A top backgammon Giant described the recent match series between Cary Hoarty (USA, age 20) and Kentaro Meijo (Japan, age 16) as some of the best backgammon he had ever seen, while world #1 and commentator on the match, Masayuki Mochizuki (Mochy) lamented surely, given their strength at such a young age, he would soon become a dinosaur of the game!
In the UK we are lucky to have some young players who consistently perform at a world-class level. One of them has shared their thoughts from the match series, below. However, there are fathoms-too-few when compared to the depth of young player talent in games such as Go and Chess, and raising awareness of the game and its youth profile can only help to encourage new players to get involved and stay interested.
You can find the Hoarty v. Meijo video on YouTube, however in order to share some interesting and useful learning opportunities I asked four top UK players to select a play, each from a different match, and to provide a brief analysis highlighting an error, a brilliancy, or anything else of note. I think you are in for a treat.
Match 1 – Commentary by Tim Cross, BMAB Grading G3 (PR 3.68), current UK Open champion, UK national team
The quality of play in the recent Mochy Challenge between Cary and Kentaro was excellent, with both playing under PR 4 overall [For the series, PR av. Cary 3.57, Kentaro 3.72]. Watching the match, it was noticeable how many times the players found the correct move whilst the online kibitzers had agreement on the wrong move, but in this instance, I want to draw your attention to a rare blunder from Cary.
In this position Cary has a 51 to play. Cary’s style in the match was extremely aggressive, slotting much more often than splitting in the opening rolls which made his eventual play [13/8 6/5] even harder to understand. The 1 of course is obvious, covering the 5 point, but what to do with the 5. The answer almost always in the early game when you have a slight advantage is to be aggressive, therefore playing 8/3* is correct, rather than the conservative 13/8 which gives time for Kentaro to consolidate, the idea being that by hitting you may deliver a quick knockout blow but even if hit back you are in no trouble. The fact that Cary was trailing -7 -4 at this moment makes the need for aggressive play even more important. I recommend anyone of any level reading the excellent book ‘Opening Concepts‘ by Michihito Kageyama (Michy) and Roland Herrera because the opening moves are ubiquitous and set the stage for the game to come.
Match 2 – Commentary by Oliver Squire (age 19), BMAB Grading M2 (PR 5.01), UK national online team
This position stuck out to me just because of the size of the blunder it is to hit over making the 5 point (hitting is 4.75 times a blunder).
This speaks volumes about the importance of knowing what your game plan is, which Cary clearly did here as he made the 5 quickly.
Since Meijo has his 1 point made, his blitz value increases but his prime value decreases. This along with the fact Cary is down in the race suggests that he would like to play a prime v. prime game where he has the advantage. Hitting on the other hand would play right into Meijo’s hands, since he has a blitz position (stronger home board, ahead in the race, impure points made).
Another factor contributing to the size of the blunder is the level of freedom we achieve if we are successful in getting missed next roll. We still have a long way to go to achieve full freedom with our back checkers.
Next is a variation on the position, where it becomes a blunder to make the 5 point instead of hitting.
If we are successful here post-hit, we have achieved full freedom with our back checkers, turning this game into a defined state position.
This is a standard position that I’m sure most of you know. It’s a borderline redouble/take for money and the equities are almost equal here at -7 -7. What you may not know (I haven’t heard it talked about very often), is that this position is a blunder to take at -5 -5 (also a drop at -3 -3). This is due to the fact that Meijo’s recube value is significantly reduced because of the match score overflow I.e. we only need 5 points to win at -5 -5, not 8.
Match 3 – Commentary by Julian Fetterlein, BMAB Grading G3 (PR 3.87), Founder of Backgammon Workshop
Should White (Cary) recube to 4?
Mochy felt White should play on as a gammon (G:48.06%) would take him to one away from victory. Marc was unsure, citing it might be different if White was trailing in the score rather than leading -5 ‑6. Unsurprisingly, Mochy was correct and it is wrong to redouble at this score. It is also wrong to redouble if White trails -5 -4.
How can you get to make the right decision as Mochy frequently does? The answer is surprisingly easy and what I call the “Gammon Price Ratio” or GPR for short. First you need a way to know the gammon price at your score. Three simple rules do the job …
- High gammon price if it takes you to Crawford
- Highest gammon price if it wins the match exactly
- Only one point of overage negates this.
As Mochy says, at this score a gammon with the cube on 2 will take us to Crawford, so we know the gammon price is high. Turning the Cube to 4 will give us three points of overage if we win the gammon; we devalue our gammon by cubing. If cubing reduces your gammon price it is often right to play on without doubling.
ATS (-5 -6) No redouble 0.981 is better than RDT 0.837
@ -5 -4 No redouble 1.281 is better than the opponent passing our recube.
@-11 -11 No redouble 1.039 is better than the opponent passing our recube.
Match 4 – Commentary by Lawrence Powell, BMAB Grading M1 (PR 5.14), UK national team, 3rd place in 2018 World Backgammon Championship
Prime v. Prime
The following position arose with Cary leading -3 -5. With a 6 prime and the strong threat of escaping via Kentaro’s 5 point the double is clear.
A good rule of thumb when being doubled in a prime v. prime position is that it is always a take. Whilst this is an exaggeration the natural instinct is to look at the negative sequences and drop like a shot. One has to recognise that when your opponent is shooting at one escaping number, they may not get it for a significant time. This will often give you reasonable chances. One learns to ignore the fear and take.
This is often the case even with a major defect in one’s position. I think this is why Kentaro steeled himself to take, as well as not having much time to consider all aspects [Kentaro had 1.26 remaining on the clock, 55 seconds after the take]. This and the score where he is behind and his opponent is 3 away so gammons are not so painful as they are not efficient for one’s opponent. The problem is there are a couple of clear defects and a more subtle one.
Timing: The major aspect to look at is timing which is roughly the number of spare pips of the checkers not in the prime, possibly adjusted if high numbers start getting blocked. At first glance it looks as though Cary only has 11 pips waiting for his escaping number. However, because Kentaro’s back checkers are not at the edge of the prime then Cary’s checkers on the 8 point are also pretty much available which makes a big difference. It should be mentioned that, although inflexible, Kentaro also has a fair bit of timing in his checkers on his 8 point.
Flexibility: Kentaro’s front position is inflexible, particularly with the dilly builder on his 3 point. Apart from being awkward it means the chances of equalising by making his 5 point are slim.
Opportunity: A more subtle weakness is that, as well as a 4, if Cary gets a 1 then he has both 3s and 4s to escape. There is not the risk of being attacked and closed out when splitting with the 1 due to his own 6 prime.
Having pointed all this out the take does look reckless and many players would not even consider a take. However, I think it will be instructive to present 3 adjusted positions to show why a top player could fall into this trap when thinking quickly.
If we move blacks back checkers up to his 23 point, then it is barely a double and a very big take.
If black closes his 2 point whilst maintaining the same pip-count and timing it becomes a very big take even with the back checkers not being at the edge of the prime. Admittedly this position also increases flexibility and chances of closing one’s 5 point.
In fact, just increasing flexibility and 3 pips more timing and it is pretty much a take even with the other two weaknesses. Increasing the timing/flexibility anymore it is an easy take and even a no double if bringing the spare on the 21 point back above the 5 point.
I think many players would drop some or all of these 3 adjusted positions and they show why the rule ‘prime v prime is always a take’ is generally a good one.
Here Kentaro, black, has a 44 to play. In a blitz position, particularly having made the 1 point, it is usual not to worry about making points in order. Whilst the higher points are still preferable this is usually offset by having more builders trained on the higher points to make those points afterwards.
In the current position XG sees the actual play making the 2 point a serious blunder. Why?
A reason is that one is blitzing only one checker and without much outfield cover having lost the mid-point. One has only 2 or 3 made points after the play so entry is likely. Thus, one is having to attack on the next roll most of the time and burying another couple of checkers on the 2 point takes away a lot of that attacking power, particularly reducing pointing numbers. Having another checker sent back if forced to hit loose would be a major setback. Further, one is trying to blitz with an eye on containment. This means higher points in board do have a higher value and also points in the outfield are still useful.
Another factor is that one has 4 checkers back in the opponent’s home board, so a complete close-out is impossible without them and they need escaping at some point. A large double like this allows one to escape a checker and bring it to help where the action is.
Another exception to the normal rule of thumb which helps maintain the interest of the game.
Thank you to Tim, Oliver, Jooles, and Lawrence, your contributions were insightful and very much appreciated.
Cary and Kentaro both played at a very high level, clearly their future backgammon careers are bright, but they also made mistakes, and if you watch the recorded live stream you will see they both at times played under significant time pressure. In match 1 Cary started game 5 with 11 seconds on the clock. Of course, Cary won it using only 4 of those 11 seconds! Their performances felt real by which I mean human and relatable. In the post-match interview Kentaro identified a lack of focus towards the end of the series and a fundamental misunderstanding of a prime v. prime position (as picked out by Lawrence) that may have cost him the win. Mochy recommended that Cary spend more time studying the opening moves and balancing his aggressive style with correct play. We can all work on our game, that’s what makes it so fascinating.
Bring on the next Challenge!
The analysis above was based on the original match files, below and/or rollout data generated by the contributing authors. [Match files were made publicly available by Mochy/Backgammon Galaxy]
Image credit: Mochy Challenge 2 featured image courtesy of Backgammon Galaxy.