Jul 14, 2011

Magriel's Safe vs Bold criteria

As far as I know, Magriel's Safe vs Bold criteria is probably most cited part of all backgammon literature.

In all the books I've read it is at least mentioned, and in many it is explained in the detail.

Magriel wrote this rule 35 years ago, much before the backgammon bots era, but it has passed the test of time and it is still very valuable rule when deciding about candidate moves in the middle game.





Six criteria for deciding if you should play safe or bold:

  1. Do you have an advanced anchor? With an advanced anchor you can play more boldly, as you always have a safe spot to come out from a bar if you are hit.

  2. How strong is opponent's home board? The more points he has, the more safely you should play.

  3. How strong is your home board? Do you have more points closed than your opponent? If your board is strong, you can play more boldly.

  4. Does your opponent have blots in his home board? If he has blots, you can play boldly as you will have return shots if you're hit.

  5. Number of checkers you have back. The more checkers you have back, the more boldly you can play, because another checker sent back is not a problem.

  6. Number of checkers your opponent has back. When he has zero or one checker back, bold play is called for.



Sometimes all six criteria will point to the one direction, either safe or bold. But, more often some criteria will point to the one direction and other to the other direction. It takes practice to weight criteria and to correctly decide about the move.

Let's look at the following example:
is Player 2

score: 0
pip: 137
                         
Unlimited Game
                          pip: 132
score: 0

is Player 1
XGID=---Bb-D-C---cF---c-c-bb---:0:0:1:52:0:0:0:0:10
to play 52

You escaped with both checkers so obviously you don't have an advanced anchor [safe].
Your opponent has strong board [safe] and your board is weaker than his [safe].
He doesn't have any blots in his home board [safe].
You don't have any checkers back [safe] and he has more checkers back than you [safe].

It is obvious you must play safe.

13/8 13/11 may seem constructive and safe because it only leaves indirect shot, but you're giving your opponent a chance to turn the game around by hitting you with 6 rolls (61, 52, 43).
This position calls for completely safe move, such as 13/6.


Compare it to this position:
is Player 2

score: 0
pip: 141
                         
Unlimited Game
                          pip: 128
score: 0

is Player 1
XGID=---BbBC-B---cF--ab-d-ba---:0:0:1:52:0:0:0:0:10
to play 52

You still don't have an advanced anchor [safe].
Your opponent now has only two points in his home board [bold] and your home board is stronger than his [bold].
He has a blot on his 3pt [bold].
Just as in previous position, you don't have any checkers back [safe] and he has more checkers back than you [safe].

We have a tie. Three criteria for bold (13/8 13/11) and three for safe (13/6).

His blot on 3pt is the key. If you play bolder 13/8 13/11, in order to hit you he must abandon his anchor and use numbers on both dice. Meaning he will leave you direct hit from the bar on 22pt and if you fail to hit there you'll have an opportunity to hit either on 11pt or 4pt.
Bolder, more positional move is correct in this position.


7 comments:

  1. Isn't the race/score status also a good safe vs bold criterion?

    Ahead in the race / in the match => safe
    Behind in the race / in the match => bold

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