Webby's Backgammon Quiz 1
Analysis of Positions

Below you will find what the program Jellyfish V.3.00 (level 7, using the bear off database) regards as the top 4 plays of each position. I have not had chance to roll them out personally but I have made the positions available for you on my download page should you be inclined.

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1) 5 point match, Blue leads 2:0, Pip count: Blue 86 / White 175.

Blue to play 5-4?

Move	Rkg.	Equity	Eq. Dif.
(a) 13/4	2.	0.974	0.017
(b) 11/6 5/1	4.	0.910	0.081
(c) 11/6 13/9	1.	0.991	0.000
(d) 13/8 13/9	3.	0.922	0.069

This is a pay now or pay later situation. White has no Home board to speak of, but will improve it within the next few rolls. The resulting position of 11/6 13/9 looks loose but as White has no board it makes sense to start moving closer to home now while the going is good.

2) 5 point match, Match is even 0:0, Pipcount: Blue 160 / White 160.

Blue to play 3-1?

Move	Rkg.	Equity	Eq. Dif.
(a) 24/21 6/5	4.	-0.050	0.119
(b) 24/20	2.	0.000	0.069
(c) 24/21 24/23	3.	-0.023	0.092
(d) 8/5 6/5	1.	0.069	0.000

Moving a checker from the 24 point 3 or 4 pips results in White being in an attacking position against the advanced blot when it is not at this stage necessary. Blue has an opportunity to make his 5 point early in the game and should do so now. The blot left on the 8 point, if hit, will set Blue back in the race but Blues overall position would be stronger than whites offsetting the pip loss. If white misses the blot on the 8 point and Blue covers then Blue is a favorite to win.

3) 5 point match, Match is even 0:0, Pipcount: Blue 57 / White 45.

Blue to play 4-2?

Move	Rkg.	Equity	Eq. Dif.
(a) 5/1 5/3	4.	0.466	0.088
(b) 6/2* 2/off	1.	0.554	0.000
(c) 4/off 4/2*	2.	0.522	0.032
(d) 6/2* 6/4	3.	0.521	0.033

This game is by no means over if white springs out next roll. This is why the top 3 moves hit on the 2 point. "hit and pass" is the top choice as it takes off a checker and keeps flexibility. The blot on the 6 point, if hit, may well have a return shot with whites blot on the 20 point. Of importance is that if white misses the blot on the 6 point and stays on the bar, Blue can probably clear the 6 point next move.

4) 5 point match, Match is even 0:0, Pipcount: Blue 52 / White 59.

Blue to play 3-1?

Move	Rkg.	Equity	Eq. Dif.
(a) 3/off 6/5	4.	0.831	0.148
(b) 5/2* 3/2	1.	0.979	0.000
(c) 3/off 1/off	3.	0.854	0.125
(d) 5/2* 2/1	2.	0.894	0.085

This position caused quite a lot of discussion in RGB (usenet). The reason being that many (myself included) were of the opinion that the resulting position of 5/2* 3/2 with 1 spare on the 6 point was a very dangerous position to be in (e.g. 6/x leaves a blot). It was concluded however that as hitting with the race so close was paramount, this was in the larger scheme of things the best play to make and that one shouldn't worry too much about the single spare on the 6 point.

5) 5 point match, Match is even 0:0, Pipcount: Blue 141 / White 132.

Blue to play 3-2?

Move	Rkg.	Equity	Eq. Dif.
(a) 8/5 6/4	1.	-0.147	0.000
(b) 8/5 8/6	4.	-0.194	0.047
(c) 8/3	2.	-0.183	0.036
(d) 6/3 6/4	3.	-0.191	0.044

Pretty awful position I got myself into here. Flexibility and distribution is poor. Placing one checker on both the 4 and 5 point (slotting) gives me the opportunity to make those highly valued points next roll, or at least 1 of them.8/3 is tempting but it is making the wrong point. The 5 and 4 points are Blues goal here. Unstacking the 8 and 6 points is an added bonus.

6) 5 point match, Match is even 0:0, Pipcount: Blue 140 / White 177.

Blue to play 5-5?

Move	Rkg.	Equity	Eq. Dif.
(a) 23/8 13/8	1.	0.506	0.000
(b) 23/18 13/8(3)	2.	0.485	0.021
(c) 23/18 13/8(2) 6/1	4.	0.422	0.084
(d) 18/8 13/8(2)	3.	0.453	0.053

I confess to having blundered on this one myself when it occurred (c). The importance here is to keep flexibility and not to come in too fast against whites 2-3 back game. Keeping a checker back on the 18 point is important as it limits whites ability to build up his board with ease. Isn't hindsight a wonderful thing.

7) 5 point match, Blue is leading 1:0, Pipcount: Blue 146 / White 164.

Blue to play 3-2 ?

Move	Rkg.	Equity	Eq. Dif.
(a) 6/3* 3/1*	3.	-0.069	0.022
(b) 16/11	4.	-0.085	0.038
(c) 16/13 8/6	2.	-0.065	0.018
(d) 6/4* 4/1*	1.	-0.047	0.000

Surprised me a little this choice, as I was of the opinion that burying a checker on the 1 point was a bit premature at this stage of the game. I suspect the reason is that blues tactical position is poor and unstacking the 6 point may well recirculate a checker to be used to greater effect elsewhere. Putting 2 checkers on the bar makes 6s especially double 6s bad for white.

8) 5 point match, Match is even 0:0, Pipcount: Blue 82 / White 110.

Blue to play 6-2?

Move	Rkg.	Equity	Eq. Dif.
(a) 9/3 4/2	2.	0.194	0.062
(b) 9/1	1.	0.256	0.000
(c) 9/3 6/4	4.	-0.128	0.384
(d) 13/7 9/7	3.	-0.003	0.259

I tried to be a smartypants and look for a "clever" play in the game (d)... it was wrong.. That's why I'm using this position to illustrate the concept of "take what the dice give you". Note the blot on the 4 point should stay where it is for flexibility. 3s become less awkward.

9) 5 point match, Blue is leading 1:0, Pipcount: Blue 161 / White 145.

Blue to play 3-2 from the bar?

Move	Rkg.	Equity	Eq. Dif.
(a) 25/22* 22/20	3.	-0.016	0.056
(b) 25/22* 24/22	4.	-0.036	0.076
(c) 25/22* 20/18	1.	0.040	0.000
(d) 25/22* 8/6	2.	0.002	0.038

Isn't 25/22 24/22 tempting folks :) It leaves a double anchor, but can't really be classed as a back game. With a reasonable offensive position and white with 2 men back, it is not correct to play defensively here. This is why Jellyfish prefers 20/18 for the 2 as it puts blue within direct (1-6) range of an additional blot.

10) 5 point match, Blue is leading 3:2, Pipcount: Blue 128 / White 114.

Blue to play 4-2?

Move	Rkg.	Equity	Eq. Dif.
(a) 6/2* 7/5	2.	-0.152	0.170
(b) 6/2* 24/22	1.	0.018	0.000
(c) 6/2* 13/11	3.	-0.174	0.192
(d) 6/2* 6/4	4.	-0.232	0.250

If blue does not safety his blots in whites home this turn then he is asking for serious trouble, too many numbers make a point on blues head. You may have considered 13/7 but as just mentioned, you HAVE to safety those blots in Whites home. Hitting white is clear as blue has the better board with more men back and trails in the race. These are 3 of the set criteria as per Paul Magriel's backgammon bible "Backgammon" for playing bold, you also can't afford to allow white to run his rear checker to safety. So safetying the blots and hitting wins the day.

Disclaimer: Jellyfish can get it wrong.. not often .. but it can. If you are adamant that Jellyfish has got a position wrong then let me know and I'll check it out. You might also want to open it up for discussion, this can easily be done by using my Guestbook as a sounding board or perhaps download the position(s) and roll them out for yourself (Jellyfish Analyser required).

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