A long time ago I started writing a book about Markov chains, Brownian
motion, and diffusion. I soon had two hundred pages of manuscript and my
publisher was enthusiastic. Some years and several drafts later, I had a
thot: sand pages of manuscript, and my publisher was less enthusiastic.
So we made it a trilogy: Markov Chains Brownian Motion and Diffusion
Approximating Countable Markov Chains familiarly - Me, B & D, and ACM. I
wrote the first two books for beginning graduate students with some
knowledge of probability; if you can follow Sections 3.4 to 3.9 of
Brownian Motion and Diffusion you're in. The first two books are quite
independent of one another, and completely independent of the third.
This last book is a monograph, which explains one way to think about
chains with instantaneous states. The results in it are supposed to be
new, except where there are spe- cific disclaimers; it's written in the
framework of Markov Chains. Most of the proofs in the trilogy are new,
and I tried hard to make them explicit. The old ones were often elegant,
but I seldom saw what made them go. With my own, I can sometimes show
you why things work. And, as I will argue in a minute, my demonstrations
are easier technically. If I wrote them down well enough, you may come
to agree.