A *(Learning Lounge) course, partly about the _(Arrow system) and partly relating to _(Monad)s.

<a href="http://citeseer.nj.nec.com/venema97crash.html">A Crash Course in Arrow Logic</a> (1997) is by now the only online available paper on arrow logic.

Also refer to the offline book <a href="http://www.mlbook.org/">Modal Logic</a> from the same author et al. Alas! Now that the book is in print it is no more downloadable.