Regarding this as pruning knowledge is rather exaggerated. First wikipedia deletions are not deletions, they are just hidden from most users but can be viewed or restored. Second this is not primary knowledge it is a very short and incomplete summary of the primary sources.

I didn't realize that deletion is not permanent.

In what manner is the content hidden? Will it show up in search engine results? Will an anonymous user like myself see the content?

Check it out for yourself: http://en.wikipedia.org/w/index.php?title=Alice_programming_...

> A page with this title has previously been deleted. If you are creating a new page with different content, please continue. If you are recreating a page similar to the previously deleted page, or are unsure, please first contact the deleting administrator using the information provided below.

Minor correction here: the "Alice programming language" page was deleted, only to be moved to "Alice (programming language)". The one you want is here:

http://en.wikipedia.org/w/index.php?title=Alice_(programming...

Nice catch -- it still illustrates what a deleted page looks like though.