For the kids?

This review has been printed in the October 2015 issue of Chess Life.  A penultimate (and unedited) version of the review is reproduced here.  My thanks to the good folks at Chess Life for allowing me to do so.


Hertan, Charles. Basic Chess Openings for Kids: Play Like a Winner from Move One. Alkmaar: New in Chess, 2015. ISBN 978-9056915971. HB 160pp. List $18.95.

Müller, Karsten. Chess Endgames for Kids. London: Gambit Publications, 2015. ISBN 978-1910093610. HB 128pp. List $16.95; currently $13.56 at Amazon.

The number of children playing chess continues to grow, but there remains relatively few good books for them to study. Part of this involves a generational shift away from paper and towards the world of apps, but I suspect that it also has to do with the difficulty of actually writing for children. There are precious few instructional works that manage to entertain and enlighten without sliding into farce.

Two books explicitly aimed at kids – Basic Chess Openings for Kids by Charles Hertan, and Chess Endgames for Kids by Karsten Müller – have recently been published. Both authors have impressive track records, but do these new efforts really work as books for children?

Basic Chess Openings for Kids is Charles Hertan’s fourth book with New in Chess, and his third written for children. The new book has much in common with its predecessors (Power Chess for Kids and Power Chess for Kids 2), including its terminology and the four helpful characters who ask questions along the way. For those unfamiliar with Hertan’s earlier works, a brief chapter on piece value and counting attackers / defenders is included, as are a glossary of terms and twenty quiz positions.

Hertan believes that the main goal of the opening can be summarized as follows: “get your pieces into action quickly and effectively!” (10) He argues that development or mobility is thus key to good opening play, and to that end, he devotes full chapters (2-5) to developing knights, bishops, rooks and queens. Chapter 6 focuses on the relation between pawn and piece play, analyzing two pairs of opening ‘schemes’ to make his points. The book concludes with an outline of five typical opening mistakes in Chapter 7.

Hertan’s basic strategy – investigating what each piece ‘likes’ to unpack good piece play – is solid, and his ideas-based approach to the opening is good for beginners. The reading level is not simple, so it might vex young readers, and I do worry a bit about the wide variance in the level of ideas presented. It’s one thing for beginners to see why knights like to be on c3 and f3, and another entirely for them to grasp the concept of outposts or knight maneuvers in the Ruy Lopez. I suspect that this is a book that would reward re-reading as players climb the ratings list.

Karsten Müller is, with apologies to our own Daniel Naroditsky, the world’s leading authority on the endgame. Having authored three classic books and fourteen DVDs on the topic, Chess Endgames for Kids is his work aimed at the youth market. The book is very good indeed, but I’m not convinced that it’s really designed for kids.

Chess Endgames for Kids consists of 50 distinct lessons or mini-chapters. Some of the initial lessons cover very basic endgames, including king and queen versus king and king and rook versus king. The complexity ramps up dramatically, however, and it does so very quickly.

Just about half the book is devoted to king and pawn endings and rook and pawn endings. The king and pawn coverage begins with the rule of the square, key squares and the opposition. I’m not convinced that most juniors need to know more than this before they reach Class C. Reti’s famous study (Lesson 12) is more aesthetically pleasing than educational for the beginner, and Bahr’s Rule (Lesson 15) is simply overkill.

We find much the same in the lessons on rook and pawn endings. The analysis of basic positions like Philidor and Lucena (Lessons 34-36) is useful and appropriate for novice players, but even Hikaru Nakamura lacked knowledge – or so he claimed on Twitter, anyway – of the Vančura position (Lesson 38) in his draw against Radjabov at the Gashimov Memorial in 2014.

Knowing Vančura is obviously important, as is the concept of the bodycheck in rook versus pawn endings (Lesson 32). The question is: for whom? Beginners would do probably do better with Winning Chess Endings by Seirawan or Silman’s Complete Endgame Course, and younger novices might best served by starting with Ten Ways to Succeed in the Endgame by Onions and Regis.

Chess Endgames for Kids is best seen as a terse endgame primer, slightly less complex than similar efforts by de la Villa (100 Endgames You Must Know) and Nunn (Understanding Chess Endgames). It is excellent for players with some experience who need to learn key theoretical endings, and it’s a steal at $16.95 in hardcover.

Book Note: Karolyi on Tal

Because there are just too many books coming out to keep up with, I’ll be doing some brief book notes along with my longer, in-depth reviews and essays. This is the second of those notes. – JH

Karolyi, Tibor. Mikhail Tal’s Best Games 1: 1949-1959, The Magic of Youth. Glasgow: Quality Chess, 2014. ISBN 978-1907982774. PB 448pp. List $29.95, currently $23.70 on Amazon.

Karolyi, Tibor. Mikhail Tal’s Best Games 2: 1960-1971, The World Champion. Glasgow: Quality Chess, 2015. ISBN 978-1907982798. PB 360pp. List $29.95, currently $21.74 on Amazon.

In the course of researching the games of Mikhail Tal for a forthcoming Chess Life review, I had the opportunity – and the pleasure – to spend some time with Tibor Karolyi’s two volumes on Tal. (A third, covering the remainder of Tal’s playing career, is in press.) Excluding Tal’s own efforts, there are no finer books on Tal in print.

Karolyi follows a recipe in these two books that he first cooked up in his two books on Karpov for Quality Chess. (Those books, Karpov’s Strategic Wins 1: The Making of a Champion and Karpov’s Strategic Wins 2: The Prime Years, can also be recommended.) He breaks Tal’s career down by year, interspersing deeply annotated games with discussion of tournament situation, personalities, and Tal’s personal life. Summaries of each year’s results conclude chapters, and indexes by player and page number are included along with a rough index of themes found in Tal’s games.

While Karolyi includes many of Tal’s most famous sacrificial efforts, he also analyses more ‘workman-like’ games, including no small number of his endgames. Karolyi is a diligent analyst, and while he (like many of his Quality Chess brethren) can sometimes present more analysis than can be easily digested, this is surely preferable to offering too little. The image of Tal we get through these books is of a much more well-rounded player than commonly thought.

Karolyi also spends a lot of time, and obviously spent a lot of effort, contextualizing each game. In some cases he sheds light on the identity of Tal’s opponent, while in others he sketches the situation Tal found himself in while playing the game. Many personal anecdotes are relayed, and the book is much richer for it.

69 fully annotated games are found in Volume 1, while Volume 2 contains 66 complete scores. Dozens of fragments and game citations (some with notes) are given as well. When the third volume is released, Karolyi will have given the chess world a comprehensive and compelling account of Tal the player and Tal the man. It will only further burnish the legend that is Mikhail Tal.

Learning from Gelfand

This review has been printed in the September 2015 issue of Chess Life.  A penultimate (and unedited) version of the review is reproduced here.  My thanks to the good folks at Chess Life for allowing me to do so.


Gelfand, Boris, and Jacob Aagaard. Positional Decision Making in Chess. Glasgow: Quality Chess, 2015. ISBN 978-1-78483-006-9. 288pp. HB $34.95. [Note that Quality Chess has only released the hard cover version to specialized chess retailers, and a paperback should be on Amazon in the nearish future.]

Positional Decision Making in Chess is Boris Gelfand’s second book, the first being his 2005 My Most Memorable Games. Were it simply another batch of his annotated games, it would well be worth our attention. Very few of the world’s elite put pen to paper (fingers to keys?) while they are still active players.

Most of Kasparov’s many books emerged only after his retirement. Books by Anand and Kramnik predate their World Championship reigns, while the bulk of Shirov’s output now comes in DVD form. Recent works by Giri and Polgar are excellent, but Giri’s best years are ahead of him while Polgar has retired from tournament play.

So when a player like Boris Gelfand – a six-time Candidate, the 2012 Challenger for the World Championship and the 13th ranked active player in the world – writes [1] a book about his games, we chess bibliophiles tend to take notice. And all the more in this case, for Gelfand has given us a superlative book.

My Most Memorable Games is, on the whole, a traditional ‘best games’ collection. It is evident from even the first pages of Positional Decision Making in Chess that Gelfand has something else in mind with his new book. As he writes in the Preface,

…the intention of this book is not to focus on the accuracy of the moves I made at the board… but on the thought process that led me to finding them in the first place. … [T]hroughout we have focused on the reasons for the decisions and plans I made, and also the limitations of my thinking during the game. (8)

While (sometimes copious) analysis of Gelfand’s games is provided, the real focus of the book is how Gelfand takes decisions over the board, with positional decisions front and center. The games of Akiba Rubinstein – Gelfand’s favorite player – are enlisted in this effort, and special emphasis is placed on Rubinstein’s influence on Gelfand along with his relevance for contemporary chess theory.

There is much to like here. It’s good to see Rubinstein get his due as player and theoretician, especially as there are very few legitimate books about him in print. Gelfand’s annotations are clear, and his descriptions of his opponents are both respectful and revealing. The book’s surprisingly personal feel is amplified by the photographs strewn throughout its pages.

For me, however, the central theme of the book only appears between the lines of the text: Gelfand’s relationship to the computer. No one can dispute the changes wrought on chess and its play by our silicon friends. Nor, if we are honest, can we overlook the way in which most players trust engine evaluations blindly, almost outsourcing their thinking to the computer. (Look at Twitter or the ICC chat during the next big tournament if you doubt this.)

What is most interesting to me about Positional Decision Making in Chess is seeing how Gelfand, a member of the last generation to come of age before the rise of the machines, thinks about engines and their limitations. Gelfand trusts his intuition – this word appears repeatedly in the text – and prefers to view engines as tools for understanding rather than as infallible oracles. Rarely have I seen such honest and practical discussion of the topic. For instance:

…I am a strong believer in the value of a chess education built on thorough knowledge of the classics [like Rubinstein – JH]. Any attempt to emulate the engines and their 2,000,000 moves a second is doomed to fail. We need to supplement calculation with all other weapons available. And one of these is intuition, which is strongly rooted in pattern recognition. (58)

Extremely often the computer will suggest moves that no human would consider. And when we do not feel it delivers us a clear understanding of why this move is good, I cannot see that it makes sense to follow its recommendations. (199)

If only those kibitzers on ICC would heed Gelfand’s warning!

By providing us a window into his decision making, and by showing us – warts and all – both the limits and triumphs of his thought, Boris Gelfand does much more than merely offer us edifying games to study. The author of Positional Decision Making in Chess is an exemplar for all of us who struggle to learn from the computer without succumbing to its siren call. This might well be the book of the year, and serious students of modern chess practice should not miss out on its lessons.

[1] I would be remiss if I did not mention the role of Gelfand’s ‘helper,’ Jacob Aagaard, in the construction of this book. Aagaard, himself a very well regarded author and pedagogue, recorded extensive discussions with Gelfand and used them as the basis for the written text. It appears that most of the conceptual content should be attributed to Gelfand, while the style, structure, and some of the pedagogy are Aagaard’s.

Teaching Tactical Awareness

This review has been printed in the August 2015 issue of Chess Life.  A penultimate (and unedited) version of the review is reproduced here.  My thanks to the good folks at Chess Life for allowing me to do so.


Schlepütz, Volker, and John Emms. The Chess Tactics Detection Workbook. London: Everyman Chess, 2014. ISBN 978-1781941188. 336pp. PB $27.95.

It is the most common piece of advice given to the amateur player: “if you want to improve your chess, study tactics.” So, like the diligent students we are, that’s what we do.

We slog through pages and pages of bare diagrams, flipping to the back of the book to see what we missed. We try all the web-based tactics trainers, refusing to give in to frustration when our winning-but-not-winning-enough moves are marked wrong for reasons we can’t fathom. We head to our next tournament, chests puffed out and tactical Spidey-sense cranked to 11.

And then we miss a mate-in-two and lose to an eight-year old. And we wonder why on earth we waste our time with this stupid game.

There is little doubt that the study of tactics is indeed necessary, if not sufficient, for chess improvement. Still, those of us who have spent time with Blokh and Brennan and Reinfeld (not to mention know all-too-well the limitations of such study. It’s easy to find a killer shot when you know one exists in the position. It’s much harder when your clock is ticking away and there’s no teacher nudging you towards the correct move.

Not a few authors have made creative attempts to overcome this problem in their books. Some, like Emmanuel Neiman (Tune Your Chess Tactics Antenna) and Martin Weteschnik (Chess Tactics from Scratch), aim to teach you how to decipher typical positions and discover common tactical themes. Others, like Ray Chang (Practical Chess Exercises), broaden the range of exercises, forcing you to look beyond raw tactics in the search for the best move.

With The Chess Tactics Detection Workbook, Volker Schlepütz and John Emms also attempt to teach tactical awareness while avoiding the artificiality of bulk puzzle solving. Readers are presented with the raw scores of 120 games (or fragments of games) played by combatants rated from 1100-1700. They are instructed to play through the games, put on their “tactics detective hats,” and note the points where one or both players missed something. Points are given for each correct answer, and readers are encouraged to keep a running point total.

Here’s an example of a game (#75 in the book) contested between players rated somewhere between 1301 and 1500. What did one or both players miss? Answers at the end of the column.

Decrop,B – Hilven,G [C13]
Brasschaat, 2007

1.e4 e6 2.d4 d5 3.Nd2 dxe4 4.Nxe4 Nf6 5.Bg5 Nbd7 6.Nf3 h6 7.Bxf6 Nxf6 8.Bd3 b6 9.Bb5+ Nd7 10.Ne5 Bd6 11.Qg4 Bxe5 12.dxe5 [*]

I can see how readers would be attracted to this book and its method. Most of the game fragments are short enough to avoid taxing one’s attention, and the points system assists in keeping the reader involved and engaged in solving. There are, however, a few important limitations. Because most of the solving ends with the late opening or early middlegame (full games are given in the solutions), there is little engagement with endgame tactics or broader attacking themes. What’s more, the scent of artificiality is not fully expunged here, as all of the blunders are tactical in nature, and no credit is given for finding positional or strategic mistakes.

Part of me also wonders whether Schlepütz and Emms have really done something new here. Surely we can find precedent for this “unique framework” for tactical training in long-running solitaire chess columns by Danny King or Chess Life’s own Bruce Pandolfini. C.J.S. Purdy recommended covering and guessing the victor’s moves in annotated games back in 1947, something that ChessBase users can easily do by using the ‘training’ tab in the game window.

These caveats notwithstanding, I suspect that class players looking to improve tactically would find The Chess Tactics Detection Workbook useful, as would teachers looking for lesson ideas. Schlepütz and Emms may not have found a true novelty here, but the training method is fresh enough to warrant your consideration.


For White: 11.Qg4? “White started correctly by playing 10.Ne5, but 11.Qg4? doesn’t follow it up accurately. 11.Nxd6+! (2 points) clears the diagonal and 11…cxd6 12.Nxf7! forks queen and rook. After 12…Kxf7 the king has been attracted to a fatal square. 13.Qf3+ forks the king and rook, winning an exchange and a pawn overall. (2 points)” 11.Qf3 and 11.Nxf7 (2 points) are deemed lesser variants of 11.Nxd6!

For Black: 9…Nd7? “allows White to gain material, as shown above (1 point). Instead, Black should play 9…Bd7 (1 point). Earlier, Black should probably avoid 8…b6 which invites tactics by weakening both the a4-e8 and h1-a8 diagonals.”

A Dvoretsky Duo

Dvoretsky, Mark. For Friends & Colleagues: Volume II, Reflections on My Profession. Milford: Russell Enterprises, 2015. ISBN 978-1941270035. PB 360pp. List $29.95, currently list price on Amazon.

Dvoretsky, Mark. Recognizing Your Opponent’s Resources: Developing Preventive Thinking. Milford: Russell Enterprises, 2015. ISBN 978-1941270004. PB 360pp. List $24.95, currently $20ish on Amazon.

Reflections on My Profession is the second volume in Mark Dvoretsky’s autobiographical diptych. In my review of the first book in the series, titled Profession: Chess Coach, I described it as a “memoir of his life in chess.” Reflections on My Profession is a true companion volume to Profession: Chess Coach. The bulk of the book is devoted to explaining – sometimes polemically – what Dvoretsky takes to be best practices for chess coaching and improvement. Reading the two together, we get a more holistic picture of Dvoretsky as a man and as a trainer than we would by reading either by themselves.

Reflections on My Profession consists of a series of essays, with most having been published elsewhere and reprinted here in updated form. There are three main divisions: “Competitions,” dealing with over-the-board play by him or his students; “Chess Literature: What and How to Read,” where Dvoretsky investigates (and in some cases, castigates) recent articles and books of interest; and “Training Mastery,” the bulk of the book, where Dvoretsky lays out the basic tenets of his training methods.

The first section of the book is mildly interesting, but mainly for the analysis. The second and the third sections are, in my opinion, of much greater value. Accordingly I will devote some lines to these two sections before moving on.

In his discussion of chess literature, Dvoretsky points us towards good annotators (Matthew Sadler and Grigory Sanakoev) and calls out charlatans (Hans Berliner). His preface to the Russian edition of John Nunn’s Secrets of Practical Chess is basically a list of book recommendations, and aspiring masters would do well to work their way through his choices.

In an aside, Dvoretsky argues (144) that classic books should be brought back into print, but with a twist. He describes the need for introducing a contemporary co-author who would correct analytical errors and introduce additional material. I suspect that it is not a coincidence that one of his recommended books, Spielmann’s The Art of Sacrifice in Chess, has just been republished by Russell with Karsten Müller playing the co-author’s role. Müller’s additions appear in blue, and he has also added what amounts to another book’s worth of material to the text. It looks promising.

The third section of Reflections on My Profession, devoted to chess training, consists of two main types of chapters. There are ‘practical’ chapters, where Dvoretsky offers readers problems to solve from his famed card index, and there are ‘theoretical’ chapters where he explains the role of the trainer and best practices for improvement.

Perhaps the clearest statement of his vision for chess training comes in the first chapter of this section, “Philosophy of Training Work.” Trainers must work to develop player’s strengths while overcoming their weaknesses. They do so by offering their pupils clear examples or ‘chess images’ for study, and also by providing them problems to solve. Dvoretsky is clear in his belief that chess improvement comes through practice. A good trainer provides her pupils the kinds of exercises that will burnish their strengths and mend their flaws, and it is only through consistent solving of problems that players can hope to obtain better results.

Dvoretsky describes the selection of appropriate problems for solving in “Solve for Yourself!” Most of his discussion, while interesting on an intellectual level, is of little use for the majority of readers. We aren’t strong enough to discern our own weaknesses, and our understanding limits our ability to create material for self-training. The problems used as examples can, however, be salvaged for training purposes. Recently I used five of them to good effect in a session with our Denker representative. Here’s one of them.


“White is up a rook and a pawn, but how can he defend himself from being mated?”

Dvoretsky’s path to chess improvement is not easy. If we leave aside the fact that most of us recoil from the kind of active learning he prescribes, there is still the matter of finding (a) appropriate and (b) sufficient positions. In a previous review I had lamented the fact that for all of his output, Dvoretsky had yet to publish a book of problems specifically for solving. An ambitious reader could mine Reflections on My Profession for suitable positions, as I did with our Denker rep, or she could turn to the second book under review in this essay.

Recognizing Your Opponent’s Resources: Developing Preventive Thinking is a translation of three books that have appeared in German (Aufmerksamkeit gegenüber gegnerischen Möglichkeiten: Trainingshandbuch, Band 1; Ausschlussmethode & Falenspiel: Trainingshandbuch, Band 2; Prophylaktisches Denken: Trainingshandbuch, Band 3). This book, however, appears to have been translated from the original Russian, something that the bibliography (slight as it is) fails to make clear.

If Dvoretsky is known for one concept or insight, it is certainly that of prophylaxis. As he defines it in Secrets of Positional Play, prophylactic thinking is “the habit of constantly asking yourself what the opponent wants to do, what he would play if it were him to move, the ability to find an answer to this question and to take account of it in the process of coming to a decision.” (28) Recognizing Your Opponents Resources is, in a nutshell, a collection of problems for solving that all revolve around prophylaxis.

There are four chapters in this book. Each begins with a small lesson on the chapter’s theme, and this is followed by a batch of positions for solving along with their solutions. “Pay Attention to Your Opponent’s Resources” has 180 problems. “The Process of Elimination” has 106. “Traps” has 36, and “Prophylactic Thinking” has 154. (The polyglots among you will note that the chapter titles correspond rather well with the German titles listed above.) It is basically the puzzle book that Dvoretsky never published, until now.

In each chapter the problems tend to run from easier to harder, where ‘easy’ and ‘hard’ should be understood as being relative to Dvoretsky’s very high standards. Here are two from the chapter on “Prophylatic Thinking.” The first is the 7th in the problem set, while the second is the 152nd. White is to move in both cases.



(Solutions for both problems)

For Friends and Colleagues: Reflections on My Profession is something of a niche publication, and coaches, trainers and Dvoretsky acolytes will make up its main readership. Every 2000+ player looking for training material should pick up Recognizing Your Opponent’s Resources. It’s hard to think of a book that provides the strong player more bang for his improvement buck, and it’s hard to think of another book that treats its topic so well.

You little stinkers…

This review has been printed in the July 2015 issue of Chess Life.  A penultimate (and unedited) version of the review is reproduced here.  My thanks to the good folks at Chess Life for allowing me to do so.


Roycroft, John. Stinking Bishops. self-published. ISBN 978-1-869874-20-9. PB, 84 + xiv pp. Available from USCF Sales ($19.95) and Chess4Less ($10.00).

No one writes chess books to get rich. Sales figures for even the most famous of chess writers pale in comparison to the Franzens and Grishams of the publishing world. Still, most authors expect to make at least a little money on their books. Chess publishing remains a for-profit enterprise, subject to the laws of supply and demand. Cash, as the Wu-Tang Clan said, rules everything around me, and this is why there are always new opening and improvement books being published. They might sell!

Imagine my delight, then, when I read John Roycroft’s Stinking Bishops, an eminently uncommercial work if ever there were one! Stinking Bishops – named after a fetid English cheese that, when cut, resembles a Bishop’s mitre – is an 84 page self-published book devoted to just two endgame positions. Both are presented here, and White is to move in both cases.

‘Unlike bishops’

‘Like bishops’

[Notice anything strange about the second diagram? The double check appears to be impossible, right? Not if (Black was to move) there was a black pawn on e2 that captured a White piece on d1 and promoted to a rook! Odd indeed… but not impossible.]

What’s so interesting about these two positions that they merit such attention? Each one represents the maximum length win for rook, bishop and pawn vs. rook and bishop according to 7-man tablebases (exhaustive databases of endgame positions). It’s White to move and win in 184 moves in the ‘like bishops’ diagram, and a ‘mere’ 159 moves to victory in the ‘unlike bishops’ position.

I know what you’re thinking: “watching paint dry would be more fun than reading this book.” Were this book written by just anyone, you might be right. But John Roycroft is not just anyone, and this is not just any book. Roycroft is the former editor of EG, the world’s definitive endgame and study magazine, and an International Judge of Chess Compositions. He is also familiar with the world of computing, having worked for IBM for many years.

It is easy to dismiss the importance of the ‘oracle’ – Roycroft’s honorific for the tablebase – from a practical perspective. What good is winning in 159 (or 184) moves when over-the-board endgames can be drawn in 50? (USCF Rule 14F, ‘The Fifty-Move Rule’) What’s the point of studying such endgames when no human can possibly remember the exact sequence of moves needed to win?

Roycroft pulls off a very neat trick in Stinking Bishops. He takes the arcane moves given by the tablebase and goes some distance in discerning the hidden logic beneath them. Each position is first presented with a raw list of moves that lead to the forced win, and then Roycroft investigates dozens of the key moves and positions. His notes are witty and wordy, often addressed to an imagined interlocutor, and they effectively assist the reader in grasping the necessity of certain moves as White marches to victory.

In his foreword to the book, Chess Life’s own Daniel Naroditsky congratulates Roycroft for his ability to explain the esoteric moves of the computer in very human ways, saying that he “was unable to put the book down” until he’d finished it! Not all of us are endgame columnists, of course, but Stinking Bishops really is a delightful romp through two (sometimes mind-numbingly complex) endings.

I can’t imagine that this book will sell well, given its topic and that there is no publisher to promote it. Still, I don’t think Roycroft will mind. This was a book written for love of the game, and it will – perhaps with the help of this review – find its way into the hands of those who will appreciate its many, many charms.

And Then There Were Two

Komodo 9, written by Don Dailey, Larry Kaufman and Mark Lefler. Available (1) with Fritz GUI from Amazon ($80ish as of 5/28), (2) for download with Fritz GUI from ($73.50 w/o VAT as of 5/28) and (3) directly from the Komodo website without GUI for $59.98; also available as part of a 1 year subscription package for $99.97.

Stockfish 6, written by the Stockfish Collective. Open-source and available at the Stockfish website.


Now that Houdini seems to have gone gentle into that good night, there are two engines vying for the title of strongest chess engine in the world. Those two engines – Stockfish and Komodo – have each seen new releases in recent months. Stockfish 6 was released at the end of January, while Komodo 9 became available at the end of April from and the end of May from ChessBase.

Last year I wrote a review of Komodo 8 and Stockfish 5 that was republished at, and much of what I wrote there applies here as well. Fear not, frazzled reader: you don’t need to go back and read that review, as most of the key points will be reiterated here.

First things first: any top engine (Komodo, Stockfish, Houdini, Rybka, Fritz, Hiarcs, Junior, Chiron, Critter, Equinox, Gull, Fire, Crafty, among many others) is plenty strong to beat any human player alive. This is not because each of these engines are equally strong. While they don’t always play the absolute best moves, none of the aforementioned engines ever make big mistakes. Against fallible humans, that’s a recipe for domination. It’s nearly useless – not to mention soul-crushing! – to play full games against the top engines, although I do recommend using weaker engines (Clueless 1.4, Monarch, Piranha) as sparring partners for playing out positions or endgames.

Even if all the major engines can beat us, they’re not all created equal. Three major testing outfits – CCRL, CEGT, and IPON – engage in ongoing and extensive testing of all the best engines, and they do so by having the engines play thousands of games against one another at various time controls. In my previous review I noted that Komodo, Stockfish and Houdini were the top three engines on the lists, and in that order. This remains the case after the release of Komodo 9 and Stockfish 6:

CCRL (TC 40 moves/40 min, 4-cpu computers):
1. Komodo 9, 3325 (Komodo 8 was rated 3301)
2. Stockfish 6, 3310 (Stockfish 5 was rated 3285)
3. Houdini 4, 3269

40/4: 1. Komodo 9, 2. Stockfish 6, 3. Houdini 4
G/5’+3”: 1. Komodo 9, 2. Stockfish 6, 3. Houdini 4
40/20: 1. Komodo 9, 2. Stockfish 6, 3. Houdini 4 (NB: list includes multiple versions of each engine)
40/120: 1. Stockfish 6, 2. Komodo 8 (does not yet include version 9), 3. Houdini 4 (NB””: list includes multiple versions of each engine)

1. Komodo 9, 3190 (Komodo 8 was 3142)
2. Stockfish 6, 3174 (Stockfish 4 was 3142)
3. Houdini 4, 3118

The results are fairly clear. Komodo 9 is ever so slightly stronger than Stockfish 6 when it comes to engine-engine play, and this advantage seems to grow when longer time controls are used.

For my purposes, though, what’s important is an engine’s analytical strength. This strength is indicated by engine-engine matches, in part, but it is also assessed through test suites and – perhaps most importantly – by experience. Some engines might be more trustworthy in specific types of positions than others or exhibit other misunderstandings. Erik Kislik, for instance, reports in his April 2015 Chess Life article on the TCEC Finals – some of which appeared in his earlier Chessdom piece on TCEC Season 6 – that only Komodo properly understood the imbalance of three minor pieces against a queen. There are undoubtedly other quirks known to strong players who use engines on a daily basis.

In my previous review I ran Komodo, Stockfish and Houdini (among others) through two test suites on my old Q8300. Since then I’ve upgraded my hardware, and now I’m using an i7-4790 with 12gb of RAM and an SSD for the important five and six-man Syzygy tablebases included with ChessBase’s Endgame Turbo 4. (Note: if you have an old-fashioned hard drive, only use the five-man tbs in your search; if you use the six-man, it will slow the engine analysis down dramatically.) Because I have faster hardware I thought that a more difficult test suite would be in order, and – lucky me! – just such a suite was recently made available in the TalkChess forums. I gave Komodo 9 and Stockfish 6 one minute per problem to solve the 112 problems in the suite, and the results were as follows:

Komodo 9 solved 37 out 110 problems (33.6%) with an average time/depth of 20.04 seconds and 24.24 ply. Stockfish 6 solved 30/110 (27.2%) with an average time/depth of 20.90 seconds and 29.70 ply. (Note that while there are 112 problems in the suite, two of them were rejected by both engines because they had incomplete data.) The entire test suite along with embedded results can be found at:

I have also been using both Komodo 9 and Stockfish 6 in my analytical work and study. So that you might also get a feeling for how each evaluates typical positions, I recorded a video of the two at work.  Each engine ran simultaneously (2 cpus, 2gb of RAM) as I looked at a few games of interest, most of which came from Alexander Baburin’s outstanding e-magazine Chess Today. The video is 14 minutes long. You can replay the games at this link:

Komodo 9 and Stockfish 6 in comparative analysis

Even a brief glance at the above video will make clear just how good top engines are becoming in their ability to correctly assess positions, but it also shows (in Gusev-Averbakh) that they are far from perfect. They rarely agree fully in positions that are not clear wins or draws, and this is due to the differences in evaluation and search between the two. Broadly speaking, we can say that evaluation is the criteria or heuristics used by each engine to ‘understand’ a position, while search is the way that the engine ‘prunes’ the tree of analysis. While many engines might carry similar traits in their evaluation or search, none are identical, and this produces the differences in play and analysis between them.

Stockfish 6 is a rather deep searcher. It achieves these depths through aggressive pruning of the tree of analysis. While there are real advantages to this strategy, not the least of which is quick analytical sight and tactical ingenuity, there are some drawbacks. Stockfish can miss some resources hidden very deep in the position. I find it to be a particularly strong endgame analyst, in part because it now reads Syzygy tablebases and refers to them in its search. Stockfish is an open-source program, meaning that it is free to download and that anyone can contribute a patch, but all changes to evaluation or search are tested on a distributed network of computers (“Fishtest”) to determine their value.

Komodo 9 is slightly more aggressive in its pruning than is Komodo 8, and it is slightly faster in its search as well. (Both changes seem to have been made, to some degree, with the goal of more closely matching Stockfish’s speed – an interesting commercial decision.) While Komodo’s evaluation is, in part, automatically tuned through automated testing, it is also hand-tuned (to what degree I cannot say) by GM Larry Kaufman.

The result is an engine that feels – I know this sounds funny, but it’s true – smart. It seems slightly more attuned to positional nuances than its competitors, and as all the top engines are tactical monsters, even a slight positional superiority can be important.  I have noticed that Komodo is particularly good at evaluating positions where material imbalances exist, although I cannot say exactly why this is the case!

As more users possess multi-core systems, the question of scaling – how well an engine is able to make use of those multiple cores – becomes increasingly important. Because it requires some CPU cycles to hand out different tasks to the processors in use, and because some analysis will inevitably be duplicated on multiple CPUs, there is not a linear relation between number of CPUs and analytical speed.

Komodo 8 was reputedly much better than Stockfish 5 in its implementation of parallel search, but recent tests published on the Talkchess forum suggest that the gap is narrowing. While Stockfish 6 sees an effective speedup of 3.6x as it goes from 1 to 8 cores, Komodo 9’s speedup is about 4.5x. And the gap is further narrowed if we consider the developmental versions of Stockfish, where the speedup is now around 4x.

Hardcore engine enthusiasts have, as the above suggests, become accustomed to downloading developmental versions of Stockfish. In an effort to serve some of the same market share, the authors of Komodo have created a subscription service that provides developmental versions of Komodo to users. This subscription, which costs $99.97, entitles users to all official versions of Komodo released in the following year along with developmental versions on a schedule to be determined. Only those who order Komodo directly from the authors are currently able to choose this subscription option.

The inevitable question remains: which engine should you choose? My answer is the same now as it was in my previous review. You should choose both – and perhaps more.

Both Komodo and Stockfish are insanely strong engines. There remain some positions, however, where one engine will get ‘stuck’ or otherwise prove unable to discern realistic (i.e. human) looking moves for both sides. In that case it is useful to query another engine to get a second (or perhaps even third) opinion. I find myself using Komodo 9 more than Stockfish 6 in my day-to-day work, but your mileage may well vary. Serious analysts, no matter their preference, will want to have both Komodo 9 and Stockfish 6 as part of their ‘teams.’