Reorganizing the code. Moved nlsat to its own directory.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

src/nlsat/nlsat_explain.h

@@ -0,0 +1,64 @@
+/*++
+Copyright (c) 2012 Microsoft Corporation
+
+Module Name:
+
+    nlsat_explain.h
+
+Abstract:
+
+    Functor that implements the "explain" procedure defined in Dejan and Leo's paper.
+
+Author:
+
+    Leonardo de Moura (leonardo) 2012-01-13.
+
+Revision History:
+
+--*/
+#ifndef _NLSAT_EXPLAIN_H_
+#define _NLSAT_EXPLAIN_H_
+
+#include"nlsat_solver.h"
+#include"nlsat_scoped_literal_vector.h"
+#include"polynomial_cache.h"
+
+namespace nlsat {
+    class evaluator;
+    
+    class explain {
+        struct imp;
+        imp * m_imp;
+    public:
+        explain(solver & s, assignment const & x2v, polynomial::cache & u, atom_vector const & atoms, atom_vector const & x2eq,
+                evaluator & ev);
+        ~explain();
+
+        void reset();
+        void set_simplify_cores(bool f);
+        void set_full_dimensional(bool f);
+        void set_minimize_cores(bool f);
+
+        /**
+           \brief Given a set of literals ls[0], ... ls[n-1] s.t.
+           - n > 0
+           - all of them are arithmetic literals.
+           - all of them have the same maximal variable.
+           - (ls[0] and ... and ls[n-1]) is infeasible in the current interpretation.
+
+           Let x be the maximal variable in {ls[0], ..., ls[n-1]}.
+
+           Remark: the current interpretation assigns all variables in ls[0], ..., ls[n-1] but x.
+
+           This procedure stores in result a set of literals: s_1, ..., s_m
+           s.t.
+                 - (s_1 or ... or s_m or ~ls[0] or ... or ~ls[n-1]) is a valid clause
+                 - s_1, ..., s_m do not contain variable x.
+                 - s_1, ..., s_m are false in the current interpretation
+        */
+        void operator()(unsigned n, literal const * ls, scoped_literal_vector & result);
+    };
+
+};
+
+#endif