eq explain

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/math/polysat/eq_explain.h

@@ -0,0 +1,30 @@
+/*++
+Copyright (c) 2021 Microsoft Corporation
+
+Module Name:
+
+    Conflict explanation
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2021-03-19
+    Jakob Rath 2021-04-6
+
+--*/
+#pragma once
+#include "math/polysat/explain.h"
+
+namespace polysat {
+
+    class solver;
+
+    class eq_explain : public explainer {
+    private:
+        bool try_explain1(pvar v, signed_constraint c, conflict& core);
+        bool explain_zero(pvar v, pdd& a, pdd& b, signed_constraint c, conflict& core);
+    public:
+        eq_explain(solver& s) : explainer(s) {}
+        bool try_explain(pvar v, conflict& core) override;
+    };
+
+}