mirror of
https://github.com/Z3Prover/z3
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add model correction
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
parent
c75fd02c95
commit
2428bf18f1
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@ -97,9 +97,10 @@ namespace opt {
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// e.g. t2/a2 >= t3/a3
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// then replace a3*x + t3 by t3/a3 - t2/a2 <= 0
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//
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bound_type model_based_opt::maximize(rational& value) {
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inf_eps model_based_opt::maximize() {
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SASSERT(invariant());
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unsigned_vector other;
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unsigned_vector bound_trail, bound_vars;
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while (!objective().m_vars.empty()) {
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TRACE("opt", tout << "tableau\n";);
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var v = objective().m_vars.back();
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@ -120,17 +121,79 @@ namespace opt {
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mul_add(m_objective_id, - coeff/bound_coeff, bound_row_index);
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m_rows[bound_row_index].m_alive = false;
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bound_trail.push_back(bound_row_index);
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bound_vars.push_back(x);
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}
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else {
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return unbounded;
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return inf_eps::infinity();
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}
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}
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value = objective().m_value;
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if (objective().m_type == t_lt) {
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return strict;
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//
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// update the evaluation of variables to satisfy the bound.
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update_values(bound_vars, bound_trail);
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rational value = objective().m_value;
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if (objective().m_type == t_lt) {
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return inf_eps(inf_rational(value, rational(-1)));
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}
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else {
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return non_strict;
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return inf_eps(inf_rational(value));
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}
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}
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void model_based_opt::update_values(unsigned_vector const& bound_vars, unsigned_vector const& bound_trail) {
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rational eps(0);
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for (unsigned i = bound_trail.size(); i > 0; ) {
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--i;
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unsigned x = bound_vars[i];
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row const& r = m_rows[bound_trail[i]];
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rational val = r.m_coeff;
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rational x_coeff;
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vector<var> const& vars = r.m_vars;
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for (unsigned j = 0; j < vars.size(); ++j) {
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var const& v = vars[j];
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if (x = v.m_id) {
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x_coeff = v.m_coeff;
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}
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else {
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val += m_var2value[v.m_id]*v.m_coeff;
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}
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}
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SASSERT(!x_coeff.is_zero());
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val /= -x_coeff;
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// Adjust epsilon to be s
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if (eps.is_zero() || (!val.is_zero() && eps > abs(val))) {
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eps = abs(val)/rational(2);
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}
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if (eps.is_zero() || (!r.m_value.is_zero() && eps > abs(r.m_value))) {
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eps = abs(r.m_value)/rational(2);
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}
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//
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//
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// ax + t < 0
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// <=> x < -t/a
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// <=> x := -t/a - epsilon
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//
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if (x_coeff.is_pos() && r.m_type == t_lt) {
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val -= eps;
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}
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//
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// -ax + t < 0
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// <=> -ax < -t
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// <=> -x < -t/a
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// <=> x > t/a
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// <=> x := t/a + epsilon
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//
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if (x_coeff.is_pos() && r.m_type == t_lt) {
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val -= eps;
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}
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else if (x_coeff.is_neg() && r.m_type == t_lt) {
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val += eps;
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}
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m_var2value[x] = val;
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}
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}
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@ -343,6 +406,10 @@ namespace opt {
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return v;
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}
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rational model_based_opt::get_value(unsigned var) {
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return m_var2value[var];
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}
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void model_based_opt::set_row(unsigned row_id, vector<var> const& coeffs, rational const& c, ineq_type rel) {
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row& r = m_rows[row_id];
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rational val(c);
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@ -23,6 +23,7 @@ Revision History:
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#include "util.h"
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#include "rational.h"
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#include"inf_eps_rational.h"
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namespace opt {
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@ -38,7 +39,7 @@ namespace opt {
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non_strict
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};
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typedef inf_eps_rational<inf_rational> inf_eps;
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class model_based_opt {
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public:
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@ -71,8 +72,7 @@ namespace opt {
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bool invariant();
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bool invariant(unsigned index, row const& r);
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row& objective() { return m_rows[0]; }
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row& objective() { return m_rows[0]; }
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bool find_bound(unsigned x, unsigned& bound_index, rational& bound_coeff, unsigned_vector& other, bool is_pos);
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@ -83,6 +83,8 @@ namespace opt {
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void mul_add(unsigned row_id1, rational const& c, unsigned row_id2);
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void set_row(unsigned row_id, vector<var> const& coeffs, rational const& c, ineq_type rel);
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void update_values(unsigned_vector const& bound_vars, unsigned_vector const& bound_trail);
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public:
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@ -91,6 +93,9 @@ namespace opt {
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// add a fresh variable with value 'value'.
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unsigned add_var(rational const& value);
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// retrieve updated value of variable.
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rational get_value(unsigned var_id);
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// add a constraint. We assume that the constraint is
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// satisfied under the values provided to the variables.
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void add_constraint(vector<var> const& coeffs, rational const& c, ineq_type r);
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@ -98,12 +103,13 @@ namespace opt {
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// Set the objective function (linear).
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void set_objective(vector<var> const& coeffs, rational const& c);
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//
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// find a maximal value for the objective function over the current values.
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// in other words, the returned maximal value may not be globally optimal,
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// but the current evaluation of variables are used to select a local
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// optimal.
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bound_type maximize(rational& value);
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//
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inf_eps maximize();
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void display(std::ostream& out) const;
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void display(std::ostream& out, row const& r) const;
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@ -1459,23 +1459,20 @@ namespace opt {
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lbool context::run_qsat_opt() {
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SASSERT(is_qsat_opt());
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app_ref objective(m);
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opt::bound_type bound;
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expr_ref value(m);
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lbool result = qe::maximize(m_hard_constraints, objective, value, bound, m_params);
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if (result != l_undef) {
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switch (bound) {
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case opt::unbounded:
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case opt::strict:
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case opt::non_strict:
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// set_max
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break;
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// TBD:
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default:
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break;
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}
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objective const& obj = m_objectives[0];
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app_ref term(obj.m_term);
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if (obj.m_type == O_MINIMIZE) {
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term = m_arith.mk_uminus(term);
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}
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return l_undef;
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inf_eps value;
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lbool result = qe::maximize(m_hard_constraints, term, value, m_params);
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if (result != l_undef && obj.m_type == O_MINIMIZE) {
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value.neg();
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}
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if (result != l_undef) {
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m_optsmt.update_lower(obj.m_index, value);
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m_optsmt.update_upper(obj.m_index, value);
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}
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return result;
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}
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}
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@ -61,7 +61,9 @@ namespace opt {
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void get_model(model_ref& mdl, svector<symbol>& labels);
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model* get_model(unsigned index) const { return m_models[index]; }
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void update_lower(unsigned idx, inf_eps const& r);
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void update_upper(unsigned idx, inf_eps const& r);
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void reset();
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@ -82,6 +84,7 @@ namespace opt {
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lbool update_upper();
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};
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};
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@ -965,37 +965,57 @@ namespace qe {
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typedef opt::model_based_opt::var var;
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typedef vector<var> vars;
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opt::bound_type maximize(expr_ref_vector const& fmls, model& mdl, app* t, expr_ref& value, expr_ref& bound) {
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opt::inf_eps maximize(expr_ref_vector const& fmls, model& mdl, app* t, expr_ref& bound) {
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opt::model_based_opt mbo;
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opt::inf_eps value;
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obj_map<expr, rational> ts;
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obj_map<expr, unsigned> tids;
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vars coeffs;
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rational c(0), mul(1);
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linearize(mdl, mul, t, c, ts);
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linearize(mdl, mul, t, c, ts);
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extract_coefficients(ts, tids, coeffs);
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mbo.set_objective(coeffs, c);
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for (unsigned i = 0; i < fmls.size(); ++i) {
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linearize(mdl, mbo, fmls[i], tids);
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}
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rational val;
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opt::bound_type result = mbo.maximize(val);
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value = a.mk_numeral(val, false);
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switch (result) {
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case opt::unbounded:
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value = mbo.maximize();
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expr_ref val(a.mk_numeral(value.get_rational(), false), m);
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if (!value.is_finite()) {
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bound = m.mk_false();
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break;
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case opt::strict:
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bound = a.mk_le(value, t);
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break;
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case opt::non_strict:
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bound = a.mk_lt(value, t);
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break;
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return value;
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}
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// update model
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ptr_vector<expr> vars;
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obj_map<expr, unsigned>::iterator it = tids.begin(), end = tids.end();
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for (; it != end; ++it) {
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expr* e = it->m_key;
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if (is_uninterp_const(e)) {
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unsigned id = it->m_value;
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func_decl* f = to_app(e)->get_decl();
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expr_ref val(a.mk_numeral(mbo.get_value(id), false), m);
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mdl.register_decl(f, val);
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}
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else {
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TRACE("qe", tout << "omitting model update for non-uninterpreted constant " << mk_pp(e, m) << "\n";);
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}
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}
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if (value.get_infinitesimal().is_neg()) {
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bound = a.mk_le(val, t);
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}
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else {
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bound = a.mk_lt(val, t);
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}
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return result;
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return value;
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}
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void extract_coefficients(obj_map<expr, rational> const& ts, obj_map<expr, unsigned>& tids, vars& coeffs) {
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return m_imp->a.get_family_id();
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}
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opt::bound_type arith_project_plugin::maximize(expr_ref_vector const& fmls, model& mdl, app* t, expr_ref& value, expr_ref& bound) {
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return m_imp->maximize(fmls, mdl, t, value, bound);
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opt::inf_eps arith_project_plugin::maximize(expr_ref_vector const& fmls, model& mdl, app* t, expr_ref& bound) {
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return m_imp->maximize(fmls, mdl, t, bound);
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}
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bool arith_project(model& model, app* var, expr_ref_vector& lits) {
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@ -22,14 +22,15 @@ namespace qe {
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class arith_project_plugin : public project_plugin {
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struct imp;
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imp* m_imp;
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imp* m_imp;
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public:
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arith_project_plugin(ast_manager& m);
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virtual ~arith_project_plugin();
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virtual bool operator()(model& model, app* var, app_ref_vector& vars, expr_ref_vector& lits);
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virtual bool solve(model& model, app_ref_vector& vars, expr_ref_vector& lits);
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virtual family_id get_family_id();
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opt::bound_type maximize(expr_ref_vector const& fmls, model& mdl, app* t, expr_ref& value, expr_ref& bound);
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opt::inf_eps maximize(expr_ref_vector const& fmls, model& mdl, app* t, expr_ref& bound);
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};
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bool arith_project(model& model, app* var, expr_ref_vector& lits);
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@ -213,9 +213,9 @@ class mbp::impl {
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public:
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opt::bound_type maximize(expr_ref_vector const& fmls, model& mdl, app* t, expr_ref& value, expr_ref& bound) {
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opt::inf_eps maximize(expr_ref_vector const& fmls, model& mdl, app* t, expr_ref& bound) {
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arith_project_plugin arith(m);
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return arith.maximize(fmls, mdl, t, value, bound);
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return arith.maximize(fmls, mdl, t, bound);
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}
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void extract_literals(model& model, expr_ref_vector& fmls) {
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m_impl->extract_literals(model, lits);
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}
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opt::bound_type mbp::maximize(expr_ref_vector const& fmls, model& mdl, app* t, expr_ref& value, expr_ref& bound) {
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return m_impl->maximize(fmls, mdl, t, value, bound);
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opt::inf_eps mbp::maximize(expr_ref_vector const& fmls, model& mdl, app* t, expr_ref& bound) {
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return m_impl->maximize(fmls, mdl, t, bound);
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}
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@ -76,7 +76,7 @@ namespace qe {
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\brief
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Maximize objective t under current model for constraints in fmls.
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*/
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opt::bound_type maximize(expr_ref_vector const& fmls, model& mdl, app* t, expr_ref& value, expr_ref& bound);
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opt::inf_eps maximize(expr_ref_vector const& fmls, model& mdl, app* t, expr_ref& bound);
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};
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}
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@ -1162,8 +1162,7 @@ namespace qe {
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m_level(0),
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m_mode(mode),
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m_avars(m),
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m_free_vars(m),
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m_value(m)
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m_free_vars(m)
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{
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reset();
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}
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@ -1283,17 +1282,15 @@ namespace qe {
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}
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app* m_objective;
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expr_ref m_value;
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opt::bound_type m_bound;
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opt::inf_eps m_value;
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bool m_was_sat;
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lbool maximize(expr_ref_vector const& fmls, app* t, expr_ref& value, opt::bound_type& bound) {
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lbool maximize(expr_ref_vector const& fmls, app* t, opt::inf_eps& value) {
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expr_ref_vector defs(m);
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expr_ref fml = negate_core(fmls);
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hoist(fml);
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m_objective = t;
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m_value = 0;
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m_bound = opt::unbounded;
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m_value = opt::inf_eps();
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m_was_sat = false;
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m_pred_abs.abstract_atoms(fml, defs);
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fml = m_pred_abs.mk_abstract(fml);
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throw tactic_exception(s.c_str());
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}
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value = m_value;
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bound = m_bound;
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return l_true;
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}
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@ -1327,16 +1323,16 @@ namespace qe {
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TRACE("qe", tout << "maximize: " << core << "\n";);
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m_was_sat |= !core.empty();
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expr_ref bound(m);
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m_bound = m_mbp.maximize(core, mdl, m_objective, m_value, bound);
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m_value = m_mbp.maximize(core, mdl, m_objective, bound);
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m_ex.assert_expr(bound);
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}
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};
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lbool maximize(expr_ref_vector const& fmls, app* t, expr_ref& value, opt::bound_type& bound, params_ref const& p) {
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lbool maximize(expr_ref_vector const& fmls, app* t, opt::inf_eps& value, params_ref const& p) {
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ast_manager& m = fmls.get_manager();
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qsat qs(m, p, qsat_maximize);
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return qs.maximize(fmls, t, value, bound);
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return qs.maximize(fmls, t, value);
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}
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};
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@ -114,7 +114,7 @@ namespace qe {
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void collect_statistics(statistics& st) const;
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};
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lbool maximize(expr_ref_vector const& fmls, app* t, expr_ref& value, opt::bound_type& bound, params_ref const& p);
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lbool maximize(expr_ref_vector const& fmls, app* t, opt::inf_eps& value, params_ref const& p);
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}
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@ -23,6 +23,7 @@ Revision History:
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#include"debug.h"
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#include"vector.h"
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#include"rational.h"
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#include"inf_rational.h"
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template<typename Numeral>
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class inf_eps_rational {
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