is this an issue with missing DTZ ?

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Spliffjiffer
Posts: 169
Joined: Thu Aug 02, 2012 5:48 pm
Location: Germany

is this an issue with missing DTZ ?

Post by Spliffjiffer » Tue Jun 18, 2019 2:46 pm

i have no 7-men syzygy's DTZ installed, only some WDL (among these is KBPPvKBP)
[d]2b5/8/3k3p/P7/8/3K1BP1/8/8 b - - 0 1
here SF lost with 1...Bh3 ?? while WDL is giving 0.00 for 1...Kc5 (only move)...SF was running on multiPV=1.
if i look "into its brain" by using multiPV say =5 its showing 1...Kc5 as 3rd best move with a score of 0.00 while all other moves have a -149.xx or -mate score (after ms's of search). i used latest SF-dev.

im pretty much confused that SF is choosing loosing moves while knowing that 1...Kc5 is a draw...might this be a problem with the DTZ i have not installed or do only i have this problem...some confirmation about this strange behavior ?
Wahrheiten sind Illusionen von denen wir aber vergessen haben dass sie welche sind.

Spliffjiffer
Posts: 169
Joined: Thu Aug 02, 2012 5:48 pm
Location: Germany

Re: is this an issue with missing DTZ ?

Post by Spliffjiffer » Tue Jun 18, 2019 4:09 pm

little update:
i think i found out that this issue happens only after some patch released on exactely the 09.06.2019...sry for not beeing able to delimit this further (internet connection problems)...sry for the (probably) misleading headline as well because it seems pretty much clear now to me that this is not an issue with DTZ !!?
Wahrheiten sind Illusionen von denen wir aber vergessen haben dass sie welche sind.

syzygy
Posts: 4426
Joined: Tue Feb 28, 2012 10:56 pm

Re: is this an issue with missing DTZ ?

Post by syzygy » Tue Jun 18, 2019 7:45 pm

So with multiPV=5 Stockfish is showing 5 moves that lose, lose, draw, lose, lose in that order? That's pretty weird...

It is correct that Kc5 draws and all other moves lose:
https://syzygy-tables.info/?fen=2b5/8/3 ... _b_-_-_0_1

Of course it should not play a move that is known to lose if there is a move that is known to draw. But none of the June 9 patches seem to relate to the relevant code.

zullil
Posts: 5278
Joined: Mon Jan 08, 2007 11:31 pm
Location: PA USA
Full name: Louis Zulli

Re: is this an issue with missing DTZ ?

Post by zullil » Tue Jun 18, 2019 7:56 pm


Spliffjiffer
Posts: 169
Joined: Thu Aug 02, 2012 5:48 pm
Location: Germany

Re: is this an issue with missing DTZ ?

Post by Spliffjiffer » Tue Jun 18, 2019 8:21 pm

@ syzygy: yes thats correct: with multiPV=5 last SF-dev's are showing: lose, lose, draw, lose, lose ...insane but true (here on my pc at least)

@Louis: thanks for the related link...seems like a bug indeed from my pov :-(
Wahrheiten sind Illusionen von denen wir aber vergessen haben dass sie welche sind.

syzygy
Posts: 4426
Joined: Tue Feb 28, 2012 10:56 pm

Re: is this an issue with missing DTZ ?

Post by syzygy » Tue Jun 18, 2019 9:13 pm

syzygy wrote:
Tue Jun 18, 2019 7:45 pm
But none of the June 9 patches seem to relate to the relevant code.
I overlooked that this patch makes changes to "tbRank" in search.cpp and search.h. So that must be the problem. Should be happening in 6-piece positions too, I guess.

Spliffjiffer
Posts: 169
Joined: Thu Aug 02, 2012 5:48 pm
Location: Germany

Re: is this an issue with missing DTZ ?

Post by Spliffjiffer » Wed Jun 19, 2019 12:58 am

i see that the bug was found and already fixed (as far as i understood)...im glad that i could help a tiny bit in terms of verifying when to search...this should close the thread, thx for the replys :-)
Wahrheiten sind Illusionen von denen wir aber vergessen haben dass sie welche sind.

syzygy
Posts: 4426
Joined: Tue Feb 28, 2012 10:56 pm

Re: is this an issue with missing DTZ ?

Post by syzygy » Wed Jun 19, 2019 10:54 pm

Spliffjiffer wrote:
Wed Jun 19, 2019 12:58 am
i see that the bug was found and already fixed (as far as i understood)...im glad that i could help a tiny bit in terms of verifying when to search...this should close the thread, thx for the replys :-)
Thanks for reporting!

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