1,3 or 2,3 pt backgames??
William C. Bitting
It's DMP in both the below positions. O has 11 to play in each case.
It appears clear to me that one should commit to playing a backgame in
both cases. In particular, I would not be concerned with more blots being
hit; indeed, might make a play to make that more likely.
In general, is a 1, 3 point backgame more advantageous than a 2, 3
point backgame? Or do the different situations in A and B suggest that
different choices should be made?
What success rate might be expected in these type backgames assuming
good timing is preserved?
While the below situations don't offer the choice, if you were in
similar positions but with 2 men on the 1, 2 points, would you stay
with those points for a backgame or shift to 1, 3 or 2, 3?
A.+ 1 2 3 4 5 6 7 8 9 10 11 12 +
| O O O X X X | | X X O |
| O O X X X | | X X |
| O X | | X |
===========================================
| O | | |
| O O | | O X |
| O O | | O X O X |
+24 23 22 21 20 19 18 17 16 15 14 13 +
B.+ 1 2 3 4 5 6 7 8 9 10 11 12 +
| O O X X X | O | X O |
| O O X X X | | X O |
| O X 4 | | |
===========================================
| O O | | O X |
| X X O O | | O O X |
+24 23 22 21 20 19 18 17 16 15 14 13 +
Marc Gray
effectiveness of a backgame. It is, in my humble opinion, as follows:
2-3 ... the best
1-3 ... almost as good
1-4 ... very good
2-4 ... pretty good
1-2 ... weak
3-4 ... poor
2-5 ... poor
Other dual-point combinations are not considered.
The reason that a 1-2 backgame is so weak is that the defender can pile
all of his spares on the 6 and 7 points "killing" his rolls containing 5's
and 6's. This in turn destroys the timing of the backgame player.
In general the back game player may have a potent game when he trails by a
great deal, e.g. 110 - 150 pips. A perfectly timed backgame supplies the
backgame player with approx. 60% wins! The losses are nearly all gammons.
Thus, in games where gammons are irrelevant, e.g. double match point one
may consider voluntarily playing a backgame. Otherwise, backgames have
been described as the "goal line stands" of backgammon. They are to be
avoided when possible.
--
no a me alienum puto
Marcus Brooks
The only backgames I consider playing are (in order of best
winning chance)
1-2*
1-3
2-3
1-4
* The 1-2 backgame requires much more timing that is usually available,
and I strongly recommend against playing it unless you have
extremely good timing (I think I've played about 3 successful 1-2
backgames in my life! But when the opportunity arises, it
can generate an enourmous amount of shots!!!)
Any other backgames are prayers (although many times better than
nothing). If I get stuck with a 1-5 or 2-5, I usually run the
5's and pray to avoid the gammon.
At DMP, a good backgame can infuriate your opponent! Cube position and
match score are extremely important considerations when deciding to
commit to a backgame.
Marcus
mbrooks on FIBS
I play 18-20, 19-20, 14-15 in the above example.
>
>B.+ 1 2 3 4 5 6 7 8 9 10 11 12 +
> | O O X X X | O | X O |
> | O O X X X | | X O |
> | O X 4 | | |
> ===========================================
> | O O | | O X |
> | X X O O | | O O X |
> +24 23 22 21 20 19 18 17 16 15 14 13 +
>
>
I play bar-1, 1-2 (2), 16-17. Shifting to the 2-3 backgame is
important here to preserve your timing. X has too much time for
me to feel safe play at 1-3 at this point. 2-3 also has the
potential to force X into some ugly sixes.
Stephen Turner
>
> Bill, what I think that you need to know is the linear ORDER of
> effectiveness of a backgame. It is, in my humble opinion, as follows:
>
> 2-3 ... the best
> 1-3 ... almost as good
> 1-4 ... very good
> 2-4 ... pretty good
> 1-2 ... weak
> 3-4 ... poor
> 2-5 ... poor
>
> Other dual-point combinations are not considered.
>
Robertie makes an important point: that people worry about, and books advise
about, the relative merits of different backgames, but usually you've just got
to grab whichever two points you can. Usually you don't get a choice.
If you do get a choice of points or a chance of switching points you not only
want to bear in mind which backgames are best but how good your timing is. 23
may be better than 34 in general, but if your timing is dodgy you might need
to step up to a more advanced backgame (if you have the choice) to get the
shots sooner.
--
Stephen R. E. Turner
Stochastic Networks Group, Statistical Laboratory, University of Cambridge
e-mail: sr...@cam.ac.uk WWW: http://www.statslab.cam.ac.uk/~sret1/home.html
"I always keep one big file in case I run out of space." A colleague of mine
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