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overhaul of proof format for new solver

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This commit overhauls the proof format (in development) for the new core.

NOTE: this functionality is work in progress with a long way to go.
It is shielded by the sat.euf option, which is off by default and in pre-release state.
It is too early to fuzz or use it. It is pushed into master to shed light on road-map for certifying inferences of sat.euf.

It retires the ad-hoc extension of DRUP used by the SAT solver.
Instead it relies on SMT with ad-hoc extensions for proof terms.
It adds the following commands (consumed by proof_cmds.cpp):

- assume  - for input clauses
- learn   - when a clause is learned (or redundant clause is added)
- del     - when a clause is deleted.

The commands take a list of expressions of type Bool and the
last argument can optionally be of type Proof.
When the last argument is of type Proof it is provided as a hint
to justify the learned clause.

Proof hints can be checked using a self-contained proof
checker. The sat/smt/euf_proof_checker.h class provides
a plugin dispatcher for checkers.
It is instantiated with a checker for arithmetic lemmas,
so far for Farkas proofs.

Use example:
```
(set-option :sat.euf true)
(set-option :tactic.default_tactic smt)
(set-option :sat.smt.proof f.proof)
(declare-const x Int)
(declare-const y Int)
(declare-const z Int)
(declare-const u Int)
(assert (< x y))
(assert (< y z))
(assert (< z x))
(check-sat)
```

Run z3 on a file with above content.
Then run z3 on f.proof

```
(verified-smt)
(verified-smt)
(verified-smt)
(verified-farkas)
(verified-smt)
```
This commit is contained in:
Nikolaj Bjorner 2022-08-28 17:44:33 -07:00
parent 9922c766b9
commit e2f4fc2307
37 changed files with 809 additions and 1078 deletions
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51
src/sat/smt/euf_solver.h
View file

@ -60,11 +60,10 @@ namespace euf {
std::ostream& display(std::ostream& out) const;
};
class solver : public sat::extension, public th_internalizer, public th_decompile, public sat::print_clause {
class solver : public sat::extension, public th_internalizer, public th_decompile, public sat::clause_eh {
typedef top_sort<euf::enode> deps_t;
friend class ackerman;
class user_sort;
// friend class sat::ba_solver;
struct stats {
unsigned m_ackerman;
unsigned m_final_checks;
@ -175,26 +174,22 @@ namespace euf {
void log_antecedents(std::ostream& out, literal l, literal_vector const& r);
void log_antecedents(literal l, literal_vector const& r);
void log_justification(literal l, th_explain const& jst);
void drat_log_decl(func_decl* f);
void drat_log_params(func_decl* f);
void drat_log_expr1(expr* n);
ptr_vector<expr> m_drat_todo;
obj_hashtable<ast> m_drat_asts;
bool m_drat_initialized{ false };
void init_drat();
ast_pp_util m_clause_visitor;
void on_clause(unsigned n, literal const* lits, sat::status st) override;
void def_add_arg(unsigned arg);
void def_end();
void def_begin(char id, unsigned n, std::string const& name);
bool m_proof_initialized = false;
void init_proof();
ast_pp_util m_clause_visitor;
bool m_display_all_decls = false;
void on_clause(unsigned n, literal const* lits, sat::status st) override;
void on_lemma(unsigned n, literal const* lits, sat::status st);
void on_proof(unsigned n, literal const* lits, sat::status st);
std::ostream& display_literals(std::ostream& out, unsigned n, sat::literal const* lits);
void display_assume(std::ostream& out, unsigned n, literal const* lits);
void display_redundant(std::ostream& out, unsigned n, literal const* lits, expr_ref& proof_hint);
void display_deleted(std::ostream& out, unsigned n, literal const* lits);
std::ostream& display_hint(std::ostream& out, expr* proof_hint);
expr_ref status2proof_hint(sat::status st);
// relevancy
//bool_vector m_relevant_expr_ids;
//bool_vector m_relevant_visited;
//ptr_vector<expr> m_relevant_todo;
//void init_relevant_expr_ids();
//void push_relevant(sat::bool_var v);
bool is_propagated(sat::literal lit);
// invariant
void check_eqc_bool_assignment() const;
@ -347,16 +342,16 @@ namespace euf {
// proof
bool use_drat() { return s().get_config().m_drat && (init_drat(), true); }
bool use_drat() { return s().get_config().m_drat && (init_proof(), true); }
sat::drat& get_drat() { return s().get_drat(); }
void drat_bool_def(sat::bool_var v, expr* n);
void drat_eq_def(sat::literal lit, expr* eq);
void drat_log_expr(expr* n);
void bool_def(bool_var v, unsigned n);
bool visit_clause(unsigned n, literal const* lits);
void display_clause(unsigned n, literal const* lits);
void visit_expr(expr* e);
void display_expr(expr* e);
void set_tmp_bool_var(sat::bool_var b, expr* e);
bool visit_clause(std::ostream& out, unsigned n, literal const* lits);
void display_assert(std::ostream& out, unsigned n, literal const* lits);
void visit_expr(std::ostream& out, expr* e);
std::ostream& display_expr(std::ostream& out, expr* e);
void on_instantiation(unsigned n, sat::literal const* lits, unsigned k, euf::enode* const* bindings);
scoped_ptr<std::ostream> m_proof_out;
// decompile
bool extract_pb(std::function<void(unsigned sz, literal const* c, unsigned k)>& card,