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fixes to proof logging and checking

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This commit is contained in:
Nikolaj Bjorner 2022-10-15 12:42:50 +02:00
parent 4388719848
commit 993ff40826
7 changed files with 100 additions and 27 deletions
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4
src/cmd_context/extra_cmds/proof_cmds.cpp
View file

@ -182,9 +182,9 @@ public:
}
m_solver->pop(1);
std::cout << "(verified-smt";
if (proof_hint) std::cout << " " << mk_bounded_pp(proof_hint, m, 4);
if (proof_hint) std::cout << "\n" << mk_bounded_pp(proof_hint, m, 4);
for (expr* arg : clause)
std::cout << " " << mk_bounded_pp(arg, m);
std::cout << "\n " << mk_bounded_pp(arg, m);
std::cout << ")\n";
add_clause(clause);
}

62
src/sat/smt/arith_proof_checker.h
View file

@ -143,17 +143,13 @@ namespace arith {
SASSERT(m_todo.empty());
m_todo.push_back({ mul, e });
rational coeff1;
expr* e1, *e2, *e3;
expr* e1, *e2;
for (unsigned i = 0; i < m_todo.size(); ++i) {
auto [coeff, e] = m_todo[i];
if (a.is_mul(e, e1, e2) && a.is_numeral(e1, coeff1))
if (a.is_mul(e, e1, e2) && is_numeral(e1, coeff1))
m_todo.push_back({coeff*coeff1, e2});
else if (a.is_mul(e, e1, e2) && a.is_uminus(e1, e3) && a.is_numeral(e3, coeff1))
m_todo.push_back({-coeff*coeff1, e2});
else if (a.is_mul(e, e1, e2) && a.is_uminus(e2, e3) && a.is_numeral(e3, coeff1))
m_todo.push_back({ -coeff * coeff1, e1 });
else if (a.is_mul(e, e1, e2) && a.is_numeral(e2, coeff1))
m_todo.push_back({coeff*coeff1, e1});
else if (a.is_mul(e, e1, e2) && is_numeral(e2, coeff1))
m_todo.push_back({ coeff * coeff1, e1 });
else if (a.is_add(e))
for (expr* arg : *to_app(e))
m_todo.push_back({coeff, arg});
@ -163,15 +159,21 @@ namespace arith {
m_todo.push_back({coeff, e1});
m_todo.push_back({-coeff, e2});
}
else if (a.is_numeral(e, coeff1))
else if (is_numeral(e, coeff1))
r.m_coeff += coeff*coeff1;
else if (a.is_uminus(e, e1) && a.is_numeral(e1, coeff1))
r.m_coeff -= coeff*coeff1;
else
add(r, e, coeff);
}
m_todo.reset();
}
bool is_numeral(expr* e, rational& n) {
if (a.is_numeral(e, n))
return true;
if (a.is_uminus(e, e) && a.is_numeral(e, n))
return n.neg(), true;
return false;
}
bool check_ineq(row& r) {
if (r.m_coeffs.empty() && r.m_coeff > 0)
@ -182,9 +184,12 @@ namespace arith {
}
// triangulate equalities, substitute results into m_ineq, m_conseq.
void reduce_eq() {
// check consistency of equalities (they may be inconsisent)
bool reduce_eq() {
for (unsigned i = 0; i < m_eqs.size(); ++i) {
auto& r = m_eqs[i];
if (r.m_coeffs.empty() && r.m_coeff != 0)
return false;
if (r.m_coeffs.empty())
continue;
auto [v, coeff] = *r.m_coeffs.begin();
@ -193,6 +198,7 @@ namespace arith {
resolve(v, m_ineq, coeff, r);
resolve(v, m_conseq, coeff, r);
}
return true;
}
@ -231,7 +237,8 @@ namespace arith {
bool check_farkas() {
if (check_ineq(m_ineq))
return true;
reduce_eq();
if (!reduce_eq())
return true;
if (check_ineq(m_ineq))
return true;
@ -244,7 +251,8 @@ namespace arith {
// after all inequalities in ineq have been added up
//
bool check_bound() {
reduce_eq();
if (!reduce_eq())
return true;
if (check_ineq(m_conseq))
return true;
if (m_ineq.m_coeffs.empty() ||
@ -401,8 +409,10 @@ namespace arith {
return false;
}
num_le = coeff.get_unsigned();
if (!add_implied_ineq(false, jst))
if (!add_implied_ineq(false, jst)) {
IF_VERBOSE(0, display(verbose_stream() << "did not add implied eq"));
return false;
}
++j;
continue;
}
@ -418,10 +428,24 @@ namespace arith {
if (num_le == 0) {
// we processed all the first inequalities,
// check that they imply one half of the implied equality.
if (!check())
return false;
reset();
VERIFY(add_implied_ineq(true, jst));
if (!check()) {
// we might have added the wrong direction of the implied equality.
// so try the opposite inequality.
add_implied_ineq(true, jst);
add_implied_ineq(true, jst);
if (check()) {
reset();
add_implied_ineq(false, jst);
}
else {
IF_VERBOSE(0, display(verbose_stream() << "failed to check implied eq "));
return false;
}
}
else {
reset();
VERIFY(add_implied_ineq(true, jst));
}
}
}
else

2
src/sat/smt/euf_proof.cpp
View file

@ -46,7 +46,7 @@ namespace euf {
* so it isn't necessarily an axiom over EUF,
* We will here leave it to the EUF checker to perform resolution steps.
*/
void solver::log_antecedents(literal l, literal_vector const& r, eq_proof_hint* hint) {
void solver::log_antecedents(literal l, literal_vector const& r, th_proof_hint* hint) {
TRACE("euf", log_antecedents(tout, l, r););
if (!use_drat())
return;

19
src/sat/smt/euf_proof_checker.cpp
View file

@ -19,6 +19,7 @@ Author:
#include "ast/ast_pp.h"
#include "ast/ast_util.h"
#include "ast/ast_ll_pp.h"
#include "ast/arith_decl_plugin.h"
#include "sat/smt/euf_proof_checker.h"
#include "sat/smt/arith_proof_checker.h"
#include "sat/smt/q_proof_checker.h"
@ -58,15 +59,29 @@ namespace euf {
class eq_proof_checker : public proof_checker_plugin {
ast_manager& m;
arith_util m_arith;
expr_ref_vector m_trail;
basic_union_find m_uf;
svector<std::pair<unsigned, unsigned>> m_expr2id;
ptr_vector<expr> m_id2expr;
svector<std::pair<expr*,expr*>> m_diseqs;
svector<std::pair<expr*,expr*>> m_diseqs;
unsigned m_ts = 0;
void merge(expr* x, expr* y) {
m_uf.merge(expr2id(x), expr2id(y));
IF_VERBOSE(10, verbose_stream() << "merge " << mk_bounded_pp(x, m) << " == " << mk_bounded_pp(y, m) << "\n");
merge_numeral(x);
merge_numeral(y);
}
void merge_numeral(expr* x) {
rational n;
expr* y;
if (m_arith.is_uminus(x, y) && m_arith.is_numeral(y, n)) {
y = m_arith.mk_numeral(-n, x->get_sort());
m_trail.push_back(y);
m_uf.merge(expr2id(x), expr2id(y));
}
}
bool are_equal(expr* x, expr* y) {
@ -118,7 +133,7 @@ namespace euf {
}
public:
eq_proof_checker(ast_manager& m): m(m) {}
eq_proof_checker(ast_manager& m): m(m), m_arith(m), m_trail(m) {}
expr_ref_vector clause(app* jst) override {
expr_ref_vector result(m);

34
src/sat/smt/euf_solver.cpp
View file

@ -200,16 +200,36 @@ namespace euf {
s().assign(lit, sat::justification::mk_ext_justification(s().scope_lvl(), idx));
}
/**
Retrieve set of literals r that imply r.
Since the set of literals are retrieved modulo multiple theories in a single implication
we lose theory specific justifications. For proof logging we use a catch all rule "smt"
for the case where an equality is derived using more than congruence closure.
To create fully decomposed justifications it will be necessary to augment the justification
data-structure with information about the equality that is implied by the theory.
Then each justification will imply an equality s = t assuming literals 'r'.
The theory lemma is then r -> s = t, where s = t is an equality that is available for the EUF hint.
The EUF hint is resolved against r -> s = t to eliminate s = t and to create the resulting explanation.
Example:
x - 3 = 0 => x = 3 by arithmetic
x = 3 => f(x) = f(3) by EUF
resolve to produce clause x - 3 = 0 => f(x) = f(3)
*/
void solver::get_antecedents(literal l, ext_justification_idx idx, literal_vector& r, bool probing) {
m_egraph.begin_explain();
m_explain.reset();
if (use_drat() && !probing)
push(restore_size_trail(m_explain_cc, m_explain_cc.size()));
auto* ext = sat::constraint_base::to_extension(idx);
bool has_theory = false;
if (ext == this)
get_antecedents(l, constraint::from_idx(idx), r, probing);
else
else {
ext->get_antecedents(l, idx, r, probing);
has_theory = true;
}
for (unsigned qhead = 0; qhead < m_explain.size(); ++qhead) {
size_t* e = m_explain[qhead];
if (is_literal(e))
@ -220,10 +240,20 @@ namespace euf {
SASSERT(ext != this);
sat::literal lit = sat::null_literal;
ext->get_antecedents(lit, idx, r, probing);
has_theory = true;
}
}
m_egraph.end_explain();
eq_proof_hint* hint = (use_drat() && !probing) ? mk_hint(l, r) : nullptr;
th_proof_hint* hint = nullptr;
if (use_drat() && !probing) {
if (has_theory) {
r.push_back(~l);
hint = mk_smt_hint(symbol("smt"), r);
r.pop_back();
}
else
hint = mk_hint(l, r);
}
unsigned j = 0;
for (sat::literal lit : r)
if (s().lvl(lit) > 0) r[j++] = lit;

2
src/sat/smt/euf_solver.h
View file

@ -193,7 +193,7 @@ namespace euf {
// proofs
void log_antecedents(std::ostream& out, literal l, literal_vector const& r);
void log_antecedents(literal l, literal_vector const& r, eq_proof_hint* hint);
void log_antecedents(literal l, literal_vector const& r, th_proof_hint* hint);
void log_justification(literal l, th_explain const& jst);
typedef std::pair<expr*, expr*> expr_pair;

4
src/sat/tactic/goal2sat.cpp
View file

@ -284,11 +284,15 @@ struct goal2sat::imp : public sat::sat_internalizer {
if (v == sat::null_bool_var) {
if (m.is_true(t)) {
sat::literal tt = sat::literal(mk_bool_var(t), false);
if (m_euf && ensure_euf()->use_drat())
ensure_euf()->set_bool_var2expr(tt.var(), t);
mk_root_clause(tt);
l = sign ? ~tt : tt;
}
else if (m.is_false(t)) {
sat::literal ff = sat::literal(mk_bool_var(t), false);
if (m_euf && ensure_euf()->use_drat())
ensure_euf()->set_bool_var2expr(ff.var(), t);
mk_root_clause(~ff);
l = sign ? ~ff : ff;
}