2010-08-11 Match 5-4/Answer

Here are John O'Hagan's thoughts on this play and the evaluation below that:

This position came up in a match I was playing against David Rockwell at the recent Summer Sizzler tournament in Bloomington, IL.  David (black) was leading our 9-point match 1-0 and I rolled a 54 in this position.


After entering with the forced 4, there are only two reasonable choices with the 5.  You can either hit loose on the ace or play 11/6.  Which is the better approach?


Hitting is somewhat thematic in that White has the bigger board and it could pay big dividends if Black dances or enters with 42.  On the other hand it strips the 6-point, leaves 5 blots around the board, and risks losing our racing lead if Black rolls an ace.


How about 11/6?  That lowers the blot count from 5 to 3, doesn't risk losing as much racing equity as the hitting play, and puts another valuable spare on the 6-point where it can be useful for attacking purposes if Black doesn't anchor up soon.  It does however allow Black to play his entire roll and he does have lots of good numbers:  2s,3s, and 10s hit, 4s anchor, and everything else except 51 does something good for Black's game. 


Over the board, I wasn't really sure but chose to play 11/6.  David then responded with a crushing 33 which hit twice and made his 4-point.  He later doubled me out of the game and went on to win the match 9-0.


After the match, we discussed this and a few other positions that came up in our match.  David seemed to think 11/6 was right while I, probably unduly influenced by the crushing result in our "one game rollout", was having second thoughts.  I talked myself into thinking that I had made a mistake since hitting would have given David a lot more bad rolls than my actual play.   


The Extreme Gammon rollout shows that 11/6 is the better play.  It wins a little more often and also wins a few more net gammons than hitting loose on the ace.  Apparently the gains from attacking in this position are just not quite worth stripping the 6-point and leaving so many blots.