CCRL Discussion Board

I've always wondered how opening books are actually implemented in typical chess engines

A lot of KNNkP mates force a knight sacrifice

It's not necessarily harder to win with fewer peices

If you actually want 'sensible' play, just use a combination of DTM and DTZ50

DTM for cases where mate can be forced in less then 50 moves, and DTZ50 when it takes longer then 50 moves.

Well I'm still learning the basics of C++

I just finished making an Othello playing console program

This forum hasn't been very active lately.

me too

Although the hardware part shouldn't be problematic for 3 and 4 man bases.

I still haven't gotten around to even writing a 2-1 generator

I'm not really knowledgeable about the relative speeds of memory and hard drives, but if the disparity is big enough, would it make sense to store a compressed version on the hard drive and decompress it whenever you access it?

For complicated positions, wouldn't it be more efficient to generate both at once?
One idea I had was using negative numbers for losses, 0 fr a draw, and positive numbers for wins

Well it seems like the biggest bottleneck would be the function that determines which positions each position can move into either forward, or in reverse

Here is a method I came up with for generating DTM(k) tables assuming I ever get around to programming it How can I improve it? At each point the DTM(k-1) table would be stored in memory, along with the current one in progress For each position If the value of the position in DTM(k-1) is not mate in...

If I were trying to write my own generator, what would the easiest/most efficient language be?

uh, for KRK, DTZ50 is the same as DTM

now KQKR on the other hand...

so basically I have to learn to program and make my own?

Sorry, if this is an easily answered question in a FAQ or something. Where can I get DTZ50 tablebases and generators to play with?

The problem is that there is no solid answer, because fallible opponents are fallible in different ways Good luck teaching the computer to read minds In fact, even with a single person, there is still huge variation. Some traps you'll see, some you won't There are various heuristics you can make up,...

I still don't see what the point of using anything other then DTZ50 is

DTZ50 is sufficient for perfect play, and it is also the smallest possible tablebase that has this property

Are there any positions you know of where the side to go first loses in KQRkqr or similar endgames ?

It's not that DTZ50 doesn't store all 100 values per state, it is just heavily compressed
Just think of it as using 100 bits and then applying run length compression

On the other hand, there is a compelling case that castling should reset the 50 move counter. I assume that the only reason that they didn't put it in the rules is that it never comes up in actual play.

However one important advantage of WDL50 is that it allows to construct a DTZ50. So if I want kpppkpp in DTZ50 I have to generate all the necessary WDL50 tables first. This is the reason why I am going to contribute my CPU time towards WDL50 generation when the generator will be available. Are you ...

Storing WTM only in plies would take a lot less space then storing both WTM and BTM in moves

Wasn't this problem already addressed in the dtx thread?

Although with 4 queens, theres a good chance of having mate in one anyway. Mate in two is practically guaranteed. One partial solution might be to include a complete tablebase (DTM for every possible position and move count) should be included for 4, maybe 5 piece positions, since this shouldn't tak...

I agree that seeing all pawns promoted by following DTZ50 will be funny. However, an engine author could easily add some code like "if we are two queens up, stop pushing the pawns and look for a mate". Or something more clever. The alternative t oDTZ50 is DTZ which does not guarantee you ...