mirror of
https://github.com/Z3Prover/z3
synced 2025-04-08 10:25:18 +00:00
cheap_eqs
Signed-off-by: Lev Nachmanson <levnach@hotmail.com>
This commit is contained in:
parent
b5fc9635c4
commit
c2cead4fb6
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@ -24,7 +24,7 @@ class lp_bound_propagator {
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// and u, v reference the same column
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class vertex {
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unsigned m_row;
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unsigned m_index; // in the row
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unsigned m_column; // in the row
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ptr_vector<vertex> m_children;
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mpq m_offset; // offset from parent (parent - child = offset)
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vertex* m_parent;
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@ -33,14 +33,14 @@ class lp_bound_propagator {
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public:
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vertex() {}
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vertex(unsigned row,
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unsigned index,
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unsigned column,
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const mpq & offset) :
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m_row(row),
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m_index(index),
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m_column(column),
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m_offset(offset),
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m_parent(nullptr),
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m_level(0) {}
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unsigned index() const { return m_index; }
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unsigned column() const { return m_column; }
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unsigned row() const { return m_row; }
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vertex* parent() const { return m_parent; }
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unsigned level() const { return m_level; }
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@ -53,11 +53,11 @@ class lp_bound_propagator {
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}
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const ptr_vector<vertex> & children() const { return m_children; }
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std::ostream& print(std::ostream & out) const {
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out << "row = " << m_row << ", m_index = " << m_index << ", parent = " << m_parent << " , offset = " << m_offset << ", level = " << m_level << "\n";;
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out << "row = " << m_row << ", column = " << m_column << ", parent = " << m_parent << " , offset = " << m_offset << ", level = " << m_level << "\n";;
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return out;
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}
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bool operator==(const vertex& o) const {
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return m_row == o.m_row && m_index == o.m_index;
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return m_row == o.m_row && m_column == o.m_column;
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}
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};
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hashtable<unsigned, u_hash, u_eq> m_visited_rows;
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@ -73,14 +73,17 @@ class lp_bound_propagator {
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// these maps map a column index to the corresponding index in ibounds
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std::unordered_map<unsigned, unsigned> m_improved_lower_bounds;
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std::unordered_map<unsigned, unsigned> m_improved_upper_bounds;
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struct signed_index {
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class signed_column {
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bool m_sign;
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unsigned m_index;
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signed_index() : m_index(UINT_MAX) {}
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bool not_set() const { return m_index == UINT_MAX; }
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bool is_set() const { return m_index != UINT_MAX; }
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unsigned m_column;
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public:
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signed_column() : m_column(UINT_MAX) {}
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bool not_set() const { return m_column == UINT_MAX; }
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bool is_set() const { return m_column != UINT_MAX; }
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bool sign() const { return m_sign; }
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unsigned index() const { return m_index; }
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bool& sign() { return m_sign; }
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unsigned column() const { return m_column; }
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unsigned& column() { return m_column; }
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};
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T& m_imp;
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@ -216,15 +219,16 @@ public:
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return true;
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}
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bool set_sign_and_index(const mpq& c, signed_index& i, unsigned k) {
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if (c.is_one()) {
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i.m_sign = false;
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i.m_index = k;
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bool set_sign_and_column(signed_column& i, const row_cell<mpq> & c) {
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if (c.coeff().is_one()) {
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i.sign() = false;
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i.column() = c.var();
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return true;
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}
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if (c.is_minus_one()){
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i.m_sign = true;
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i.m_index = k;
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else if (c.coeff().is_minus_one()){
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i.sign() = true;
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i.column() = c.var();
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return true;
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}
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return false;
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@ -232,7 +236,7 @@ public:
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void try_add_equation_with_fixed_tables(vertex *v) {
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SASSERT(m_fixed_vertex);
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unsigned v_j = column(v);
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unsigned v_j = v->column();
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unsigned j;
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if (!lp().find_in_fixed_tables(v->offset(), is_int(v_j), j))
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return;
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@ -240,34 +244,34 @@ public:
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find_path_on_tree(path, v, m_fixed_vertex);
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explanation ex = get_explanation_from_path(path);
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explain_fixed_column(ex, j);
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add_eq_on_columns(ex, v_j, column(v));
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add_eq_on_columns(ex, j, v->column());
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}
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void create_root(unsigned row_index) {
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SASSERT(!m_root && !m_fixed_vertex);
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signed_index x, y;
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signed_column x, y;
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mpq offset;
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if (!is_offset_row_tree(row_index, x, y, offset))
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if (!is_tree_offset_row(row_index, x, y, offset))
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return;
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TRACE("cheap_eq", display_row_info(row_index, tout););
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if (y.not_set()) {
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m_root = alloc(vertex, row_index, x.m_index, offset);
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m_root = alloc(vertex, row_index, x.column(), offset);
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m_fixed_vertex = m_root;
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return;
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}
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// create root with the offset zero
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m_root = alloc(vertex, row_index, x.m_index, mpq(0));
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m_root = alloc(vertex, row_index, x.column(), mpq(0));
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// we have x + sign_y * y + offset = 0
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// x.offset is set to zero as x plays the role of m_root
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// if sign_y = true then y.offset() = offset + x.offset()
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// else y.offset() = - offset - x.offset()
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if (!y.m_sign)
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if (!y.sign())
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offset.neg();
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vertex *v = alloc(vertex, row_index, y.m_index, offset);
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vertex *v = alloc(vertex, row_index, y.column(), offset);
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m_root->add_child(v);
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}
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@ -277,18 +281,18 @@ public:
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// returns the vertex to start exploration from, or nullptr
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vertex* add_child_from_row(unsigned row_index, vertex* parent) {
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signed_index x, y;
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signed_column x, y;
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mpq offset;
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if (!is_offset_row_tree(row_index, x, y, offset))
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if (!is_tree_offset_row(row_index, x, y, offset))
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return nullptr;
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if (y.not_set()) {
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SASSERT(column(parent) == column(row_index, x.m_index));
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SASSERT(parent->column() == x.column());
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if (m_fixed_vertex) {
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vertex* v = alloc(vertex, row_index, x.m_index, - offset);
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vertex* v = alloc(vertex, row_index, x.column(), - offset);
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parent->add_child(v);
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return v;
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}
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vertex *v = alloc(vertex, row_index, x.m_index, parent->offset());
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vertex *v = alloc(vertex, row_index, x.column(), parent->offset());
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m_fixed_vertex = v;
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parent->add_child(v);
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// need to shift the tree so v.offset() becomes equal to - offset
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@ -296,27 +300,29 @@ public:
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return v;
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}
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SASSERT(x.is_set() && y.is_set());
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if (column(parent) == column(row_index, x.index())) {
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vertex *vx = alloc(vertex, row_index, x.index(), parent->offset());
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if (parent->column() == x.column()) {
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vertex *vx = alloc(vertex, row_index, x.column(), parent->offset());
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// mpq x_c = rat_sign(x.sign());
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// mpq y_c = rat_sign(y.sign());
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// we have x_c*x + y_c*y + offset = 0
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// y = - offset/y_c - ( x_c/y_c )vx.offset;
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bool x_c_y_c = x.sign() ^ y.sign();
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mpq y_offs = (y.sign()? offset: - offset) - (x_c_y_c? - vx->offset() : vx->offset());
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vertex *vy = alloc(vertex, row_index, y.index(), y_offs);
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vertex *vy = alloc(vertex, row_index, y.column(), y_offs);
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parent->add_child(vx);
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vx->add_child(vy);
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return vy; // start exploring from vy
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} else {
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vertex *vy = alloc(vertex, row_index, y.index(), parent->offset());
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SASSERT(parent->column() == y.column());
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vertex *vy = alloc(vertex, row_index, y.column(), parent->offset());
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// mpq x_c = rat_sign(x.sign());
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// mpq y_c = rat_sign(y.sign());
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// we have x_c*x + y_c*y + offset = 0
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// x = - offset/x_c - ( y_c/x_c )vy.offset;
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bool y_c_x_c = x.sign() ^ y.sign();
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mpq x_offs = (x.sign()? offset: -offset) - (y_c_x_c? - vy->offset(): vy->offset());
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vertex *vx = alloc(vertex, row_index, y.index(), x_offs);
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vertex *vx = alloc(vertex, row_index, y.column(), x_offs);
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parent->add_child(vy);
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vy->add_child(vx);
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return vx;
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}
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@ -330,8 +336,8 @@ public:
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vertex *k; // the other vertex
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if (m_offset_to_verts.find(v->offset(), k)) {
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if (column(k) != column(v) &&
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!is_equal(column(k),column(v)))
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if (k->column() != v->column() &&
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!is_equal(k->column(), v->column()))
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report_eq(k, v);
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} else {
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TRACE("cheap_eq", tout << "registered offset " << v->offset() << " to " << v << "\n";);
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@ -340,7 +346,7 @@ public:
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if (m_fixed_vertex) {
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unsigned j;
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unsigned v_col = column(v);
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unsigned v_col = v->column();
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if (lp().find_in_fixed_tables(v->offset(), is_int(v_col), j)) {
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if (j != v_col) {
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explanation ex;
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@ -360,14 +366,13 @@ public:
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void clear_for_eq() {
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m_visited_rows.reset();
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m_visited_columns.reset();
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m_offset_to_verts.reset();
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m_root = nullptr;
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}
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// we have v_i and v_j, indices of vertices at the same offsets
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void report_eq(vertex* v_i, vertex* v_j) {
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SASSERT(v_i != v_j);
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TRACE("cheap_eq", tout << column(v_i) << " = " << column(v_j) << "\nu = ";
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TRACE("cheap_eq", tout << v_i->column() << " = " << v_j->column() << "\nu = ";
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v_i->print(tout) << "\nv = "; v_j->print(tout) <<"\n";
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display_row_of_vertex(v_i, tout);
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display_row_of_vertex(v_j, tout);
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display_row_of_vertex(k, tout);
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});
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lp::explanation exp = get_explanation_from_path(path);
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add_eq_on_columns(exp, column(v_i), column(v_j));
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add_eq_on_columns(exp, v_i->column(), v_j->column());
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}
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void add_eq_on_columns(const explanation& exp, lpvar v_i_col, lpvar v_j_col) {
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SASSERT(v_i_col != v_j_col);
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unsigned i_e = lp().column_to_reported_index(v_i_col);
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unsigned j_e = lp().column_to_reported_index(v_j_col);
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TRACE("cheap_eq", tout << "reporting eq " << i_e << ", " << j_e << "\n";
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void add_eq_on_columns(const explanation& exp, lpvar j, lpvar k) {
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SASSERT(j != k);
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unsigned je = lp().column_to_reported_index(j);
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unsigned ke = lp().column_to_reported_index(k);
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TRACE("cheap_eq", tout << "reporting eq " << je << ", " << ke << "\n";
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for (auto p : exp) {
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lp().constraints().display(tout, [this](lpvar j) { return lp().get_variable_name(j);}, p.ci());
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});
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m_imp.add_eq(i_e, j_e, exp);
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m_imp.add_eq(je, ke, exp);
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}
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/**
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@ -601,9 +606,6 @@ public:
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}
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return out;
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}
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lpvar column(const vertex* v) const {
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return lp().get_row(v->row())[v->index()].var();
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}
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void cheap_eq_tree(unsigned row_index) {
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TRACE("cheap_eq", tout << "row_index = " << row_index << "\n";);
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@ -619,6 +621,7 @@ public:
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TRACE("cheap_eq", tout << "tree size = " << verts_size(););
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delete_tree(m_root);
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m_root = m_fixed_vertex = nullptr;
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m_offset_to_verts.reset();
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}
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unsigned verts_size() const {
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@ -647,7 +650,7 @@ public:
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}
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void go_over_vertex_column(vertex * v) {
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lpvar j = column(v);
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lpvar j = v->column();
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if (!check_insert(m_visited_columns, j))
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return;
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@ -655,7 +658,6 @@ public:
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unsigned row_index = c.var();
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if (!check_insert(m_visited_rows, row_index))
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continue;
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m_visited_rows.insert(row_index);
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vertex *u = add_child_from_row(row_index, v);
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if (u) {
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explore_under(u);
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@ -711,21 +713,21 @@ public:
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// Will return x such that x.m_sign = false.
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// In case of only one non fixed column, and the function returns true,
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// this column would be represened by x
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bool is_offset_row_tree(
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bool is_tree_offset_row(
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unsigned row_index,
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signed_index & x,
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signed_index & y,
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signed_column & x,
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signed_column & y,
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mpq& offset) {
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const auto & row = lp().get_row(row_index);
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for (unsigned k = 0; k < row.size(); k++) {
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const auto& c = row[k];
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if (column_is_fixed(c.var()))
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continue;
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if (x.m_index == UINT_MAX) {
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if (!set_sign_and_index(c.coeff(), x, k))
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if (x.not_set()) {
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if (!set_sign_and_column(x, c))
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return false;
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} else if (y.m_index == UINT_MAX) {
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if (!set_sign_and_index(c.coeff(), y, k))
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} else if (y.not_set()) {
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if (!set_sign_and_column(y, c))
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return false;
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} else
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return false;
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@ -741,18 +743,18 @@ public:
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offset += c.coeff() * get_lower_bound_rational(c.var());
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}
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if (offset.is_zero() &&
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x.is_set() && y.is_set() && (x.m_sign != y.m_sign) &&
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!is_equal(row[x.m_index].var(), row[y.m_index].var())) {
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x.is_set() && y.is_set() && (x.sign() != y.sign()) &&
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!is_equal(x.column(), y.column())) {
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lp::explanation ex;
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explain_fixed_in_row(row_index, ex);
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add_eq_on_columns(ex, row[x.m_index].var(), row[y.m_index].var());
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add_eq_on_columns(ex, x.column(), y.column());
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}
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if (x.m_sign) {
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if (x.sign()) {
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// flip the signs
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x.m_sign = false;
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x.sign() = false;
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if (y.is_set()) {
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y.m_sign = !y.m_sign;
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y.sign() = !y.sign();
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}
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offset.neg();
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}
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