Capcha I got wrong :(

server cloud usually means positions that end up in the server DB with evaluation. on the other hand also puzzles are added to the cloud one way or another. so its a bit double edged. as you can see from the captcha this game appears in the puzzle DB even without a computer analysis from the servers (unless someone clicked the button by now), so it got uploaded after it was mined from a PGN which stems from a database of played games that got loaded into the GPU-puzzle miner thing and then after sucessful mining was added to the puzzle DB.

as of now - since they are finished with the migration and doublechecking puzzles after SF14 - the way to get your puzzle into the pool (whether you found the tactic or not) is to:

1. play rapid/classical games (not sure if they have to be rated)
2. analyze them

so its all back to normal again.

ima ping @benwerner now, coz he is pro with puzzles and always very helpful with those concerns. this might give us a little more insight and also a truth-check, since most of what im throwing around is hearsay =)

@Rookitiki Puzzles are only generated from games that have server analysis. They aren't checked the moment they are analyzed though. That wouldn't even be possible given the current setup since there are way too many games. And we don't need to generate that many puzzles anyway. There's a separate server that gets the games at some point and then randomly selects some of them with some random preference to slower and higher rated games I believe and then tries to create puzzles from them. I also don't think there's much GPU stuff involved. Pretty much all the hard work is running Stockfish which I don't believe is able to use a GPU.

Captchas aren't taken from the puzzle pool though. There's really no need for that. Captchas are just mate-in-1s after all and don't need to make for amazing puzzles or something like that so they are very easy to "generate". You can just take a few thousand games that ended in checkmate and remove the last move. Maybe check that there's only one solution (I think that's the case for captchas at least) but that doesn't require Stockfish either. You can just check all the legal moves and check whether they are mate. That's easily doable with some chess logic. Doesn't require a full engine or much computing power.

Side note: If you can't find the mate, you can always just click on the game link next to the captcha and see the solution.

thanks for the clarification! cheers, glad you found the time! keep it up!

since 80% of what i said was false, good thing i pinged you =)

@benwerner Thanks for taking the time to bang that explanation out. The separate pool for captchas explains why the one in this case came from a game that hadn't been analyzed.

> randomly selects some of them with some random preference to slower and higher rated games
I'm guessing this is because you'd go hunting for harder puzzles in higher rated games and easier puzzles in lower rated? Although it's funny I've seen so many puzzles where the player totally missed the tactic. So theoretically I guess an amazing puzzle could come from a 700 rated game where it was completely lost on the players lol.

Oh by the way, captchas have have multiple mate in 1s. I've seen them with 6 before.

Thanks again for giving us a slice of your valuable time.

@Rookitiki said in #24:
> since 80% of what i said was false, good thing i pinged you =)
Not at all. I'm sure 99% of what you said was right just that any little errors just stick in our mind more. And yea, good thing you pinged him so he could point out the hearsay for us all to benefit from.