Question about 7-piece adjudication

[Nordlandia]

If games is to be auto adjudicated at seven pieces. Do that nullify the need of probing 5-men syzygy during search.

7-piece adj is probably fine without 5-men during search right?

Is the speed sacrificed to probe 5-men wasted if games it to be auto terminated at 7-pieces anyway ?

The ideal scenario as of 2020 is to probe 6-men during search and adjudicate at 7-pieces. Good idea for engine tournmanets.

[phhnguyen]

I think there are some ambiguities/different cases here, let check some cases:

1) Engine view
7-men endgames are not enough:
- OK you are winning at 7 men, but what happens if your opponent does not give up and the chess GUI doesn’t know to stop at 7 men? You need to continue and probe fewer endgames
- Some engines don’t know 7-men Syzygy but fewer, say 5-men. Even the current board has more than 7-men, those engines may search out and probe 5-men

But enough:
- If all engines and chess GUI know to probe 7-men: you don’t need fewer endgames

2) Chess GUI view
7 men only is enough (if the chess GUI can adjudicate games by 7-men endgames). The chess GUI doesn’t need to probe fewer-men endgames since it can stop all games at 7-men. Fewer-men endgames are completely useless for the GUI.

However, engines in tournaments may need fewer-men endgames for their searches because of (1)

BTW, from endgames n to n+1 men, the data may increase tens times. That mean you save very little (in terms of percentage) by removing fewer-men endgames

[syzygy]

The easy answer: just leave the probing to the engine. You are not an engine programmer and the formulation of the question alone tells me that giving a technical answer is not going to help anyone here.

But make sure you have 5-piece WDL tables if you are using 6-piece WDL tables etc.

[Ozymandias]

If games is to be auto adjudicated at seven pieces.

What GUI do you use for that?

[Nordlandia]

I just wanted to know if automatic 7-piece adjudcation renders the usefulness of probing 5-men during search as almost unnecessary.

Banksia GUI support it.

[syzygy]

I just wanted to know if automatic 7-piece adjudcation renders the usefulness of probing 5-men during search as almost unnecessary.

But why do you want to know that? Are you going to turn off 5-men probing in the engine you are using? Engines don't have an option for that. (Or are you going to write to engine developers telling them to stop probing 5-men TBs or to give you such an option? Please don't do that, they can use their time far more productively than having to answer to such requests.)


I think the answer to your question was given already: if the root position has >5 pieces and the engine is probing 6-men TBs, the engine will not even get to probing positions with 5 pieces. Any path from the root position to a 5-piece position will necessarily cross a 6-piece position, which will be probed (which ends that branch of the search tree) before the engine gets to the 5-piece position. Basically this is the same reason as why the GUI would never get to adjudicate a 6-piece position if it is adjudicating 7-piece positions. You can't go from the starting positon to a position with 6 pieces without first coming across a position with 7 pieces (which immediately ends the game by adjudication). It would be different in games in which a player could capture multiple pieces at the same time, e.g. atomic chess.

However, Syzygy 6-men WDL TBs REQUIRE the presence of 3/4/5-men WDL TBs because of how the compression scheme works. Same for 7 and 3/4/5/6. So you, as a user, should just make sure that you keep those 5-men WDL TBs if you want to use 6-men WDL TBs.