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Diffstat (limited to 'minisat/solver/Solver.H')
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diff --git a/minisat/solver/Solver.H b/minisat/solver/Solver.H new file mode 100644 index 0000000..80c8337 --- /dev/null +++ b/minisat/solver/Solver.H @@ -0,0 +1,309 @@ +/****************************************************************************************[Solver.h] +MiniSat -- Copyright (c) 2003-2006, Niklas Een, 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 Solver_h +#define Solver_h + +#include <cstdio> + +#include "Vec.h" +#include "Heap.h" +#include "Alg.h" + +#include "SolverTypes.H" + + +//================================================================================================= +// Solver -- the main class: + + +class Solver { +public: + + // Constructor/Destructor: + // + Solver(); + ~Solver(); + + // Problem specification: + // + Var newVar (bool polarity = true, bool dvar = true); // Add a new variable with parameters specifying variable mode. + bool addClause (vec<Lit>& ps); // Add a clause to the solver. NOTE! 'ps' may be shrunk by this method! + + // Solving: + // + bool simplify (); // Removes already satisfied clauses. + bool solve (const vec<Lit>& assumps,bool cleanup=true); // Search for a model that respects a given set of assumptions. + bool solve (); // Search without assumptions. + bool okay () const; // FALSE means solver is in a conflicting state + + void clearTrail(); + + // 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 (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. + + // 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. + + //ADDED METHODS + int getTrailSize() const{return trail.size();} + int getTrailVar(int index) const{return var(trail[index]);} + bool getTrailSign(int index) const{return sign(trail[index]);} + + // Mode of operation: + // + double var_decay; // Inverse of the variable activity decay factor. (default 1 / 0.95) + double clause_decay; // Inverse of the clause activity decay factor. (1 / 0.999) + double random_var_freq; // The frequency with which the decision heuristic tries to choose a random variable. (default 0.02) + 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) + bool expensive_ccmin; // Controls conflict clause minimization. (default TRUE) + int polarity_mode; // Controls which polarity the decision heuristic chooses. See enum below for allowed modes. (default polarity_false) + int verbosity; // Verbosity level. 0=silent, 1=some progress report (default 0) + + enum { polarity_true = 0, polarity_false = 1, polarity_user = 2, polarity_rnd = 3 }; + + // Statistics: (read-only member variable) + // + uint64_t starts, decisions, rnd_decisions, propagations, conflicts; + uint64_t clauses_literals, learnts_literals, max_literals, tot_literals; + +protected: + + // Helper structures: + // + 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) { } + }; + + friend class VarFilter; + struct VarFilter { + const Solver& s; + VarFilter(const Solver& _s) : s(_s) {} + bool operator()(Var v) const { return toLbool(s.assigns[v]) == l_Undef && s.decision_var[v]; } + }; + + // Solver state: + // + bool ok; // If FALSE, the constraints are already unsatisfiable. No part of the solver state may be used! + vec<Clause*> clauses; // List of problem clauses. + vec<Clause*> 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. + vec<vec<Clause*> > watches; // 'watches[lit]' is a list of constraints watching 'lit' (will go there if literal becomes true). + vec<char> assigns; // The current assignments (lbool:s stored as char:s). + vec<char> polarity; // The preferred polarity of each variable. + vec<char> decision_var; // 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<Clause*> reason; // 'reason[var]' is the clause that implied the variables current value, or 'NULL' if none. + vec<int> level; // 'level[var]' contains the level at which the assignment was made. + 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 random_seed; // Used by the random variable selection. + double progress_estimate;// Set by 'search()'. + bool remove_satisfied; // Indicates whether possibly inefficient linear scan for satisfied clauses should be performed in 'simplify'. + + // 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; + + // Main internal methods: + // + void insertVarOrder (Var x); // Insert a variable in the decision order priority queue. + Lit pickBranchLit (int polarity_mode, double random_var_freq); // Return the next decision variable. + void newDecisionLevel (); // Begins a new decision level. + void uncheckedEnqueue (Lit p, Clause* from = NULL); // Enqueue a literal. Assumes value of literal is undefined. + bool enqueue (Lit p, Clause* from = NULL); // Test if fact 'p' contradicts current state, enqueue otherwise. + Clause* propagate (); // Perform unit propagation. Returns possibly conflicting clause. + void cancelUntil (int level); // Backtrack until a certain level. + void analyze (Clause* 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, int nof_learnts); // Search for a given number of conflicts. + void reduceDB (); // Reduce the set of learnt clauses. + void removeSatisfied (vec<Clause*>& cs); // Shrink 'cs' to contain only non-satisfied clauses. + + // Maintaining Variable/Clause activity: + // + void varDecayActivity (); // Decay all variables with the specified factor. Implemented by increasing the 'bump' value instead. + 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 (Clause& c); // Attach a clause to watcher lists. + void detachClause (Clause& c); // Detach a clause to watcher lists. + void removeClause (Clause& c); // 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. + + // Misc: + // + int decisionLevel () const; // Gives the current decisionlevel. + uint32_t abstractLevel (Var x) const; // Used to represent an abstraction of sets of decision levels. + double progressEstimate () const; // DELETE THIS ?? IT'S NOT VERY USEFUL ... + + // Debug: + void printLit (Lit l); + template<class C> + void printClause (const C& c); + void verifyModel (); + void checkLiteralCount(); + + // 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 void Solver::insertVarOrder(Var x) { + if (!order_heap.inHeap(x) && decision_var[x]) order_heap.insert(x); } + +inline void Solver::varDecayActivity() { var_inc *= var_decay; } +inline void Solver::varBumpActivity(Var v) { + if ( (activity[v] += var_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 *= clause_decay; } +inline void Solver::claBumpActivity (Clause& c) { + if ( (c.activity() += cla_inc) > 1e20 ) { + // Rescale: + for (int i = 0; i < learnts.size(); i++) + learnts[i]->activity() *= 1e-20; + cla_inc *= 1e-20; } } + +inline bool Solver::enqueue (Lit p, Clause* from) { return value(p) != l_Undef ? value(p) != l_False : (uncheckedEnqueue(p, from), true); } +inline bool Solver::locked (const Clause& c) const { return reason[var(c[0])] == &c && value(c[0]) == l_True; } +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 toLbool(assigns[x]); } +inline lbool Solver::value (Lit p) const { return toLbool(assigns[var(p)]) ^ sign(p); } +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 assigns.size(); } +inline void Solver::setPolarity (Var v, bool b) { polarity [v] = (char)b; } +inline void Solver::setDecisionVar(Var v, bool b) { decision_var[v] = (char)b; if (b) { insertVarOrder(v); } } +inline bool Solver::solve () { vec<Lit> tmp; return solve(tmp); } +inline bool Solver::okay () const { return ok; } + + + +//================================================================================================= +// Debug + etc: + + +#define reportf(format, args...) ( fflush(stdout), fprintf(stderr, format, ## args), fflush(stderr) ) + +static inline void logLit(FILE* f, Lit l) +{ + fprintf(f, "%sx%d", sign(l) ? "~" : "", var(l)+1); +} + +static inline void logLits(FILE* f, const vec<Lit>& ls) +{ + fprintf(f, "[ "); + if (ls.size() > 0){ + logLit(f, ls[0]); + for (int i = 1; i < ls.size(); i++){ + fprintf(f, ", "); + logLit(f, ls[i]); + } + } + fprintf(f, "] "); +} + +static inline const char* showBool(bool b) { return b ? "true" : "false"; } + + +// Just like 'assert()' but expression will be evaluated in the release version as well. +static inline void check(bool expr) { assert(expr); } + + +inline void Solver::printLit(Lit l) +{ + reportf("%s%d:%c", sign(l) ? "-" : "", var(l)+1, value(l) == l_True ? '1' : (value(l) == l_False ? '0' : 'X')); +} + + +template<class C> +inline void Solver::printClause(const C& c) +{ + for (int i = 0; i < c.size(); i++){ + printLit(c[i]); + fprintf(stderr, " "); + } +} + + +//================================================================================================= +#endif |