1. A computer implemented method of information retrieval in a file system, comprising the steps of: displaying a portion of a hierarchical tree that is representative of a repository of memorized files, levels of said hierarchical tree comprising directories and subdirectories thereunder; and displaying a special virtual directory in each of said directories and said subdirectories; invoking a semantic operator by selection of said special virtual directory; displaying elements of at least a subtree of said hierarchical tree, said elements being selected by said semantic operator.