Webby's Backgammon Quiz 2
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 and the analysis of "The Backgammon Handbook" author and accomplished Backgammon player Martin Fischer, translated and edited by yours truly. All the positions have been rolled out with Snowie pro 12,000 times and the equity differences between the top 2 moves are in generally larger than the first quiz. This in English means that the answers are correct within all reasonable certainty :-) The positions in Jellyfish format can be downloaded from my download page, should you wish to roll them out yourself.

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1) 5 point match, Blue trails 0:2, Pip count: Blue 124 / White 112.

Blue to play 5-2?

Move	Rkg.	Equity	Eq. Dif.
(a) 8/3 6/4*	2.	-0.491	0.122
(b) 14/9 6/4*	1.	-0.369	0.000
(c) 14/9 8/6	3.	-0.495	0.126
(d) 13/8 13/11	4.	-0.506	0.137

Blue is in trouble. Behind in the race, weaker home board and is forced to leave a shot with this roll. Blue has to fight for a foothold in this game and that means attacking whites blot on the 4 point with 6/4*. The 5 should be brought down from the 14 point as it provides the most covering numbers next roll. Blue is behind anyway so leaving the 2 outfield blots is not as risky as it might appear. All other moves are too passive and give white the chance to show a nasty cube.

2) 5 point match, Blue leads 2:0, Pipcount: Blue 152 / White 146.

Blue to play 1-1?

Move	Rkg.	Equity	Eq. Dif.
(a) 8/7 6/5(3)	2.	0.153	0.057
(b) 8/7(2) 6/5(2)	4.	0.146	0.064
(c) 6/4 6/4	1.	0.210	0.000
(d) 8/5 6/5	3.	0.151	0.059

The advantage of 6/4 6/4 is that it makes a second home board point without leaving an indirect shot. In addition the prime is improved from a 3.5 point prime to a broken 5 prime. Also of note, is that white has to do something with the blot on the 16 point before plans of using a whole roll to run, this gives Blue time to bring builders down from his midpoint to make the 5 point without great risk. Sometimes you have to break the general rule of building home board points without breaks.

3) 5 point match, Blue trails 3:2, Pipcount: Blue 176 / White 149.

Blue to play 6-3?

Move	Rkg.	Equity	Eq. Dif.
(a) 24/18 8/5*	1.	-0.235	0.000
(b) 24/15	3.	-0.328	0.093
(c) 22/16 8/5*	2.	-0.322	0.087
(d) 22/13	4.	-0.343	0.108

The overriding characteristic of this position is that of White having a pip lead of 18 and threatening to run to safety. A high anchor and an attacking position should be Blues goal. 3 checkers on the 24 point is a big "no-no" so that's where we move the 6 in order to grab whites bar point (high anchor), possibly provoking a blot hitting contest which would favor Blue. Hitting is pretty much a must, thereby starting an attacking position. More checkers back and behind in the race are solid reasons to make a bold play. Any other move is too passive.

4) 5 point match, Match is even 0:0, Pipcount: Blue 99 / White 124.

Blue to play 5-3?

Move	Rkg.	Equity	Eq. Dif.
(a) 13/8 13/10	3.	0.662	0.171
(b) 13/8 4/1*	4.	0.366	0.467
(c) 6/1* 4/1	1.	0.833	0.000
(d) 8/3 6/3	2.	0.666	0.167

Alert! Alert! Cube at 2 and good gammon chance. This is the key to this position. Gammon here would make the score 4-0 to Blue. Blue HAS to go for it. White has 12 crossovers to make before bearing off which is ample to gammon White with a 1 checker close out. Note: Hitting on the ace point in general is not advisable, the big advantage here is that White will have to come in on the 2 or 3 point which will suit the builders and potential hitters on the 8 point just fine ;-) Blue is nicely positioned for a successful blitz and should not consider the somewhat instinctive 8/3 6/3 play. The plays are not close.

5) 5 point match, Match is even 0:0, Pipcount: Blue 149 / White 146.

Blue to play 5-3?

Move	Rkg.	Equity	Eq. Dif.
(a) 8/3* 6/3	1.	0.311	0.000
(b) 16/11 13/10	3.	0.202	0.109
(c) 16/8	4.	0.193	0.118
(d) 16/11 6/3*	2.	0.234	0.077

The natural play is also the best play here. Don't fret to much about the blots left on the 8, 11 and 16 points, look at those 2 juicy blots in Whites home board :-). Playing passive safe plays only cause problems later on in positions like this. Flexibility and point making numbers should try to be maximised, especially early in a game.

6) 3 point match, Match is even 0:0, Pipcount: Blue 158 / White 155.

Blue to play 2-1?

Move	Rkg.	Equity	Eq. Dif.
(a) 24/22 23/22	2.	0.028	0.122
(b) 6/4* 6/5*	1.	0.150	0.000
(c) 23/21 6/5*	3.	0.027	0.123
(d) 6/5* 5/3	4.	0.017	0.133

The faint hearted won't like the 6/4* 6/5* move. It leaves a whopping 25 roll combinations which hit. The 5 and 4 points are valuable and should be fought for early in the game. 23/21 6/5* leaves 20 combinations which hit, only 5 less than the double hit. White is forced to roll well next turn with the double hit and should white fail to hit then Blue could take a decisive advantage next roll. 24/22 23/22 is a blunder. Way too passive and doesn't come close.

7) 5 point match, Blue is trailing 1:3, Pipcount: Blue 151 / White 149.

Blue to play 2-2 ?

Move	Rkg.	Equity	Eq. Dif.
(a) 8/4 6/4(2)	2.	-0.047	0.100
(b) 13/11 8/4 6/4	3.	-0.062	0.115
(c) 7/5(2) 6/4(2)	1.	+0.053	0.000
(d) 13/11 6/4(3)	4.	-0.086	0.139

The key to understanding this position is to realise that Blue does not have to play the prime vs prime game but can also make attacking moves or moves that prepare for an attack.Unstacking the heavy 6 point and making the important 5 point puts pressure on White to perform. Note: Bringing 2 checkers down from the midpoint to the 9 point is likely to result in a prime vs prime battle in which White will have the better timing (unlikely to be forced to break the prime first.)

8) 5 point match, Match is even 0:0, Pipcount: Blue 157 / White 140.

Blue to play 6-4?

Move	Rkg.	Equity	Eq. Dif.
(a) 15/11* 11/5*	1.	-0.583	0.000
(b) 13/7 15/11*	3.	-0.716	0.133
(c) 15/9 13/9	4.	-0.760	0.177
(d) 13/3	2.	-0.667	0.084

Bad day in the office for Blue :-) Horrible position to be in. Blue needs time to get some form of structure going, either defensive or offensive. Hitting on the 11 point (15/11*) strips White of a potential builder for the important 21 point and catches up in the race a bit (only 17 behind). Blue must now consider the 6. With 3 men back Blue HAS to use his/her checkers efficiently to form a prime, that means slotting the valuable 5 point and hitting at the same time (11/5*). White has 3 checkers on the bar. Blues blots, if hit, may help towards either the making of the 21 point or a possible 1-4 backgame position. Any other move is just too weak and puts little pressure on white to roll well.

9) 5 point match, Match is even 0:0, Pipcount: Blue 123 / White 119.

Blue to play 4-1?

Move	Rkg.	Equity	Eq. Dif.
(a) 6/1	2.	-0.395	0.116
(b) 13/9 8/7	3.	-0.439	0.160
(c) 7/3 4/3	1.	-0.279	0.000
(d) 8/4 8/7	4.	-0.479	0.200

The instinctive move is more than likely 6/1. It is wrong because if you look ahead to the type of game that is developing you will notice a prime vs prime battle on the horizon. White will have to stay an awful long time on the bar in order for Blue to extricate his back men safely. If the blitz fails (highly likely) then that is pretty much the end of it. Blue then has poor timing and will have great difficulties winning with 2 men still back. Note: Blues timing would be bad in a prime vs prime battle. Blues blot on the 1 point, if hit, can perhaps start to make the 21 point safely and his timing may improve.

10) 5 point match, Match is even 0:0, Pipcount: Blue 142 / White 129.

Blue to play 2-1 from the bar?

Move	Rkg.	Equity	Eq. Dif.
(a) 25/24 8/6	3.	-0.233	0.105
(b) 25/23 8/7	2.	0.231	0.103
(c) 25/22	1.	-0.128	0.000
(d) 25/24 13/11	4.	-0.322	0.194

Another position that isn't for the faint hearted :-) Closer analysis though shows 25/22 not to be as risky as one might think. White will not want to break his prime to hit or cover as he only has the 1 builder at the scene. Creeping up to the edge of the prime is always a good idea in these kind of positions. Making the 23 point is weak because to escape you need a 1 AND a six rather than just a six. Timing also becomes an issue as the more advanced your anchor is the quicker gaps will appear to break free of a prime.

Disclaimer: The answers to these positions are based on three separate evaluations. Jellyfish's standard evaluation at level 7, extensive roll outs and the study of the positions from a top drawer player. It is unlikely that any of these answers are wrong but cannot be ruled out as until someone or a program masters the game of backgammon then all positions in theory are debatable. If you are adamant that 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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