Robert Stojnic schrieb: Wikimedia Germany has contracted Neil Harris to work on implementing deep category intersection. The goal is basically a rewrite of my sucky CatScan tool. The result is hopefully fast & generic enough so it can be used as a service that integrates with the current search infrastructure. The project has started, there is funding and a project plan. I expect to see usable results soon. In fact, I hope to present this at the developer meeting in april (neil, contact me about attending) and discuss the integration into lucene search. I agree that full recursive flattening of the current category structure leads to bad results some times (especially on the english wikipedia, commons is quite bad too), a depth of 5 however is generally useful. One common use case is intersecting a content category with a maintenance category, for organizing editorial work in a wiki project. In that case, at least one category comes from a template. Atomic categorization aka tagging however also sucks: the tags are either too generic (so it's hard to find stuff) or too specific (you never know what to search for). tags implying/including other tags is very useful. which is exactly what categories with deep intersection will provide. -- daniel