"The Not So Enormous Theorem," by John Horgan. Scientific American,April 1996, page 29.
This article describes efforts of finite group theorists to get on paper acomplete proof of the "Enormous Theorem"---the classification of finite simplegroups. At present, the proof resides in a series of papers spanning about15,000 pages. The new effort aims to reduce the number of pages to 3,000 andto correct some of the omissions and weaknesses in the earlier papers.Recently the AMS published the second in what is to be a 15-volume setcontaining the proof.