This is not news by any means, but there are a few good entries in the Stanford Encyclopedia that are worth bringing everyone’s attention to. The first is the algebra entry. It is written by Vaughan Pratt. Both Restall’s Introduction to Substructural Logics and Dunn and Hardegree’s Algebraic Methods in Philosophical Logic make it clear that there are important links between algebra and various areas of logic. Both books are also very well written, although Restall’s has an unfortunate number of typos. There is also an entire entry on the mathematics of boolean algebra, which at first brush seems to be the least well written of the three. Finally there is an article on category theory, which I gather isn’t that popular as a subject except at Carnegie Mellon and among some physicists. Eventually they will teach it again at CMU and I will take it; then I will be able to comment on the SEP article. It looks good to my untutored eye though.