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https://github.com/Z3Prover/z3
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fixing bounds calculation
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner
parent
cb6c6332b3
commit
975474f560
2 changed files with 156 additions and 37 deletions
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@ -28,6 +28,7 @@ Notes:
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#include "pb_rewriter_def.h"
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#include "sparse_matrix_def.h"
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#include "simplex_def.h"
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#include "mpz.h"
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namespace smt {
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@ -244,7 +245,15 @@ namespace smt {
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SASSERT(m_bound > 0);
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SASSERT(ctx.get_assignment(lit) == l_false);
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unsigned index = m_bound + 1;
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for (unsigned i = 0; i <= m_bound; ++i) {
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//
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// We give preference to a watched literal in position 1..m_bound.
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// Notice, that if a literal occurs multiple
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// times in m_args, within [0..m_bound] then it is inserted into the watch
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// list for this cardinality constraint. For each occurrence, a callback
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// to assign is made.
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//
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for (unsigned i = m_bound + 1; i > 0; ) {
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--i;
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if (m_args[i] == lit) {
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index = i;
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break;
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@ -261,9 +270,6 @@ namespace smt {
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if (ctx.get_assignment(lit2) != l_false) {
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TRACE("pb", tout << "swap " << lit2 << "\n";);
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std::swap(m_args[index], m_args[i]);
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if (ctx.get_assignment(m_args[0]) == l_false) {
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std::swap(m_args[0], m_args[index]);
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}
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th.watch_literal(lit2, this);
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return l_undef;
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}
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@ -1016,9 +1022,8 @@ namespace smt {
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}
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lits.push_back(lit);
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ctx.mk_th_axiom(get_id(), lits.size(), lits.c_ptr());
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lit.neg();
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for (unsigned i = 0; i < c->size(); ++i) {
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literal lits2[2] = { lit, c->lit(i) };
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literal lits2[2] = { ~lit, c->lit(i) };
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ctx.mk_th_axiom(get_id(), 2, lits2);
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}
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dealloc(c);
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@ -1104,7 +1109,7 @@ namespace smt {
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m_stats.m_num_conflicts++;
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context& ctx = get_context();
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justification* js = 0;
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if (proofs_enabled()) {
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if (proofs_enabled()) {
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js = alloc(theory_lemma_justification, get_id(), ctx, lits.size(), lits.c_ptr());
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}
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resolve_conflict(c, lits);
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@ -1117,7 +1122,6 @@ namespace smt {
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m_stats.m_num_propagations++;
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context& ctx = get_context();
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TRACE("pb", tout << "#prop: " << c.num_propagations() << " - " << lits << " " << c.lit() << " => " << l << "\n";);
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ctx.assign(l, ctx.mk_justification(
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card_justification(
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c, get_id(), ctx.get_region(), lits.size(), lits.c_ptr(), l)));
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@ -1910,9 +1914,7 @@ namespace smt {
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ctx.set_mark(v);
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++m_num_marks;
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}
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if (lvl > ctx.get_base_level()) {
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inc_coeff(l, offset);
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}
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inc_coeff(l, offset);
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}
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void theory_pb::process_card(card& c, int offset) {
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@ -1930,25 +1932,113 @@ namespace smt {
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SASSERT(ctx.get_assignment(c.lit()) == l_true);
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}
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void theory_pb::inc_coeff(literal l, int offset) {
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if (l.sign()) {
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m_bound -= offset;
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void theory_pb::validate_lemma() {
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uint_set seen;
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int value = -m_bound;
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context& ctx = get_context();
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for (unsigned i = 0; i < m_active_coeffs.size(); ++i) {
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bool_var v = m_active_coeffs[i];
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if (seen.contains(v)) {
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continue;
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}
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seen.insert(v);
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int coeff = get_coeff(v);
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if (coeff == 0) continue;
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if (coeff < 0 && ctx.get_assignment(v) != l_true) {
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value -= coeff;
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}
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else if (coeff > 0 && ctx.get_assignment(v) != l_false) {
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value += coeff;
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}
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}
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std::cout << "bound: " << m_bound << " value " << value << " lemma is " << (value >= 0 ? "sat" : "unsat") << "\n";
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}
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void theory_pb::inc_coeff(literal l, int offset) {
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SASSERT(offset > 0);
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bool_var v = l.var();
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SASSERT(v != null_bool_var);
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if (static_cast<bool_var>(m_coeffs.size()) <= v) {
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m_coeffs.resize(v + 1, 0);
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}
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if (m_coeffs[v] == 0) {
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int coeff0 = m_coeffs[v];
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if (coeff0 == 0) {
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m_active_coeffs.push_back(v);
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}
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int inc = l.sign() ? -offset : offset;
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m_coeffs[v] += inc;
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int coeff1 = inc + coeff0;
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m_coeffs[v] = coeff1;
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if (coeff0 > 0 && 0 > coeff1) {
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m_bound += coeff1;
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}
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else if (coeff0 < 0 && 0 < coeff1) {
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m_bound += coeff0;
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}
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}
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/**
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\brief attempt a cut and simplification of constraints.
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*/
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void theory_pb::cut() {
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unsigned g = 0;
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for (unsigned i = 0; i < m_active_coeffs.size(); ++i) {
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bool_var v = m_active_coeffs[i];
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int coeff = m_coeffs[v];
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if (coeff == 0) {
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m_active_coeffs[i] = m_active_coeffs.back();
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m_active_coeffs.pop_back();
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continue;
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}
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if (coeff < 0) {
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coeff = -coeff;
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}
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if (m_bound < coeff) {
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m_coeffs[v] = m_bound;
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}
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if (g == 0) {
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g = static_cast<unsigned>(coeff);
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}
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else if (g != 1) {
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g = u_gcd(g, static_cast<unsigned>(coeff));
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}
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}
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if (g != 1 && g != 0) {
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uint_set seen;
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for (unsigned i = 0; i < m_active_coeffs.size(); ++i) {
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bool_var v = m_active_coeffs[i];
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if (!seen.contains(v)) {
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seen.insert(v);
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m_coeffs[v] /= g;
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}
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}
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m_bound /= g;
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TRACE("pb", display_resolved_lemma(tout << "cut\n"););
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}
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}
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#if 0
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void theory_pb::reduce2(int s1, int alpha, bool_var v, card& asserting) {
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// m_coeffs one for each boolean variable.
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int beta = coeff_of(v);
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if (beta == 1) {
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process_card(asserting, alpha);
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return;
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}
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int s2 = slack(asserting);
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while (beta * s1 + s2 * alpha >= 0) {
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bool_var x = pick_var(asserting);
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reduce();
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reduce_degree();
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s2 = s2 + delta_slack;
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}
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}
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#endif
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bool theory_pb::resolve_conflict(card& c, literal_vector const& confl) {
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TRACE("pb", display(tout, c, true); get_context().display(tout););
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TRACE("pb", display(tout, c, true); );
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bool_var v;
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context& ctx = get_context();
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@ -1966,9 +2056,11 @@ namespace smt {
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m_num_marks = 0;
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m_bound = c.k();
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m_antecedents.reset();
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m_resolved.reset();
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literal_vector ante;
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process_card(c, 1);
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// point into stack of assigned literals
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literal_vector const& lits = ctx.assigned_literals();
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@ -1977,12 +2069,12 @@ namespace smt {
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b_justification js;
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literal conseq = ~confl[2];
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while (m_num_marks > 0) {
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v = conseq.var();
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TRACE("pb", display_resolved_lemma(tout << conseq << "\n"););
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int offset = get_coeff(v);
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if (offset == 0) {
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@ -1991,19 +2083,20 @@ namespace smt {
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else if (offset < 0) {
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offset = -offset;
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}
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SASSERT(offset > 0);
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js = ctx.get_justification(v);
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TRACE("pb", tout << "conseq: " << conseq << "\n";);
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validate_lemma();
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// ctx.display(std::cout, js);
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inc_coeff(conseq, offset);
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m_bound += offset;
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//
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// Resolve selected conseq with antecedents.
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//
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int bound = 1;
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switch(js.get_kind()) {
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case b_justification::CLAUSE: {
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@ -2016,7 +2109,7 @@ namespace smt {
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}
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unsigned num_lits = cls.get_num_literals();
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if (cls.get_literal(0) == conseq) {
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process_antecedent(cls.get_literal(1), offset);
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process_antecedent(cls.get_literal(1), offset);
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}
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else {
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SASSERT(cls.get_literal(1) == conseq);
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@ -2047,12 +2140,14 @@ namespace smt {
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}
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else {
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process_card(pbj->get_card(), offset);
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bound = pbj->get_card().k();
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}
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break;
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}
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default:
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UNREACHABLE();
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}
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m_bound += offset * bound;
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process_next_resolvent:
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@ -2068,11 +2163,30 @@ namespace smt {
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SASSERT(ctx.get_assign_level(v) == m_conflict_lvl);
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ctx.unset_mark(v);
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m_resolved.push_back(idx);
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--idx;
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--m_num_marks;
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}
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validate_lemma();
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TRACE("pb", display_resolved_lemma(tout << "done\n"););
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uint_set seen;
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int count = 0, sz = 0;
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for (unsigned i = 0; i < m_active_coeffs.size(); ++i) {
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bool_var v = m_active_coeffs[i];
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if (seen.contains(v)) {
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continue;
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}
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seen.insert(v);
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int coeff = get_coeff(v);
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if (coeff == 0) continue;
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if (coeff < 0) coeff = -coeff;
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++sz;
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count += coeff;
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}
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std::cout << "New " << count << "(" << sz << ") >= " << m_bound << " " << c.size() << " >= " << c.k() << " new diff: " << count - m_bound << " old diff: " << c.size() - c.k() << "\n";
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return true;
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}
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@ -2188,19 +2302,18 @@ namespace smt {
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unsigned lvl;
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out << "num marks: " << m_num_marks << "\n";
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out << "conflict level: " << m_conflict_lvl << "\n";
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for (unsigned i = lits.size(); i > 0;) {
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--i;
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v = lits[i].var();
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for (unsigned i = 0; i < m_resolved.size(); ++i) {
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v = lits[m_resolved[i]].var();
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lvl = ctx.get_assign_level(v);
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out << lvl << ": " << lits[i] << " " << (ctx.is_marked(v)?"m":"u") << " ";
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out << lvl << ": " << lits[i] << " ";
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ctx.display(out, ctx.get_justification(v));
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}
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if (!m_antecedents.empty()) {
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out << m_antecedents << " ==> ";
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}
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int bound = m_bound;
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uint_set seen;
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bool first = true;
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for (unsigned i = 0; i < m_active_coeffs.size(); ++i) {
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bool_var v = m_active_coeffs[i];
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if (seen.contains(v)) {
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@ -2209,24 +2322,26 @@ namespace smt {
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seen.insert(v);
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int coeff = get_coeff(v);
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if (coeff == 0) {
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// skip
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continue;
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}
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else if (coeff == 1) {
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out << literal(v) << " ";
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if (!first) {
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out << " + ";
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}
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if (coeff == 1) {
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out << literal(v);
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}
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else if (coeff == -1) {
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out << literal(v, true) << " ";
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bound -= coeff;
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out << literal(v, true);
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}
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else if (coeff > 0) {
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out << coeff << " " << literal(v) << " ";
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out << coeff << " * " << literal(v);
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}
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else {
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out << (-coeff) << " " << literal(v, true) << " ";
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bound -= coeff;
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out << (-coeff) << " * " << literal(v, true);
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}
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first = false;
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}
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out << " >= " << bound << "\n";
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out << " >= " << m_bound << "\n";
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}
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std::ostream& theory_pb::display(std::ostream& out, arg_t const& c, bool values) const {
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@ -365,6 +365,7 @@ namespace smt {
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// Conflict resolution, cutting plane derivation.
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//
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unsigned m_num_marks;
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unsigned_vector m_resolved;
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unsigned m_conflict_lvl;
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svector<int> m_coeffs;
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svector<bool_var> m_active_coeffs;
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@ -379,8 +380,11 @@ namespace smt {
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bool resolve_conflict(card& c, literal_vector const& conflict_clause);
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void process_antecedent(literal l, int offset);
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void process_card(card& c, int offset);
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void cut();
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bool is_proof_justification(justification const& j) const;
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void validate_lemma();
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void hoist_maximal_values();
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void validate_final_check();
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