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Complete euf project with eq and diseq on pure representatives

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This commit is contained in:
Arie Gurfinkel 2018-06-12 17:23:46 -07:00
parent b246389267
commit 535b8893ae
3 changed files with 65 additions and 27 deletions
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43
src/qe/qe_mbi.cpp
View file

@ -33,18 +33,18 @@ Notes:
Sketch of approach by example:
A: s <= 2a <= t & f(a) = q
B: t <= 2b <= s + 1 & f(b) != q
1. Extract arithmetic consequences of A over shared vocabulary.
A -> s <= t & (even(t) | s < t)
A -> s <= t & (even(t) | s < t)
2a. Send to B, have B solve shared variables with EUF_B.
epsilon b . B & A_pure
epsilon b . t <= 2b <= s + 1 & s <= t & (even(t) | s < t)
= t <= s + 1 & (even(t) | t <= s) & s <= t & (even(t) | s < t)
= even(t) & t = s
epsilon b . t <= 2b <= s + 1 & s <= t & (even(t) | s < t)
= t <= s + 1 & (even(t) | t <= s) & s <= t & (even(t) | s < t)
= even(t) & t = s
b := t div 2
B & A_pure -> B[b/t div 2] = f(t div 2) != q & t <= s + 1
@ -53,13 +53,13 @@ Notes:
A & B_pure -> false
Invoke the ping-pong principle to extract interpolant.
2b. Solve for shared variables with EUF.
epsilon a . A
epsilon a . A
= a := (s + 1) div 2 & s < t & f((s + 1) div 2) = q
3b. Send to B. Produces core
3b. Send to B. Produces core
s < t & f((s + 1) div 2) = q
4b Solve again in arithmetic for shared variables with EUF.
@ -71,7 +71,7 @@ Notes:
Send to B, produces core (s != t | f(t div 2) != q)
5b. There is no longer a solution for A. A is unsat.
--*/
#include "ast/ast_util.h"
@ -138,7 +138,7 @@ namespace qe {
void prop_mbi_plugin::block(expr_ref_vector const& lits) {
m_solver->assert_expr(mk_not(mk_and(lits)));
}
}
// -------------------------------
// euf_mbi, TBD
@ -158,8 +158,8 @@ namespace qe {
void operator()(expr*) {}
};
euf_mbi_plugin::euf_mbi_plugin(solver* s, solver* sNot):
m(s->get_manager()),
euf_mbi_plugin::euf_mbi_plugin(solver* s, solver* sNot):
m(s->get_manager()),
m_atoms(m),
m_solver(s),
m_dual_solver(sNot) {
@ -205,11 +205,11 @@ namespace qe {
// use the dual solver to find a 'small' implicant
m_dual_solver->get_unsat_core(core);
TRACE("qe", tout << "core: " << core << "\n";);
// project the implicant onto vars
// project the implicant onto vars
tg.set_vars(vars, false);
tg.add_lits(core);
lits.reset();
lits.append(tg.project());
lits.reset();
lits.append(tg.project(*mdl));
TRACE("qe", tout << "project: " << lits << "\n";);
return mbi_sat;
case l_undef:
@ -232,8 +232,8 @@ namespace qe {
void euf_mbi_plugin::block(expr_ref_vector const& lits) {
m_solver->assert_expr(mk_not(mk_and(lits)));
}
}
/** --------------------------------------------------------------
* ping-pong interpolation of Gurfinkel & Vizel
@ -255,7 +255,7 @@ namespace qe {
auto* t2 = turn ? &b : &a;
mbi_result next_res = (*t1)(vars, lits, mdl);
switch (next_res) {
case mbi_sat:
case mbi_sat:
if (last_res == mbi_sat) {
itp = nullptr;
return l_true;
@ -264,7 +264,7 @@ namespace qe {
break; // continue
case mbi_unsat: {
if (lits.empty()) {
// TBD, either a => itp and itp => !b
// TBD, either a => itp and itp => !b
// or b => itp and itp => !a
itp = mk_and(itps[!turn]);
return l_false;
@ -282,7 +282,7 @@ namespace qe {
case mbi_augment:
break;
case mbi_undef:
return l_undef;
return l_undef;
}
turn = !turn;
last_res = next_res;
@ -319,4 +319,3 @@ namespace qe {
}
}
};

39
src/qe/qe_term_graph.cpp
View file

@ -24,6 +24,7 @@ Notes:
#include "ast/for_each_expr.h"
#include "ast/occurs.h"
#include "qe/qe_term_graph.h"
#include "model/model_evaluator.h"
namespace qe {
@ -546,6 +547,7 @@ namespace qe {
u_map<expr*> m_term2app;
u_map<expr*> m_root2rep;
model_ref m_model;
expr_ref_vector m_pinned; // tracks expr in the maps
expr* mk_pure(term const& t) {
@ -565,6 +567,7 @@ namespace qe {
return pure;
}
bool is_better_rep(expr *t1, expr *t2) {
if (!t2) return t1 != nullptr;
return m.is_unique_value(t1) && !m.is_unique_value(t2);
@ -740,20 +743,49 @@ namespace qe {
return is_uninterp_const(rhs) && !occurs(rhs, lhs);
}
/// Add equalities and disequalities for all pure representatives
/// based on their equivalence in the model
void model_complete(expr_ref_vector &res) {
if (!m_model) return;
obj_map<expr,expr*> val2rep;
model_evaluator mev(*m_model);
for (auto &kv : m_root2rep) {
expr *rep = kv.m_value;
expr_ref val(m);
expr *u = nullptr;
if (!mev.eval(rep, val)) continue;
if (val2rep.find(val, u)) {
res.push_back(m.mk_eq(u, rep));
}
else {
val2rep.insert(val, rep);
}
}
ptr_buffer<expr> reps;
for (auto &kv : val2rep) {
reps.push_back(kv.m_value);
}
res.push_back(m.mk_distinct(reps.size(), reps.c_ptr()));
}
public:
projector(term_graph &tg) : m_tg(tg), m(m_tg.m), m_pinned(m) {}
void set_model(model &mdl) { m_model = &mdl; }
void reset() {
m_tg.reset_marks();
m_term2app.reset();
m_root2rep.reset();
m_pinned.reset();
m_model.reset();
}
expr_ref_vector project() {
expr_ref_vector res(m);
purify();
mk_lits(res);
mk_pure_equalities(res);
model_complete(res);
reset();
return res;
}
@ -780,6 +812,13 @@ namespace qe {
return p.project();
}
expr_ref_vector term_graph::project(model &mdl) {
m_is_var.reset_solved();
projector p(*this);
p.set_model(mdl);
return p.project();
}
expr_ref_vector term_graph::solve() {
// reset solved vars so that they are not considered pure by projector
m_is_var.reset_solved();

10
src/qe/qe_term_graph.h
View file

@ -23,6 +23,7 @@ Notes:
#include "util/plugin_manager.h"
#include "qe/qe_solve_plugin.h"
#include "qe/qe_vartest.h"
#include "model/model.h"
namespace qe {
@ -85,8 +86,6 @@ namespace qe {
void display(std::ostream &out);
bool is_pure_def(expr* atom, expr *& v);
void solve_for_vars();
public:
term_graph(ast_manager &m);
@ -111,9 +110,10 @@ namespace qe {
* onto the vocabulary of decls (if exclude is false) or outside the
* vocabulary of decls (if exclude is true).
*/
expr_ref_vector project();
expr_ref_vector solve();
expr_ref_vector project();
expr_ref_vector solve();
expr_ref_vector project(model &mdl);
};
}