Z3 sources

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

lib/spc_literal_selection.h

@@ -0,0 +1,95 @@
+/*++
+Copyright (c) 2006 Microsoft Corporation
+
+Module Name:
+
+    spc_literal_selection.h
+
+Abstract:
+
+    Superposition Calculus Literal Selection
+
+Author:
+
+    Leonardo de Moura (leonardo) 2008-02-05.
+
+Revision History:
+
+--*/
+#ifndef _SPC_LITERAL_SELECTION_H_
+#define _SPC_LITERAL_SELECTION_H_
+
+#include"spc_clause.h"
+#include"order.h"
+
+namespace spc {
+    
+    /**
+       \brief Abstract functor for literal selection.
+    */
+    class literal_selection {
+    public:
+        virtual ~literal_selection() {}
+        /**
+           \brief Updates the selected status flag of the literals of the given clause.
+        */
+        virtual void operator()(clause * cls) = 0;
+    };
+
+    /**
+       \brief Never selects a literal. This strategy is supposed to be good for planning problems 
+       of TPTP.
+    */
+    class no_literal_selection : public literal_selection {
+    public:
+        virtual void operator()(clause * cls) {}
+    };
+
+    
+    /**
+       \brief Selects a negative literal l with the largest V(l)
+       where V is defined as:
+
+       - difference in symbol count for the left-right hand sides of equalities, .
+
+       - symbol count for other predicates
+       
+    */
+    class diff_literal_selection : public literal_selection {
+    protected:
+        ast_manager & m_manager;
+    public:
+        diff_literal_selection(ast_manager & m):m_manager(m) {}
+        virtual void operator()(clause * cls);
+    };
+
+    /**
+      \brief Selects a negative literal using the following algo:
+
+      - if there is x != y, select it.
+
+      - else if there is negative ground literal, select the smallest one.
+
+      - else if use the approach in diff_literal_selection.
+    */
+    class complex_literal_selection : public diff_literal_selection {
+    public:
+        complex_literal_selection(ast_manager & m):diff_literal_selection(m) {}
+        virtual void operator()(clause * cls);
+    };
+
+    /**
+       \brief Similar to diff_literal_selection, but a literal
+       is not selected if the clause contains a positive literal
+       greater than all other literals.
+    */
+    class max_no_selection : public diff_literal_selection {
+        order & m_order;
+    public:
+        max_no_selection(order & o):diff_literal_selection(o.get_manager()), m_order(o) {}
+        virtual void operator()(clause * cls);
+    };
+
+};
+
+#endif /* _SPC_LITERAL_SELECTION_H_ */