Russell Sherwood

Turning the Table(base)s

Russell Sherwood  Sunday, June 17, 2018

Tablebases are one of those facets of knowledge of (correspondence) chess that are taken as granted as being understood by all but are often not!

In simple terms what are they?

Wikipedia defines them as “An endgame tablebase is a computerized database that contains precalculated exhaustive analysis of chess endgame positions. It is typically used by a computer chess engine during play, or by a human or computer that is retrospectively analysing a game that has already been played.”

Clear now? Maybe not! Let’s start at the beginning. If we have two pieces, the only outcome of the position is a draw.  Not a lot of help. If we have three pieces, it could be a draw or a Win/Loss – depending on the pieces and their positions. The Endgame tablebase has every possible combination and position on the board stored in its table(s). These are linked to together, so the table can provide a definitive answer to the theoretical outcome of the position.

Tablebase development has reached the point that 6 piece tablebases are widely available and 7 piece ones are available from limited sources. Limited 8 piece are in development but are not publicly available.

What is worth considering is that Tablebase development is a slow process – this is due to the staggering amount of computing power required to calculate them as the number of pieces increases, thus it is not expected to see rapid releases of larger tables on a rapid basis.

In addition to this, the storage requirements for Tablebases are significant. Currently, 7 piece tablebases are only available online and are not practical for the typical home user to install locally.

Why are Tablebases important to Chess Engines

Let us consider for a moment how an engine evaluates a position. Generally, most have very little specific, definitive knowledge but use a general approach which considers a number of factors – Material, Space, King Safety……to calculate a score for a specific position. The relative scores for possible choices are compared and the best line is built by following the “best” scores.

The problem with the approach for endgames is that the specifics of the position can have a massive influence on the correct move, which is general approach will not see. This is the reason why we see massive engine scores on drawn position or visa-versa.

With a tablebase this issue is avoided as the engine, knowing it has tablebases available, probes them when the analysis reaches that number of pieces on the board. It now has a definitive result – Win, Lose or Draw, which it can then use to “correct” its analysis of a position.

This means, in theory, at least that the engine is better able to navigate late middlegame and endgame positions.

For the CC player Tablebases should always be installed, where available as without them you will find promising looking positions turning to draws and draws turning to defeats!

So there are one set of definitive tablebases?

Er, no! There are a few different types available:

Thompson, Edwards, Nalimov, Scorpio, Gaviota, Lomonsov and Syzygy


The differences between these tend to cover the number of pieces available, Information provided and the size of the tables.

A good summary of this can be found at

In terms of information provided we have two main types:

Depth to Mate: This is, as you might guess, the number of moves from a position, with the best play by both sides, to mate.

Win, Draw, Loss: Here we have the simple outcome of a position.


For pure engine use, WDL is adequate as once the engine has a result it can modify its search accordingly, whereas DTM is of more interest to Human Analysts. Newer tables tend to come in the WDL format as it is much more compact, which is valuable as the number of pieces increases.


Which should I get?

For local set up its hard to get beyond Nalimov, Scorpio or Syzygy. In terms of functionality, most engines will directly link to Syzygy, whereas the other two tend to be linked via the GUI.

If we consider size Scorpio is the smallest, followed closely (in relative terms anyway) by Syzygy, with Nailimov being a distant third.

Probably the main factor is going to be your source – are you going to buy it on a Disk or Download it?

Taking these three factors into account the probable choice is 1) Syzygy 2) Scorpio 3) Nalimov.  OF course, on top of this, the really serious player will probably obtain links to Lomonsov’s 7 Piece table as well!


What Else?

This is not quite the end of the story. It is possible to create Tablebases from a specific position. There are some older pieces of software such as FinalGen or Freezer which will calculate from a specific position. These are very slow and take up a lot of storage but may be of interest to some players.



Should there be sufficient interest I will write a run through on how to set up TB on the major Engine/GUI platforms.

Welsh Friendly Matches Update

Russell Sherwood  Wednesday, June 6, 2018

In line with our largest Friendly Match vs Italy being soon to start, I had a run through the archives in terms of our past matches

I have included our participation in some of the "vs the rest" matches.

To date we have taken part in 29 Matches, winning 9, drawing 3 and losing 16 (with one in progress)!

This performance should be taken with a large bag of salt for two reasons:

1) Our attitude to Friendly matches has been one of fun and player development 

2) With 1) in mind we regularly took matches on carrying a significant elo deficit.

When the scoreline is adjusted for Elo difference we see a much more encouraging picture, 22 wins, 6 Losses and 1 in progress. Taking nothing away from our opponents these performances are a significant part of the development of players now advancing Welsh CC on a Domestic and International level!

The plan for Friendlies for the 2018-2019 season will be released in the near future


    Start Boards Weblink For Against Open % ES ES% Result ES Result
Wales Peru Oct-12 13 15.5 10.5 0 60% 12.5 48% Win Win
Wales Sweden Nov-12 9 3.5 14.5 0 19% 8.5 47% Loss Loss
Wales Netherlands Apr-13 19 16.5 21.5 0 43% 15.8 42% Loss Win
Wales Spain Jun-13 15 11.5 18.5 0 38% 15.4 51% Loss Loss
Wales Venuzuela Aug-13 6 6 6 0 50% 4.9 41% Draw Win
Wales Latvia Sep-13 10 6 14 0 30% 7.4 37% Loss Loss
Wales USA Dec-13 21 20 22 0 48% 21.2 50% Loss Loss
ROE Germany Mar-14 7 5.5 8.5 0 39% 6.6 47% Loss Loss
ROE Italy Mar-14 3 4 2 0 67% 3.7 61% Win Win
Wales Ireland May-14 5 4 6 0 40% 3.0 30% Loss Win
Wales Venuzuela Aug-14 14 11 17 0 39% 9.8 35% Loss Win
Wales Poland Nov-14 21 14 28 0 33% 11.9 28% Loss Win
Wales NSW Jan-15 24 28 20 0 58% 20.8 43% Win Win
Wales Scotland Jan-15 20 20.5 19.5 0 51% 15.1 38% Win Win
Wales Germany Jan-15 25 20 30 0 40% 21.4 43% Loss Loss
Wales Scheming Mind Feb-15 22 24 20 0 55% 12.7 29% Win Win
Wales Finland Feb-15 26 22 30 0 42% 14.9 29% Loss Win
Wales India Apr-15 22 28.5 15.5 0 65% 16.3 37% Win Win
Wales Czech Rep May-15 28 35 21 0 63% 24.9 44% Win Win
Wales France May-15 30 24 36 0 40% 16.7 28% Loss Win
Wales Australia Oct-15 34 33.5 34.5 0 49% 27.02 40% Loss Win
ROE Czech Rep Dec-15 5 5 5 0 50% 4.82 48% Draw Win
Wales Netherlands Apr-16 24 14.5 33.5 0 30% 13.92 29% Loss Win
Wales USA Apr-16 22 24 20 0 55% 22 50% Win Win
Wales Austria Jul-16 21 9.5 32.5 0 23% 7.56 18% Loss Win
Wales Yorkshire Nov-16 16 15 17 0 47% 14.4 45% Loss Win
Wales  Indonesia Dec-16 9 9 9 0 50% 5.94 33% Draw Win
Wales Mexico Jul-17 14 7 14 7 33% 13.5 48% Open Open
Wales  USA Jun-16 5 6.5 3.5 0 65% 5 50% Win Win



Moving on up!

Russell Sherwood  Saturday, June 2, 2018

Making the move from 2300 to 2400+ (or 2400 to 2500) , once you have a fixed rating, is one of the most difficult things to do in Correspondence Chess.


The main thing to consider is that at this point you now need to win games. Many players coming up the ranking gain a glut of rating points by simply drawing with higher rated players.

So what do we need to do to “kick on”?  The ideas below come from a number of sources: Interviews with strong players, original research, published comments from strong players and deduction!

  • Management of Game Load
    • Whilst it is very possible to play a large number of games (See Industrial Chess) the reality is that we face a very simple equation of Total Time Available / Number of games in play, which gives us a time per game. We can make improvements which allow us to play a few more games but the reality is the higher the correctly applied time per game, the higher the likelihood of a successful outcome. Thus we should look to control the number of games we play closely. This is not always as simple as staying in the “Goldilocks zone” is not always easy. How many games is this? Common advice is somewhere in the 20’s but I tend to think in terms of how many games I have in each phase of the game: Pre-Opening, Opening, Middlegame, Late middle game and Ending and look to keep a mix running through.
  • Event Selection
    • If we are managing our game load this leads to how to select the events to participate in. Here a mix is essential of type, level and player make-up. I believe for interest’s sake this should include a combination of team events and International Friendlies but the majority of events should be at the highest level you can play against. In addition to the level of opposition, the source should also be considered. There are patterns in terms of style, openings and the like in specific countries and knowing what you want to avoid/not avoid is very valuable! At the very least you should have a plan for the next 12-24 months. It is also helpful to share this with any Team Captain’s or National Federation Organisers so that this can be built into their plans.
  • Eyes on the Prize
    • Do you want a Title, rating growth or advancement in an event? You might say all three but your approach will be modified by the answer to the question. For example, I have recently focused on advancing in a number of Open events, which has cost me rating points as I have had to “expose” myself to a lower rating pool of players. Knowing what want till allow you to advance in a smoother more cohesive fashion towards your goal.
  • Approach
    • What is your approach? Do you want to win with Black or is drawing adequate to your plan? The majority of players at the higher levels of CC are content to simply draw with black (or to be more precise limit whites chances to win). Where do you stand on this? A thought to fall into this pot: If you look at the stats for black wins at the higher end of CC, it is truly tiny (look for yourself – see #6). If we consider #1 then there is an argument that we should not expend that much time on black for a relatively small chance of success, drawing quickly and putting the resources into our White games. Of course the counter to this is true – play certain double-edged openings and expel resources in original play to try and grab that small edge from there. Which Openings – see #5
  • Opening Selection
    • Openings in CC are a very different beast to that in OTB. Some fearsome openings in OTB (e.g. Najdorf) are drawing tools in CC. This has led to a move to adopt more fluid openings – typically Reti systems, where the opening book has been left behind after only a few moves. The other area of interest is transposition and move order manipulations. A good primer on the subject is Soltis “Transpo Tricks” . The point of both these approaches is to remove the weaker player’s best resource – deep open books and game databases. These are probably the biggest leveller in CC, rather than engines. We can also look at utilising statistics against a player. For example if we can find a line which fairly decent statistics but that has not been played for a while then it may be that we can find a favourable innovation and thence trick our opponent into this line!  I know I have been trying this approaches of late in some International opens, specifically against lower rated opposition with promising results
  • Database Management
    • It is necessary to have a significant, up to date, source of games to advance with CC but it is essential to be able to manipulate this data to be able to turn it into useful information. For example do you know how to do a position search? There are some good texts – “Chess in the Digital age” covering how to utilise Chessbase in particular
  • Engine Manipulation
    • Once we reach 2300 it can be assumed that all your opponents know the basic of utilising an Engine but to move on you need to know a number of other techniques including: Which Engines are good in what positions, Backsliding, Next Best, Limited Search, Null Move, Wide vs Narrow, Canyons……….the list is long (I count almost 30 on it) . In itself these methods probably won’t win you that many games but they will pick off lower rated opposition relying on primitive methods and may give you some useful positions against higher rated opposition. Regardless of your style of play knowing how to avoid the traps is the bare minimum necessary knowledge!
  • Exhaustive Analysis
    • A key distinction I have observed with higher rated players is that they analyse for more exhaustively. This does not necessarily mean deeper but does mean they tend to look wider and also until a line is resolved. This means much more work and reinforces a key reason why the highest rated players play so few games. Consider an example – we might have a player who starts using IA and an opening book. After a while they will then start to look at more than the principal variation, finally, they will expand the tree they look at again a much wider span of moves. Clearly, all moves cannot be considered but we should consider how we decide which moves to examine and which to not!
  • Out-thinking and Outplaying your opponent
    • At the higher levels if we assume that our opponent has comparable resources to us when we need to consider how we outthink the opponent. This starts with better preparation, especially in the Opening but also determine if they have any tells (for example do they tend to utilise a specific engine or favour a certain approach?) This is a very wide area but ultimately we are looking to find the cracks in what they do.
  • Staying on the cutting edge
    • Whatever your approach to CC, you need to keep on the cutting edge if you want to make it to the higher echelons. This means many things but includes which databases, engines, Opening theory. Chess moves ever faster and the line which was solid last year may be busted now.
  • Knowing what’s best.
    • A simple truth of CC is that following the engine’s output blindly will lead to draws or losses but there is a strange phenomenon where players seem unwilling to disagree with the Engine, simply because it does not give a high evaluation. We need to show the courage to ignore the engine. Of course, the engine is often (mostly?) right but we should consider if we disagree with it, who is right? This should be done by checking what the engine considers a refutation of your move? Is it really?
  • Patience
    • CC is a slow-moving sport (yes it is a sport!), so don’t worry about slow-moving opponents or the like put your efforts into beating you, other opponents!
  • Learn Chess
    • Our edge in CC is two areas: Strategic play and Endgames (and one leads to the other!) The more effort you put into developing your abilities in this area the more likely you will be able to make winning decisions!


Personally, I know what I need to do to improve my rating and move onto higher ratings – invent a time machine! Seriously in my case, as I have missed IM Norms on a number of occasions by half a point, with the massive number of games that I play, then reducing my game load will achieve that targets!


Reading books alone will not aid you in this endeavour but there are a number of books that will help you get there faster – if internalised and applied!


  • A number of my posts here cover most of the knowledge required to get to 2300
  • Pump up your rating – Alex Smith
  • Under the Surface – Jan Markos
  • Small Steps to Giant Improvement – Sam Shankland
  • World Champion at 3rd Attempt – Grigory Sanakoev
  • Thinking inside the Box – Jacaob Aagaard
  • Modern Chess Analysis –  Robin Smith
  • Matjaz Pirs article on the Bdf Website
  • Transpo Tricks – Andrew Soltis
  • Grandmaster Opening Preparation – Jan Ehlvest


If you are interested in determining what is holding you back get in touch at [email protected]

News from the Front - May 2018 - Non-National Team Events

Russell Sherwood  Saturday, May 19, 2018

4th British Webserver Team Tournament

1st Division

Stand out Welsh performers are Austin Lockwood and Russell Sherwood on 3.5/6

2nd Division

A commanding performance from Y Gweilch NiMo, sees them secure promotion to the Top tier, just ahead of long-time rivals BCCA Sovereigns. Stand out performer is Andrew Gibbons on board 4 on 5/6. Gareth Yeo is also worth of mention, scoring 4/5 playing for the Civil Service Team,

3rd Division

Despite losing a player to silent withdrawal the Welsh Irregulars managed to avoid relegation. Stand out performer was Paul Scott on 5/6          

4th Division

no Welsh teams here but Marc Wakeham, playing for Natcor B scored an excellent 6.5/7, although not enough to get his team promoted!


States & Regions CCC

1st Division

Early days yet with only 40/72 games completed.  US West 1 have taken an early lead, although being gifted two points by silent withdrawal has helped. West Wales remain well placed in second place, although the event is still wide open! 

This event has been a baptism of fire for a number of Welsh player’s; giving them their first opportunity to play in team events much stronger than others available in the UK.


2nd Division

Celtic Warriors sit in mid-table, although with much work to do if they wish to look for a promotion place.


3rd Division

No Welsh Teams here! A Mexican select team is doing very well on 6.5/7 and looking a likely contender to top the division

Counties & Districts

1st Division – Ward Higgs

With 19 games remaining a close finish is likely with defending champions West Wales A currently in 3rd place. East Wales A are in 4th place a point behind but with two games in hand. It is sad that defaults may have a negative say in the deciding the outcome of the event

2nd Division – Sinclair

A tight finished ensues with 4 teams still in with a realistic shout of promotion. Again a real shame with so many defaults taking place. Time perhaps for team captains to vet candidates closer

West Wales B are hovering above the relegation zone, relying on other results to continue their stay in the 2nd Tier.

3rd Division – Butler Thomas

East Wales B has completed their campaign with a much improved 7.5/16, ending up in a Mid Table position.

British Correspondence Team Tournament

Y Dreigiau Cymreig sits in 4th place 1.5 points behind leaders BCCA Alekhine but with 3 games in hand. A fairly tight event with only CS Administrators struggling, despite the best efforts of rising Welsh talent Gareth Yeo! Luckily for them, rule changes prevent their relegation.

Well done to Fred Clough in picking up 100% in his games to get YDC off to a flying start.

I was elected to Lead, not to read!

Russell Sherwood  Sunday, May 13, 2018

I've written many Chess book reviews over the years but have often felt that the method used to score them has been rather weak - a typical 1 to 5 rating system. So I sat down and considered what I look for in a Book (or Video or podcast or blog....)  and then asked a few others for input. From this came the list below

  1. Value for Money – If I am going to have to pay £25 for a book, I will expect much more than something I get for £5
  2. Spelling/Grammar/Readability – Speaks for itself!
  3. Originality – Do we really need another book of type X?
  4. Content – How useful/interesting is the stuff in the book (or video)?  I could write an opening treatise in an evening using ChessBase and a few basic tools but it would only be a dump of games/lines with very little explanation.
  5. Credibility – Why should I take notice of this author? A little subjective this but would you rather read a book on the Najdorf by Kasparov, Davies or Sherwood?
  6. Durability – How well will the book stand the test of time? Some do very well indeed, whilst others (say most Opening books older than a few years, date very quickly).
  7. Would I buy it (again)?
  8. Relevance to CC - As a CC player how relevant is this book? (Thanks to Neil Limbert for this one)

Answering and scoring these criteria should give a much more objective measure of the value of a book to the CC player.  I've written a number of new reviews and reworked some older ones and will start to publish these over the coming weeks.

In addition, in the spirit of a certain popular TV Car Show, I will set up a leaderboard.

If you wish to review a book let me know and I will let you have more detail on the scoring system!


So for a really good book, we are looking for one which is good VFM, which is readable (Good spelling and Grammar should be a given), with Original Great content. The Author must be credible and the content must stand the test of time (which means if it’s an opening treatise it needs to be fairly new, whereas Game collections can be much older)

Poka Yoke

Russell Sherwood  Tuesday, May 8, 2018

Poka-yoke [poka joke] is a Japanese term that means "mistake-proofing" or "inadvertent error prevention". The key word in the second translation, often omitted, is "inadvertent".

Many a Correspondence Chess Player has lost a game by an administrative blunder, either making a one move howler or not entering the move intended.

Following some discussion, it is worth sharing that a piece of software exists which can almost eliminate this issue.

The Software in question is Correspondence Play software which comes as part of the Aquarium software package. Once set up the software downloads your games from the ICCF server. You then can analyse the game (either in place or in the Aquarium package) and then make your move via the interface. This is where the clever bit comes in: An engine can be set up to run for a short period before the move is transmitted to 

If the move drops the engine's evaluation of the position more than a specified threshold, the engine will not transmit the move without an additional "Are you sure" type override.

This will not stop you making deep positional mistakes or errors the engine does not recognise but it will eliminate almost all simple blunders!


Zero to Hero?

Russell Sherwood  Sunday, April 22, 2018

There is a most interesting Chess experiment taking place at the moment LCZero. This is the development of a Chess Engine based on Deep Learning, utilising the methods purported to have been used by Google's AlphaGo Project.

So where is it up to now - well the latest version of the engine is now operating at around 2500 Elo (there is some debate about the actual rating). Compared to top of the line Chess Engines this is weak but consider, it was operating at below 2000 elo less than a month ago!

You can get involved (with almost no effort)! Details are at 

Well worth keeping an eye on!

Making a HASH of it!

Russell Sherwood  Sunday, April 22, 2018

Note: It's amazing the pictures you get searching for Hash!

I've been asked this question by a number of people recently so an explanation of Hash files and their interactions with Engines is probably overdue.

Hash Files (Also known as Transposition Tables) are a tool utilised by Engines to facilitate the use of multiple processors. In very simple terms when we run an engine with multiple cores, rather than all the cores working on one position, there are actually single cores working on multiple nodes. These nodes start to make up a map of all of the moves which emanate from the start position.

In practice, the larger these tables are the better and a "rule of thumb" is to set them to around 50% of the RAM on the computer.

An advanced use is the saving of Hashtables. If deep searching is your thing then this allows you to save your analysis and reload it at a later date and return very quickly to the same depth.

Almost all major engines allow this use of HashTables. Stockfish 9 is the exception, although almost every Stockfish variant does have this functionality! So how do we do this?

(I'm using Houdini and Chessbase as an example, the method is more or less the same for all others)

1) Create a Folder where you are going to store the Hash File. Remeber that each of these files will be probably be Gigabytes in size so you need plenty of spare space on your drive.

2) Decide on the naming format you will use for these files. It could be the ICCF Game Number or whatever you want.

3) Double Click on the Engine Name in the Engine Window

4) Click "Advanced" in the Load Engine Window

5) Click "Engine Parameters" 

6) Enter the File and Location for the Hash file in the "Hash file" Window - For example it could be C:\Hash\Test1

7) Select "Never Clear Hash"

8) Click OK

9) Run your Analysis and then click the Stop Icon

10) When you want to save Follow Steps 3-4-5 then Click  "Save Hash to File"

11) When it has saved you will be able to Click OK, OK, OK to return to the front screen.

12) When you want to reload this file you simply  follow steps 3-4-5, change the file to the name you want to load and click " Load Hash From File"

13) When the Load is finished, click OK, OK, OK and you are good to go.

When you have made your move you do not need to automatically create a new file but if you either (a) Don't follow the principle variation or (b) Move further away from the original position the effectiveness of the process reduces dramatically!


Happy Hunting!


Russell Sherwood  Thursday, March 22, 2018

Mayjaz Pirs Site

For those of you who do not know Matjaz is a Correspondence GM and has been the German’s Chess Federation’s Performance Development Director, help numerous players towards achieving individual and team success. His own website has been around for a while but when a significant upgrade at the start of 2018. Lots of little nuggets of information here!

Niko Sarakenidis Site.

I had been aware of Niko for some time – he contributed to the Engine section of GM Aagaard's book “Thinking outside the box”. This is his personal blog and has a lot of interesting content for the CC player. Niko has also been active recently in defending CC against the always provocative, usually ill-informed and misjudged Nigel Short’s rather unpleasant comments about CC  (who, for his sake, I hope never meets a radical, religious, female CC player “down a dark alley”!)

There is some gold for the aspiring player but you need to go back through his posts and use a translator at times!

ICCF World Zone Site

The New ICCF World Zone came into being in January 2018 via the Merger of the NAPZ and South American zones. It has a snazzy new website well worth a look, although some of its claims (The best place in ICCF to practice correspondence chess) are clearly incorrect!



Russell Sherwood  Thursday, March 22, 2018

Mayjaz Pirs Site

For those of you who do not know Matjaz is a Correspondence GM and has been the German’s Chess Federation’s Performance Development Director, help numerous players towards achieving individual and team success. His own website has been around for a while but when a significant upgrade at the start of 2018. Lots of little nuggets of information here!

Niko Sarakenidis Site.

I had been aware of Niko for some time – he contributed to the Engine section of GM Aagaard's book “Thinking outside the box”. This is his personal blog and has a lot of interesting content for the CC player. Niko has also been active recently in defending CC against the always provocative, usually ill-informed and misjudged Nigel Short’s rather unpleasant comments about CC  (who, for his sake, I hope never meets a radical, religious, female CC player “down a dark alley”!)

There is some gold for the aspiring player but you need to go back through his posts and use a translator at times!

ICCF World Zone Site

The New ICCF World Zone came into being in January 2018 via the Merger of the NAPZ and South American zones. It has a snazzy new website well worth a look, although some of its claims (The best place in ICCF to practice correspondence chess) are clearly incorrect!


Welsh Correspondence Chess FederationBritish Correspondence Chess AssociationSchemingMind Internet Correspondence Chess ClubSocial Correspondence Chess AssociationWelsh Chess UnionInternational Correspondence Chess Association