Algebra, as we know it today, consists of many different ideas, concepts and results. A rough estimate of the number of these different items would be somewhere between 50,000 and 200,000. Many of them have been named and many more could (and perhaps should) have a name or a convenient designation. In addition to primary information, this handbook provides references to relevant articles, books and lecture notes. It will publish articles as they are received and thus the reader will find in this second volume articles from five different sections. The advantages of this scheme are two-fold: accepted articles will be published quickly; and the outline of the Handbook can be allowed to evolve as the various volumes are published. One of the main aims of the Handbook is to provide professional mathematicians with sufficient information for working in areas other than their own specialist fields.