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

Yde Venema's _("A Crash Course in Arrow Logic"| http://citeseer.nj.nec.com/venema97crash.html) (1997) is by now the only online available paper on arrow logic.

Also refer to the offline book _(Modal Logic|http://www.mlbook.org/) (Venema et al.), a great book on modal logic. Once it was downloadable, but no longer.