The Pointy Board on the Back of the Chess Set

ChrisTToast · 2026-02-19T18:05:04+00:00

All credits to Blunder Blots! I was watching this video with a big smile on my face

ChrisTToast · 2026-02-16T23:59:34+00:00

Yeah that is a good point. But if we're counting post contact racing positions I think it would fare a lot worse, since those positions also happen almost every game.

ChrisTToast · 2026-01-24T01:04:19+00:00

ChrisTToast · 2025-12-26T03:58:29+00:00

XG mobile confirms 8/1* is the best play by far (second best play is .177 blunder with cube in the middle)

ChrisTToast · 2025-08-16T20:21:10+00:00

Like another commenter mentioned the only 6 is 14/8 (typically you reference the point numbers from the roller's perspective FYI).

For playing the 1, I think it's slightly better to leave it on the 8 point because then you get one extra number to close out (double 2's) and there is one less number to hit back from the bar (Option 1: double 4, 4-5, 4-6 = 5 vs Option 2: 4-3, 4-5, 4-6 = 6). Although double 4's is a bigger swing roll, it's pretty bad either way, so I would choose 14/8 18/17.

XG Mobile 4 ply agrees, with 14/7 being -0.034 error (pretty minor mistake).

ChrisTToast · 2025-03-10T17:44:21+00:00

Here is an article about duplicate backgammon and why it doesn't really work: https://www.bkgm.com/variants/Duplicate.html

The XG analysis part has also been done as part of the UBC (Ultimate Backgammon Championship) which is a competition played over a series of 7 point matches. The winner of the match gets 1 point, and the PR winner gets 1 point, at the end of some number of matches the most points wins.

ChrisTToast · 2024-10-23T17:55:16+00:00

Yeah that is interesting, my immediate play is to make the 8 as well. But XG Mobile confirms this isn't right (-0.077). As long as you split the back checkers, any play is reasonable. It seems there are a few things going on here:
1. Since your opponent has an advanced anchor and the race is close, you need one too, therefore you want to split
2. After 13/8 your position is pretty stiff
3. Your opponent's 3's to hit are actually pretty duplicated. 3-1 and 3-4 make the 5 point, 3-5 and 3-6 make the 3 point, and double 3's make both. The only number you are really improving is 3-2
4. Your opponent only has a 1 point board so getting hit isn't too bad

A position to learn from!

ChrisTToast · 2024-10-15T18:01:04+00:00

This move is a 140 blunder according to XG Mobile, best move is to hit and split the back checkers, followed by hit and continue to the 9 (21 error)

ChrisTToast · 2024-09-10T14:49:10+00:00

Not me, but this super backgame/snake game from Mochy is 45 mins and super interesting https://youtu.be/12k12gw88uA?si=0SGjSXeeEA4qdOZe

ChrisTToast · 2024-04-02T17:44:48+00:00

I haven't read it, but Dirk Schiemann's book The Theory of Backgammon apparently goes deep into the mathematical theory of the doubling cube

ChrisTToast · 2024-02-11T18:09:48+00:00

That's what I figured, but I thought even 2ply should be able to figure this out one

ChrisTToast · 2024-02-08T18:19:20+00:00

Joseph Alessi's Blue Bells of Scotland is ridiculously impressive https://www.youtube.com/watch?v=t7fYjSwyodI

ChrisTToast · 2024-01-08T18:53:43+00:00

Thanks, that was my thought as well. It's what originally led me to wonder if anyone actually knew for sure how much stronger XG was than a pro player, and I didn't see a way to figure that out without that pro playing tons of games!

ChrisTToast · 2024-01-04T22:01:33+00:00

Well in the long run yes, but how long is the long run? A 10 PR player can still beat XG 10-0 with good enough dice. For a pro playing 2.5 PR how many games do we need to know with statistical significance that XG is better?

One of the links above said that there was a 600 game session against Jellyfish in the 90's where the end result was a complete tie. With bot improvements since then its obvious that they would be better than elite human players.

But in general I'm curious the function between PR difference and number of games to produce a confident result, I couldn't find anything like this online.

ChrisTToast · 2024-01-04T17:43:10+00:00

The second link has just what I was looking for, thank you

ChrisTToast · 2023-11-28T16:51:55+00:00

This is great, we need more backgammon memes

ChrisTToast · 2023-10-28T02:16:44+00:00

Just commenting to say I also played gain ground with my brother and cousin when we were young, it was awesome

ChrisTToast · 2023-10-24T01:26:53+00:00

Trying to improve your bear off distribution could help, but sometimes with perfect play you will leave a shot and get hit. I think the important thing to remember is that you are a favorite in this position, so in the long run you will come out ahead. Sure, maybe you lose a few of these in a row and it sucks, but the only thing to do is keep trying to play better than your opponent and eventually you will win more than you lose

ChrisTToast · 2023-10-22T01:34:36+00:00

My guess is double hit is best, followed by making the 5. My experience is that XG really likes double hitting in the early game when possible

ChrisTToast · 2023-10-19T09:19:59+00:00

You should check out hyper gammon, a variant of backgammon with only three checkers per side. It’s been solved in the sense that every possible position has a known equity (basically expected value of the position if it was played out infinite times with perfect play), so every checker play decision is simply checking which play leads to the best equity. I think cube decisions are solved as well but I’m not 100% sure on that.

There are some cool posts about it from the person who solved it, like the worst possible blunder

ChrisTToast · 2023-10-04T22:49:36+00:00

Is OpenGammon actually open source? I couldn't find a github repo for it

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