Hacker News Reader

Correct, that's what it is doing. It is a very fast and surprisingly strong way of evaluating the position. Of course stronger engines do a hell of a lot more than this and gives weightings based on the positions of other pieces, but most of them have something like this as a baseline.

Exactly! Indeed some engines (the Micro-Max engine) just tries to move all pieces towards the center, and it still works pretty well! (http://home.hccnet.nl/h.g.muller/pcsqr.html) I wanted to add the table though, as I thought it made the games more interesting, and gave a nice handle on tweaking the engine.

PST stand for piece-square-table. You keep the static evaluation simple and fast, and let the search hash out the dynamic details. The search is surprising effective at its job, and trying to evaluate a position statically is surprisingly difficult.