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February 8, 2012

Replies to 31P

Following up my earlier post on opening replies.  I want to take an isolated look at replies to each opening roll. 

I start with 31P.  All replies are from the XG opening book, available at this link (

Replies are presented in an experimental format.  I list the best reply, and also alternative plays.  Which alternate plays I show is subjective - sometimes I list them and somtimes I don't.  I list them usually if I think the plays are sufficiently close in equity, or if the alternate play is a mistake I could see myself making.

Note the color coding.  I made-up definitions for the size of an error as follows:

.005 or smaller I consider anything this small to be tied
.005 to .02  Small error
.02 to .06 Medium error
.06 or greater Blunder

As with the match equity table, I performed the original work in Excel.  Everything is formatted and sized great within Excel.  Not sure how this look in a blog post.  Hopefully everything translates OK.  Feedback welcome.

One last note.  As I go through the replies to individual opening rolls, it is quite possible my answers will disagree with what I wrote in the Opening Reply Project.  One reason is age - those replies were generated last year on my previous blog.  Also, in some cases, several plays are essentially tied.  I tended to choose plays which I thought were thematically similar.  Even if not necessarily the technically best play, I figured I would benefit from having a similar strategy to tackle related positions.  For example, I like to bring a checker down from the midpoint whenever I hit loose in the inner board, even if hit & split is sometimes the better play.

Replies to 31P Error Key Tie Small Medium Blunder
Per XG opening Book < .005 < .02 < .06 > .06
General Notes
31P best opening roll.  Unless you double or make a point, opponent wins already high 50's & gammons high teens
Opponent has started nice prime.  Split is mandatory and priming is wrong game plan.  All Two Down and Slots are way wrong.
32Z is a bit better than 32S b/c you start a less desirable point for your opponent (ie, not the next point of his prime)
63S is .015 better than 63R while 64R is .015 better than 64S.  The 1 pip for racing appears to be the difference
64 Surprises.  64S and 64P wrong but that that bad. 
22 and 33 Surprises.  22N wrong conceptually but not too bad.  Same with 33 plays 33@ and 33E (wrong but that terrible)
11e and and 32Z are most logical and correct, but the alternate plays 32S and 11N are essentally tied
Reply Roll BEST 2nd 3rd 4th
Point Making Rolls 31 P 8/5, 6/5                  
42 P 8/4, 6/4          
53 P 8/3, 6/3          
61 P 13/7, 8/7          
Split or Slot 21 S 24/23, 1311 $ 13/11, 6/5 0.0572            
41 S 24/23, 13/9          
51 S 24/23, 13/8          
Split or Two Down 54 D 13/9, 13/8                  
52 S 24/22, 13/8          
43 Z 24/21, 13/9 D 13/10, 13/9 0.0224      
            prime is wrong concept b/c opp has better prime already      
32 Z 24/22, 13/10 S 24/21, 13/11 0.0073      
            split mandatory, but better to go for point he wants to make less      
6-X Rolls 65 R 24/13                  
64 R 24/14 S 24/18, 13/9 0.0142 P 8/2, 6/2 0.0189  
      Run is .015 better than Split            
63 S 24/18, 13/10 R 24/15 0.0152      
      Split is .015 better than Run            
62 S 24/18, 13/11 R 24/16 0.0415      
Doubles 11 e 24/22, 6/5(2) N 8/7(2), 6/5(2) 0.0029            
22 E 24/22(2), 6/4(2) N 13/11(2), 6/4(2) 0.0132      
33 B 24/21(2), 13/10(2) @ 24/18(2) 0.0175 E 24/21(2), 6/3(2) 0.0196  
44 P 13/5(2)          
55 P 13/3(2)          
66 B 24/18(2), 13/7(2)          


  1. Main difference between 31P-63R and 31P-64R is not a pip, but connectivity of the checker on 14pt to the 8pt. This results in better chance of running to safety next roll.


  2. Nice to hear from you boss. Thanks for sharing.