Jason (jcreed) wrote,

Another day that just seemed to go by without me really noticing. Got up sort of late, thinking about prooving decidability of a Petri theory plus a finite number of copies of (a -o e) -o a. Realized that it goes through pretty easily if I multiply out the number of places (or, equivalently, the number of dimensions in the VAS) by how many copies there are, disjoining over the possible tree configurations. Anyway, it makes for a partial result that has a snappy statement: the difference between a known decidable problem (namely, some Petri theory plus (a -o e) -o a) and all of MELL is (at most) a single bang.

Got McDonald's for lunch. Module systems happened. Bob ripped on this one paper vigorously, and wondered out loud why he bothered including it since it was so bad. Sadly, I don't remember which one it was off the top of my head. Complexity theory got into the proof of IP=PSPACE. Wow. Some seriously beautiful math going on there. I don't follow quite all of the details, but I'm keeping up with the big picture at least, and I like Rudich's description of the proof in terms of epsilon-links. Modularity is definitely as valuable an idea for writing proofs as for writing programs, even if you don't already believe proofs and programs are the same thing :)

Was going to go over to leah's house to watch more of the jazz documentary, but she spontaneously became busy again. Got subway for lunch. Didn't really finish it. Ack. I really need to find some hot, conveniently obtainable food that doesn't turn my stomach quite so much. I am starting to notice a lot lately that the more fried food (i.e. most likely in soy or peanut oil, to which I am somewhat allergic) I eat the less well I feel. Starvation is not a good plan.

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