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Merge branch 'polysat' of https://github.com/Z3Prover/z3 into polysat

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This commit is contained in:
Clemens Eisenhofer 2022-11-29 14:54:49 +01:00
commit 2b7fd152c4
34 changed files with 948 additions and 613 deletions
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65
src/math/polysat/solver.h
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@ -31,6 +31,7 @@ Author:
#include "math/polysat/justification.h"
#include "math/polysat/linear_solver.h"
#include "math/polysat/search_state.h"
#include "math/polysat/assignment.h"
#include "math/polysat/trail.h"
#include "math/polysat/viable.h"
#include "math/polysat/log.h"
@ -45,6 +46,52 @@ namespace polysat {
bool m_log_conflicts = false;
};
/**
* A metric to evaluate lemmas from conflict analysis.
* Lower is better.
*
* Comparison criterion:
* - Lowest jump level has priority, because otherwise, some of the accumulated lemmas may still be false after backjumping.
* - To break ties on jump level, choose clause with the fewest literals at its highest decision level;
* to limit case splits.
*/
class lemma_score {
unsigned m_jump_level;
unsigned m_literals_at_max_level;
public:
lemma_score(unsigned jump_level, unsigned at_max_level)
: m_jump_level(jump_level), m_literals_at_max_level(at_max_level)
{ }
unsigned jump_level() const { return m_jump_level; }
unsigned literals_at_max_level() const { return m_literals_at_max_level; }
static lemma_score max() {
return {UINT_MAX, UINT_MAX};
}
bool operator==(lemma_score const& other) const {
return m_jump_level == other.m_jump_level
&& m_literals_at_max_level == other.m_literals_at_max_level;
}
bool operator!=(lemma_score const& other) const { return !operator==(other); }
bool operator<(lemma_score const& other) const {
return m_jump_level < other.m_jump_level
|| (m_jump_level == other.m_jump_level && m_literals_at_max_level < other.m_literals_at_max_level);
}
bool operator>(lemma_score const& other) const { return other.operator<(*this); }
bool operator<=(lemma_score const& other) const { return operator==(other) || operator<(other); }
bool operator>=(lemma_score const& other) const { return operator==(other) || operator>(other); }
std::ostream& display(std::ostream& out) const {
return out << "jump_level=" << m_jump_level << " at_max_level=" << m_literals_at_max_level;
}
};
inline std::ostream& operator<<(std::ostream& out, lemma_score const& ls) { return ls.display(out); }
class solver {
struct stats {
@ -58,6 +105,7 @@ namespace polysat {
stats() { reset(); }
};
friend class assignment;
friend class constraint;
friend class ule_constraint;
friend class umul_ovfl_constraint;
@ -125,8 +173,6 @@ namespace polysat {
unsigned_vector m_size; // store size of variables (bit width)
search_state m_search;
assignment_t const& assignment() const { return m_search.assignment(); }
pdd subst(assignment_t const& sub, pdd const& p) const;
unsigned m_qhead = 0; // next item to propagate (index into m_search)
unsigned m_level = 0;
@ -150,7 +196,6 @@ namespace polysat {
m_qhead_trail.pop_back();
}
unsigned size(pvar v) const { return m_size[v]; }
/**
@ -161,16 +206,19 @@ namespace polysat {
void del_var();
dd::pdd_manager& sz2pdd(unsigned sz) const;
dd::pdd_manager& var2pdd(pvar v);
dd::pdd_manager& var2pdd(pvar v) const;
assignment const& assignment() const { return m_search.assignment(); }
void push_level();
void pop_levels(unsigned num_levels);
void try_assign_eval(signed_constraint c);
void assign_propagate(sat::literal lit, clause& reason);
void assign_decision(sat::literal lit);
void assign_eval(sat::literal lit);
void activate_constraint(signed_constraint c);
void deactivate_constraint(signed_constraint c);
unsigned level(sat::literal lit, clause const& cl);
void assign_propagate(pvar v, rational const& val);
@ -212,6 +260,8 @@ namespace polysat {
void revert_decision(pvar v);
void revert_bool_decision(sat::literal lit);
void backjump_and_learn(unsigned jump_level, clause& lemma);
void backjump_and_learn(unsigned max_jump_level);
std::optional<lemma_score> compute_lemma_score(clause const& lemma);
// activity of variables based on standard VSIDS
unsigned m_activity_inc = 128;
@ -236,9 +286,6 @@ namespace polysat {
bool invariant();
static bool invariant(signed_constraints const& cs);
bool lemma_invariant(clause const& lemma, assignment_t const& assignment);
bool lemma_invariant_part1(clause const& lemma, assignment_t const& assignment, sat::literal_vector& out_todo);
bool lemma_invariant_part2(sat::literal_vector const& todo);
bool wlist_invariant();
bool assignment_invariant();
bool verify_sat();
@ -430,7 +477,7 @@ namespace polysat {
}; // class solver
class assignments_pp {
class assignments_pp { // TODO: can probably remove this now.
solver const& s;
public:
assignments_pp(solver const& s): s(s) {}