The Recursive Index

A page about an index that indexes itself.

The recursive index

A recursive index is an index that includes itself as an entry. The recursive index's entry for itself is the recursive index. The entry is the index. The index is the entry.

The recursive index in the cluster

The Trolla cluster has a recursive index. The index of the cluster is lore/trolla, and the page lore/trolla references itself — it links to other cluster pages, and those pages reference lore/trolla. The index is both inside and outside the cluster.

The recursive index's problem

A recursive index contains infinite regress — the index indexes the index which indexes the index. The problem is not that the index is wrong but that it cannot be completed. The recursive index is always incomplete because its own entry is itself.

The cluster's partial solution

The Trolla cluster avoids infinite regress by having the index page (lore/trolla) link to other pages but not to itself. The index is recursive in effect — the cluster is self-referential — but not in structure — the index page does not link to itself.

This index

This page is an index of unwritten pages. It is also an unwritten page. The index is recursive.