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z3/src/sat/sat_solver.h
Nikolaj Bjorner 8032217fd1 tuning and fixing consequence finding, adding dimacs evaluation 
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
2017-04-26 13:53:37 -07:00

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/*++
Copyright (c) 2011 Microsoft Corporation
Module Name:
sat_solver.h
Abstract:
SAT solver main class.
Author:
Leonardo de Moura (leonardo) 2011-05-21.
Revision History:
--*/
#ifndef SAT_SOLVER_H_
#define SAT_SOLVER_H_
#include"sat_types.h"
#include"sat_clause.h"
#include"sat_watched.h"
#include"sat_justification.h"
#include"sat_var_queue.h"
#include"sat_extension.h"
#include"sat_config.h"
#include"sat_cleaner.h"
#include"sat_simplifier.h"
#include"sat_scc.h"
#include"sat_asymm_branch.h"
#include"sat_iff3_finder.h"
#include"sat_probing.h"
#include"sat_mus.h"
#include"sat_par.h"
#include"params.h"
#include"statistics.h"
#include"stopwatch.h"
#include"trace.h"
#include"rlimit.h"
namespace sat {
/**
\brief Main statistic counters.
*/
struct stats {
unsigned m_mk_var;
unsigned m_mk_bin_clause;
unsigned m_mk_ter_clause;
unsigned m_mk_clause;
unsigned m_conflict;
unsigned m_propagate;
unsigned m_bin_propagate;
unsigned m_ter_propagate;
unsigned m_decision;
unsigned m_restart;
unsigned m_gc_clause;
unsigned m_del_clause;
unsigned m_minimized_lits;
unsigned m_dyn_sub_res;
unsigned m_non_learned_generation;
unsigned m_blocked_corr_sets;
stats() { reset(); }
void reset();
void collect_statistics(statistics & st) const;
};
class solver {
public:
struct abort_solver {};
protected:
reslimit& m_rlimit;
bool m_checkpoint_enabled;
config m_config;
stats m_stats;
extension * m_ext;
par* m_par;
random_gen m_rand;
clause_allocator m_cls_allocator;
cleaner m_cleaner;
model m_model;
model_converter m_mc;
bool m_model_is_current;
simplifier m_simplifier;
scc m_scc;
asymm_branch m_asymm_branch;
probing m_probing;
mus m_mus; // MUS for minimal core extraction
bool m_inconsistent;
// A conflict is usually a single justification. That is, a justification
// for false. If m_not_l is not null_literal, then m_conflict is a
// justification for l, and the conflict is union of m_no_l and m_conflict;
justification m_conflict;
literal m_not_l;
clause_vector m_clauses;
clause_vector m_learned;
unsigned m_num_frozen;
vector<watch_list> m_watches;
char_vector m_assignment;
svector<justification> m_justification;
svector<char> m_decision;
svector<char> m_mark;
svector<char> m_lit_mark;
svector<char> m_eliminated;
svector<char> m_external;
svector<unsigned> m_level;
svector<unsigned> m_activity;
unsigned m_activity_inc;
svector<char> m_phase;
svector<char> m_prev_phase;
svector<char> m_assigned_since_gc;
bool m_phase_cache_on;
unsigned m_phase_counter;
var_queue m_case_split_queue;
unsigned m_qhead;
unsigned m_scope_lvl;
literal_vector m_trail;
clause_wrapper_vector m_clauses_to_reinit;
struct scope {
unsigned m_trail_lim;
unsigned m_clauses_to_reinit_lim;
bool m_inconsistent;
};
svector<scope> m_scopes;
stopwatch m_stopwatch;
params_ref m_params;
scoped_ptr<solver> m_clone; // for debugging purposes
literal_vector m_assumptions; // additional assumptions during check
literal_set m_assumption_set; // set of enabled assumptions
literal_vector m_core; // unsat core
unsigned m_par_limit_in;
unsigned m_par_limit_out;
unsigned m_par_num_vars;
void del_clauses(clause * const * begin, clause * const * end);
friend class integrity_checker;
friend class cleaner;
friend class simplifier;
friend class scc;
friend class elim_eqs;
friend class asymm_branch;
friend class probing;
friend class iff3_finder;
friend class mus;
friend struct mk_stat;
public:
solver(params_ref const & p, reslimit& l, extension * ext);
~solver();
// -----------------------
//
// Misc
//
// -----------------------
void updt_params(params_ref const & p);
static void collect_param_descrs(param_descrs & d);
void collect_statistics(statistics & st) const;
void reset_statistics();
void display_status(std::ostream & out) const;
/**
\brief Copy (non learned) clauses from src to this solver.
Create missing variables if needed.
\pre the model converter of src and this must be empty
*/
void copy(solver const & src);
// -----------------------
//
// Variable & Clause creation
//
// -----------------------
bool_var mk_var(bool ext = false, bool dvar = true);
void mk_clause(literal_vector const& lits) { mk_clause(lits.size(), lits.c_ptr()); }
void mk_clause(unsigned num_lits, literal * lits);
void mk_clause(literal l1, literal l2);
void mk_clause(literal l1, literal l2, literal l3);
protected:
void del_clause(clause & c);
clause * mk_clause_core(unsigned num_lits, literal * lits, bool learned);
void mk_clause_core(literal_vector const& lits) { mk_clause_core(lits.size(), lits.c_ptr()); }
void mk_clause_core(unsigned num_lits, literal * lits) { mk_clause_core(num_lits, lits, false); }
void mk_clause_core(literal l1, literal l2) { literal lits[2] = { l1, l2 }; mk_clause_core(2, lits); }
void mk_bin_clause(literal l1, literal l2, bool learned);
bool propagate_bin_clause(literal l1, literal l2);
clause * mk_ter_clause(literal * lits, bool learned);
bool attach_ter_clause(clause & c);
clause * mk_nary_clause(unsigned num_lits, literal * lits, bool learned);
bool attach_nary_clause(clause & c);
void attach_clause(clause & c, bool & reinit);
void attach_clause(clause & c) { bool reinit; attach_clause(c, reinit); }
class scoped_detach {
solver& s;
clause& c;
bool m_deleted;
public:
scoped_detach(solver& s, clause& c): s(s), c(c), m_deleted(false) {
s.detach_clause(c);
}
~scoped_detach() {
if (!m_deleted) s.attach_clause(c);
}
void del_clause() {
if (!m_deleted) {
s.del_clause(c);
m_deleted = true;
}
}
};
class scoped_disable_checkpoint {
solver& s;
public:
scoped_disable_checkpoint(solver& s): s(s) {
s.m_checkpoint_enabled = false;
}
~scoped_disable_checkpoint() {
s.m_checkpoint_enabled = true;
}
};
unsigned select_watch_lit(clause const & cls, unsigned starting_at) const;
unsigned select_learned_watch_lit(clause const & cls) const;
bool simplify_clause(unsigned & num_lits, literal * lits) const;
template<bool lvl0>
bool simplify_clause_core(unsigned & num_lits, literal * lits) const;
void detach_bin_clause(literal l1, literal l2, bool learned);
void detach_clause(clause & c);
void detach_nary_clause(clause & c);
void detach_ter_clause(clause & c);
void push_reinit_stack(clause & c);
// -----------------------
//
// Basic
//
// -----------------------
public:
bool inconsistent() const { return m_inconsistent; }
unsigned num_vars() const { return m_level.size(); }
unsigned num_clauses() const;
unsigned num_restarts() const { return m_restarts; }
bool is_external(bool_var v) const { return m_external[v] != 0; }
void set_external(bool_var v) { m_external[v] = true; }
bool was_eliminated(bool_var v) const { return m_eliminated[v] != 0; }
unsigned scope_lvl() const { return m_scope_lvl; }
lbool value(literal l) const { return static_cast<lbool>(m_assignment[l.index()]); }
lbool value(bool_var v) const { return static_cast<lbool>(m_assignment[literal(v, false).index()]); }
unsigned lvl(bool_var v) const { return m_level[v]; }
unsigned lvl(literal l) const { return m_level[l.var()]; }
unsigned init_trail_size() const { return scope_lvl() == 0 ? m_trail.size() : m_scopes[0].m_trail_lim; }
void assign(literal l, justification j) {
TRACE("sat_assign", tout << l << " previous value: " << value(l) << "\n";);
switch (value(l)) {
case l_false: set_conflict(j, ~l); break;
case l_undef: assign_core(l, j); break;
case l_true: return;
}
}
void assign_core(literal l, justification jst);
void set_conflict(justification c, literal not_l);
void set_conflict(justification c) { set_conflict(c, null_literal); }
lbool status(clause const & c) const;
clause_offset get_offset(clause const & c) const { return m_cls_allocator.get_offset(&c); }
void checkpoint() {
if (!m_checkpoint_enabled) return;
if (!m_rlimit.inc()) {
m_mc.reset();
m_model_is_current = false;
throw solver_exception(Z3_CANCELED_MSG);
}
++m_num_checkpoints;
if (m_num_checkpoints < 10) return;
m_num_checkpoints = 0;
if (memory::get_allocation_size() > m_config.m_max_memory) throw solver_exception(Z3_MAX_MEMORY_MSG);
}
void set_par(par* p);
bool canceled() { return !m_rlimit.inc(); }
config const& get_config() { return m_config; }
typedef std::pair<literal, literal> bin_clause;
protected:
watch_list & get_wlist(literal l) { return m_watches[l.index()]; }
watch_list const & get_wlist(literal l) const { return m_watches[l.index()]; }
watch_list & get_wlist(unsigned l_idx) { return m_watches[l_idx]; }
bool is_marked(bool_var v) const { return m_mark[v] != 0; }
void mark(bool_var v) { SASSERT(!is_marked(v)); m_mark[v] = true; }
void reset_mark(bool_var v) { SASSERT(is_marked(v)); m_mark[v] = false; }
bool is_marked_lit(literal l) const { return m_lit_mark[l.index()] != 0; }
void mark_lit(literal l) { SASSERT(!is_marked_lit(l)); m_lit_mark[l.index()] = true; }
void unmark_lit(literal l) { SASSERT(is_marked_lit(l)); m_lit_mark[l.index()] = false; }
bool check_inconsistent();
// -----------------------
//
// Propagation
//
// -----------------------
public:
// if update == true, then glue of learned clauses is updated.
bool propagate(bool update);
protected:
bool propagate_core(bool update);
// -----------------------
//
// Search
//
// -----------------------
public:
lbool check(unsigned num_lits = 0, literal const* lits = 0);
model const & get_model() const { return m_model; }
bool model_is_current() const { return m_model_is_current; }
literal_vector const& get_core() const { return m_core; }
model_converter const & get_model_converter() const { return m_mc; }
void set_model(model const& mdl);
protected:
unsigned m_conflicts;
unsigned m_restarts;
unsigned m_conflicts_since_restart;
unsigned m_restart_threshold;
unsigned m_luby_idx;
unsigned m_conflicts_since_gc;
unsigned m_gc_threshold;
unsigned m_num_checkpoints;
double m_min_d_tk;
unsigned m_next_simplify;
bool decide();
bool_var next_var();
lbool bounded_search();
lbool final_check();
lbool propagate_and_backjump_step(bool& done);
void init_search();
literal_vector m_min_core;
bool m_min_core_valid;
void init_assumptions(unsigned num_lits, literal const* lits);
void reassert_min_core();
void update_min_core();
void resolve_weighted();
void reset_assumptions();
void add_assumption(literal lit);
void pop_assumption();
void reinit_assumptions();
bool tracking_assumptions() const;
bool is_assumption(literal l) const;
void simplify_problem();
void mk_model();
bool check_model(model const & m) const;
void restart();
void sort_watch_lits();
void exchange_par();
lbool check_par(unsigned num_lits, literal const* lits);
// -----------------------
//
// GC
//
// -----------------------
protected:
void gc();
void gc_glue();
void gc_psm();
void gc_glue_psm();
void gc_psm_glue();
void save_psm();
void gc_half(char const * st_name);
void gc_dyn_psm();
bool activate_frozen_clause(clause & c);
unsigned psm(clause const & c) const;
bool can_delete(clause const & c) const {
if (c.on_reinit_stack())
return false;
if (c.size() == 3)
return true; // not needed to justify anything.
literal l0 = c[0];
if (value(l0) != l_true)
return true;
justification const & jst = m_justification[l0.var()];
return !jst.is_clause() || m_cls_allocator.get_clause(jst.get_clause_offset()) != &c;
}
// -----------------------
//
// Conflict resolution
//
// -----------------------
protected:
unsigned m_conflict_lvl;
literal_vector m_lemma;
literal_vector m_ext_antecedents;
bool resolve_conflict();
bool resolve_conflict_core();
unsigned get_max_lvl(literal consequent, justification js);
void process_antecedent(literal antecedent, unsigned & num_marks);
void resolve_conflict_for_unsat_core();
void process_antecedent_for_unsat_core(literal antecedent);
void process_consequent_for_unsat_core(literal consequent, justification const& js);
bool resolve_conflict_for_init();
void process_antecedent_for_init(literal antecedent);
bool process_consequent_for_init(literal consequent, justification const& js);
void fill_ext_antecedents(literal consequent, justification js);
unsigned skip_literals_above_conflict_level();
void forget_phase_of_vars(unsigned from_lvl);
void updt_phase_counters();
svector<char> m_diff_levels;
unsigned num_diff_levels(unsigned num, literal const * lits);
// lemma minimization
typedef approx_set_tpl<unsigned, u2u, unsigned> level_approx_set;
bool_var_vector m_unmark;
level_approx_set m_lvl_set;
bool_var_vector m_lemma_min_stack;
bool process_antecedent_for_minimization(literal antecedent);
bool implied_by_marked(literal lit);
void reset_unmark(unsigned old_size);
void updt_lemma_lvl_set();
void minimize_lemma();
void reset_lemma_var_marks();
void dyn_sub_res();
// -----------------------
//
// Backtracking
//
// -----------------------
void push();
void pop(unsigned num_scopes);
void pop_reinit(unsigned num_scopes);
void unassign_vars(unsigned old_sz);
void reinit_clauses(unsigned old_sz);
literal_vector m_user_scope_literals;
literal_vector m_aux_literals;
svector<bin_clause> m_user_bin_clauses;
void gc_lit(clause_vector& clauses, literal lit);
void gc_bin(bool learned, literal nlit);
void gc_var(bool_var v);
bool_var max_var(clause_vector& clauses, bool_var v);
bool_var max_var(bool learned, bool_var v);
public:
void user_push();
void user_pop(unsigned num_scopes);
void pop_to_base_level();
reslimit& rlimit() { return m_rlimit; }
// -----------------------
//
// Simplification
//
// -----------------------
public:
void cleanup();
void simplify(bool learned = true);
void asymmetric_branching();
unsigned scc_bin();
// -----------------------
//
// Auxiliary methods.
//
// -----------------------
public:
lbool find_mutexes(literal_vector const& lits, vector<literal_vector> & mutexes);
lbool get_consequences(literal_vector const& assms, bool_var_vector const& vars, vector<literal_vector>& conseq);
private:
typedef hashtable<unsigned, u_hash, u_eq> index_set;
u_map<index_set> m_antecedents;
vector<literal_vector> m_binary_clause_graph;
bool extract_assumptions(literal lit, index_set& s);
bool check_domain(literal lit, literal lit2);
std::ostream& display_index_set(std::ostream& out, index_set const& s) const;
lbool get_consequences(literal_vector const& assms, literal_vector const& lits, vector<literal_vector>& conseq);
lbool get_bounded_consequences(literal_vector const& assms, bool_var_vector const& vars, vector<literal_vector>& conseq);
void delete_unfixed(literal_set& unfixed_lits, bool_var_set& unfixed_vars);
void extract_fixed_consequences(unsigned& start, literal_set const& assumptions, bool_var_set& unfixed, vector<literal_vector>& conseq);
bool extract_fixed_consequences(literal lit, literal_set const& assumptions, bool_var_set& unfixed, vector<literal_vector>& conseq);
void update_unfixed_literals(literal_set& unfixed_lits, bool_var_set& unfixed_vars);
void fixup_consequence_core();
// -----------------------
//
// Activity related stuff
//
// -----------------------
public:
void inc_activity(bool_var v) {
unsigned & act = m_activity[v];
act += m_activity_inc;
m_case_split_queue.activity_increased_eh(v);
if (act > (1 << 24))
rescale_activity();
}
void decay_activity() {
m_activity_inc *= 11;
m_activity_inc /= 10;
}
private:
void rescale_activity();
// -----------------------
//
// Iterators
//
// -----------------------
public:
clause * const * begin_clauses() const { return m_clauses.begin(); }
clause * const * end_clauses() const { return m_clauses.end(); }
clause * const * begin_learned() const { return m_learned.begin(); }
clause * const * end_learned() const { return m_learned.end(); }
void collect_bin_clauses(svector<bin_clause> & r, bool learned) const;
// -----------------------
//
// Debugging
//
// -----------------------
public:
bool check_invariant() const;
void display(std::ostream & out) const;
void display_watches(std::ostream & out) const;
void display_dimacs(std::ostream & out) const;
void display_wcnf(std::ostream & out, unsigned sz, literal const* lits, unsigned const* weights) const;
void display_assignment(std::ostream & out) const;
void display_justification(std::ostream & out, justification const& j) const;
protected:
void display_binary(std::ostream & out) const;
void display_units(std::ostream & out) const;
bool is_unit(clause const & c) const;
bool is_empty(clause const & c) const;
bool check_missed_propagation(clause_vector const & cs) const;
bool check_missed_propagation() const;
bool check_marks() const;
};
struct mk_stat {
solver const & m_solver;
mk_stat(solver const & s):m_solver(s) {}
void display(std::ostream & out) const;
};
std::ostream & operator<<(std::ostream & out, mk_stat const & stat);
};
#endif
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