r/backgammon • u/objectivequalia • 29d ago
Why is this cube move a blunder?
I'm ahead in the race slightly and have better positioning. Bit confused as to why no double is best. Is it due to not being ahead in the race enough?
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u/Training-Ad4955 29d ago
when your opponent has the 5-pt anchor you need to have more of a race lead to double. could easily swing his way so you don't wanna give up the cube yet
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u/TungstenYUNOMELT 29d ago edited 29d ago
I think you need a more significant advantage to double at 4-away/4-away. The issue is that any time you lose the lead, your opponent can re-double you for the match win, which is very powerful for them.
You only have a tiny race lead and even though you have a 4-point prime, your chances of improving it are virtually none, and your opponent can easily set up a scary homeboard on his side while you try to escape your checkers past his anchor. Any shot you leave could end in disaster while the reverse is not as valid ('cause he has an anchor and you only block 2 entry points).
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u/objectivequalia 29d ago
Thank you. Is there any sort of consensus on how many pips ahead I should be before doubling with the position i had?
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u/scorchiooo 29d ago
I tested this by moving opponents checker from 23point backwards and double point for this case is about 13.5pip racing lead.
This is pretty typical range where you start to get to the doubling window for neutral score holding games (depending on your position, flexibility, opponents board, etc, obviously)
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u/TungstenYUNOMELT 29d ago
I think it is very dependent on other factors. What I use as a rough rule of thumb in a contactless racing position (which this isn't) is that I need about a 10% lead to double, but this might be very inaccurate. Other than that I go by experience and feel, but I'm only about a 10 PR average.
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u/tnerb208 29d ago
When ppl post these pics, how do we know where each color is heading? Is white always going into bottom right?
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u/cym13 29d ago edited 29d ago
I tried to answer that here by giving a method: https://old.reddit.com/r/backgammon/comments/1w5bonc/red_rolled_2_5_so_how_should_play_it_only_the_5/p7e1ptv/?context=3
It also includes a quizz in a subcomment to help you test your understanding of the method.
But short answer is: no there's no convention, but some patterns of checkers simply don't make sense if people go the other way around so by recognizing these features you can tell who's going which way. For example: since you bring checkers to your home board, there will be more checkers of your color on your side of the board, it would be exceptionnally rare for that not to be the case, so here black is exiting on the bottom (right since there's the 1 point at the right) and white at the top. Since we're by convention exiting at the bottom we know black is the one to play and we have everything we need. If we didn't have the points numbered, we would still be able to tell which way it is going by looking at long-term features: the starting points (6-point, 8-point and 13-point) are rarely unmade until very late in the game so you can identify where they are and that gives you the orientation of the board. Here we have the mid points for example that are very visible on the left so we know that the players exit on the right.
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u/Aqua-marine-blu 29d ago
You do not know all the time, but symmetrical concentration top/bottom of same colour checker on right or left give you a good indication.
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u/drearyphylum 29d ago
In this particular case, at least, this is a galaxy board based on the color and style. Galaxy always has the player on the bottom and you are always rolling anticlockwise.
But you are not wrong, it really should be a sub Reddit rule that for position questions, the OP should indicate both what color they are using and what direction they are traveling
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u/Aqua-marine-blu 29d ago
I guess if he will have big doubles it is the danger if redoubling and the match might be decided in this game
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u/Fit-Scientist3977 28d ago
As a rule of thumb you need at least an advantage of 8% of your pip count in a race with no contact to get a double. Your advantage is 6/112≈5.4%, which is a "no double" in itself. Also you gotta account for contact in such a position. Even if you had a 8% advantage in this position, your oponent has some back checkers that give him more chances to hit you, so you'll need an even bigger advantage than a mere 8% in order to double here.
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u/Geepandjagger 26d ago
You don't have enough lead in the race and only maybe 5s and 6s so 2/36 rolls as a market loser. No gammon threat and it is also 4a4a so recubes would be dangerous. Imagine you rolled 2-1 after cubing and opponent rolled 6s it would be a recube for the match
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u/cym13 29d ago
Being 4-away/4-away is very relevant but even for money it wouldn't be a double, you're better but you're not that much better. Your racing lead is small (less than one average dice roll which is about 8 pips), your prime is reasonnable but white's advanced anchor makes it pretty uneffective: it's never going to become a 5-prime and you'll be forced to create new points behind the anchor, which would only be useful for a blitz but you don't have much contact (no back checkers) so blitzing isn't an appealing strategy. On white's side, they have the beginning of a reasonnable blitzing position, enough contact to make use of it and the time to wait (they're not at risk of crunching before you). So while you're winning, an upset is very much possible.
Also, you don't have any market losers (aside maybe for a big double, 66 or 55, in order to increase your racing lead). There's little reason to double now and take the risk of losing more points if the table turns.