# Simple play problem

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This week we are going to look at a relatively simple play problem but it is one that many would get wrong over the board including this author!

Backgammon strategy position

How should black play his 64? There are three choices:

(a) 20/14, 7/3
(b) 7/1*, 7/3
(c) 20/10

Before reading take at least a couple of minutes to decide how you would play the role and equally as importantly, why.

Now let’s look at the relative merits of each play:

(a) gets one checker out from behind white’s mini-prime (note that 9 of black’s numbers don’t let him move any of the checkers on his 21-pt). It also creates a five-point prime against white’s lone back checker. On the downside any 6 by white will be a winning roll as he holds the doubling cube and can probably play on for a gammon with little risk. White does have some horror numbers in 55, 54 and 44 and 22 isn’t wonderful.

(b) also creates a five-point prime but has the added advantage of putting white on the bar against a five-point board. On the downside of this play is the fact that there are still three black checkers partially trapped on white’s 4-pt.

(c) solves the problem of the three trapped checkers by releasing one of them. It gives white some additional bad numbers. Now 64 and 61 also leave black a direct shot. The downside of this play is that if white rolls a 2 he will have a winning position unless black re-enters immediately.

So which is the correct play? As with many decisions in backgammon it is a question of balancing risk against reward. You need to balance your experience with some detailed analysis such as we have done above to reach the right conclusion.

I got this wrong over the board by playing (b) which is actually bad enough to be a blunder! I was deceived by the opportunity to put a checker on the bar.

Backgammon strategy position

There are two key points about (a) and (c):

• They both escape a back checker. Computers have taught us the importance of escaping from behind even small primes such as this one.

• They allow white to leave another blot exposed with quite a few numbers. This in turn leads to black winning more gammons – a factor that the majority of people will have overlooked when doing their analysis.

(a) is much better than (c) because:

It is much easier for black to make a full prime after this roll than (c); it wins more gammons and it loses fewer gammons. In fact it is the clear winner by a huge margin – just look at the rollout data. I’ll wager not more than one in five readers will have got this problem correct.

Chris Bray