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> 100 bits / ~12 bytes
> 18 bits / ~2 bytes
I didn’t want to spend a whole lot of effort tracking the arithmetic after this. Was it actually 28 bytes? 27 because I can squeeze those extras into one shared byte?
Original title is: > Compressing chess positions for fun and profit Which unlike that here is correct: you can store a board , the positions, in 26B; not an arbitrary length game!
Most games could possibly be encoded in less than 26 bytes. There are not that many legal moves each time and if you sort them by probability it may not require many bits to describe which one the players chose.
Meanwhile the non-comp-sci dev in me is like, "why not just store every position in a simple JSON so everyone can read it and everything can parse it". Yeah, it might be half a kB, but you don't have to run through mental gymnastics just to render the pieces...
You need a compact encoding for chess engines that explore billions of states as fast as possible to plan the best move.
There are two more things that should be considered. Both of them unlikely to influence a position, but they can matter - just like the en passant target. The fifty move rule[0] is quite simple, just store a number, fits in five bits. But the threefold repetition rule[1] is quite a pickle - it basically means that to know everything about a position you need to know every position that occurred before it. [0] https:/…
But the standard, FEN, doesn't store that either. It's used more in the context of a full game than with individual positions.
Meanwhile the non-comp-sci dev in me is like, "why not just store every position in a simple JSON so everyone can read it and everything can parse it". Yeah, it might be half a kB, but you don't have to run through mental gymnastics just to render the pieces...
Meanwhile the non-comp-sci dev in me is like, "why not just store every position in a simple JSON so everyone can read it and everything can parse it". Yeah, it might be half a kB, but you don't have to run through mental gymnastics just to render the pieces...
People like to use bots to run thousands or millions of simulated games to test how good their bot is at chess and have it ranked.
Other people like to use the bots that were created to play chess as practice toward a certain skill level. Beginners can pick bots that are proven to be beginner level, through thousands or millions of simulated games.
The smaller the data footprint for the games, the faster and more efficiently the bots can play, which reduces cost and time. In a more practical sense, AI/ML algorithms can be more efficient with tiny data sizes for a bunch of complicated reasons.
So, overall, this is "nerd sniping" to develop better chess players, both human and automated. It's not the most extensible presentation, I'll grant you, but I'm sure it's as fun as Regex Golf, or any other data-packing stuff.
P.S. I'm sure the comp-sci dev in you already knew all this; this is just a bill in case anyone read your comment and truly didn't already know all of this.
Earlier quoted context omitted.
You need a compact encoding for chess engines that explore billions of states as fast as possible to plan the best move.
Well, this is arguably a kind of compression, right? So you'd be trading CPU time for fewer bytes? Is that a desirable tradeoff at chess engine scales?
An interesting cognitive phenomenon: if you ask chess experts and novices to memorize and recall an arbitrary chessboard, the experts are significantly better than the novices _only if_ the board is a legal board that can be arrived at during play. If it is not a legal board, there's no particular difference between novices and experts. Original ref: Chase & Simon 1973, Perception in Chess. This is usually taken to m…
Storing a chess position in 26 bytes. Storing a game is also interesting. The number of legal moves varies depending on the position. You could try to define a variable length encoding by giving more likely moves a shorter encoding, but the ordering would need to be deterministic so it could be decoded (running Stockfish for a second isn't).