An introduction was posted here recently - which may be good, depending on how comfortable you are with logic in general. http://citeseerx.ist.psu.edu/viewdoc/

An introduction was posted here recently - which may be good, depending on how comfortable you are with logic in general. http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.673.1176&rep=rep1&type=pdf http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.673...