Older blog entries for fzort (starting at number 114)

shlomif: did you actually read the Nichomachean Ethics? The thing is repulsive. If it really is, as some say, one of the central works of western civilization, it's no wonder we're in such bad shape. Bertrand Russell said it better:

There is in Aristotle an almost complete absence of what may be called benevolence or philanthropy. The sufferings of mankind, in so far as he is aware of them, do not move him emotionally; he holds them intellectually to be an evil, but there is no evidence that they cause him unhappiness except when the sufferers happen to be his friends.

Implementation of logical operations on a domino substrate

Abstract. This paper presents some simple ideas about domino gates. Domino gates are implementations of logical operations using toppling dominos to represent the movement of information (bits). (...) The domino model can be used as a representation of single-shot wave gates in unconstrained media, such as sub-excitable Belousov-Zhabotinsky reactors. On a practical note, they are slightly easier to set up and use than collision models using 'billiard balls'.

More at the International Center of Unconventional Computing.

It's been a hectic day in production support land. My head hurts. And I still have stuff to do - will probably leave at around 21:30 PM, making this a 14 hours day.

Anyway, I skipped lunch and instead worked a bit on this problem. After much head scratching, came up with a O (N^2*M) dynamic programming solution (with N the length of the sequence and M the size of the alphabet). Was really proud of myself for about 3 minutes, until I noticed that N can be as large as 100000. Boom. Anyway, my worthless non- solution is here (sorry, in Java - as I said, I did it at work). Space can be reduced to just O(N*M), but that doesn't help with time.

laburu: I'll get around to answering your e-mail eventually, I swear.

Dang. I can't get any hacking time during the week.

Ah well. Lunch break, and I've just solved this problem. It requires more insight than code, so I could work on it for the past couple of days while in the train, in the bathroom, etc. The resulting program is small and simple, but I had to deploy some hardcore permutation group theory to arrive at the solution. I wonder if there's a simple "Aha!" insight that I'm missing. If you think there is, I'd really love to hear.

Here's another screenshot. But better make that next week...

I'm coding a game. Here's a screenshot. Think Missile Command meets Typespeed. Should hit freshmeat sometime this week.

R.I.P., Arthur Clarke.

Coding is moving at a glacial pace. SLOC count: 990.

Started a complete rewrite of the chess playing engine in vulcan. Hopefully the new design is much better.

Current SLOC count: 550.

Yesterday I did items 1 to 3 of the TODO list in my last post. There's a working windoze binary here, cross-compiled with mingw32 under linux. Had to cross-compile SDL, zlib and libpng, but this made it really easy (thank you, SDL team!).

I'll put a new version up soon. Should do a binary rpm too.