Z3 sources

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

lib/occurs.h

@@ -0,0 +1,36 @@
+/*++
+Copyright (c) 2006 Microsoft Corporation
+
+Module Name:
+
+    occurs.h
+
+Abstract:
+
+    <abstract>
+
+Author:
+
+    Leonardo de Moura (leonardo) 2007-06-07.
+
+Revision History:
+
+--*/
+#ifndef _OCCURS_H_
+#define _OCCURS_H_
+
+class expr; 
+class func_decl;
+
+/**
+   \brief Return true if n1 occurs in n2
+*/
+bool occurs(expr * n1, expr * n2);
+
+/**
+   \brief Return true if d is used in n
+*/
+bool occurs(func_decl * d, expr * n);
+
+#endif /* _OCCURS_H_ */
+