Michael Crane explains: One of Nicky Check's favourite things to say when playing backgammon is referring to The Zone! What actually is The Zone? Several players have attempted to define and fine-tune this on bgonline's forum.
Here's a simple (and accurate definition so far as many players are concerned);
Nack Ballard: as defined in the Glossary (pp. 114–121) of ‘Backgammon Openings’ (2007): Zone ... The area consisting of a player's inner board plus any outside points within 6 pips of an unmade inside point.
Nack: For example, black begins with eight checkers in the zone (three on his 8-point and five on his 6-point). The zone is frequently but not always the same as a player's 11-point through 1-point.
Positions #1 & #2 will further clarify.
Before black plays his 32, he has eight checkers in the zone. After he plays his 32, he has ten checkers in the zone (the status of his 12-point and 11-point checkers having gone from non-zone to zone). White has twelve checkers in the zone.
Tom Keith isn't so sure and asks the question, Is this really the best definition? For example, suppose you have a checker on your 11-point and a closed 5-point. You could have more checkers in the zone if you moved the two checkers on your 5- to your 4-point, but I don't think your chances of winning a blitz go up.
Well, it's clearly not correct to go with Tom's example, it might put more checkers in the zone, but at the expense of losing some very valuable points.
Stick Rice says: Honestly, for the definition I don't care if my winning chances go up or not. I don't think it matters to the definition of the zone and agree with Nack's definition. However, which position below would you rather have, #3 or #4?
Tom agrees with Stick: Agreed that winning chances is not your focus here. Isn't the idea of counting checkers in the zone to help get a feel for whether you'll be able to successfully carry out a blitz? (Which may not be related to winning chances.)
In total agreement with Tom, Nack asks us to consider four positions, (the first two being Stick's above). With black on roll, his equity of each position, according to Snowie evaluation, is shown along with the total checkers in the zone.
Nack explains: Position #6 and Position #8 are the same (as each other) except for ownership of the 11-point and 10-point, respectively. In both cases, black has eleven checkers in the zone, and the equities are close (0.821 vs 0.828).
Positions #5 and #7 are also the same (as each other) except for ownership of the 11-point and 10-point. However, Position #5 has only nine checkers in the zone (because the 11-point checkers, which don't bear on the open 4-point, are not part of the count), while Position #7 has eleven checkers in the zone. The equity of Position #7 is therefore much higher (0.946 vs .0809).
Next, consider Position #3 vs Position #4. In both cases, there are eleven checkers in the zone, but Position #3's equity is much higher (0.946 vs .0828). Why? Because the 5-point is much more valuable than the 4-point (common knowledge).
Having affirmed that the 5-point is much more valuable than the 4-point, consider Position #1 vs Position #2. Despite owning the weaker 4-point, Positions #2's equity is higher (0.828 vs .0809)! Why? Because there are eleven checkers in the zone instead of only nine.
All this helps illustrate that the zone concept is worthwhile, and that it makes good sense to not count the 11-point checkers as in the zone in Position #1.
Tom: I agree it is good to have checkers bearing on unmade points. But this is true in priming games just as much as in blitzing games. Maybe you use the concept of the "zone" differently than I do. I'm interested in assessing blitz chances.
Nack agrees with Tom that it is true in priming games just as much as in blitzing games; and that he's also interested in assessing blitz chances.
Nack goes on: Me, too, Tom -- and that's a very good point. But either the zone is a useful concept in discussing a particular position or it is not. (Either it has a blitzy element or it does not.) To the degree that it is, the question is: which checkers should be counted?
In a sophisticated model, one would want to count every checker that can still participate in closing inside points. Even checkers on the 24-point can eventually be part of a blitz, though they would get a small fractional value. The mid-point checkers, which are closer to the action, would get a higher partial value, but not nearly as high as checkers that are in direct range (within 6 pips of) an inside point.
Checkers on the 11-point when the 5-point is already made are not in direct range but they are even closer to the action than the mid-point, and would therefore get a still higher partial value.
The checkers with clearly the most value would be those that directly bear on as many inside points as possible (typically the checkers on the 6-point, and on the 8-point when the 1-point is already made).
However, we are discussing a basic model: one in which a checker is counted a checker as 1 or 0. For a basic model, I believe it is useful to acknowledge that there is a substantial dropoff when comparing checkers that are within direct range (within 6 pips of) an unmade inside point, to those that are not.
I have modified Stick's first position to position #11 below, so that it is more obviously blitzish. It is the middle position of a series, the only variable being black's 15-point, which is replaced by his 13-point, 11-point, 9-point and finally his 7-point. Equities (Snowie evals) are included in the captions. Below the last position is a summary.
Below is a summary, with equities. Each parenthetical value is the difference between that equity and the previous one.
Note the big jump in value that occurs when the 11-point checkers, which are not in the zone (as I define it), are brought into the zone.
Tom asks Nack: As I understand it, the traditional notion of checkers in the zone is that 10 or more checkers is enough to try a blitz. Fewer than 10 is not enough. (Obviously you have to weigh this with other considerations.)
Clearly, 10 checkers in the zone is blitzier than 9. However, 11 is blitzier than 10, and 9 is blitzier than 8. There may be a bigger change from 9 to 10, but I don't think it's relatively monumental. [xxx] is Nactation (click here)
might lead one to conclude it is right to blitz with 9 in the zone but not 8 in the zone. Comparing other early game positions might lead one to conclude that it is right to blitz with 11 in the zone but not 10 in the zone. As I see it (consistent with the implication in your parenthetical phrase), much depends on the opponent's board strength and/or her blots/builders, and on the strength of the alternative candidate move.
Also, it is not always clear when to classify a move as a blitzing play.
Naturally, 8/5* [or 8/4*] is part of the play. If you also hit on the ace point (having only 8 checkers in the zone), does that mean you are making a blitzing play or are you hoping to get hit back less often, thereby protecting your lead in the race? Are these two ideas mutually exclusive? (Rhetorical questions.)
The question then arises whether or not any dead checkers should count (eg. 3 on the ace-point).
Nack comes in with a few more positions and a few questions.
With reference to #20 & #21 above;
(1) How many checkers does black have in the zone before the play?
(2) (a) In Pos #20, how would you play 43 for black? (b) How many checkers does he have in the zone after your play?
(3) (a) In the Pos #21, how would you play 32 for black? (b) How many checkers does he have in the zone after your play?
Okay, now suppose the initial blitz fails, White gets in a recube, black ends up with an ace-point holding game, White leaves a double shot and black hits both checkers. He can now try blitzing again.
(4) (a) How many checkers does black have in the zone in the Pos #22? (b) What do you believe is the correct cube action?
(5) (a) How many checkers does black have in the zone in Pos #23? (b) What do you believe is the correct cube action?
(6) In the Positions #20, #21, #22 & #23, do you think the third checker on black's 2-point should be counted as being in the zone?
(7) If you answered "no" to 6, do you think it's worth refining the definition of zone so that dead checkers are excluded from the count? (Does the situation arise frequently enough to bother?)
Here are my answers:
Do you agree with my answers?
This is what Nack had to say: In case you’re curious, the answers I aimed for were the same as Michael's except for the following:
3a) 24/22, 13/10. [Logic: Playing 13/11 doesn’t get it into the zone, so black may as well attack the outfield blot instead. That’s how the answer differs conceptually from that of 2a, where 13/9 does get into the zone.]
4b) D/Take. [Logic: The 9-point checker is in the zone, giving Black a sufficiently strong position to double. Compare to 5b ND/Take because the 11-point checker is out of the zone and therefore less potent than the 9-point builder.]
Stick Rice has the final say: I want to note these positions still fit my criteria. These are not positions where I would use the phrase "in the zone" to describe them nor to analyse them.
So, where is, in the zone? Opinion is slightly divided but I reckon it’s safe to go with our opening paragraph, “ The area consisting of a player's inner board plus any outside points within 6 pips of an unmade inside point.”
But, should it be refined to exclude ‘dead’ checkers or not? What do you think, Nicky?
by the persons mentioned herein and it appears with the consent of all concerned.
Nactation - Introduction