§ Christopher's Law

All roads lead to Hitler.
In five links or fewer.

The theory says that every article on English Wikipedia reaches Adolf Hitler by following at most five links within the articles. Type in a search term and the engine finds the shortest path and shows every step. Every search grows an index of known paths, so the next search gets faster.

Think the theory is wrong?

The index

Distribution of known distances

How the theory is holding up

Look up the index

Search among pages that already have a known distance. Click a result to see the stored path.

    Recent searches

    Longest paths

    The pages furthest from the target among everything searched so far. Can you find one above five?

    How the search works

    1. The index is seeded. On first start, every article that links to Adolf Hitler is fetched. They get distance 1. Because that list also includes pages that mention him only in a footnote, the final step of every path is verified against the article text before a result is shown.
    2. Breadth first. The outgoing links of the start page are read from the article body. Links that only appear in footnotes, reference lists or citations do not count, and neither do helper pages such as ISBN or other identifiers. The one exception is an article whose body links nowhere at all (some stubs): rather than call it a dead end, the search follows its reference links and marks that step "via references". If any remaining link is in the index, the path is complete: the start page's distance is the link's distance plus one.
    3. Hubs first. Pages likely to sit close to the target (countries, years, wars, politics) are expanded first, and the search stops as soon as the shortest path is proven.
    4. The index learns. Every page that gets expanded has its distance and "next hop" stored in the database, and all outgoing links are cached. The next search that passes a known page finishes immediately.