CCRL Discussion Board

Big news here : https://plus.google.com/100454521496393505718#100454521496393505718/posts See also : http://rybkaforum.net/cgi-bin/rybkaforum/topic_show.pl?tid=24816;pg=5 Questions for the future : - Distribution of newly created EGTs (43, 43p, 51) - 43/43p WDL tables (more suitable for near-term wi...

Re 'making sure a position is not visited (again), or discovering that it has to be revisited': 'Following the tree' is in some cases infeasible, and even when feasible, is hardly communicable to a reader. The only solution is to recompute the EGT for the variant of chess with some set of positions...

Always interesting to discuss new metrics. I had also another metric idea that I call “distance to positive conversion” (DTPC or DTP maybe ?). DTC has the defect that it considers conversion moves by the losing side as goals. This results in the fact that these moves, which are generally threats (an...

Am I right that a complete set of 7men bitbases won't help the creation of DTM-Bases? You’re right. Building a DTM tablebase needs having DTM for all subendings, bitbases are not enough. I'm not aware of any such code. Discussing an early effort is nice, but I'm not sure what this even means, pract...

I'd be glad to copy the 6-men full set to anyone who sends me a disk, for free (just have return shipping expenses covered).
But I live in France, and I only can handle external USB drives.

Tell me there if you're interested, I'll PM you.

No misunderstanding. When I mentioned simultaneous WDL + WDL50 generation, I am assuming two totally independent processes. However, now that I think about it, perhaps generation can be speeded up if the same table is already available in a counterpart metric. But this is not too important optimiza...

So I think the mass generation will go in parallel in both WDL and WDL50. So having both of these metrics in the basic specs is the only way out that I can see. The good thing is that techically WDL and WDL50 are very similar to implement (unlike DTM vs DTM50). Beware, reading this I would like to ...

Generator compatible with all of the following metrics : DTM, DTC, DTZ, WDL, DTZ50, WDL50. This modularity should be not too hard a requirement. DTZ50/WDL50 might be seen as a possible later add-on but it would be handy to get fast availability of such a code in order to build 3-6men DTZ50 tables as...

This can be subject to discussion, of course, so I give just a first vision. Undoubtedly it will evolve with other ones. First key element : The necessity to take a low road, using very simple metrics Let’s admit it : 7-men is a gigantic task. To have a clear view of this, we shall compare it with w...

This question has to be collectively answered, of course, but one can try to make a first general picture. Other opinions are welcome ! Users of TBs are : - “Real play community” : chess players, chess engine developers and users, endgame theorists, - problemists, - EGTB enthusiasts. Real play commu...

All metrics potentially suitable for 7-men are listed below. Some metrics such as DTM50 or DTR are not mentioned : these are “sophisticated metrics”, definitely worth a try on 3-4-5-(6) men but not on 7-men where metric simplicity and lightweight are absolutely essential. DTM Gives distance to mate ...

Metric choice is a fundamental question and has to be undertaken with careful reasoning. One may handle the problem by addressing the following questions : 1- What are the different metrics and their characteristics (chessical characteristics, soft & hard constraints for computing & storing ...

The challenge with DTZ comes from a) Properly handling the pawn slices and conversions (not required with DTM). b) Handling some corner cases not present in DTM DTM is a very nice metric to be sure, but beware of not setting the bar too high by selecting a difficult metric on an inherently ambitiou...

It means that winning positions where the losing side - before being mated - can always force a 50-move sequence without a capture or pawn move are regarded as draws by the DTZ50 table. If you play with 50-move rule it is the DTZ50 table, not the DTM table, who gives the correct result. The above kn...

This position is indeed the maximal knnkp position for DTM. DTZ50 is exactly the metric needed for this problem. I’ve explored a bit the DTZ50 knnkp table (at http://www.chess.jaet.org/endings - the site offered online multimetric access, but unfortunately it is down nowadays) and I’m sure that this...

To calculate the overall number of positions in a given ending, you place kings first, then pawns (if any), then the remaining pieces. In the case of krppkrp : There are 1806 different positions of kings (taking a vertical symmetry into account) among which 106 leave 48 free squares for pawns (both ...

krppkrp has 583 Giga positions, when all 6-men (33+42) has 4489. This gives an estimate of 1153*583/4489 = 150 Gb for the krppkrp table in Nalimov format (DTM), with not-so-good accuracy, so consider it to be in the 100-200 Gb range. Using Gaviota (a new and more compact DTM format) would cut this b...

I’ve downloaded all the 6-men Nalimovs. (thanks to all e-mule sharers, and many thanks to Steinar whose site http:// tablebase.sesse.net is an invaluable resource for such a quest). Then I could use them to complete the list of longest checkmates currently held at http://kirill-kryukov.com/chess/lon...

Draws do not have a depth in the DTM (depth to mate) metric. However they _might_ have a depth in the DTZ (depth to move-count zeroing move) or even DTC (depth to conversion and/or mate) metrics. Yes, and many other metrics for draws could also be built under the following rules : - both sides are ...

About notations : In EGTBs, a "?" is a move that changes (always downwards for the side making it) the evaluation of the position : win to draw, draw to loss, or win to loss. A “!” is a move that is not the unique legal move but is the only one who doesn’t change the evaluation of the posi...

The fact is, the notions of good looking position, promising start, having an advantage, etc… disappear completely in the world of fully solved games such as (currently) any chess position with 6 pieces or less. As soon as perfect knowledge becomes available, every position gets a definitive assessm...

Problem reduction with two pawns fixed has only to do with pawns of opposite colors – which is not the case there – hasn’t it ?

Very interesting news In this thread in rybkaforum :
http://rybkaforum.net/cgi-bin/rybkaforu ... l?tid=8477

Ok, main line has been fixed. How can this be verified ? Here’s a paper about implementing formal verification techniques in TB building in order to be absolutely sure that results are flawless. Results are given for 3-4 men only, though, and this technique might not be suitable for handling much bi...

Hmm… main line is clearly flawed as someone reported (wn can take br at move 142), and therefore DTM=545 claim (built upon it) might well also be. Author also speaks of a “hard calculation taking almost 12 hours”. I would be absolutely astonished if such a result could be achieved so fast. krbnkqn h...