+/**
+ * The "Categoryfinder" class takes a list of articles, creates an internal
+ * representation of all their parent categories (as well as parents of
+ * parents etc.). From this representation, it determines which of these
+ * articles are in one or all of a given subset of categories.
+ *
+ * Example use :
+ * <code>
+ * # Determines whether the article with the page_id 12345 is in both
+ * # "Category 1" and "Category 2" or their subcategories, respectively
+ *
+ * $cf = new Categoryfinder ;
+ * $cf->seed (
+ * array ( 12345 ) ,
+ * array ( "Category 1","Category 2" ) ,
+ * "AND"
+ * ) ;
+ * $a = $cf->run() ;
+ * print implode ( "," , $a ) ;
+ * </code>
+ *
+ */