mv util/lp to math/lp

Signed-off-by: Lev Nachmanson <levnach@hotmail.com>

src/math/lp/constraint.h

@@ -0,0 +1,99 @@
+/*++
+Copyright (c) 2017 Microsoft Corporation
+
+Module Name:
+
+    <name>
+
+Abstract:
+
+    <abstract>
+
+Author:
+    Nikolaj Bjorner (nbjorner)
+    Lev Nachmanson (levnach)
+
+Revision History:
+
+
+--*/
+
+#pragma once
+namespace lp {
+class constraint; // forward definition
+struct constraint_hash {
+    size_t operator() (const constraint* c) const;
+};
+
+struct constraint_equal {
+    bool operator() (const constraint * a, const constraint * b) const;
+};
+
+class constraint { // we only have less or equal for the inequality sign, which is enough for integral variables
+    int                                              m_id;  
+    bool                                             m_is_ineq;
+    polynomial                                       m_poly;
+    mpq                                              m_d; // the divider for the case of a divisibility constraint
+    std::unordered_set<constraint_index>             m_assert_origins; // these indices come from the client and get collected during tightening
+public :
+    unsigned id() const { return m_id; }
+    const polynomial & poly() const { return m_poly; }
+    polynomial & poly() { return m_poly; }
+    std::unordered_set<constraint_index> & assert_origins() { return m_assert_origins;}
+    const std::unordered_set<constraint_index> & assert_origins() const { return m_assert_origins;}
+    bool is_lemma() const { return !is_assert(); }
+    bool is_assert() const { return m_assert_origins.size() == 1; }
+    bool is_ineq() const { return m_is_ineq; }
+    const mpq & divider() const { return m_d; }
+public:
+    constraint(
+        unsigned id,
+        constraint_index assert_origin,
+        const polynomial & p,
+        bool is_ineq):
+        m_id(id),
+        m_is_ineq(is_ineq),
+        m_poly(p)
+    { // creates an assert
+        m_assert_origins.insert(assert_origin);
+    }
+    constraint(
+        unsigned id,
+        const std::unordered_set<constraint_index>& origins,
+        const polynomial & p,
+        bool is_ineq):
+        m_id(id),
+        m_is_ineq(is_ineq),
+        m_poly(p),
+        m_assert_origins(origins)
+    {}
+
+
+    
+    constraint(
+        unsigned id,
+        const polynomial & p,
+        bool is_ineq):
+        m_id(id),
+        m_is_ineq(is_ineq),
+        m_poly(p) { // creates a lemma
+    }
+        
+public:
+    constraint() {}
+
+    const mpq & coeff(var_index j) const {
+        return m_poly.coeff(j);
+    }
+    const vector<monomial>& coeffs() const { return m_poly.m_coeffs;}
+
+    bool is_tight(unsigned j) const {
+        const mpq & a = m_poly.coeff(j);
+        return a == 1 || a == -1;
+    }
+    void add_predecessor(const constraint* p) {
+        lp_assert(p != nullptr);
+        for (auto m : p->assert_origins())
+            m_assert_origins.insert(m); }
+};
+}