FIBS Board backgammon forum

13/10, 13/11

I havent voted yet, as I am seeking opinions here...In this case, I would move 13-11 and 24-21.  However, if it were my opening move, I would move 13-10,13-11.  The difference is that here I am a bit scared of doing that because he has the split back pair.  I shall await others thought first though - and see if anyone can persuade me to do something better :-)  Those are the only two moves I would consider at this point.

For an opening 3-2 I'd play 13/10 13/11, but 24/21 13/11 is equally good. 24/22 13/10, the other split and build play does a little bit worse in bot rollouts. 13/8 is safe but too stodgy for an opening play.

Here, there are two differences to consider: the matchscore means we should generally try to avoid games with high gammon rates, and go more for games with high (single) winning chances. Splitting your backcheckers is a good way to reduce gammon losses (often also gammon wins). Bringing down two builders as with 13/10 13/11 is a slightly more gammonish play. So, the score argues slightly for splitting.

Also, it's not the opening roll, but a reply to factotum's opening 5-1 24/23 13/8. The split backcheckers mean that indirect shots in the outfield are almost doubled in number, and that makes 13/10 13/11 riskier and argues for 24/21 13/11. But we're also behind in the race now (after the move, factotum is on roll with a 1 pip advantage), whereas after an opening 3-2 you're ahead 5 pips. Behind in the race you should focus more on blocking or attacking opponent, rather than running or splitting, so this argues for 13/10 13/11.

The unimaginative 13/8 may also be a contender here, since factotum's split backcheckers make outfield blots more vulnerable and thus argue slightly for safer play, but I'd think it's a bit too safe and unconstructive here.

Bottom line: I'd go for 24/21 13/11, but 13/10 13/11 might be as good and even 13/8 could be close. 24/22 13/10 can't be too bad either, but likely better to play the 3 and 2 the other way around.

Bringing down two builders is the usual opening.  But the split back checkers make that play more risky - it's a quadruple indirect shot instead of a double indirect shot.

We want to avoid gammons here, so making an anchor should be a priority. We make more anchors by moving one back checker than two.

These two observations argue for playing on both sides of the board - either 24/22 13/10 or 24/21 13/11.  Of the two, the second allows us to make the 21 point more easily - that's much more valuable than the 22 point.  We're not really looking to make either the 11 or 10 outfield points, so it's irrelevant  which we sit on for a little while. Thus, 24/21 13/11 is better than 24/22 13/10. 

So,  24/21 13/11 is my vote.

That said, my hunch  is that the other "both sides" play (24/22 13/10) is not that far behind.  Likewise, the other reasonable plays are not that far behind either: two builders (13/11 13 10), move both backmen (  24/22 24/21), even the  candlestick move (13/8) is not that bad.

Looks like the team found the best move out of five that are all close. The most important thing here is to avoid the 6/1* loose hit, which would be (almost) a blunder.

    1. Cubeful 4-ply    24/21 13/11                  Eq.:  -0,2079
        47,51  11,65   0,41 -  52,49  14,55   0,48
        4-ply cubeful prune
    2. Cubeful 4-ply    13/11 13/10                  Eq.:  -0,2239 ( -0,0161)
        47,11  12,99   0,43 -  52,89  15,21   0,75
        4-ply cubeful prune
    3. Cubeful 4-ply    24/22 13/10                  Eq.:  -0,2245 ( -0,0166)
        47,05  11,59   0,38 -  52,95  15,11   0,50
        4-ply cubeful prune
    4. Cubeful 4-ply    13/8                         Eq.:  -0,2289 ( -0,0210)
        47,07  11,93   0,35 -  52,93  14,95   0,54
        4-ply cubeful prune
    5. Cubeful 4-ply    24/22 24/21                  Eq.:  -0,2379 ( -0,0300)
        47,06  10,69   0,40 -  52,94  15,12   0,43
        4-ply cubeful prune
    6. Cubeful 4-ply    6/1*                         Eq.:  -0,2987 ( -0,0908)
        45,52  11,59   0,33 -  54,48  16,02   0,69
        4-ply cubeful prune