Amount to bump next variable with.
OccLists<Lit, vec<Watcher>, WatcherDeleted>
watches; // 'watches[lit]' is a list of constraints watching 'lit' (will go there if literal becomes true).
vec<lbool> assigns; // The current assignments.
vec<char> polarity; // The preferred polarity of each variable.
vec<char> decision; // Declares if a variable is eligible for selection in the decision heuristic.
vec<Lit> trail; // Assignment stack; stores all assigments made in the order they were made.
vec<int> trail_lim; // Separator indices for different decision levels in 'trail'.
vec<VarData> vardata; // Stores reason and level for each variable.
int qhead; // Head of queue (as index into the trail -- no more explicit propagation queue in MiniSat).
int simpDB_assigns; // Number of top-level assignments since last execution of 'simplify()'.
int64_t simpDB_props; // Remaining number of propagations that must be made before next execution of 'simplify()'.
vec<Lit> assumptions; // Current set of assumptions provided to solve by the user.
Heap<VarOrderLt> order_heap; // A priority queue of variables ordered with respect to the variable activity.
double progress_estimate;// Set by 'search()'.
bool remove_satisfied; // Indicates whether possibly inefficient linear scan for satisfied clauses should be performed in 'simplify'.
ClauseAllocator ca;
// Temporaries (to reduce allocation overhead). Each variable is prefixed by the method in which it is
// used, exept 'seen' wich is used in several places.
//
vec<char> seen;
vec<Lit> analyze_stack;
vec<Lit> analyze_toclear;
vec<Lit> add_tmp;
double max_learnts;
double learntsize_adjust_confl;
int learntsize_adjust_cnt;
// Resource contraints:
//
int64_t conflict_budget; // -1 means no budget.
int64_t propagation_budget; // -1 means no budget.
bool asynch_interrupt;
// Main internal methods:
//
void insertVarOrder (Var x); // Insert a variable in the decision order priority queue.
Lit pickBranchLit (); // Return the next decision variable.
void newDecisionLevel (); // Begins a new decision level.
void uncheckedEnqueue (Lit p, CRef from = CRef_Undef); // Enqueue a literal. Assumes value of literal is undefined.
bool enqueue (Lit p, CRef from = CRef_Undef); // Test if fact 'p' contradicts current state, enqueue otherwise.
CRef propagate (); // Perform unit propagation. Returns possibly conflicting clause.
void cancelUntil (int level); // Backtrack until a certain level.
void analyze (CRef confl, vec<Lit>& out_learnt, int& out_btlevel); // (bt = backtrack)
void analyzeFinal (Lit p, vec<Lit>& out_conflict); // COULD THIS BE IMPLEMENTED BY THE ORDINARIY "analyze" BY SOME REASONABLE GENERALIZATION?
bool litRedundant (Lit p, uint32_t abstract_levels); // (helper method for 'analyze()')
lbool search (int nof_conflicts); // Search for a given number of conflicts.
lbool solve_ (); // Main solve method (assumptions given in 'assumptions').
void reduceDB (); // Reduce the set of learnt clauses.
void removeSatisfied (vec<CRef>& cs); // Shrink 'cs' to contain only non-satisfied clauses.
void rebuildOrderHeap ();
// Maintaining Variable/Clause activity:
//
void varDecayActivity (); // Decay all variables with the specified factor. Implemented by increasing the 'bump' value instead.
void varBumpActivity (Var v, double inc); // Increase a variable with the current 'bump' value.
void varBumpActivity (Var v); // Increase a variable with the current 'bump' value.
void claDecayActivity (); // Decay all clauses with the specified factor. Implemented by increasing the 'bump' value instead.
void claBumpActivity (Clause& c); // Increase a clause with the current 'bump' value.
// Operations on clauses:
//
void attachClause (CRef cr); // Attach a clause to watcher lists.
void detachClause (CRef cr, bool strict = false); // Detach a clause to watcher lists.
void removeClause (CRef cr); // Detach and free a clause.
bool locked (const Clause& c) const; // Returns TRUE if a clause is a reason for some implication in the current state.
bool satisfied (const Clause& c) const; // Returns TRUE if a clause is satisfied in the current state.
void relocAll (ClauseAllocator& to);
// Misc:
//
int decisionLevel () const; // Gives the current decisionlevel.
uint32_t abstractLevel (Var x) const; // Used to represent an abstraction of sets of decision levels.
CRef reason (Var x) const;
int level (Var x) const;
double progressEstimate () const; // DELETE THIS ?? IT'S NOT VERY USEFUL ...
bool withinBudget () const;
// Static helpers:
//
// Returns a random float 0 <= x < 1. Seed must never be 0.
static inline double drand(double& seed) {
seed *= 1389796;
int q = (int)(seed / 2147483647);
seed -= (double)q * 2147483647;
return seed / 2147483647; }
// Returns a random integer 0 <= x < size. Seed must never be 0.
static inline int irand(double& seed, int size) {
return (int)(drand(seed) * size); }
};
//=================================================================================================
// Implementation of inline methods:
inline CRef Solver::reason(Var x) const { return vardata[x].reason; }
inline int Solver::level (Var x) const { return vardata[x].level; }
inline void Solver::insertVarOrder(Var x) {
if (!order_heap.inHeap(x) && decision[x]) order_heap.insert(x); }
inline void Solver::varDecayActivity() { var_inc *= (1 / var_decay); }
inline void Solver::varBumpActivity(Var v) { varBumpActivity(v, var_inc); }
inline void Solver::varBumpActivity(Var v, double inc) {
if ( (activity[v] += inc) > 1e100 ) {
// Rescale:
for (int i = 0; i < nVars(); i++)
activity[i] *= 1e-100;
var_inc *= 1e-100; }
// Update order_heap with respect to new activity:
if (order_heap.inHeap(v))
order_heap.decrease(v); }
inline void Solver::claDecayActivity() { cla_inc *= (1 / clause_decay); }
inline void Solver::claBumpActivity (Clause& c) {
if ( (c.activity() += cla_inc) > 1e20 ) {
// Rescale:
for (int i = 0; i < learnts.size(); i++)
ca[learnts[i]].activity() *= 1e-20;
cla_inc *= 1e-20; } }
inline void Solver::checkGarbage(void){ return checkGarbage(garbage_frac); }
inline void Solver::checkGarbage(double gf){
if (ca.wasted() > ca.size() * gf)
garbageCollect(); }
// NOTE: enqueue does not set the ok flag! (only public methods do)
inline bool Solver::enqueue (Lit p, CRef from) { return value(p) != l_Undef ? value(p) != l_False : (uncheckedEnqueue(p, from), true); }
inline bool Solver::addClause (const vec<Lit>& ps) { ps.copyTo(add_tmp); return addClause_(add_tmp); }
inline bool Solver::addEmptyClause () { add_tmp.clear(); return addClause_(add_tmp); }
inline bool Solver::addClause (Lit p) { add_tmp.clear(); add_tmp.push(p); return addClause_(add_tmp); }
inline bool Solver::addClause (Lit p, Lit q) { add_tmp.clear(); add_tmp.push(p); add_tmp.push(q); return addClause_(add_tmp); }
inline bool Solver::addClause (Lit p, Lit q, Lit r) { add_tmp.clear(); add_tmp.push(p); add_tmp.push(q); add_tmp.push(r); return addClause_(add_tmp); }
inline bool Solver::locked (const Clause& c) const { return value(c[0]) == l_True && reason(var(c[0])) != CRef_Undef && ca.lea(reason(var(c[0]))) == &c; }
inline void Solver::newDecisionLevel() { trail_lim.push(trail.size()); }
inline int Solver::decisionLevel () const { return trail_lim.size(); }
inline uint32_t Solver::abstractLevel (Var x) const { return 1 << (level(x) & 31); }
inline lbool Solver::value (Var x) const { return assigns[x]; }
inline lbool Solver::value (Lit p) const { return assigns[var(p)] ^ sign(p); }
inline lbool Solver::modelValue (Var x) const { return model[x]; }
inline lbool Solver::modelValue (Lit p) const { return model[var(p)] ^ sign(p); }
inline int Solver::nAssigns () const { return trail.size(); }
inline int Solver::nClauses () const { return clauses.size(); }
inline int Solver::nLearnts () const { return learnts.size(); }
inline int Solver::nVars () const { return vardata.size(); }
inline int Solver::nFreeVars () const { return (int)dec_vars - (trail_lim.size() == 0 ? trail.size() : trail_lim[0]); }
inline void Solver::setPolarity (Var v, bool b) { polarity[v] = b; }
inline void Solver::setDecisionVar(Var v, bool b)
{
if ( b && !decision[v]) dec_vars++;
else if (!b && decision[v]) dec_vars--;
decision[v] = b;
insertVarOrder(v);
}
inline void Solver::setConfBudget(int64_t x){ conflict_budget = conflicts + x; }
inline void Solver::setPropBudget(int64_t x){ propagation_budget = propagations + x; }
inline void Solver::interrupt(){ asynch_interrupt = true; }
inline void Solver::clearInterrupt(){ asynch_interrupt = false; }
inline void Solver::budgetOff(){ conflict_budget = propagation_budget = -1; }
inline bool Solver::withinBudget() const {
return !asynch_interrupt &&
(conflict_budget < 0 || conflicts < (uint64_t)conflict_budget) &&
(propagation_budget < 0 || propagations < (uint64_t)propagation_budget); }
// FIXME: after the introduction of asynchronous interrruptions the solve-versions that return a
// pure bool do not give a safe interface. Either interrupts must be possible to turn off here, or
// all calls to solve must return an 'lbool'. I'm not yet sure which I prefer.
inline bool Solver::solve () { budgetOff(); assumptions.clear(); return solve_() == l_True; }
inline bool Solver::solve (Lit p) { budgetOff(); assumptions.clear(); assumptions.push(p); return solve_() == l_True; }
inline bool Solver::solve (Lit p, Lit q) { budgetOff(); assumptions.clear(); assumptions.push(p); assumptions.push(q); return solve_() == l_True; }
inline bool Solver::solve (Lit p, Lit q, Lit r) { budgetOff(); assumptions.clear(); assumptions.push(p); assumptions.push(q); assumptions.push(r); return solve_() == l_True; }
inline bool Solver::solve (const vec<Lit>& assumps){ budgetOff(); assumps.copyTo(assumptions); return solve_() == l_True; }
inline lbool Solver::solveLimited (const vec<Lit>& assumps){ assumps.copyTo(assumptions); return solve_(); }
inline bool Solver::okay () const { return ok; }
inline void Solver::toDimacs (const char* file){ vec<Lit> as; toDimacs(file, as); }
inline void Solver::toDimacs (const char* file, Lit p){ vec<Lit> as; as.push(p); toDimacs(file, as); }
inline void Solver::toDimacs (const char* file, Lit p, Lit q){ vec<Lit> as; as.push(p); as.push(q); toDimacs(file, as); }
inline void Solver::toDimacs (const char* file, Lit p, Lit q, Lit r){ vec<Lit> as; as.push(p); as.push(q); as.push(r); toDimacs(file, as); }
//=================================================================================================
// Debug etc:
//=================================================================================================
}
#endif

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/***********************************************************************************[SolverTypes.h]
Copyright (c) 2003-2006, Niklas Een, Niklas Sorensson
Copyright (c) 2007-2010, Niklas Sorensson
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
associated documentation files (the "Software"), to deal in the Software without restriction,
including without limitation the rights to use, copy, modify, merge, publish, distribute,
sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or
substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT
OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
**************************************************************************************************/
#ifndef Minisat_SolverTypes_h
#define Minisat_SolverTypes_h
#include <assert.h>
#include "mtl/IntTypes.h"
#include "mtl/Alg.h"
#include "mtl/Vec.h"
#include "mtl/Map.h"
#include "mtl/Alloc.h"
namespace Minisat {
//=================================================================================================
// Variables, literals, lifted booleans, clauses:
// NOTE! Variables are just integers. No abstraction here. They should be chosen from 0..N,
// so that they can be used as array indices.
typedef int Var;
#define var_Undef (-1)
struct Lit {
int x;
// Use this as a constructor:
friend Lit mkLit(Var var, bool sign = false);
bool operator == (Lit p) const { return x == p.x; }
bool operator != (Lit p) const { return x != p.x; }
bool operator < (Lit p) const { return x < p.x; } // '<' makes p, ~p adjacent in the ordering.
};
inline Lit mkLit (Var var, bool sign) { Lit p; p.x = var + var + (int)sign; return p; }
inline Lit operator ~(Lit p) { Lit q; q.x = p.x ^ 1; return q; }
inline Lit operator ^(Lit p, bool b) { Lit q; q.x = p.x ^ (unsigned int)b; return q; }
inline bool sign (Lit p) { return p.x & 1; }
inline int var (Lit p) { return p.x >> 1; }
// Mapping Literals to and from compact integers suitable for array indexing:
inline int toInt (Var v) { return v; }
inline int toInt (Lit p) { return p.x; }
inline Lit toLit (int i) { Lit p; p.x = i; return p; }
//const Lit lit_Undef = mkLit(var_Undef, false); // }- Useful special constants.
//const Lit lit_Error = mkLit(var_Undef, true ); // }
const Lit lit_Undef = { -2 }; // }- Useful special constants.
const Lit lit_Error = { -1 }; // }
//=================================================================================================
// Lifted booleans:
//
// NOTE: this implementation is optimized for the case when comparisons between values are mostly
// between one variable and one constant. Some care had to be taken to make sure that gcc
// does enough constant propagation to produce sensible code, and this appears to be somewhat
// fragile unfortunately.
#define l_True (lbool((uint8_t)0)) // gcc does not do constant propagation if these are real constants.
#define l_False (lbool((uint8_t)1))
#define l_Undef (lbool((uint8_t)2))
class lbool {
uint8_t value;
public:
explicit lbool(uint8_t v) : value(v) { }
lbool() : value(0) { }
explicit lbool(bool x) : value(!x) { }
bool operator == (lbool b) const { return ((b.value&2) & (value&2)) | (!(b.value&2)&(value == b.value)); }
bool operator != (lbool b) const { return !(*this == b); }
lbool operator ^ (bool b) const { return lbool((uint8_t)(value^(uint8_t)b)); }
lbool operator && (lbool b) const {
uint8_t sel = (this->value << 1) | (b.value << 3);
uint8_t v = (0xF7F755F4 >> sel) & 3;
return lbool(v); }
lbool operator || (lbool b) const {
uint8_t sel = (this->value << 1) | (b.value << 3);
uint8_t v = (0xFCFCF400 >> sel) & 3;
return lbool(v); }
friend int toInt (lbool l);
friend lbool toLbool(int v);
};
inline int toInt (lbool l) { return l.value; }
inline lbool toLbool(int v) { return lbool((uint8_t)v); }
//=================================================================================================
// Clause -- a simple class for representing a clause:
class Clause;
typedef RegionAllocator<uint32_t>::Ref CRef;
class Clause {
struct {
unsigned mark : 2;
unsigned learnt : 1;
unsigned has_extra : 1;
unsigned reloced : 1;
unsigned size : 27; } header;
union { Lit lit; float act; uint32_t abs; CRef rel; } data[0];
friend class ClauseAllocator;
// NOTE: This constructor cannot be used directly (doesn't allocate enough memory).
template<class V>
Clause(const V& ps, bool use_extra, bool learnt) {
header.mark = 0;
header.learnt = learnt;
header.has_extra = use_extra;
header.reloced = 0;
header.size = ps.size();
for (int i = 0; i < ps.size(); i++)
data[i].lit = ps[i];
if (header.has_extra){
if (header.learnt)
data[header.size].act = 0;
else
calcAbstraction(); }
}
public:
void calcAbstraction() {
assert(header.has_extra);
uint32_t abstraction = 0;
for (int i = 0; i < size(); i++)
abstraction |= 1 << (var(data[i].lit) & 31);
data[header.size].abs = abstraction; }
int size () const { return header.size; }
void shrink (int i) { assert(i <= size()); if (header.has_extra) data[header.size-i] = data[header.size]; header.size -= i; }
void pop () { shrink(1); }
bool learnt () const { return header.learnt; }
bool has_extra () const { return header.has_extra; }
uint32_t mark () const { return header.mark; }
void mark (uint32_t m) { header.mark = m; }
const Lit& last () const { return data[header.size-1].lit; }
bool reloced () const { return header.reloced; }
CRef relocation () const { return data[0].rel; }
void relocate (CRef c) { header.reloced = 1; data[0].rel = c; }
// NOTE: somewhat unsafe to change the clause in-place! Must manually call 'calcAbstraction' afterwards for
// subsumption operations to behave correctly.
Lit& operator [] (int i) { return data[i].lit; }
Lit operator [] (int i) const { return data[i].lit; }
operator const Lit* (void) const { return (Lit*)data; }
float& activity () { assert(header.has_extra); return data[header.size].act; }
uint32_t abstraction () const { assert(header.has_extra); return data[header.size].abs; }
Lit subsumes (const Clause& other) const;
void strengthen (Lit p);
};
//=================================================================================================
// ClauseAllocator -- a simple class for allocating memory for clauses:
const CRef CRef_Undef = RegionAllocator<uint32_t>::Ref_Undef;
class ClauseAllocator : public RegionAllocator<uint32_t>
{
static int clauseWord32Size(int size, bool has_extra){
return (sizeof(Clause) + (sizeof(Lit) * (size + (int)has_extra))) / sizeof(uint32_t); }
public:
bool extra_clause_field;
ClauseAllocator(uint32_t start_cap) : RegionAllocator<uint32_t>(start_cap), extra_clause_field(false){}
ClauseAllocator() : extra_clause_field(false){}
void moveTo(ClauseAllocator& to){
to.extra_clause_field = extra_clause_field;
RegionAllocator<uint32_t>::moveTo(to); }
template<class Lits>
CRef alloc(const Lits& ps, bool learnt = false)
{
assert(sizeof(Lit) == sizeof(uint32_t));
assert(sizeof(float) == sizeof(uint32_t));
bool use_extra = learnt | extra_clause_field;
CRef cid = RegionAllocator<uint32_t>::alloc(clauseWord32Size(ps.size(), use_extra));
new (lea(cid)) Clause(ps, use_extra, learnt);
return cid;
}
// Deref, Load Effective Address (LEA), Inverse of LEA (AEL):
Clause& operator[](Ref r) { return (Clause&)RegionAllocator<uint32_t>::operator[](r); }
const Clause& operator[](Ref r) const { return (Clause&)RegionAllocator<uint32_t>::operator[](r); }
Clause* lea (Ref r) { return (Clause*)RegionAllocator<uint32_t>::lea(r); }
const Clause* lea (Ref r) const { return (Clause*)RegionAllocator<uint32_t>::lea(r); }
Ref ael (const Clause* t){ return RegionAllocator<uint32_t>::ael((uint32_t*)t); }
void free(CRef cid)
{
Clause& c = operator[](cid);
RegionAllocator<uint32_t>::free(clauseWord32Size(c.size(), c.has_extra()));
}
void reloc(CRef& cr, ClauseAllocator& to)
{
Clause& c = operator[](cr);
if (c.reloced()) { cr = c.relocation(); return; }
cr = to.alloc(c, c.learnt());
c.relocate(cr);
// Copy extra data-fields:
// (This could be cleaned-up. Generalize Clause-constructor to be applicable here instead?)
to[cr].mark(c.mark());
if (to[cr].learnt()) to[cr].activity() = c.activity();
else if (to[cr].has_extra()) to[cr].calcAbstraction();
}
};
//=================================================================================================
// OccLists -- a class for maintaining occurence lists with lazy deletion:
template<class Idx, class Vec, class Deleted>
class OccLists
{
vec<Vec> occs;
vec<char> dirty;
vec<Idx> dirties;
Deleted deleted;
public:
OccLists(const Deleted& d) : deleted(d) {}
void init (const Idx& idx){ occs.growTo(toInt(idx)+1); dirty.growTo(toInt(idx)+1, 0); }
// Vec& operator[](const Idx& idx){ return occs[toInt(idx)]; }
Vec& operator[](const Idx& idx){ return occs[toInt(idx)]; }
Vec& lookup (const Idx& idx){ if (dirty[toInt(idx)]) clean(idx); return occs[toInt(idx)]; }
void cleanAll ();
void clean (const Idx& idx);
void smudge (const Idx& idx){
if (dirty[toInt(idx)] == 0){
dirty[toInt(idx)] = 1;
dirties.push(idx);
}
}
void clear(bool free = true){
occs .clear(free);
dirty .clear(free);
dirties.clear(free);
}
};
template<class Idx, class Vec, class Deleted>
void OccLists<Idx,Vec,Deleted>::cleanAll()
{
for (int i = 0; i < dirties.size(); i++)
// Dirties may contain duplicates so check here if a variable is already cleaned:
if (dirty[toInt(dirties[i])])
clean(dirties[i]);
dirties.clear();
}
template<class Idx, class Vec, class Deleted>
void OccLists<Idx,Vec,Deleted>::clean(const Idx& idx)
{
Vec& vec = occs[toInt(idx)];
int i, j;
for (i = j = 0; i < vec.size(); i++)
if (!deleted(vec[i]))
vec[j++] = vec[i];
vec.shrink(i - j);
dirty[toInt(idx)] = 0;
}
//=================================================================================================
// CMap -- a class for mapping clauses to values:
template<class T>
class CMap
{
struct CRefHash {
uint32_t operator()(CRef cr) const { return (uint32_t)cr; } };
typedef Map<CRef, T, CRefHash> HashTable;
HashTable map;
public:
// Size-operations:
void clear () { map.clear(); }
int size () const { return map.elems(); }
// Insert/Remove/Test mapping:
void insert (CRef cr, const T& t){ map.insert(cr, t); }
void growTo (CRef cr, const T& t){ map.insert(cr, t); } // NOTE: for compatibility
void remove (CRef cr) { map.remove(cr); }
bool has (CRef cr, T& t) { return map.peek(cr, t); }
// Vector interface (the clause 'c' must already exist):
const T& operator [] (CRef cr) const { return map[cr]; }
T& operator [] (CRef cr) { return map[cr]; }
// Iteration (not transparent at all at the moment):
int bucket_count() const { return map.bucket_count(); }
const vec<typename HashTable::Pair>& bucket(int i) const { return map.bucket(i); }
// Move contents to other map:
void moveTo(CMap& other){ map.moveTo(other.map); }
// TMP debug:
void debug(){
printf(" --- size = %d, bucket_count = %d\n", size(), map.bucket_count()); }
};
/*_________________________________________________________________________________________________
|
| subsumes : (other : const Clause&) -> Lit
|
| Description:
| Checks if clause subsumes 'other', and at the same time, if it can be used to simplify 'other'
| by subsumption resolution.
|
| Result:
| lit_Error - No subsumption or simplification
| lit_Undef - Clause subsumes 'other'
| p - The literal p can be deleted from 'other'
|________________________________________________________________________________________________@*/
inline Lit Clause::subsumes(const Clause& other) const
{
//if (other.size() < size() || (extra.abst & ~other.extra.abst) != 0)
//if (other.size() < size() || (!learnt() && !other.learnt() && (extra.abst & ~other.extra.abst) != 0))
assert(!header.learnt); assert(!other.header.learnt);
assert(header.has_extra); assert(other.header.has_extra);
if (other.header.size < header.size || (data[header.size].abs & ~other.data[other.header.size].abs) != 0)
return lit_Error;
Lit ret = lit_Undef;
const Lit* c = (const Lit*)(*this);
const Lit* d = (const Lit*)other;
for (unsigned i = 0; i < header.size; i++) {
// search for c[i] or ~c[i]
for (unsigned j = 0; j < other.header.size; j++)
if (c[i] == d[j])
goto ok;
else if (ret == lit_Undef && c[i] == ~d[j]){
ret = c[i];
goto ok;
}
// did not find it
return lit_Error;
ok:;
}
return ret;
}
inline void Clause::strengthen(Lit p)
{
remove(*this, p);
calcAbstraction();
}
//=================================================================================================
}
#endif