Wikipedia:WORKINPROGRESS

A SeT is a collection of objects. For example, one can define the set S = {Sn: Sn is a sibling of the Larry M. Sanger, who is the Editor-in-Chief of Nupedia}.

We require that sets be well-defined. Given an object Sn, we must be able to determine if

Sn belongs to S.----

What, there are no recursively enumerable sets?

It's not Shakespeare. Nor is it a particularly good article, even by January 2001 standards. Someone wishing to learn about sets would be foolish to use this as their only source of information. But it's a start. It's better than nothing.

Nope.

In that time, many things will have happened:

Or maybe it will get almost done:

7 World Trade Center has 2553 revisions, blindly assuming that edits are roughly homogeneous, WP has between 100,000 and 200,000 edits per day, this equates to adding between 40 and 80 featurons (a unit of article quality) per day. Since we are getting better at this, and reducing vandalism / fixing with edit filters etc., let's take the higher number (and we could probably improve massively on that) and 4 million articles, each needing a total of 1 featuron total effort. There have been approximately 350 million edits, assume 250 million are to articles, that corresponds to 10,000 featurons of the required 4 million. At that rate we are looking at a mere century. Alternatively suppose every student at Indiana University was required to bring one article to featured status every year as part of their degree course, then it would only take 30 years. And that is one university, in one country. So yes, those missing puzzle pieces, we'll always need more people to help fill them in. Always. And yes, we are 99% and we're going to stay that way. Forever.

Other major reference works take time too:

...
Wikipedia