mv util/lp to math/lp

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

src/math/lp/explanation.h

@@ -0,0 +1,49 @@
+/*++
+Copyright (c) 2017 Microsoft Corporation
+
+Module Name:
+
+    <name>
+
+Abstract:
+
+    <abstract>
+
+Author:
+    Nikolaj Bjorner (nbjorner)
+    Lev Nachmanson (levnach)
+
+Revision History:
+
+
+--*/
+#pragma once
+#include <unordered_set>
+#include "math/lp/lp_utils.h"
+namespace lp {
+class explanation {
+    vector<std::pair<mpq, constraint_index>> m_explanation;
+    std::unordered_set<unsigned> m_set_of_ci;
+public:
+    void clear() { m_explanation.clear(); m_set_of_ci.clear(); }
+    vector<std::pair<mpq, constraint_index>>::const_iterator begin() const { return m_explanation.begin(); }
+    vector<std::pair<mpq, constraint_index>>::const_iterator end() const { return m_explanation.end(); }
+    void push_justification(constraint_index j, const mpq& v) {
+        m_explanation.push_back(std::make_pair(v, j));
+    }
+    void push_justification(constraint_index j) {
+        if (m_set_of_ci.find(j) != m_set_of_ci.end()) return;
+        m_set_of_ci.insert(j);
+        m_explanation.push_back(std::make_pair(one_of_type<mpq>(), j));
+    }
+
+    void add(const explanation& e) { for (auto j: e.m_set_of_ci) add(j); }
+
+    void add(unsigned ci) { push_justification(ci); }
+    
+    void add(const std::pair<mpq, constraint_index>& j) { push_justification(j.second, j.first); }
+
+    bool empty() const {  return m_explanation.empty();  }
+    size_t size() const { return m_explanation.size(); }
+};
+}