A few posts ago, when I told you how amazingly simple it turned out to be to sample independent sets with PyMC. Remember when I said that it was working a little differently than I expected, though? I sent an email to the pymc-users mailing list, and, in just a few days, one of the developers, Anand Patil, replied to say that there was a little typo in their code which was making the chain reject with the probability it was supposed to accept with. (I’m realizing that it is hard to make a story about debugging python code sound exciting, so let’s skip the build up and cut to the thrilling conclusion.) Anand fixed the bug, which required changing one word, but also required finding that one word in the right 1200-line file. 
Some of the folks I corresponded with from the PyMC list didn’t know what I was talking about with this sampling independent sets stuff, so I thought I’d expand a little bit on it now, as a attempt at gratitude.
Healthy Algorithms 