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Backgammon => Backgammon problems => Topic started by: dorbel on June 23, 2015, 12:16:25 PM

Title: Bundalongadorbel
Post by: dorbel on June 23, 2015, 12:16:25 PM
This is going to be a thread, to which I hope to contribute every day, featuring an interesting match position. As soon as I can figure out how to show the position, I'll be right back!
Title: Re: Bundalongadorbel
Post by: dorbel on June 24, 2015, 10:37:18 AM
And here is the position. White to play 5-3, score 0-0 to 13. White can make his 3pt or he can hit loose. Which is right?
Title: Re: Bundalongadorbel
Post by: dorbel on June 25, 2015, 03:12:00 PM
White to play 5-3. 13/5* is right and 8/3, 5/3 is a small error. The idea is to take away half of Black's next roll and of course a lot of the equity swing comes from turning Black's 6-6 from best roll to worst roll. Black is a favourite to hit back, but a lot of the rolls that hit would play well anyway, so it isn't a disaster. When Black can't hit, White is on roll with his 5pt slotted, always nice.
Hitting is also correct at dmp and gammongo and by a small margin at gammonsave as well. However, a beginner/intermediate playing an expert might do quite well to choose the simpler 8/3, 5/3, but beginners that know how to vary their play for stronger opponent's are rare birds indeed.
Over the board, I chose to hit, but I already knew it was right, so no thought required.

Here's one I got wrong. White to play 4-3. The score is still 0-0.

Title: Re: Bundalongadorbel
Post by: dorbel on June 26, 2015, 02:43:51 PM
Yesterday's position looks as if there isn't much happening, but it does illustrate an important theme. It's important for White to get he blot on his 24pt into play, so that he can hit from there (if he gets the chance) without breaking his anchor. So 24/20 is the important bit and then you can choose a three. I selected the second best play, 11/8, but it doesn't apply much pressure and 6/3* is correct. My play is right at gammonsave, which implies that I am not playing aggressively enough. "When in doubt, hit" remains one of bg's enduring guidelines.

Later in the game, we got to this next position, where White has to think about cubing. It's a monster pass of course, but is it too good? We'll see tomorrow.
Title: Re: Bundalongadorbel
Post by: dorbel on June 27, 2015, 02:22:21 PM
The right answer for yesterday is actually double/pass, with playing on having an equity of .982 compared to the equity of 1.0 for cashing. The question of whether to cash this sort of position or play on is always hard to answer. If I'm not sure I usually double anyway, putting a point on the score sheet that I don't have to earn with good play, but I guessed that this was much too good, wrongly. This is a reference position if you like to keep them, one where the equity is almost the same regardless of what you do.
Things went well for a while, but then Black managed to hit back during a fight for White's 5pt. With both sides having a man on the bar, what is the right cube action here?
Title: Re: Bundalongadorbel
Post by: socksey on June 27, 2015, 03:40:34 PM
White has a far better board and easy out so I would go with a cube.


Title: Re: Bundalongadorbel
Post by: dorbel on June 28, 2015, 09:44:45 AM
White should indeed double from the bar, even entering without hitting is a market loser if Black dances and for Black, this is a very big pass. Black actually wins this about one game in 3, but loses a huge 43% gammons. In the match I cashed and led 1-0 to 13.
Boards too dark and hard to see? Here's a new one.
In game two, Red rolled 6-4 and made her 2pt. Once upon a time this was the play that marked you as a fish, but times have changed and this is now correct at gammongo and other scores where the player trails. How should White respond with his 3-2?
Title: Re: Bundalongadorbel
Post by: dorbel on June 29, 2015, 11:50:31 AM
So, White to play 3-2. The temptation is to split at the back, working towards securing a high anchor, but 13/10, 13/11 is best by a very small margin. Because Red has made her 2pt, it's going to be very hard for her to make a containing blockade. The 2pt and the 8pt can't be part of the same prime, so no hurry for White to split. Splitting actually plays into Red's hands, as it gives her targets to attack and blitz, where her 2pt will be useful.
I played 24/21, 13/11, but that isn't even the best split, as it moves to a point that Red would prefer as a target. 24/22, 13/10 is the best split. The match play is a small mistake, -0.028ppg.
The rest of game 2 proceeded along uninteresting lines and I eventually cashed to lead 2-0 to 13.
In game 3 we arrived at the position below, White on roll and contemplating a cube. What's the correct cube action for both sides here?

Title: Re: Bundalongadorbel
Post by: NIHILIST on June 29, 2015, 07:44:24 PM
This thread is like the sound of one hand clapping.

Bob
Title: Re: Bundalongadorbel
Post by: stog on June 29, 2015, 08:48:33 PM
the thread or your post Nihole?

they are interesting positions and thoughtful commentaries

why not contribute some of your own instead of vacuous criticism
Title: Re: Bundalongadorbel
Post by: TimDugan on June 29, 2015, 10:48:03 PM
My play would be a double/take ... anyone else?
Title: Re: Bundalongadorbel
Post by: NIHILIST on June 30, 2015, 05:29:52 AM
Stog writes 
Quote
they are interesting positions and thoughtful commentaries

why not contribute some of your own instead of vacuous criticism

They may be interesting positions, but I don't see much in the way of commentary except that of the author. I only can hope he doesn't get bruised patting himself on the back.

I have contributed what I consider to be thoughtful commentaries on many occasions which have often been greeted by vacuous criticism, some of it your own. I don't recall you ever inserting yourself to chastise any of my critics.

No harm, no foul, or, in the words of a former client, NEVER EXPLAIN, NEVER COMPLAIN.

BTW, if I had referred to dorbel as DIMBELL or DORKBEL, no doubt you would have censored that. I guess you feel that only you can use derogatory names without fear of censorship. It's a cheap shot which in my opinion demonstrates your own brand of hypocrisy and is unworthy of anyone claiming to be an impartial moderator of debate and discussion.

Bob
Title: Re: Bundalongadorbel
Post by: PersianLord on July 01, 2015, 10:06:42 PM
StogNihole writes  
They may be interesting positions, but I don't see much in the way of commentary except that of the author. I only can hope he doesn't get bruised patting himself on the back.

I have contributed what I consider to be thoughtful commentaries on many occasions which have often been greeted by vacuous criticism, some of it your own. I don't recall you ever inserting yourself to chastise any of my critics.

No harm, no foul, or, in the words of a former client, NEVER EXPLAIN, NEVER COMPLAIN.

BTW, if I had referred to dorbel as DIMBELL or DORKBEL, no doubt you would have censored that. I guess you feel that only you can use derogatory names without fear of censorship. It's a cheap shot which in my opinion demonstrates your own brand of hypocrisy and is unworthy of anyone claiming to be an impartial moderator of debate and discussion.

Bob

We salute you Leviathan.

-------

stog: this user is now banned
Title: Re: Bundalongadorbel
Post by: stog on July 02, 2015, 04:43:12 PM
Nihole writes

Quote
I guess you feel that only you can use derogatory names without fear of censorship. It's a cheap shot which in my opinion demonstrates your own brand of hypocrisy and is unworthy of anyone claiming to be an impartial moderator of debate and discussion.

1/ I am not a Moderator I run this site and 2/ I am not impartial

and for someone who dishes out sh** you seem to be extremely thin skinned when some of it splashes on you and 3/ you are banned reason -- Negativity and trying my time/patience.
Title: Re: Bundalongadorbel
Post by: OLIN on May 22, 2019, 10:37:51 AM
The theme of whether to cash this sort of position or play on is for each situation difficult to answer. In the event that I don't know I regularly twofold at any rate, putting a point on the score sheet that I don't have to win with incredible play, yet.
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