< Earlier Kibitzing · PAGE 13 OF 13 ·
|Feb-16-19|| ||vonKrolock: Leela crashed in an equal position during the 66th game...|
|May-03-19|| ||Ron: Hopefully a small contribution to chess knowledge:|
In the following position, Black to play:
click for larger view
Stockfish 9 evaluates the position: + (1.21) Depth=59/68 0:20:01 2824 MN
However, that is an over evaluation.
There is a drawing line--only one--for Black which starts with Rb3
|May-26-19|| ||MissScarlett: Is <Arena> the best <UCI-compatible> program to use with Stockshit or are they much of a muchness?|
|Jul-27-19|| ||Ron: In the following position, White to play:
click for larger view
White is up a pawn, but its a draw due to opposite colored bishops.
Stockfish 9 over-evaluates this position for White:
+ (1.01) Depth=87/89 2286 kN/s
The Monte Carlo methods used by Rybka and AlphaZero would probably determine an accurate evaluation.
|Jul-27-19|| ||AylerKupp: <<MissScarlett> Is <Arena> the best <UCI-compatible> program to use with Stockshit or are they much of a muchness?>|
I don't think that you can say that any chess engine GUI that supports the UCI protocol can be considered better or worse to use with a particular engine. The motivation behind the UCI protocol (and any protocol) is to be able to communicate with any chess engine that supports that protocol without knowing what engine it is communicating with.
The "goodness" of a GUI is what it allows you to do and how easily it allows you to do it. I personally use Area because it supports many of the things that I want to do with chess engines (run analyses, play games against it, conduct engine vs. engine tournaments, etc.). And once you get over its somewhat steep learning curve, it works well. And, as a bonus, it's free.
|Jul-31-19|| ||gambitfan: Can we trust Stockfish ?
In the Opening Explorer, after 1 e4 e5 2 Nf3 Nc6 3 Bc4 Nf6 4 0-0 d6 5 d4 ?! (2 games · 1871-1949) the Opening Explorer gives 5 ... exd4 (126 games) or 5 ... Nxd4 (1 game)
Stockfish gives :
1) -0.42 (18 ply) 5...♗xd4 6.♘g5 ♘h6 7.c3 ♗b6 8.h3 O-O 9.♘f3 ♘a5 10.♗d3 ♗e6 11.♘a3 ♘c6 12.♘g5 ♗d7 13.♘c4 ♔h8 14.♘xb6
On chess.com this move is said as an INACCURACY...
What can we think of Sockfish ???
|Jan-19-20|| ||scholes: Stockfish 11 released. Official release notes below|
<It is our pleasure to release Stockfish 11 to our fans and supporters.
Downloads are freely available at http://stockfishchess.org/download/
This version 11 of Stockfish is 50 Elo stronger than the last version, and
150 Elo stronger than the version which famously lost a match to AlphaZero
two years ago. This makes Stockfish the strongest chess engine running on
your smartphone or normal desktop PC, and we estimate that on a modern four
cores CPU, Stockfish 11 could give 1:1000 time odds to the human chess champion
having classical time control, and be on par with him. More specific data,
including nice cumulative curves for the progression of Stockfish strength
over the last seven years, can be found on [our progression page], at
[Stefan Pohl site] or at [NextChessMove].
In October 2019 Stockfish has regained its crown in the TCEC competition,
beating in the superfinal of season 16 an evolution of the neural-network
engine Leela that had won the previous season. This clash of style between an
alpha-beta and an neural-network engine produced spectacular chess as always,
with Stockfish [emerging victorious this time].
Compared to Stockfish 10, we have made hundreds of improvements to the
[codebase], from the evaluation function (improvements in king attacks,
middlegame/endgame transitions, and many more) to the search algorithm (some
innovative coordination methods for the searching threads, better pruning of
unsound tactical lines, etc), and fixed a couple of bugs en passant.
Our testing framework [Fishtest] has also seen its share of improvements
to continue propelling Stockfish forward. Along with a lot of small enhancements,
Fishtest has switched to new SPRT bounds to increase the chance of catching Elo
gainers, along with a new testing book and the use of pentanomial statistics to
be more resource-efficient.
Overall the Stockfish project is an example of open-source at its best, as
its buzzing community of programmers sharing ideas and daily reviewing their
colleagues' patches proves to be an ideal form to develop innovative ideas for
chess programming, while the mathematical accuracy of the testing framework
allows us an unparalleled level of quality control for each patch we put in
the engine. If you wish, you too can help our ongoing efforts to keep improving
it, just [get involved] :-)
Stockfish is also special in that every chess fan, even if not a programmer,
[can easily help] the team to improve the engine by connecting their PC to
Fishtest and let it play some games in the background to test new patches.
Individual contributions vary from 1 to 32 cores, but this year Bojun Guo
made it a little bit special by plugging a whole data center during the whole
year: it was a vertiginous experience to see Fishtest spikes with 17466 cores
connected playing [25600 games/minute]. Thanks Guo!
The Stockfish team
|Jan-19-20|| ||Carrots and Pizza: < scholes: Stockfish 11 released. Official release notes below>|
Thank you for this, <scholes>. I downloaded 11 already.
|Feb-01-20|| ||Ron: In the following position:
click for larger view
Stockfish 9 evaluates:
(0.70) Depth=67/74 0:09:39 1995 MN
However, Black can hold a draw.
|Feb-01-20|| ||OhioChessFan: Per <offramp> Feb 16 19, Bd7 creates all kinds of pins and skewers.|
|Jun-26-20|| ||Helios727: The current online version of Stockfish seems to have a search depth limit of 42. Does that refer to half moves or full moves?|
|Jun-26-20|| ||WannaBe: If you are talking about "ply", it's half-move.|
|Jun-26-20|| ||AylerKupp: <Helios727> Since typically all search engine depths refer to plies, I would think that the limit of 42 would apply to plies (half-moves) and not full moves. Even so, 42 plies is a decent search depth in order to have reasonable confidence in Stockfish's evaluations.|
Could you post a link to the site you were using for the on-line version of Stockfish (which I didn't know existed)? I had trouble getting to the sites listed in my Google search.
|Jun-26-20|| ||Helios727: The link for Stockfish analysis online is at:
|Jun-28-20|| ||AylerKupp: <Helios727> Thanks for the link. I used the <365chess.com>'s Stockfish analysis app to analyze the position after 1.e4 e6 2.d4 d5 3.Nc3 Bb4 . I'm a French Defense player so it's the first position that came to mind for it to analyze:
click for larger view
This Stockfish analysis app is incredibly slow. I let Stockfish analyze for more than 24 hours and it got to search ply depth of 38 with an evaluation of 4.e5 of [+0.17] as its best move. I don't know if it will stop at d=42 since I'm stopping it due to lack of interest since I think it's far too slow to be of much practical use. Did you let it continue running and it just stopped, or seemed to stop at d=42? Or did you get a message indicating that was it's limit. Maybe, since the time to analyze positions increases exponentially as the search depth increases, you just thought it had stopped.
I don't know what version of Stockfish they are using, but when I Googled "365chess stockfish analysis" the summary of the first hit said "You can analyze your positions and games online with a powerful chess engine - Stockfish. 8." But there is no mention of the Stockfish version used in the https://www.365chess.com/analysis_b... page.
The latest officially release version of Stockfish is 11, released in mid-Jan 2020, although there are other later development versions that can be downloaded. All are free.
I had my oldish 32-bit, 4-core computer analyze the same position using Stockfish 11 overnight. It reached d=38 in less than 33 minutes and after about 8½ hours it had completed its analysis d=48. At d=38 it also considered 4.e5 to be White's best move with an evaluation of [+0.18] and likewise at d=48 with an evaluation of [+0.38].
Faster computer systems will of course take less time, user <RandomVisitor> with his much more powerful system routinely posts analyses where his Stockfish reaches search depths in the low 50s.
I don't know if you do much computer chess analysis but, if you are interested in doing so, I suggest that you download and install a chess GUI and Stockfish to your computer and run your analyses there rather than rely on https://www.365chess.com/analysis_b.... I have found that with Stockfish you need to let it reach deeper plies, in the mid-30s and preferably in the low 40s, when compared to other engines in order to have similar confidence on the accuracy of their results.
There are many chess GUIs that are free to download and use as, of course, Stockfish. I personally use Arena because it is capable of doing many other things besides analysis such as running engine vs. engine matches or multi-engine tournaments, as well as let you play against the chess engine. The reason why I chose Arena when I was just getting started running computer chess analyses, besides its capabilities, is that it was free. However, Arena has a somewhat steep learning curve because of its many features but, like anything else, once you learn how to use it it's not difficult to use. But there are many other free chess GUIs that you can download that might be more to your liking.
If you are interested in getting started with doing chess analysis on your own computer and have any questions, feel free to drop me a note on my forum.
|Jun-28-20|| ||AylerKupp: <Helios727> Here's another reason why running chess engines on your own computer is important. I sometimes record information about some of the key parameters of an analysis so that I can compare the results from different engines at each ply; search depth, time required to reach that depth, total KNodes evaluated, KNodes/sec, evaluations (of course!), and the top move. I should do it more often.|
The last one indicates how stable the analysis of the position is. Sometimes the same move is consistently listed as the top move in ply after ply, particularly at the deeper plies so I then consider the analysis "stable". But sometimes the top move changes a lot between plies. I consider that analysis "unstable" and what the engine considers to be the top move in that position often depends mostly on when you stop the analysis due to time or patience limitations, or both; it's pretty much arbitrary.
The evaluation of the top move also change, sometimes significantly, on a ply-by-ply basis. At d=48 it evaluated 4.e5 at [+0.38], effectively equal. But it was as low as [0.00] at d=39 and d=40 for 4.exd5. And it evaluated 4.exd5 at d=46 at [+0.35].
In this analysis the GUI listed Stockfish's top 3 moves at each ply from d=8 to d=48, 41 plies in all. And there were 7 different moves identified as the "top move" in each of those 41 plies, with 4.exd5 considered the best move more often than all the others. In descending order of occurrence (2nd column) with White's Scoring % listed in the 3rd column, these were:
4.exd5 <22> 54.7%
4.e5 <7> 57.5%
4.a3 <6> 57.3%
4.Bd3 <2> 50.0%
4.Nge2 <2> 54.0%
4.Qg4 <1> 53.6%
4.Qd3 <1> 54.3%
Fortunately, Opening Explorer, Opening Explorer, indicates that 4.e5 is by far the most popular move, being played 7,781 times out of 10,308 games (75.5%). And 4.e5 is also, but just barely, the move that has the highest Scoring % for White. 4.e5 was also listed as Stockfish's top move in 5 of the last 6 plies analyzed. But if I had stopped my analysis at d=46, Stockfish would have indicated that 4.exd5 was the top move as it did at d=38.
So analysis of ply-by-ply information presented can be essential in determining what the best move in a given position might be, and sometimes we just have to accept that a position is not stable analysis-wise, and that that chess engine is just not capable of determining what the best move really is in a reasonable amount of time. And that's something you can't do with https://www.365chess.com/analysis_b... or other apps like it that do not provide easily recordable ply-by-ply information.
|Jun-30-20|| ||Helios727: What happens is that when I analyze a game, I sometimes have to leave the computer for long periods of time and when I come back the search depth is never above 42. I will make a point of getting a GUI. As for unstable analysis, is it possible that this simply results from situations where more than one move is equal to another and it comes down to personal style?|
|Jun-30-20|| ||AylerKupp: <Helios727> Same here. I do some short interactive analysis for blunder checking purposes but I typically run my "serious" analyses overnight, with 3 engines (typically Houdini, Komodo, and Stockfish and I average their evaluation in order to rank the moves, since multiple engines sometimes differ as to what their top move is, and their evaluations differ) and with only one core used per engine to practically eliminate multi-core engine non-determinism. So I can run all 3 engine analyses concurrently. I start my analysis, I go to bed, and in the morning check the results.|
As far as for "unstable analysis" I'll clarify that I refer to those situations where the engine(s) top move changes, at the extreme case, every search ply. After all, we want to know and play the best move. This situation typically happens when different moves have similar evaluations and after each search ply one of the moves' evaluation inches above the others by a small amount. Or, if the evaluations are truly equal, then the "top move" is the one with that evaluation that the engine finds first. In that case, any move with the same evaluation is really the "top move".
In fact, I consider several moves to be effectively equal if the difference in their evaluations is [0.50] or less, since I think that ½ pawn is probably the resolution of a human player, assuming that we think in terms of equivalent pawns, which of course we don't, although perhaps subconsciously we do. I typically map engine to human evaluations roughly as follows:
[0.00] to [0.49] = Position with equal chances for both sides (Note: Not necessarily a draw, although that's probably the most likely outcome, particularly between strong players)
[0.50] to [0.99] = White (Black) has a slight advantage.
[1.00] to [1.99] = White (Black) has a definite advantage.
> [2.00] = White (Black) likely has a winning advantage.
Then, if more than one move has an effectively equivalent evaluation, the move that we choose to play is probably pretty much based on personal style.
Good luck in your search for a suitable GUI to meet your needs. And, as I said, let me know if I can help you get started.
|Jun-30-20|| ||Helios727: I installed the Arena GUI and the Stockfish-11 engine. It appears there are three 64 bit engines in it: stockfish_20011801_64, stockfish_20011801_64_bmi2, and stockfish_20011801_64_modern. Which one do I use?|
How do I cut and paste a set of PGN text for game analysis?
Also, how do I set it up to mimic the online version of Stockfish by having it show the top three moves to choose from?
|Jul-01-20|| ||Helios727: In the meantime I installed the Tarrasch GUI, which is much simpler than Arena, so I will use it until I figure out Arena better. I see that the Stockfish engine is much faster in a PC than the online web version. This is cool.|
|Jul-01-20|| ||AylerKupp: <Helios727> Which version of 64-bit engines to install depends on how recent a computer you have. The 20011891 refers to the build number and the _bmi2 and _modern refer to the instruction set available with your computer. Each of the 3 versions is slightly faster than the others.|
The _64 is the most basic and will work with any 64-bit computer regardless of age, the _modern is suitable for 64-bit computers released since 2013 or so, and the _bmi2 version is suitable for computers from the mid 2015s and beyond. The _bmi2 will likely give the best results but not spectacularly best.
But the only foolproof way to find out which one works best is to try them. Install all 3 versions (Engines > Install Engine from the Main Menu), load the _bmi2 version (Engines > Load Engine from the Main Menu) and analyze (select Analyze) from the main window) a position, any position. If that engine version works, let it run for a little while, say 30 secs to let the kN/sec value stabilize somewhat, and record the kN/sec number. Then install the _modern and _64 versions and repeat. If only the _64 version works, you have your answer. Choose the version with the highest kN/sec value. Of course, if only the _64 version works you have your answer.
I've never pasted a PGN game text into Arena for game analysis. I instead paste a FEN string describing a particular position and start from there. You can set it up in Arena by selecting Position > Set-up a Position from the Main Menu or press Ctrl+B or select it from the icon that shows a chessboard and an arrow in the bottom right-hand corner (Arena unfortunately does not provide balloon help).
The Arena position editor is a little clunky for my tastes so I find the easiest way is to cut and paste the FEN string defining the position into Stockfish. You can create the FEN string using any one of a number of apps, I use http://www.chess-poster.com/english... to set up the position that I want to analyze, select it and copy it to the Clipboard, and in Arena from the Main Menu select Position > Get FEN from Clipboard or press <F6> to activate that position for analysis.
From the Set-up a Position pop-up menu you also specify the initial move number, the player to move, and – important – whether either or both players still have castling rights or an en-passant capture is possible (since Arena does not have a history of the moves it doesn't know whether a previous move allowed an en passant capture). Fortunately the default is no castling for either side and this is the most common situation so I don't need to specify it explicitly. But sometimes when analyzing an opening-type position castling is still possible and I forget to specify it since I'm not used to doing so.
|Jul-01-20|| ||AylerKupp: <Stockfish, Arena> Configuration (part 2 of 2)|
But you made curious so I looked up pasting a PGN into Arena. Arena has a very good Help system and I found how to do it easily. It's almost trivial; save the PGN game into a *.pgn text file and drag the *.pgn file into the Arena main screen. All this appears to do is display the PGM header information in a spreadsheet-type window. But just click on any of the cells and it will load the game into the Arena main window and display the first move. You can then click on any move and it will show the position after that move, or advance/go back moves using
As a bonus, since Arena now knows the history of the move's games, it automatically checks the proper settings for White and Black castling. However, you still have to explicitly specify the first move number and whether White or Black is to move. I didn't have a game handy that featured a possible en passant capture so I don't know if it will correctly indicate the en passant square. Try it and let me know.
To specify that the top 3 (or any number of moves) be displayed press Ctrl+1 to display a pop-up of the UCI parameters that engine allows to be changed. If you have 2 engines loaded press Ctrl+2 to modify the UCI parameters for the 2nd engine, etc.). Change MultiPV to whatever number of values you want displayed. Close the pop-up and select Analyze. Each additional value you specify will make Stockfish run a little bit slower since it has more work to do, but not noticeably so. I like the display for MultiPV > 1 better so if I'm interested in pure speed I specify MPV=2, otherwise I typically specify MPV=3 or MPV=5.
And you can save most of the information displayed by copying it to the clipboard by specifying Position > Copy Analysis to Clipboard or Shift+Ctrl+F6 (who remembers these keyboard shortcuts anyway?) and then paste them in a text editor or word processor. But there are some "features" of this operation that I will discuss if you're interested.
These engine UCI parameters are stored in a text file in the Arena folder called ArenaENG.cfg. I find it easier to just edit this file if I'm changing multiple parameters or parameters for different engines. Make sure that Arena is not loaded, load the ArenaENG.cfg file, make the changes (in the Stockfish portion of the ArenaENG.cfg file MultiPV is indicated as MPV), and save it back. Just make sure that you use a plain text editor and not a word processor to do this.
There is lot of documentation on Arena that you can find on the web. And, like I said, the Arena Help system is quite good. Just be patient, Arena is a full-featured GUI that takes time to learn how to use. And it's best that you configure it with icons for the features that you use the most to make Arena easier to use.
But I suspect that most of your future questions will be about Arena and not Stockfish and this is, after all, the Stockfish page. So I welcome you to post any further Arena-related questions on my forum so as to not clutter this Stockfish page with Stockfish off-topic information.
|Jul-02-20|| ||scholes: Stockfish wins TCEC Season 18 Superfinal. Current score 52-44. Four games to go.|
|Jul-10-20|| ||Helios727: My experience has been that when Stockfish shows an advantage of 2.5 or higher, the result is almost always a win for that side if Stockfish plays it out. AylerKupp seems to get that result at the 2.0 level. What sort of threshold result do other people here get?|
|Jul-11-20|| ||AylerKupp: <Helios727> Well, I didn't "get" anything; I didn't run any tests. My winning level threshold > [2.00] was just an opinion. Various GUIs had the default winning level to be > [1.50] and I felt that this was too optimistic, so I arbitrarily used [2.00] as a more conservative threshold. If you want to be even more conservative and want to wait until the evaluation is > [2.50] to consider the position to be winning for White, that would be fine by me.|
So it's just a guideline, nothing more. I you wanted to be more objective you could run various engine vs. engine tournaments with Stockfish playing itself. You could then calculate what the probability of a win resulting after achieving an evaluation threshold <x.xx> for, say 3, consecutive moves.
But you need to remember that these probabilities would be engine-dependent since different engines have different evaluation functions and will evaluate positions differently. Stockfish's evaluations tend to run higher than other engines' evaluations, but not always. So a win probability of 0.90 might occur when Stockfish repeatedly reaches an evaluation > <threshold 1> and for another engine this probability of 0.90 might occur when that engine reaches an evaluation > <threshold 2>
Yet another consideration is that current classic engines seem to have is dealing with fortress positions. For example see my post in Spassky vs Fischer, 1972 (kibitz #1147). Even though Stockfish's evaluations were > [+4.00], which would usually be considered winning for White, it did not recognize that it was allowing Black to achieve a fortress.
Which is a pity since it's easily recognizable by an engine. In that analysis Stockfish achieved positions which it evaluated at [+4.98] and [+4.09], usually considered winning for White, at d=36 but it was unable to improve on those evaluations as far as d=52 when I just stopped the analysis. An engine should be able to recognize that if its evaluation does not change for, say, 10 consecutive moves, then it is heading into a draw if it continues to pursue that line. Particularly if up to that point its evaluation of the positions resulting from a given move had been increasing.
The question is then, what can the engine do about it? Maybe by the time it discovers this situation it's too late to do anything about it. Or maybe it could permanently prune the branches of its search tree that satisfy that condition regardless of how high (within reason) the evaluation is so that it can concentrate on branches that, while they may have lower evaluations, provide more realistic opportunities for a win.
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