The ENGINES cannot find the winning move.. 23.Nh5+ ?

vinuU123
 In this game at move 23, the engines cannot find the winning move Nh5+ followed by Rf7+.
But rather suggests moves like 23.Nce2(analyzed up-to depth 43,didn't go further) and shows advantage in +1 range but after making Nh5+ the evaluation goes up-to +6.
Intuitively Nh5+ seems like winning.
Chess.com analysis(at depth 18) even shows Nh5+ as a bad move.
So do the engines still suffer from the horizon effect ?
ArtNJ

Depth 43 doesn't mean the engine goes to 43 ply for all possibilities.  Pruning still kills some lines way beore that.  My guess is that back to back sacrifices without immediate gain and lots of move possibilties still in play (i.e. not a single forcing sequence) is deemed too unlikely to pursue and gets pruned.  Good instincts to find one of these.  

notmtwain
vinuU123 wrote:
 
 In this game at move 23, the engines cannot find the winning move Nh5+ followed by Rf7+.
But rather suggests moves like 23.Nce2(analyzed up-to depth 43,didn't go further) and shows advantage in +1 range but after making Nh5+ the evaluation goes up-to +6.
Intuitively Nh5+ seems like winning.
Chess.com analysis(at depth 18) even shows Nh5+ as a bad move.
So do the engines still suffer from the horizon effect ?

I assume that the lichess engine didn't find it either.

Have you tried different engines on this?   Did any find the move?

ArtNJ

Lichess runs stockfish I believe, which definitely doesn't find it.  Maybe some of the others cound find it, with slightly different pruning criteria.  I wonder if Leela can find it.  

ninja888

For me it shows Nh5+

Laskersnephew

I'm running Stockfish 12 on a five year old, nothing special desktop computer. It finds 23.Nh5+ is 29 seconds.  To be fair, that's a longish time

vinuU123
Laskersnephew wrote:

I'm running Stockfish 12 on a five year old, nothing special desktop computer. It finds 23.Nh5+ is 29 seconds.  To be fair, that's a longish time

I see but it didn't show up here on both Lichess analysis and Chess.com analysis.

Why's that!?

vinuU123
notmtwain wrote:
vinuU123 wrote:
 
 In this game at move 23, the engines cannot find the winning move Nh5+ followed by Rf7+.
But rather suggests moves like 23.Nce2(analyzed up-to depth 43,didn't go further) and shows advantage in +1 range but after making Nh5+ the evaluation goes up-to +6.
Intuitively Nh5+ seems like winning.
Chess.com analysis(at depth 18) even shows Nh5+ as a bad move.
So do the engines still suffer from the horizon effect ?

I assume that the lichess engine didn't find it either.

Have you tried different engines on this?   Did any find the move?

Yep..The move didn't come up on Lichess. 

Tried LeelaC0 on android till depth 7 or 8. That too.

 

vinuU123
ArtNJ wrote:

Depth 43 doesn't mean the engine goes to 43 ply for all possibilities.  Pruning still kills some lines way beore that.  My guess is that back to back sacrifices without immediate gain and lots of move possibilties still in play (i.e. not a single forcing sequence) is deemed too unlikely to pursue and gets pruned.  Good instincts to find one of these.  

Thats a good point.

Laskersnephew

Is pruning an adjustable parameter? As I mentioned, Stockfish, running on my middle-aged desktop, found the killer move in about 30 seconds, while Stockfish running on lichess hasn't found it after several minutes,.

[UPDATE!] at 4 minutes and 15 seconds, Stockfish on lichess suddenly makes Nh5+ it's number one choice and evaluates the position as completely won for Whiter

ArtNJ

My revised guess is that Stockfish running on Lichess or Chess.com makes a sacrifice somewhere in the form of enhanced pruning (or similar) to reduce load on their servers.  Lichess does give you the option to run stockfish "on your machine" and I think chess.com does that when you select infinite analysis (?) but they might still make some choices that increase pruning to enable it to run on older machines.  

Laskersnephew

Good point, Art. 

vinuU123
ArtNJ wrote:

My revised guess is that Stockfish running on Lichess or Chess.com makes a sacrifice somewhere in the form of enhanced pruning (or similar) to reduce load on their servers.  Lichess does give you the option to run stockfish "on your machine" and I think chess.com does that when you select infinite analysis (?) but they might still make some choices that increase pruning to enable it to run on older machines.  

Aa yes good point..

Another thing is that the move also didn't come up when analysed with Stockfish (depth 26) and LC0 on an midrange android smartphone.

vinuU123
Laskersnephew wrote:

Is pruning an adjustable parameter? As I mentioned, Stockfish, running on my middle-aged desktop, found the killer move in about 30 seconds, while Stockfish running on lichess hasn't found it after several minutes,.

[UPDATE!] at 4 minutes and 15 seconds, Stockfish on lichess suddenly makes Nh5+ it's number one choice and evaluates the position as completely won for Whiter

So lichess found it😄

 

TIGERSintheNIGHT
Hi vinuU123
TIGERSintheNIGHT
do you know God and Jesus Christ.They Made us he made Everyone in the Earth 🌎
pfren

Using a recent stockfish-devel just at depth 28, which for serious correspondence chess at least, is very low. It's no secret that the chess dot com online engine is pretty weak.

 

drmrboss

Stockfish 13 NNUE Developmental version on 4 cores i5 cpu found in 4 seconds.

 

pfren
sky1983 έγραψε:

Ohhh.. It is only Stockfish 12 .. . . google search . .

 

There are also developmental builds which are issued almost daily, and one of them was used here. They will result to the official Stockfish 13, I guess late this year.

drmrboss
sky1983 wrote:

Ohhh.. It is only Stockfish 12 .. . . google search . .

This is official page of stockfish , where new developmental versions are released about 3-4 times/ week.

https://abrok.eu/stockfish/

I dont use SF 12 because , SF 13 developmental version is much stronger than SF 12 now.  happy.png