| |
BGonline.org Forums
Intermediate version (was: New Paper on Opening Replies)
Posted By: Axel Reichert In Response To: New Paper on Opening Replies (phil simborg)
Date: Sunday, 16 April 2017, at 10:45 a.m.
Hi Phil,
this reply admittedly comes very late, but somehow I overlooked Jeremy's fantastic article http://www.fortuitouspress.com/replies for two years. Then I searched for discussions about his work, found your article as well, and could not agree more. Hopefully late is better than never:
When I read about "Bagai's Replies Surprise", I was hooked immediately. As an perhaps intermediate player, I had been struggling with some of the trickier replies (e.g. 33 or 44) since I had learned the game. Reading a systematic approach with "simple heuristics that make us smart" was a real delight for me. Unfortunately, 12 rules along with 26 sub-rules were way too many for my intermediate-capacity brain. Likewise, 0.01 as a cap for tolerable errors was way too low for my usual level of play. I liked the idea, but needed it simpler. Way simpler. In my opinion, the 0.01 threshold could be relaxed considerably. To quote Kit Woolsey from http://www.bkgm.com/articles/GOL/Sep03/burger.htm:
Our goal is to play as nearly perfect as we can. This means avoiding the big blunders, or Whoppers as they are often referred to on GammOnLine. We can tolerate the small .01 or .02 errors -- in fact, quite often they turn out not to be errors. What we are trying to avoid is the .10 errors.
So I started to look at the replies pages of http://www.extremegammon.com/Openingbook.aspx to find out which sub-rules could be safely omitted for intermediates with a much larger tolerance for errors (more on this later). Finally, I found a much simpler (and, consequently, much less accurate) way for memorizing the replies. In addition, it is "embedded" into learning the opening moves (something more suited for beginners than intermediates), so in my opinion this simplified approach feels quite natural.
When conducting a boot camp for newbies in our chouette, I teach the opening moves as follows (quite similar to Walter Trice in his book):
Make a point if you can, run with 65, split otherwise (reverse with 43)
(Nactation for this would be: P, 65R, 43Z, S.) While I know that (at least according to the most precise rollouts we have so far, their results have changed over the last decade or so) you should split with 64, slot with 21 and play down with 43, the above rule is simpler, and, this is the main advantage for beginners, better applicable to the replies. They should, however, know the other main variants, since they come in handy if the standard reply move is blocked (in fact, I assume this knowledge in my simplified rules below).
Then I will teach beginners about which opening rolls are best:
31P, 42P, 61P, 65R, and the rest
And then I will embed the reply rules into this opening roll sequence:
1. Hit > 7
2. 31P
3. Hit 7
4. If hit from mid: S (or D). If hit from non-mid: D (or S)
5. 42P, 61P, 65R
6. Hit 5, 4
7. If hit: D (or S)
8. 53P, 64P, 43Z, S
According to the opening book mentioned above, this gives no Whoppers, only two "bad" replies (GNU Backgammon terminology for equity loss > 0.08) for the non-doublets. This is already pretty good for beginners. And this checklist-styled method teaches them a nice staggered set of priorities that proves valuable even much later into the game: The "worse" the reply roll, the more places to look for juicy blots to hit instead before finally giving in to playing it like the opening roll. Or, put differently, you would love to hit in the outfield with your opening roll, but unfortunately the starting position does not permit this.
Once you get more ambitious, add one sub-rule to get below the 0.08 threshold:
8a. Hit 3 with 43
By this point, GNU Backgammon's tutor will at most complain about "doubtful" moves (if you play that well for an entire match, you will usually get an "Expert" rating). If your ambition is to play replies without blunders (Ballard/Weaver terminology for equity loss > 0.06), add four further sub-rules (using Nactation):
4a. 6xS-65K
5a. 64R past D
8b. After D: $
8c. Kill 3, 2, 1 from 6
That's it for the non-doublets. The doublets, as Jeremy wrote, are trickier and require separate rules. Unfortunately, their sub-rules cannot be considered optional, since failure to play doublet replies correctly is usually much more costly than for non-doublets. Here are the simplified rules for doublets:
11. 8/7(2) 6/5(2)
a. Non-6x split: 24/22 6/5(2)
b. 6/4*(2)
22. 13/11(2) 6/4(2)
a. Hit 20, 9 along with 6/4(2)
33. 24/21(2) 13/10(2)
a. Hit 5, 3: 8/5(2) 6/3(2)
b. 13/7*(2)
44. 24/20(2) 13/9(2)
a. Hit > 3, hit again > 1, cover < 6, play on other side
55. 13/3(2)
a. Hit 3, 1 with 8/3(2) 6/1(2)
66. 24/18(2) 13/7(2)
That's it for the doublets. Again, these rules will at most lose 0.06 equity, so it will be even better than merely "Avoiding Burger King" according to Kit Woolsey. I think this is something that can easily learned and memorized by beginners and intermediates (including me as a guinea pig).
The final tally: 14 rules (12 sub-rules), 515 best plays, 115 substitutions (less than 0.06 error), and no exceptions. The average equity loss per erroneous reply is 0.01917, the average equity loss per reply is 0.003499.
Comments and critic very welcome!
Axel
| |
BGonline.org Forums is maintained by Stick with WebBBS 5.12.