the dorbel daily

Friday, 21 October 2011

Three Puzzles

There's a great temptation when writing about bg to highlight extremely rare positions where the right play is an elegant and counter-intuitive gem. As the chances of ever seeing anything like it again are vanishingly small, we don't add much to our store of knowledge, although I suppose anything that leads to our viewing backgammon as a never-ending series of puzzles is a good thing. Here's three fairly ordinary looking positions. How would you approach these? They are all from a five point match. In the first it's no score and Black has to play a 4-3.

In Position 2, Black leads 3-away, 5-away and has to play 4-4 from the bar.

Finally, same score and Black is on the bar again with a 6-2 to play.

There's no particular trick to these, but they do have a common theme. Well they have two things in common actually, I butchered all of these as Black!

Let me have your thoughts please and I'll discuss them in full in the next post.

Mochizuki Masayuki v. Matvey Natanzon, a 13pt IIBGF Match.
Mochizuki Masayuki v. Carlo Melzi, a 13pt IIBGF Match.
The XG files for these matches, annotated by me and approved by Mochy are now available, $10 each. Gnu and Snowie users can have a Gnu file with the commentary on a separate word doc. Both matches show brilliant play at the highest level and are very instructive for students at all levels.
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Until tomorrow, enjoy the game!


ah_clem said...

1)The automatic play is to make the anchor. QF tells me this is incorrect, but I'm not seeing much of anything else. Hitting loose on the three point seems overly risky since black is outboarded. As for the four, 6/2 minimizes shots, but prematurely burries a checker - once we've made the advanced anchor we can afford a more aggressive play. 11/7 slots a valuable point, but exposes X to a double direct shot which seems too aggressive. That seems to leave 13/9 - this unstacks the midpoint, and keeps the checkers in front of White's runners where they belong. It's the medium aggressive play, so I'll channel Goldilocks and declare it just right.

24/21 13/9

2) Classic pure play would be to knock white off the golden point by hitting loose. But I see that Black will be ahead by about 25 pips ofter this play, so I'll just try to win going forward instead of fighting for the five point.

So, I enter with one four (forced). Then I have a choice of making the 4 or the 9 - the 9 is better for blocking, but the 4 is a permanent asset so I'll take that instead. For the final four, I'll just quietly ylay to the 2, unstacking the six and slotting a homeboard point. bar/21 8/4(2) 6/2

3) Slot the bar or run the checker on the 21? The only other choice is 8/2 which can't be right (expose another blot, burry a checker). I'll run - If I escape, great, if not I'm still likely to make the anchor. Slotting the bar and letting White escape with tempo seems like the wrong idea, but it does unstack, so that might compensate for leaving the extra blot. bar/23 21/15

Timothy Chow said...

1. We don't have a good 4 to play whether or not we anchor, so I definitely anchor here with 24/21. Then we have to choose among 13/9, 11/7, and 6/2. 6/2 minimizes shots (16) but is anti-positional and leaves only 2 fewer shots than 13/9 so I don't think it can be better than 13/9. 11/7 leaves only one blot and slots a nice point but leaves 25 shots. I don't see any meaningful duplication that would mitigate these 25 shots. I would play 24/21 13/9.

2. Bar/21 is forced and then for the next two 4's it looks like we should decide whether to hit or to play 8/4(2). The hits don't look like they gain enough compared to 8/4(2) so I play 8/4(2). For the last 4, we have the same three choices as in Position 1: 13/9 or 11/7 or 6/2. Dumping with 6/2 again looks the least attractive; that blot on the 2pt might look "safe" but it won't be safe in the upcoming blot-hitting contest. Here, 11/7 duplicating White's 4's and 2's to hit while leaving only two blots looks better to me than 13/9. So: bar/21 11/7 8/4(2).

3. 8/2 can't be right so the choice is between 21/15 and 13/7. The running play 21/15 boldly steps into a triple shot, but we are ahead in the race and we have the stronger board so it should be considered carefully. But I don't really see that there's enough compensation for all those shots so I play bar/23 13/7.

poppp said...


1) 24/21 6/2 safest plus anchor
2) bar21 8/4(2) 11/7 leaving 2 direct hits. If I'm hit I'm hoping to make an advanced anchor … at least i've improved my board. it's very early in the game so let's fight to stop an advanced anchor on my 7pt

3) bar/23 13/7 hoping to blitz if i'm not hit. if I run most throws put me back on the bar.