3-pt anchor

[PersianLord]

I've been long believing that 3-pt anchor is better than other anchors, either advanced (4-pt,5-pt and 7-pt) or deep (1-pt and 2-pt), at least in the initial stages of the game. Here is my thesis:

Most of the times, BG games go such a way that one player has a lead in race and the other is following a holding/back game strategy. Of course, many times there are holding vs holding, priming vs priming and non-contact racing vs racing (and also blitzing vs dancing  situations, but as said, most of the times there is a gap in pip-count that the trailer gives up hopes for race and begins a holding/back game strategy to get a shot and turn the match.

But the important thing is that we DO NOT know from the beginning of the game that which way the game would develop. In the first stages of the game, almost everything is possible, and here's the point that I think the strenght of the 3-pt anchor comes to existence: It's a 'long term investment'. Now let me embark on comparing the advantages of 3-pt anchor over other anchors:

Advantages over the deep anchors

1- If the game develops into a prime vs prime situation, there is much less chance to contain the 3-pt anchor owner, in comparison to when you have deep anchors.

2- Having the 3-pt anchor, you have more controll over the outfield and thus are more able to destroy the building plans of your opponent, as his 9-pt is in the direct range of your artillery and also you have more indirect shots.

3- Having the 3-pt anchor, you will have a chance to even hit your opponent's running men even in your own outfiled: with a 6-5 on your 14-pt.

4- If you roll a double 6s or double 4s, you will have a much better chance to turn the course of the game into an effective racing vs racing state than having a deep anchor.

5- with a double 6s, you can build a valuable outfield pt in your 10-pt, while with deep anchors you can't.

Advantages over the advanced anchors

1- If the games goes in such a way that you're well behind in the race, it's usually much better to have a deep anchor as your chances to get a shot is higher. If you have an advanced anchor, your opponent will have a much easier bear-in, because he simply can get his men jump over your anchor into his home. 3-pt is not as deep as 1-pt and 2-pt anchors, but it's not advanced too and it's almost very difficult for your opponent to jump over your anchor.

2- If you'd like to follow a backgame strategy, having a 3-pt anchor is almost always neseccary. With 3-pt anchor, every other anchor makes an exellent backgame (exept for with 5-pt perhaps), but out of the 3 advanced anchors, just the 4-pt anchor can be used effectively to follow a backgame strategy and the others are almost useless.

3- If your opponent was not able to make his 7,5 and 4 pts, then he will have tough problems in bear-in stage, because he must choose between two things: either burry checkers in 1 and 2 pts, or stack them on 8 and 6 pt (or buliding pts in outfield), which both of them will harm his effective pip-count and might prove fatal if the 3-pt anchor owner rolls a big double. But with an advanced anchor, especially 5 and 7-pt anchors, the race leader will have much less troubles in making a nice board that wil pay-off in the bear-off stage.

Conclusion

Having the 3-pt anchor will serve it's owner, in almost ALL kinds of situations, though in NONE of the it's the best, but it's the ONLY anchor that has such wide-spread usage in all kinds of situations.

Now, please let me know, are these reasons just wrong illusions of an intermediate or not.

Thanks

[inim]

Best expressed in terms of equity I guess. Set up typical positions you have in mind in gnubg, and vary the anchor position. Watch the change in equity for that positions, and maybe post some summary here. See Zorba's gnubg tutorial how to do that: http://www.gammonlife.com/gnu/gnu1.htm. If you want more precise results, use rollouts rather than simple NN evals.

I agree details should be debated when equity differences are small, but I don't think we need to waste a lot of speculative words before we got some numbers and positions to talk about.

[blitzxz]

The problem with 3-point anchor and low anchors is that after opponent has made 5-point and/or 7-point they are very luckily to get stuck behind prime. So you propably can't use you're lucky doubles to level the race and they also have fewer chances to hit blots on outfield. You're more likely to hit late but that's a slim chance and you'll be doubled out way before that.

I tried couple positions with gnu. Both opponent runners to midpoint and some builders to home board. 3-point is best anchor but low splits are also very close if not better. If you give opponent also the 9-point then 5-point anchor seems to be better. With only 10-point 3-point has slight edge. With both 11 and 10 and no spares (exept of course on 13 and 6) it's borderline. (All these results with very quick roll-outs) Home board and race may have impact on these results. I would summarize that 3-point is best when your opponent has bad distribution of checkers and no key points made. And 3-point anchor is clearly superiour in back games.

[dorbel]

Disadvantages of the 22pt (3pt) anchor are that it is easily primed and that its coverage of the outfield are limited. A 22pt anchor behind a 5 prime is usually a pass, regardless of other factors. It does, as PL points out, form a part of the best backgames, but you will find that you rarely get into these when you make the 22pt anchor first. Having the 21 or 20pt is invariably superior in the opening or middle phases of the game, as less easily primed, better outfield coverage and fewer gammon losses. Of course sometimes in the late phase of a game, you may prefer to stay back on the 22pt rather than move up, but that doesn't make it stronger earlier on.

[PersianLord]

Disadvantages of the 22pt (3pt) anchor are that it is easily primed and that its coverage of the outfield are limited. A 22pt anchor behind a 5 prime is usually a pass, regardless of other factors. It does, as PL points out, form a part of the best backgames, but you will find that you rarely get into these when you make the 22pt anchor first. Having the 21 or 20pt is invariably superior in the opening or middle phases of the game, as less easily primed, better outfield coverage and fewer gammon losses. Of course sometimes in the late phase of a game, you may prefer to stay back on the 22pt rather than move up, but that doesn't make it stronger earlier on.

Thank you for the input. But that's exactly my point: 3-pt is never the best anchor, but never weakest too and a long term asset.. In other words, as you pointed, advanced anchors sometimes become useless in late phase of a game, and deep anchors are easily primed with less outfield coverage, but with 3-pt anchor, almost in every situation it can serve you, though not in the best way.

Regards

[stiefnu]

but with 3-pt anchor, almost in every situation it can serve you, though not in the best way

I was always taught that a 3-pt anchor is usually "neither fish, fowl nor decent red herring" 

Steve

[PersianLord]

Well, we had a discussion on this topic today in shouts and one of the well-known strong FIBSters provided some hints and guide, I think it's better to post them here:

-you gave advantages over deep
anchors , and advantages over advanced anchors
, the only thing is , there are disadvantages
to both as welll , and being in the middle
it gets the worst of both sides when added up
doesn't convince me they're better than either ,
basically it comes down to the pipcount a lot doesn't
it ? if you are getting way behind , the lower
ones may becoeme stronger , if you are ahead
, the higher ones are stronger , but being in
the middle just doesn't have a lot of punch in either
arena

-but you may have time to make
lower anchors later if it comes to that , so wasting
a chance to make a good high anchor for
a middle one can be a big mistake , where missing
the chance to make a low one might not , if
that idea is accurate , it tells me higher anchors are
certainly more valuable than middle ones

[cassandra]

pl

this is how i learned it:

first your 5 pts-anchor
then an anchor on your opponents 5 pts

then 4pts- and then 7pts- anchor.

greez cassandra