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75 lines
2.1 KiB
C++
75 lines
2.1 KiB
C++
/*++
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Copyright (c) 2020 Microsoft Corporation
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Module Name:
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int_gcd_test.h
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Abstract:
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Gcd_Test heuristic
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gcd test
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5*x + 3*y + 6*z = 5
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suppose x is fixed at 2.
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so we have 10 + 3(y + 2z) = 5
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5 = -3(y + 2z)
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this is unsolvable because 5/3 is not an integer.
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so we create a lemma that rules out this condition.
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Author:
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Nikolaj Bjorner (nbjorner)
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Lev Nachmanson (levnach)
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Revision History:
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--*/
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#pragma once
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#include "math/lp/lia_move.h"
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namespace lp {
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class int_solver;
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class lar_solver;
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class int_gcd_test {
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struct parity {
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mpq m_offset;
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mpq m_modulo;
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const row_strip<mpq>* m_row = nullptr;
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parity(mpq const& p, mpq const& m, row_strip<mpq> const& r):
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m_offset(p),
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m_modulo(m),
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m_row(&r)
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{}
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};
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class int_solver& lia;
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class lar_solver& lra;
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unsigned m_next_gcd = 0;
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unsigned m_delay = 0;
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mpq m_consts;
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mpq m_least_coeff;
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mpq m_lcm_den;
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unsigned_vector m_inserted_vars;
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vector<vector<parity>> m_parities;
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unsigned_vector m_visited;
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unsigned m_visited_ts = 0;
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bool is_visited(unsigned i) { return m_visited.get(i, 0) == m_visited_ts; }
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void mark_visited(unsigned i) { m_visited.setx(i, m_visited_ts, 0); }
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void reset_test();
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bool insert_parity(unsigned j, row_strip<mpq> const& r, mpq const& parity, mpq const& modulo);
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bool gcd_test();
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bool gcd_test_for_row(const static_matrix<mpq, numeric_pair<mpq>> & A, unsigned i);
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bool ext_gcd_test(const row_strip<mpq> & row);
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void fill_explanation_from_fixed_columns(const row_strip<mpq> & row);
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void add_to_explanation_from_fixed_or_boxed_column(unsigned j);
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bool accumulate_parity(const row_strip<mpq> & row, unsigned least_coeff_index);
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public:
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int_gcd_test(int_solver& lia);
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lia_move operator()();
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bool should_apply();
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};
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}
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