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apply 'to-real' coercion only on integers. bug reported by Geoff

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2016-07-20 19:03:25 -07:00
parent b56837e09b
commit f522d995d1
11 changed files with 5 additions and 2446 deletions
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5
examples/tptp/tptp5.cpp
View file

@ -828,7 +828,10 @@ class env {
}
else if (!strcmp(ch,"$to_real")) {
check_arity(terms.size(), 1);
r = to_real(terms[0]);
r = terms[0];
if (r.get_sort().is_int()) {
r = to_real(terms[0]);
}
}
else if (!strcmp(ch,"$is_int")) {
check_arity(terms.size(), 1);

405
src/opt/bcd2.cpp
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@ -1,405 +0,0 @@
/*++
Copyright (c) 2014 Microsoft Corporation
Module Name:
bcd2.cpp
Abstract:
bcd2 based MaxSAT.
Author:
Nikolaj Bjorner (nbjorner) 2014-4-17
Notes:
--*/
#include "bcd2.h"
#include "pb_decl_plugin.h"
#include "uint_set.h"
#include "ast_pp.h"
namespace opt {
// ------------------------------------------------------
// Morgado, Heras, Marques-Silva 2013
// (initial version without model-based optimizations)
//
class bcd2 : public maxsmt_solver_base {
struct wcore {
expr* m_r;
unsigned_vector m_R;
rational m_lower;
rational m_mid;
rational m_upper;
};
typedef obj_hashtable<expr> expr_set;
pb_util pb;
expr_ref_vector m_soft_aux;
obj_map<expr, unsigned> m_relax2index; // expr |-> index
obj_map<expr, unsigned> m_soft2index; // expr |-> index
expr_ref_vector m_trail;
expr_ref_vector m_soft_constraints;
expr_set m_asm_set;
vector<wcore> m_cores;
vector<rational> m_sigmas;
rational m_den; // least common multiplier of original denominators
bool m_enable_lazy; // enable adding soft constraints lazily (called 'mgbcd2')
unsigned_vector m_lazy_soft; // soft constraints to add lazily.
void set2asms(expr_set const& set, expr_ref_vector & es) const {
es.reset();
expr_set::iterator it = set.begin(), end = set.end();
for (; it != end; ++it) {
es.push_back(m.mk_not(*it));
}
}
void bcd2_init_soft(weights_t& weights, expr_ref_vector const& soft) {
// normalize weights to be integral:
m_den = rational::one();
for (unsigned i = 0; i < m_weights.size(); ++i) {
m_den = lcm(m_den, denominator(m_weights[i]));
}
if (!m_den.is_one()) {
for (unsigned i = 0; i < m_weights.size(); ++i) {
m_weights[i] = m_den*m_weights[i];
SASSERT(m_weights[i].is_int());
}
}
}
void init_bcd() {
m_trail.reset();
m_asm_set.reset();
m_cores.reset();
m_sigmas.reset();
m_lazy_soft.reset();
for (unsigned i = 0; i < m_soft.size(); ++i) {
m_sigmas.push_back(m_weights[i]);
m_soft_aux.push_back(mk_fresh());
if (m_enable_lazy) {
m_lazy_soft.push_back(i);
}
else {
enable_soft_constraint(i);
}
}
m_upper += rational(1);
}
void process_sat() {
svector<bool> assignment;
update_assignment(assignment);
if (check_lazy_soft(assignment)) {
update_sigmas();
}
}
public:
bcd2(maxsat_context& c,
weights_t& ws, expr_ref_vector const& soft):
maxsmt_solver_base(c, ws, soft),
pb(m),
m_soft_aux(m),
m_trail(m),
m_soft_constraints(m),
m_enable_lazy(true) {
bcd2_init_soft(ws, soft);
}
virtual ~bcd2() {}
virtual lbool operator()() {
expr_ref fml(m), r(m);
lbool is_sat = l_undef;
expr_ref_vector asms(m);
init();
init_bcd();
if (m.canceled()) {
normalize_bounds();
return l_undef;
}
process_sat();
while (m_lower < m_upper) {
trace_bounds("bcd2");
assert_soft();
solver::scoped_push _scope2(s());
TRACE("opt", display(tout););
assert_cores();
set2asms(m_asm_set, asms);
if (m.canceled()) {
normalize_bounds();
return l_undef;
}
is_sat = s().check_sat(asms.size(), asms.c_ptr());
switch(is_sat) {
case l_undef:
normalize_bounds();
return l_undef;
case l_true:
process_sat();
break;
case l_false: {
ptr_vector<expr> unsat_core;
uint_set subC, soft;
s().get_unsat_core(unsat_core);
core2indices(unsat_core, subC, soft);
SASSERT(unsat_core.size() == subC.num_elems() + soft.num_elems());
if (soft.num_elems() == 0 && subC.num_elems() == 1) {
unsigned s = *subC.begin();
wcore& c_s = m_cores[s];
c_s.m_lower = refine(c_s.m_R, c_s.m_mid);
c_s.m_mid = div(c_s.m_lower + c_s.m_upper, rational(2));
}
else {
wcore c_s;
rational delta = min_of_delta(subC);
rational lower = sum_of_lower(subC);
union_Rs(subC, c_s.m_R);
r = mk_fresh();
relax(subC, soft, c_s.m_R, delta);
c_s.m_lower = refine(c_s.m_R, lower + delta - rational(1));
c_s.m_upper = rational::one();
c_s.m_upper += sum_of_sigmas(c_s.m_R);
c_s.m_mid = div(c_s.m_lower + c_s.m_upper, rational(2));
c_s.m_r = r;
m_asm_set.insert(r);
subtract(m_cores, subC);
m_relax2index.insert(r, m_cores.size());
m_cores.push_back(c_s);
}
break;
}
}
m_lower = compute_lower();
}
normalize_bounds();
return l_true;
}
private:
void enable_soft_constraint(unsigned i) {
expr_ref fml(m);
expr* r = m_soft_aux[i].get();
m_soft2index.insert(r, i);
fml = m.mk_or(r, m_soft[i]);
m_soft_constraints.push_back(fml);
m_asm_set.insert(r);
SASSERT(m_weights[i].is_int());
}
void assert_soft() {
for (unsigned i = 0; i < m_soft_constraints.size(); ++i) {
s().assert_expr(m_soft_constraints[i].get());
}
m_soft_constraints.reset();
}
bool check_lazy_soft(svector<bool> const& assignment) {
bool all_satisfied = true;
for (unsigned i = 0; i < m_lazy_soft.size(); ++i) {
unsigned j = m_lazy_soft[i];
if (!assignment[j]) {
enable_soft_constraint(j);
m_lazy_soft[i] = m_lazy_soft.back();
m_lazy_soft.pop_back();
--i;
all_satisfied = false;
}
}
return all_satisfied;
}
void normalize_bounds() {
m_lower /= m_den;
m_upper /= m_den;
}
expr* mk_fresh() {
expr* r = mk_fresh_bool("r");
m_trail.push_back(r);
return r;
}
void update_assignment(svector<bool>& new_assignment) {
expr_ref val(m);
rational new_upper(0);
model_ref model;
new_assignment.reset();
s().get_model(model);
for (unsigned i = 0; i < m_soft.size(); ++i) {
new_assignment.push_back(model->eval(m_soft[i], val) && m.is_true(val));
if (!new_assignment[i]) {
new_upper += m_weights[i];
}
}
if (new_upper < m_upper) {
m_upper = new_upper;
m_model = model;
m_assignment.reset();
m_assignment.append(new_assignment);
}
}
void update_sigmas() {
for (unsigned i = 0; i < m_cores.size(); ++i) {
wcore& c_i = m_cores[i];
unsigned_vector const& R = c_i.m_R;
c_i.m_upper.reset();
for (unsigned j = 0; j < R.size(); ++j) {
unsigned r_j = R[j];
if (!m_assignment[r_j]) {
c_i.m_upper += m_weights[r_j];
m_sigmas[r_j] = m_weights[r_j];
}
else {
m_sigmas[r_j].reset();
}
}
c_i.m_mid = div(c_i.m_lower + c_i.m_upper, rational(2));
}
}
/**
* Minimum of two (positive) numbers. Zero is treated as +infinity.
*/
rational min_z(rational const& a, rational const& b) {
if (a.is_zero()) return b;
if (b.is_zero()) return a;
if (a < b) return a;
return b;
}
rational min_of_delta(uint_set const& subC) {
rational delta(0);
for (uint_set::iterator it = subC.begin(); it != subC.end(); ++it) {
unsigned j = *it;
wcore const& core = m_cores[j];
rational new_delta = rational(1) + core.m_upper - core.m_mid;
SASSERT(new_delta.is_pos());
delta = min_z(delta, new_delta);
}
return delta;
}
rational sum_of_lower(uint_set const& subC) {
rational lower(0);
for (uint_set::iterator it = subC.begin(); it != subC.end(); ++it) {
lower += m_cores[*it].m_lower;
}
return lower;
}
rational sum_of_sigmas(unsigned_vector const& R) {
rational sum(0);
for (unsigned i = 0; i < R.size(); ++i) {
sum += m_sigmas[R[i]];
}
return sum;
}
void union_Rs(uint_set const& subC, unsigned_vector& R) {
for (uint_set::iterator it = subC.begin(); it != subC.end(); ++it) {
R.append(m_cores[*it].m_R);
}
}
rational compute_lower() {
rational result(0);
for (unsigned i = 0; i < m_cores.size(); ++i) {
result += m_cores[i].m_lower;
}
return result;
}
void subtract(vector<wcore>& cores, uint_set const& subC) {
unsigned j = 0;
for (unsigned i = 0; i < cores.size(); ++i) {
if (subC.contains(i)) {
m_asm_set.remove(cores[i].m_r);
}
else {
if (j != i) {
cores[j] = cores[i];
}
++j;
}
}
cores.resize(j);
for (unsigned i = 0; i < cores.size(); ++i) {
m_relax2index.insert(cores[i].m_r, i);
}
}
void core2indices(ptr_vector<expr> const& core, uint_set& subC, uint_set& soft) {
for (unsigned i = 0; i < core.size(); ++i) {
unsigned j;
expr* a;
VERIFY(m.is_not(core[i], a));
if (m_relax2index.find(a, j)) {
subC.insert(j);
}
else {
VERIFY(m_soft2index.find(a, j));
soft.insert(j);
}
}
}
rational refine(unsigned_vector const& idx, rational v) {
return v + rational(1);
}
void relax(uint_set& subC, uint_set& soft, unsigned_vector& R, rational& delta) {
for (uint_set::iterator it = soft.begin(); it != soft.end(); ++it) {
R.push_back(*it);
delta = min_z(delta, m_weights[*it]);
m_asm_set.remove(m_soft_aux[*it].get());
}
}
void assert_cores() {
for (unsigned i = 0; i < m_cores.size(); ++i) {
assert_core(m_cores[i]);
}
}
void assert_core(wcore const& core) {
expr_ref fml(m);
vector<rational> ws;
ptr_vector<expr> rs;
rational w(0);
for (unsigned j = 0; j < core.m_R.size(); ++j) {
unsigned idx = core.m_R[j];
ws.push_back(m_weights[idx]);
w += ws.back();
rs.push_back(m_soft_aux[idx].get());
}
w.neg();
w += core.m_mid;
ws.push_back(w);
rs.push_back(core.m_r);
fml = pb.mk_le(ws.size(), ws.c_ptr(), rs.c_ptr(), core.m_mid);
s().assert_expr(fml);
}
void display(std::ostream& out) {
out << "[" << m_lower << ":" << m_upper << "]\n";
s().display(out);
out << "\n";
for (unsigned i = 0; i < m_cores.size(); ++i) {
wcore const& c = m_cores[i];
out << mk_pp(c.m_r, m) << ": ";
for (unsigned j = 0; j < c.m_R.size(); ++j) {
out << c.m_R[j] << " (" << m_sigmas[c.m_R[j]] << ") ";
}
out << "[" << c.m_lower << ":" << c.m_mid << ":" << c.m_upper << "]\n";
}
for (unsigned i = 0; i < m_soft.size(); ++i) {
out << mk_pp(m_soft[i], m) << " " << m_weights[i] << "\n";
}
}
};
maxsmt_solver_base* mk_bcd2(
maxsat_context& c, weights_t& ws, expr_ref_vector const& soft) {
return alloc(bcd2, c, ws, soft);
}
}

28
src/opt/bcd2.h
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@ -1,28 +0,0 @@
/*++
Copyright (c) 2014 Microsoft Corporation
Module Name:
bcd2.h
Abstract:
Bcd2 based MaxSAT.
Author:
Nikolaj Bjorner (nbjorner) 2014-4-17
Notes:
--*/
#ifndef BCD2_H_
#define BCD2_H_
#include "maxsmt.h"
namespace opt {
maxsmt_solver_base* mk_bcd2(maxsat_context& c, weights_t& ws, expr_ref_vector const& soft);
}
#endif

237
src/opt/fu_malik.cpp
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@ -1,237 +0,0 @@
/*++
Copyright (c) 2013 Microsoft Corporation
Module Name:
fu_malik.cpp
Abstract:
Fu & Malik built-in optimization method.
Adapted from sample code in C.
Author:
Anh-Dung Phan (t-anphan) 2013-10-15
Notes:
--*/
#include "fu_malik.h"
#include "qfbv_tactic.h"
#include "tactic2solver.h"
#include "goal.h"
#include "probe.h"
#include "tactic.h"
#include "ast_pp.h"
#include "model_smt2_pp.h"
#include "opt_context.h"
/**
\brief Fu & Malik procedure for MaxSAT. This procedure is based on
unsat core extraction and the at-most-one constraint.
Return the number of soft-constraints that can be
satisfied. Return -1 if the hard-constraints cannot be
satisfied. That is, the formula cannot be satisfied even if all
soft-constraints are ignored.
For more information on the Fu & Malik procedure:
Z. Fu and S. Malik, On solving the partial MAX-SAT problem, in International
Conference on Theory and Applications of Satisfiability Testing, 2006.
*/
namespace opt {
class fu_malik : public maxsmt_solver_base {
filter_model_converter& m_fm;
expr_ref_vector m_aux_soft;
expr_ref_vector m_aux;
model_ref m_model;
public:
fu_malik(maxsat_context& c, weights_t& ws, expr_ref_vector const& soft):
maxsmt_solver_base(c, ws, soft),
m_fm(c.fm()),
m_aux_soft(soft),
m_aux(m)
{
m_upper = rational(m_aux_soft.size() + 1);
m_lower.reset();
m_assignment.resize(m_aux_soft.size(), false);
}
/**
\brief One step of the Fu&Malik algorithm.
Input: soft constraints + aux-vars (aka answer literals)
Output: done/not-done when not done return updated set of soft-constraints and aux-vars.
- if SAT --> terminates
- if UNSAT
* compute unsat core
* add blocking variable to soft-constraints in the core
- replace soft-constraint with the one with the blocking variable
- we should also add an aux-var
- replace aux-var with a new one
* add at-most-one constraint with blocking
*/
typedef obj_hashtable<expr> expr_set;
void set2vector(expr_set const& set, expr_ref_vector & es) const {
es.reset();
expr_set::iterator it = set.begin(), end = set.end();
for (; it != end; ++it) {
es.push_back(*it);
}
}
void collect_statistics(statistics& st) const {
st.update("opt-fm-num-steps", m_aux_soft.size() + 2 - m_upper.get_unsigned());
}
void set_union(expr_set const& set1, expr_set const& set2, expr_set & set) const {
set.reset();
expr_set::iterator it = set1.begin(), end = set1.end();
for (; it != end; ++it) {
set.insert(*it);
}
it = set2.begin();
end = set2.end();
for (; it != end; ++it) {
set.insert(*it);
}
}
lbool step() {
IF_VERBOSE(1, verbose_stream() << "(opt.max_sat step " << m_aux_soft.size() + 2 - m_upper.get_unsigned() << ")\n";);
expr_ref_vector assumptions(m), block_vars(m);
for (unsigned i = 0; i < m_aux_soft.size(); ++i) {
assumptions.push_back(m.mk_not(m_aux[i].get()));
}
lbool is_sat = s().check_sat(assumptions.size(), assumptions.c_ptr());
if (is_sat != l_false) {
return is_sat;
}
ptr_vector<expr> core;
s().get_unsat_core(core);
SASSERT(!core.empty());
// Update soft-constraints and aux_vars
for (unsigned i = 0; i < m_aux_soft.size(); ++i) {
bool found = false;
for (unsigned j = 0; !found && j < core.size(); ++j) {
found = assumptions[i].get() == core[j];
}
if (!found) {
continue;
}
app_ref block_var(m), tmp(m);
block_var = m.mk_fresh_const("block_var", m.mk_bool_sort());
m_aux[i] = m.mk_fresh_const("aux", m.mk_bool_sort());
m_fm.insert(block_var->get_decl());
m_fm.insert(to_app(m_aux[i].get())->get_decl());
m_aux_soft[i] = m.mk_or(m_aux_soft[i].get(), block_var);
block_vars.push_back(block_var);
tmp = m.mk_or(m_aux_soft[i].get(), m_aux[i].get());
s().assert_expr(tmp);
}
SASSERT (!block_vars.empty());
assert_at_most_one(block_vars);
IF_VERBOSE(1, verbose_stream() << "(opt.max_sat # of non-blocked soft constraints: " << m_aux_soft.size() - block_vars.size() << ")\n";);
return l_false;
}
void assert_at_most_one(expr_ref_vector const& block_vars) {
expr_ref has_one(m), has_zero(m), at_most_one(m);
mk_at_most_one(block_vars.size(), block_vars.c_ptr(), has_one, has_zero);
at_most_one = m.mk_or(has_one, has_zero);
s().assert_expr(at_most_one);
}
void mk_at_most_one(unsigned n, expr* const * vars, expr_ref& has_one, expr_ref& has_zero) {
SASSERT(n != 0);
if (n == 1) {
has_one = vars[0];
has_zero = m.mk_not(vars[0]);
}
else {
unsigned mid = n/2;
expr_ref has_one1(m), has_one2(m), has_zero1(m), has_zero2(m);
mk_at_most_one(mid, vars, has_one1, has_zero1);
mk_at_most_one(n-mid, vars+mid, has_one2, has_zero2);
has_one = m.mk_or(m.mk_and(has_one1, has_zero2), m.mk_and(has_one2, has_zero1));
has_zero = m.mk_and(has_zero1, has_zero2);
}
}
// TBD: bug when cancel flag is set, fu_malik returns is_sat == l_true instead of l_undef
virtual lbool operator()() {
lbool is_sat = l_true;
if (m_aux_soft.empty()) {
return is_sat;
}
solver::scoped_push _sp(s());
expr_ref tmp(m);
TRACE("opt",
tout << "soft constraints:\n";
for (unsigned i = 0; i < m_aux_soft.size(); ++i) {
tout << mk_pp(m_aux_soft[i].get(), m) << "\n";
});
for (unsigned i = 0; i < m_aux_soft.size(); ++i) {
m_aux.push_back(m.mk_fresh_const("p", m.mk_bool_sort()));
m_fm.insert(to_app(m_aux.back())->get_decl());
tmp = m.mk_or(m_aux_soft[i].get(), m_aux[i].get());
s().assert_expr(tmp);
}
do {
is_sat = step();
--m_upper;
}
while (is_sat == l_false);
if (is_sat == l_true) {
// Get a list satisfying m_aux_soft
s().get_model(m_model);
m_lower = m_upper;
m_assignment.reset();
for (unsigned i = 0; i < m_soft.size(); ++i) {
expr_ref val(m);
if (!m_model->eval(m_soft[i], val)) return l_undef;
TRACE("opt", tout << val << "\n";);
m_assignment.push_back(m.is_true(val));
}
TRACE("opt", tout << "maxsat cost: " << m_upper << "\n";
model_smt2_pp(tout, m, *m_model, 0););
}
// We are done and soft_constraints has
// been updated with the max-sat assignment.
return is_sat;
}
virtual void get_model(model_ref& mdl) {
mdl = m_model.get();
}
virtual rational get_lower() const {
return rational(m_aux_soft.size())-m_upper;
}
virtual rational get_upper() const {
return rational(m_aux_soft.size())-m_lower;
}
};
maxsmt_solver_base* mk_fu_malik(maxsat_context& c, weights_t & ws, expr_ref_vector const& soft) {
return alloc(fu_malik, c, ws, soft);
}
};

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src/opt/fu_malik.h
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@ -1,37 +0,0 @@
/*++
Copyright (c) 2013 Microsoft Corporation
Module Name:
fu_malik.h
Abstract:
Fu&Malik built-in optimization method.
Adapted from sample code in C.
Author:
Anh-Dung Phan (t-anphan) 2013-10-15
Notes:
Takes solver with hard constraints added.
Returns a maximal satisfying subset of soft_constraints
that are still consistent with the solver state.
--*/
#ifndef OPT_FU_MALIK_H_
#define OPT_FU_MALIK_H_
#include "opt_solver.h"
#include "maxsmt.h"
namespace opt {
maxsmt_solver_base* mk_fu_malik(maxsat_context& c, weights_t & ws, expr_ref_vector const& soft);
};
#endif

1088
src/opt/hitting_sets.cpp
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52
src/opt/hitting_sets.h
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@ -1,52 +0,0 @@
/*++
Copyright (c) 2014 Microsoft Corporation
Module Name:
hitting_sets.h
Abstract:
Hitting set approximations.
Author:
Nikolaj Bjorner (nbjorner) 2014-06-06
Notes:
--*/
#ifndef HITTING_SETS_H_
#define HITTING_SETS_H_
#include "rational.h"
#include "statistics.h"
#include "lbool.h"
#include "rlimit.h"
namespace opt {
class hitting_sets {
struct imp;
imp* m_imp;
public:
hitting_sets(reslimit& lim);
~hitting_sets();
void add_weight(rational const& w);
void add_exists_true(unsigned sz, unsigned const* elems);
void add_exists_false(unsigned sz, unsigned const* elems);
lbool compute_lower();
lbool compute_upper();
void set_upper(rational const& r);
rational get_lower();
rational get_upper();
bool get_value(unsigned idx);
void set_cancel(bool f);
void collect_statistics(::statistics& st) const;
void reset();
};
};
#endif

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src/opt/maxhs.cpp
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/*++
Copyright (c) 2014 Microsoft Corporation
Module Name:
maxhs.cpp
Abstract:
maxhs based MaxSAT.
Author:
Nikolaj Bjorner (nbjorner) 2014-4-17
Notes:
--*/
#include "optsmt.h"
#include "hitting_sets.h"
#include "stopwatch.h"
#include "ast_pp.h"
#include "model_smt2_pp.h"
#include "uint_set.h"
#include "maxhs.h"
#include "opt_context.h"
namespace opt {
class scoped_stopwatch {
double& m_time;
stopwatch m_watch;
public:
scoped_stopwatch(double& time): m_time(time) {
m_watch.start();
}
~scoped_stopwatch() {
m_watch.stop();
m_time += m_watch.get_seconds();
}
};
// ----------------------------------
// MaxSatHS+MSS
// variant of MaxSAT-HS (Algorithm 9)
// that also refines upper bound during progressive calls
// to the underlying optimization solver for the soft constraints.
//
class maxhs : public maxsmt_solver_base {
struct stats {
stats() { reset(); }
void reset() { memset(this, 0, sizeof(*this)); }
unsigned m_num_iterations;
unsigned m_num_core_reductions_success;
unsigned m_num_core_reductions_failure;
unsigned m_num_model_expansions_success;
unsigned m_num_model_expansions_failure;
double m_core_reduction_time;
double m_model_expansion_time;
double m_aux_sat_time;
double m_disjoint_cores_time;
};
hitting_sets m_hs;
expr_ref_vector m_aux; // auxiliary (indicator) variables.
obj_map<expr, unsigned> m_aux2index; // expr |-> index
unsigned_vector m_core_activity; // number of times soft constraint is used in a core.
svector<bool> m_seed; // clause selected in current model.
svector<bool> m_aux_active; // active soft clauses.
ptr_vector<expr> m_asms; // assumptions (over aux)
stats m_stats;
bool m_at_lower_bound;
public:
maxhs(maxsat_context& c, weights_t& ws, expr_ref_vector const& soft):
maxsmt_solver_base(c, ws, soft),
m_hs(m.limit()),
m_aux(m),
m_at_lower_bound(false) {
}
virtual ~maxhs() {}
virtual void collect_statistics(statistics& st) const {
maxsmt_solver_base::collect_statistics(st);
m_hs.collect_statistics(st);
st.update("maxhs-num-iterations", m_stats.m_num_iterations);
st.update("maxhs-num-core-reductions-n", m_stats.m_num_core_reductions_failure);
st.update("maxhs-num-core-reductions-y", m_stats.m_num_core_reductions_success);
st.update("maxhs-num-model-expansions-n", m_stats.m_num_model_expansions_failure);
st.update("maxhs-num-model-expansions-y", m_stats.m_num_model_expansions_success);
st.update("maxhs-core-reduction-time", m_stats.m_core_reduction_time);
st.update("maxhs-model-expansion-time", m_stats.m_model_expansion_time);
st.update("maxhs-aux-sat-time", m_stats.m_aux_sat_time);
st.update("maxhs-disj-core-time", m_stats.m_disjoint_cores_time);
}
lbool operator()() {
ptr_vector<expr> hs;
init();
init_local();
if (!disjoint_cores(hs)) {
return l_undef;
}
seed2assumptions();
while (m_lower < m_upper) {
++m_stats.m_num_iterations;
trace_bounds("maxhs");
TRACE("opt", tout << "(maxhs [" << m_lower << ":" << m_upper << "])\n";);
if (m.canceled()) {
return l_undef;
}
lbool core_found = generate_cores(hs);
switch(core_found) {
case l_undef:
return l_undef;
case l_true: {
lbool is_sat = next_seed();
switch(is_sat) {
case l_true:
seed2hs(false, hs);
break;
case l_false:
TRACE("opt", tout << "no more seeds\n";);
IF_VERBOSE(1, verbose_stream() << "(opt.maxhs.no-more-seeds)\n";);
m_lower = m_upper;
return l_true;
case l_undef:
return l_undef;
}
break;
}
case l_false:
IF_VERBOSE(1, verbose_stream() << "(opt.maxhs.no-more-cores)\n";);
TRACE("opt", tout << "no more cores\n";);
m_lower = m_upper;
return l_true;
}
}
return l_true;
}
private:
unsigned num_soft() const { return m_soft.size(); }
void init_local() {
unsigned sz = num_soft();
app_ref fml(m), obj(m);
expr_ref_vector sum(m);
m_asms.reset();
m_seed.reset();
m_aux.reset();
m_aux_active.reset();
m_aux2index.reset();
m_core_activity.reset();
for (unsigned i = 0; i < sz; ++i) {
bool tt = is_true(m_model, m_soft[i]);
m_seed.push_back(tt);
m_aux. push_back(mk_fresh(m.mk_bool_sort()));
m_aux_active.push_back(false);
m_core_activity.push_back(0);
m_aux2index.insert(m_aux.back(), i);
if (tt) {
m_asms.push_back(m_aux.back());
ensure_active(i);
}
}
for (unsigned i = 0; i < m_weights.size(); ++i) {
m_hs.add_weight(m_weights[i]);
}
TRACE("opt", print_seed(tout););
}
void hs2seed(ptr_vector<expr> const& hs) {
for (unsigned i = 0; i < num_soft(); ++i) {
m_seed[i] = true;
}
for (unsigned i = 0; i < hs.size(); ++i) {
m_seed[m_aux2index.find(hs[i])] = false;
}
TRACE("opt",
print_asms(tout << "hitting set: ", hs);
print_seed(tout););
}
void seed2hs(bool pos, ptr_vector<expr>& hs) {
hs.reset();
for (unsigned i = 0; i < num_soft(); ++i) {
if (pos == m_seed[i]) {
hs.push_back(m_aux[i].get());
}
}
TRACE("opt",
print_asms(tout << "hitting set: ", hs);
print_seed(tout););
}
void seed2assumptions() {
seed2hs(true, m_asms);
}
//
// Find disjoint cores for soft constraints.
//
bool disjoint_cores(ptr_vector<expr>& hs) {
scoped_stopwatch _sw(m_stats.m_disjoint_cores_time);
m_asms.reset();
svector<bool> active(num_soft(), true);
rational lower(0);
update_assumptions(active, lower, hs);
SASSERT(lower.is_zero());
while (true) {
lbool is_sat = s().check_sat(m_asms.size(), m_asms.c_ptr());
switch (is_sat) {
case l_true:
if (lower > m_lower) {
m_lower = lower;
}
return true;
case l_false:
if (!shrink()) return false;
block_up();
update_assumptions(active, lower, hs);
break;
case l_undef:
return false;
}
}
}
void update_assumptions(svector<bool>& active, rational& lower, ptr_vector<expr>& hs) {
rational arg_min(0);
expr* e = 0;
for (unsigned i = 0; i < m_asms.size(); ++i) {
unsigned index = m_aux2index.find(m_asms[i]);
active[index] = false;
if (arg_min.is_zero() || arg_min > m_weights[index]) {
arg_min = m_weights[index];
e = m_asms[i];
}
}
if (e) {
hs.push_back(e);
lower += arg_min;
}
m_asms.reset();
for (unsigned i = 0; i < num_soft(); ++i) {
if (active[i]) {
m_asms.push_back(m_aux[i].get());
ensure_active(i);
}
}
}
//
// Auxiliary Algorithm 10 for producing cores.
//
lbool generate_cores(ptr_vector<expr>& hs) {
bool core = !m_at_lower_bound;
while (true) {
hs2seed(hs);
lbool is_sat = check_subset();
switch(is_sat) {
case l_undef:
return l_undef;
case l_true:
if (!grow()) return l_undef;
block_down();
return core?l_true:l_false;
case l_false:
core = true;
if (!shrink()) return l_undef;
block_up();
find_non_optimal_hitting_set(hs);
break;
}
}
}
struct lt_activity {
maxhs& hs;
lt_activity(maxhs& hs):hs(hs) {}
bool operator()(expr* a, expr* b) const {
unsigned w1 = hs.m_core_activity[hs.m_aux2index.find(a)];
unsigned w2 = hs.m_core_activity[hs.m_aux2index.find(b)];
return w1 < w2;
}
};
//
// produce the non-optimal hitting set by using the 10% heuristic.
// of most active cores constraints.
// m_asms contains the current core.
//
void find_non_optimal_hitting_set(ptr_vector<expr>& hs) {
std::sort(m_asms.begin(), m_asms.end(), lt_activity(*this));
for (unsigned i = m_asms.size(); i > 9*m_asms.size()/10;) {
--i;
hs.push_back(m_asms[i]);
}
}
//
// retrieve the next seed that satisfies state of hs.
// state of hs must be satisfiable before optimization is called.
//
lbool next_seed() {
scoped_stopwatch _sw(m_stats.m_aux_sat_time);
TRACE("opt", tout << "\n";);
// min c_i*(not x_i) for x_i are soft clauses.
// max c_i*x_i for x_i are soft clauses
m_at_lower_bound = false;
lbool is_sat = m_hs.compute_upper();
if (is_sat == l_true) {
is_sat = m_hs.compute_lower();
}
if (is_sat == l_true) {
m_at_lower_bound = m_hs.get_upper() == m_hs.get_lower();
if (m_hs.get_lower() > m_lower) {
m_lower = m_hs.get_lower();
}
for (unsigned i = 0; i < num_soft(); ++i) {
m_seed[i] = is_active(i) && !m_hs.get_value(i);
}
TRACE("opt", print_seed(tout););
}
return is_sat;
}
//
// check assignment returned by HS with the original
// hard constraints.
//
lbool check_subset() {
TRACE("opt", tout << "\n";);
m_asms.reset();
for (unsigned i = 0; i < num_soft(); ++i) {
if (m_seed[i]) {
m_asms.push_back(m_aux[i].get());
ensure_active(i);
}
}
return s().check_sat(m_asms.size(), m_asms.c_ptr());
}
//
// extend the current assignment to one that
// satisfies as many soft constraints as possible.
// update the upper bound based on this assignment
//
bool grow() {
scoped_stopwatch _sw(m_stats.m_model_expansion_time);
model_ref mdl;
s().get_model(mdl);
for (unsigned i = 0; i < num_soft(); ++i) {
ensure_active(i);
m_seed[i] = false;
}
for (unsigned i = 0; i < m_asms.size(); ++i) {
m_seed[m_aux2index.find(m_asms[i])] = true;
}
for (unsigned i = 0; i < num_soft(); ++i) {
if (m_seed[i]) {
// already an assumption
}
else if (is_true(mdl, m_soft[i])) {
m_seed[i] = true;
m_asms.push_back(m_aux[i].get());
}
else {
m_asms.push_back(m_aux[i].get());
lbool is_sat = s().check_sat(m_asms.size(), m_asms.c_ptr());
switch(is_sat) {
case l_undef:
return false;
case l_false:
++m_stats.m_num_model_expansions_failure;
m_asms.pop_back();
break;
case l_true:
++m_stats.m_num_model_expansions_success;
s().get_model(mdl);
m_seed[i] = true;
break;
}
}
}
rational upper(0);
for (unsigned i = 0; i < num_soft(); ++i) {
if (!m_seed[i]) {
upper += m_weights[i];
}
}
if (upper < m_upper) {
m_upper = upper;
m_hs.set_upper(upper);
m_model = mdl;
m_assignment.reset();
m_assignment.append(m_seed);
TRACE("opt",
tout << "new upper: " << m_upper << "\n";
model_smt2_pp(tout, m, *(mdl.get()), 0););
}
DEBUG_CODE(
for (unsigned i = 0; i < num_soft(); ++i) {
SASSERT(is_true(mdl, m_soft[i]) == m_seed[i]);
});
return true;
}
//
// remove soft constraints from the current core.
//
bool shrink() {
scoped_stopwatch _sw(m_stats.m_core_reduction_time);
m_asms.reset();
s().get_unsat_core(m_asms);
TRACE("opt", print_asms(tout, m_asms););
obj_map<expr, unsigned> asm2index;
for (unsigned i = 0; i < m_asms.size(); ++i) {
asm2index.insert(m_asms[i], i);
}
obj_map<expr, unsigned>::iterator it = asm2index.begin(), end = asm2index.end();
for (; it != end; ++it) {
unsigned i = it->m_value;
if (i < m_asms.size()) {
expr* tmp = m_asms[i];
expr* back = m_asms.back();
m_asms[i] = back;
m_asms.pop_back();
lbool is_sat = s().check_sat(m_asms.size(), m_asms.c_ptr());
TRACE("opt", tout << "checking: " << mk_pp(tmp, m) << ": " << is_sat << "\n";);
switch(is_sat) {
case l_true:
++m_stats.m_num_core_reductions_failure;
// put back literal into core
m_asms.push_back(back);
m_asms[i] = tmp;
break;
case l_false:
// update the core
m_asms.reset();
++m_stats.m_num_core_reductions_success;
s().get_unsat_core(m_asms);
TRACE("opt", print_asms(tout, m_asms););
update_index(asm2index);
break;
case l_undef:
return false;
}
}
}
return true;
}
void print_asms(std::ostream& out, ptr_vector<expr> const& asms) {
for (unsigned j = 0; j < asms.size(); ++j) {
out << mk_pp(asms[j], m) << " ";
}
out << "\n";
}
void print_seed(std::ostream& out) {
out << "seed: ";
for (unsigned i = 0; i < num_soft(); ++i) {
out << (m_seed[i]?"1":"0");
}
out << "\n";
}
//
// must include some literal not from asms.
// (furthermore, update upper bound constraint in HS)
//
void block_down() {
uint_set indices;
unsigned_vector c_indices;
for (unsigned i = 0; i < m_asms.size(); ++i) {
indices.insert(m_aux2index.find(m_asms[i]));
}
for (unsigned i = 0; i < num_soft(); ++i) {
if (!indices.contains(i)) {
c_indices.push_back(i);
}
}
m_hs.add_exists_false(c_indices.size(), c_indices.c_ptr());
}
// should exclude some literal from core.
void block_up() {
unsigned_vector indices;
for (unsigned i = 0; i < m_asms.size(); ++i) {
unsigned index = m_aux2index.find(m_asms[i]);
m_core_activity[index]++;
indices.push_back(index);
}
m_hs.add_exists_true(indices.size(), indices.c_ptr());
}
void update_index(obj_map<expr, unsigned>& asm2index) {
obj_map<expr, unsigned>::iterator it = asm2index.begin(), end = asm2index.end();
for (; it != end; ++it) {
it->m_value = UINT_MAX;
}
for (unsigned i = 0; i < m_asms.size(); ++i) {
asm2index.find(m_asms[i]) = i;
}
}
app_ref mk_fresh(sort* s) {
app_ref r(m);
r = m.mk_fresh_const("r", s);
m_c.fm().insert(r->get_decl());
return r;
}
bool is_true(model_ref& mdl, expr* e) {
expr_ref val(m);
return mdl->eval(e, val) && m.is_true(val);
}
bool is_active(unsigned i) const {
return m_aux_active[i];
}
void ensure_active(unsigned i) {
if (!is_active(i)) {
expr_ref fml(m);
fml = m.mk_implies(m_aux[i].get(), m_soft[i]);
s().assert_expr(fml);
m_aux_active[i] = true;
}
}
};
maxsmt_solver_base* mk_maxhs(
maxsat_context& c, weights_t& ws, expr_ref_vector const& soft) {
return alloc(maxhs, c, ws, soft);
}
}

29
src/opt/maxhs.h
View file

@ -1,29 +0,0 @@
/*++
Copyright (c) 2014 Microsoft Corporation
Module Name:
maxhs.h
Abstract:
HS-max based MaxSAT.
Author:
Nikolaj Bjorner (nbjorner) 2014-4-17
Notes:
--*/
#ifndef HS_MAX_H_
#define HS_MAX_H_
#include "maxsmt.h"
namespace opt {
maxsmt_solver_base* mk_maxhs(maxsat_context& c,
weights_t& ws, expr_ref_vector const& soft);
}
#endif

12
src/opt/maxsmt.cpp
View file

@ -19,10 +19,7 @@ Notes:
#include <typeinfo>
#include "maxsmt.h"
#include "fu_malik.h"
#include "maxres.h"
#include "maxhs.h"
#include "bcd2.h"
#include "wmax.h"
#include "maxsls.h"
#include "ast_pp.h"
@ -166,19 +163,10 @@ namespace opt {
else if (maxsat_engine == symbol("pd-maxres")) {
m_msolver = mk_primal_dual_maxres(m_c, m_index, m_weights, m_soft_constraints);
}
else if (maxsat_engine == symbol("bcd2")) {
m_msolver = mk_bcd2(m_c, m_weights, m_soft_constraints);
}
else if (maxsat_engine == symbol("maxhs")) {
m_msolver = mk_maxhs(m_c, m_weights, m_soft_constraints);
}
else if (maxsat_engine == symbol("sls")) {
// NB: this is experimental one-round version of SLS
m_msolver = mk_sls(m_c, m_weights, m_soft_constraints);
}
else if (is_maxsat_problem(m_weights) && maxsat_engine == symbol("fu_malik")) {
m_msolver = mk_fu_malik(m_c, m_weights, m_soft_constraints);
}
else {
if (maxsat_engine != symbol::null && maxsat_engine != symbol("wmax")) {
warning_msg("solver %s is not recognized, using default 'wmax'",

2
src/opt/opt_params.pyg
View file

@ -2,7 +2,7 @@ def_module_params('opt',
description='optimization parameters',
export=True,
params=(('optsmt_engine', SYMBOL, 'basic', "select optimization engine: 'basic', 'farkas', 'symba'"),
('maxsat_engine', SYMBOL, 'maxres', "select engine for maxsat: 'fu_malik', 'core_maxsat', 'wmax', 'pbmax', 'maxres', 'pd-maxres', 'bcd2', 'wpm2', 'sls', 'maxhs'"),
('maxsat_engine', SYMBOL, 'maxres', "select engine for maxsat: 'core_maxsat', 'wmax', 'maxres', 'pd-maxres', 'sls'"),
('priority', SYMBOL, 'lex', "select how to priortize objectives: 'lex' (lexicographic), 'pareto', or 'box'"),
('dump_benchmarks', BOOL, False, 'dump benchmarks for profiling'),
('print_model', BOOL, False, 'display model for satisfiable constraints'),