Pythagoras: No, I didn't correct my "mistake", lolol.

I anticipated (nay, hoped for, lol) a wee bit of discussion so I plugged in a qualifier.

I wouldn't say that playing for gammon means a significant difference strategy (though, of course it depends on what makes for significance).

I guess we differ if what we see as significantly different. I picked the game up again a couple of years ago at VogClub. I must admit that gammons were part of the game right from the start - whether played without the cube (first 12 months or so) or with (thereafter) - so my play is more gammon-centred than it would be if I'd been playing here. I do often play for gammons even when not necessary because that win is a thrill and so worth the risk of losing the point. (That's obviously not a good tactic for serious tournament play, so it's a good job that I don't play serious tournaments!)

But when I do play without needing a gammon then it's not a significant difference in game play. There are some differences in the opening moves (though 6-4: I'd make the point in both gammon-go and gammon-save) but the majority of the game is the same for gammon-go and gammon-save. You might have "Gammon..Gammon..Gammon" running in your mind the whole time but it may not be obvious on the board. Closing the home board is always a priority and needs those builders, double-taps are a joy in many occasions (though sometimes a foolhardy one, lol). To me it's more a toning down of aggressiveness and less risk taking. A shift in emphasis towards the race and away from the battle. But, like I said, my base level is perhaps already more gammonish than others.

We're talking about the same things here yet while Alan says "significant difference" and you say "very different", I say "tone down" and "shift in emphasis".

Pythagoras: With 6-4, making the 2 point is a good play in any situation, though 24-14 is just as good usually. While going for gammon the 2 point should be made and while saving a gammon 24-14 is correct, but the cubeless equity of either move is about the same I think.

grenv: what about 24-18 and 13-9 ?

Hrqls: These are the GnuBg rollouts. According to these, making the 2-point is a doubtful move and the standard drop-and-split is the best for the non-gammon situation and second best even in gammon-save! But in the gammon-go situation the 2-point comes to the fore.

Double match point. Gammons don't matter to either side.

#. Move _________ Win __ W.G __ W.Bg __ Lose __ L.G ___ L.Bg ___ Equity
1. 24/18 13/9 ____ 50.9% _ 20.6% _ 2.7% ... 49.1% _ 19.7% _ 2.8% ... +0.018
2. 24/14 _________ 50.5% _ 17.1% _ 2.5% ... 49.5% _ 17.4% _ 1.9% ... +0.010 (-0.008)
3. 8/2 6/2 _______ 49.4% _ 22.5% _ 3.6% ... 50.6% _ 18.9% _ 2.0% ... -0.012 (-0.030)
4. 24/20 24/18 ___ 49.1% _ 17.5% _ 2.0% ... 50.9% _ 18.8% _ 2.3% ... -0.019 (-0.037)
5. 24/20 13/7 ____ 48.9% _ 19.0% _ 2.4% ... 51.1% _ 20.1% _ 3.3% ... -0.022 (-0.040)

Error: ___________ 0.3% __ 0.6% _ 0.3% ..._ 0.3% __ 0.6% _ 0.4% ..._ 0.006


1-away, 5-away. Gammon-Save for the leader.

#. Move _________ Win __ W.G __ W.Bg __ Lose __ L.G ___ L.Bg ___ Equity
1. 24/14 _________ 50.1% _ 19.5% _ 2.9% ... 49.9% _ 13.1% _ 0.3% ... -0.202
2. 24/18 13/9 ____ 49.7% _ 21.0% _ 3.3% ... 50.3% _ 13.7% _ 0.4% ... -0.222 (-0.019)
3. 8/2 6/2 _______ 49.3% _ 22.4% _ 4.0% ... 50.7% _ 14.0% _ 0.5% ... -0.235 (-0.032)
4. 24/20 13/7 ____ 47.9% _ 19.4% _ 2.6% ... 52.1% _ 13.0% _ 0.4% ... -0.249 (-0.046)
5. 24/20 24/18 ___ 48.6% _ 18.2% _ 2.9% ... 51.4% _ 14.1% _ 0.5% ... -0.253 (-0.050)

Error: ____________ 0.2% __ 0.6% _ 0.3% ..._ 0.2% __ 0.2% _ 0.1% ..._ 0.006


5-away, 1-away. Gammon-Go for the trailer.

#. Move _________ Win __ W.G __ W.Bg __ Lose __ L.G ___ L.Bg ___ Equity
1. 8/2 6/2 ______ 50.3% _ 15.6% _ 0.4% ... 49.7% _ 18.3% _ 2.5% ... +0.245
2. 24/18 13/9 ___ 51.2% _ 13.0% _ 0.4% ... 48.8% _ 20.6% _ 2.3% ... +0.231 (-0.013)
3. 24/14 ________ 51.1% _ 11.4% _ 0.4% ... 48.9% _ 19.5% _ 2.1% ... +0.207 (-0.037)
4. 24/20 13/7 ___ 49.5% _ 13.1% _ 0.5% ... 50.5% _ 21.3% _ 3.8% ... +0.198 (-0.047)
5. 13/9 13/7 ____ 48.5% _ 14.1% _ 0.4% ... 51.5% _ 23.2% _ 4.9% ... +0.190 (-0.055)

Error: ___________ 0.2% __ 0.2% _ 0.1% ..._ 0.2% __ 0.6% _ 0.4% ..._ 0.006


Full cubeful rollout with var.redn.
1296 games, Mersenne Twister dice gen.
Seed 985902322 and quasi-random dice.
Play: 0-ply cubeful prune [expert]
Cube: 0-ply cubeful prune [expert]

(I made a mistake when doing the gammon-go rollouts in that I forgot to set the Crawford-game flag. It's thus calculated as if the cube were live for the trailer. But that's fair enough if you think of it as a 7-pointer and the trailer has won the Crawford game.)

playBunny: uhm ... care for a little explanation ? ;)

(i only played with gnubg for a couple of days and that was several months ago :))

Hrqls: Lol. I forgot the column headings. I'll put them in...

Okay, the Move number and Move columns are obvious. The percentage columns are the expected Wins, Wins by gammon (included in the Wins) and Wins by backgammon (including in Wins and W.G) plus the corresponding Lose percentages.

The Equity, is how GnuBg evaluates the potential earning power of the move. 0.000 would mean that there is as much lost as won. 0.018 would indicate a small gain. The -0.202 in the gammon-save situation means that the roll and move is not good in match terms. Perhaps Alan or Pythagoras can explain that one as I'm still uncertain about what equity means in absolute terms.

The important value from the point of view of judging the relative merits of the moves is the last figure, in brackets. This is the difference in equity between that move and the best move. With the levels that I use anything worse than -0.010 is Doubtful and anything from -0.050 is a Bad move. (Thus move 5 in the gammon-save situation is an error because 24/20 24/18 leaves the player open to several double-taps, which is hardly a gammon saving kind of thing to do!)

Hrqls: So in the double match point (DMP) situation the best moves are the drop-and-split and the run-for-home. The difference between them (0.008) is only just bigger than the possible error, so they make be closer than reported or even reversed.

In the gammon-save situation the run-for-home is more clearly judged to be the better move. In both cases GnuBg judges making the 2-point to be a fairly Doubtful move.

playBunny: I thought I had heard that computer analysis had ressurected the 2-point opener. I see you did your analysis on 0-ply, I would be interested in seeing a 3-ply result. Or does that not make sense in a rollout?

alanback: I'd love to do it and I'm sure it makes sense. But it also makes for a million cups of coffee. Well, maybe not but a 0-ply is instantaneous while 2-ply can take 3 seconds or so per dice roll and 3-ply takes about 7 seconds (both timings longer for a double and perhaps highly spread positions, etc). The rollout at 0-ply took about an hour and a half so I shudder to think what a 2-ply would require, let alone a 3-ply. There is the option of doing just the first N moves at a higher play and then reducing but I haven't tried that. I don't know that it would make that much difference on an opening move rollout. I'll have to try it ...

The writers of Gnu say that 0-ply is adequate as the errors would tend to balance out for the two players and the dice are random beyond the first two rolls anyway and blah, blah, but only the future will tell us how correct they are.

I thought I had heard that computer analysis had ressurected the 2-point opener.
Aye, I'd gained that impression as well and it's been my preferred move for some time now. There's always the possibility of operator error, lol.

Paul Magriel's updating his 70's classic to correct the "mistakes" of that era and also include more about the cube. He's doing it conjunction with some other guy (whose name I can't remember) and they're doing full rollouts on Snowie of all the openings (and maybe all replies?). Hopefully they'll be able to go well beyond 1296 which has far too high an error range for the rolls with subtle differences. I guess it'll be taken as the definitive data for the next wee while..

playBunny: I would tend to make the 2-point in games where the gammons don't matter, I thought it was back in vogue as well.

Your numbers are not all that conclusive in the matter. It looks like they would favor making the 2 point when trying for a gammon though, any conclusion on that?

Hrqls: I was only comparing the other two openings since we were talking about gammon saves and gammon goes. Of course 24-18 13-9 is possibly best overall, particularly in light of playBunny's analysis.

grenv: Aye.

I've added the gammon-go to the analysis post below. Making the point is judged best.

playBunny: I thought I had heard that computer analysis had ressurected the 2-point opener.
Aye, I'd gained that impression as well and it's been my preferred move for some time now. There's always the possibility of operator error, lol.

64 with making 2-point is the best choice in a gammon-go situation. That means when you hunt a gammon....
But it's a bit inferior in my opinion in general games' situations.....See here for some 2-ply rollouts!

Pythagoras: Hey, that looks close to what I thought!!

I would like to be able to play Backgammon counting gammons and backgammon without the cube. It should be an option for the game or tournament creator. First one to 5 or 7 without that cube is a good way to play if gammons count.

Walter Montego: Why take the cube out? it's much more interesting with it.

grenv: No, not take the cube out - it's already out of cubeless games! Add gammons in. Make them much more interesting. :=)

playBunny: I understood, but I don't even understand why you'd play a cubeless game if the cube is available, gammons or otherwise.

grenv: When I returned to Backgammon a couple of years ago I wanted to concentrate on chequer play. The cube was a complication that I didn't need - in fact, couldn't handle. I was playing a very aggressive robot and, almost invariably, accepting a cube meant that I'd lose even much of the 25-30% that were "supposed" to go my way. I just wasn't good enough at that point. Eventually (after about a year, I'd guess) I got to a very good rating and decided to add the cube. Naturally my rating plummetted as I was offering bad cubes and taking huge drops. So then came the second learning curve and ratings climb. In fact I've only recently got to the top of the list against that particular bot. (It's a GnuBg a couple of versions old and with a voracious appetite for blots and a love of blitzes and primes.)

Now I can't speak for Walter, and he's a much better player than I was when I first came back to the game, but I think doing it in stages is a good idea. Polish your chequer play, which means gammons, and then learn the cube. BrainKing's missing that middle stage, ie. multi-game matches with gammons. Perhaps N-wins matches could be just a collection of single games and N-point matches could include gammons.

grenv: i can tell you ONE reason...less clicking!

redsales:

How do resignations work in non cube match play with gammons?

Czuch Chuckers: You opponent wins one game

pgt: ahhh, so you could resign from any position and still only lose that one game? Really? OKay, thanks!

I would like to try non cube gammon matches.

Czuch Chuckers: I think pgt has misread your question. I would hope that this site if it was to have Backgammon with gammons but no doubling cube would still give the the winner of the game when his opponent resigns the gammon or backgammon he would have coming whether or not there was a cube in the game.

Walter Montego: I did not misread the question Walter. I believe my response was correct for BG as currently implemented. I guess I could have expanded it to cover some hypothetical variation which may or may not be implemented in the future.
Should a variation be implemented, I believe my response would be the same for an "n wins match", but hopefully, for an "n points match" then 2 points would be awarded for a resignation in a gammon position, and three points in a backgammon position. Ideally, the resignation should be able to specify whether the resignation offered a 1, 2 or 3 point resignation, and the other player could accept or reject the resignation accordingly (but this last point has all been discussed in the past, I believe.)

pgt: Yes, that way of resigning has been discussed. Perhaps it is me that misread his post? I think of each game, even if part of a set for a number of game points, individually. So when someone one resigns I think it should be for the current game involved, not the whole series to determine things. Perhaps both types of resigning should be offered for matches?

In a backgammon game (multi-point / multi-win games)which does NOT use the cube, a resign will only cost you 1 point - no matter where your pieces are at.

In a backgammon game which DOES use the cube, but the cube has not been turned yet, it can cost you anywhere between 1-3 points depening on where your pieces are left on the board.

BIG BAD WOLF: I thought that was exactly what we had already concluded!

playBunny: thanks! that looks like what i felt as well.

thanks for the explanations! it now shows a lot more to me :)

Pythagoras: nice site! thanks!

I never see any doubles in the opening rollouts, why is this ?

• double 6 is clear to me, 24-18 (2x) and 13-7 (2x)
  
• double 5: most probably 13-3(2x)
  
• double 4 is a doubt: 13-5(2x), or 13-9(2x) and 6-2(2x), or 8-4(2x) and 6-2(2x). I tend to go with 13-9(2x) and 24-20(2x)
  
• double 3: i have no real idea, i go either 13-8(2x) or 6-3(2x) and something else
  
• double 2: i have no idea either, i usually go 6-4(2x) and 1-5 or 13-11(2x) or 13-9
  
• double 1: 6-5(2) and 8-7(2x) ?
  

Hrqls: A game of backgammon begins with each player rolling one die. If the two dice are equal, they roll again; otherwise the player who rolled the higher number moves first, using those two dice. Thus the game can never begin with doubles.

Hrqls, KotDB : Well, the dice to go first could be an independant roll. I know that one option in playing (though not on any online site that I know of) is to roll again if you don't want to use the who-goes-first roll. That gives a considerable advantage to the starter.

I imagine that doubles are considered to give too much advantage to the first player on top of being able to go first.

Double 6, 5 and 1 - as you say.
Double 4: Make your opponent's 5-point and your 9-point as you would when moving second (unless there's a blot on your own 5-point in which case you hit it 13/5*(2) with glee).
Double 3: Attack as you suggest, though Gammon-Save would be 13/10(2)  24/21(2)
Double 2: Again attack, 13/11(2)  6/4(2).

KotDB: .
.
.
Correct although here in Greece we sometimes play it with the rule: "The winner of the starting roll doesn't use the rolls occured to determine the starting player, but rolls again!"
So we have doubles as well. And actually i prefer that games although some of my opponents don't like this and play without doubles....

Hrqls:
D-6: Yep clear.....
D-5: Clear again....
D-4: Your prefered play is the one i play too in most cases....
D-3: Many things here. It depends on the mood:-) In most cases: 6-3(2) 24-21(2) or 6-3(2) 13-10(2). I used to play 13-8(2) long ago but i found it to be inferior....
D-2: 2 choices for me: I play regularly 6-4(2) 24-22 13-11 but when i don't feel confident(55 is devastating but if you escape you are OK!) go to the superior 6-4(2) 13-11(2)....
D-1: This is clear.....

Playbunny:.
.
.
I can't find a way that there could be a blot on 5 in the starting board! Perhaps a forgotten one from the previous game.....?

Pythagoras:

How about this more bracketty version?

Make your opponent's 5-point and your 8-point (as you would when moving second (unless there's a blot on your own 5-point in which case you hit it 13/5*(2) with glee)).

KotDB: lol! *slap forehead* you are right :) i forgot about that :)

i guess the games in which i wondered about it is when my opponent had the first move and my double roll was in fact the second roll in the game

playBunny: Much better.....

playBunny & Pythagoras: thanks!
a lot depends on my mood for sure ... i know myself to play too aggressive sometimes .. but sometimes i just noticed and and tend to be quite careful :)

i always wondered if leaving the single on 8 is a bad thing (when rolling double 1 for example) .. but i guess its danger is outweighed by the move :))

thanks!

Hrqls: If your opponent has split his back men and there's a direct shot at your 8-blot then you're better off making only the 5-point. Use the other two 1s to split your own back men. 6/5(2)  24/22

What do the talkative players here think?

6-6: always 24/18(2), 13/7(2) except after 6-1 opening, then 13/7(2), 8/2(2)
5-5: usually 13/3, but sometimes 8/3(2), 6/1(2) if you hit a blot.
4-4: as playBunny suggests, except consider 24/16, 8/4(2) or 24/16, 13/9(2) if you hit a blot on 16.
3-3: Far too many options to fit.
2-2: Usually 13/11(2), 6/4(2) but sometimes 24/22(2), 6/4 (e.g. after a 4-2 opening) and occasionally 24/20, 6/4(2) if you hit a blot on 20.
1-1: either 8/7(2), 6/5(2) or 24/22, 6/5(2) depending on the situation. Don't forget to hit a blot on 20 though.

grenv: Yes, blot-splatting gets the high priority.

5-5: Always 8/3(2), 6/1(2) if you can hit a blot. Blitz time! :-)) else 13/3 because what else can you do?

4-4: Likewise 8/4*(2)  6/2(2) or 8/4(2)  6/2*(2)
3-3: And 8/5*(2)  6/3(2) or 8/5(2)  6/3*(2)

2-2: If you've done the 4-2 and made the four point then 6-4 is inadvisable. That man is a builder for the 5-point. In fact almost all advancement of builders past empty points in the home table is to be done only if forced.

1-1: 6/5(2)  6/4*

playBunny: I think I made a mistake, but want to be clear:

After the opponent plays 4-2 (which has to be 8/4, 6/4 or it's a mistake) then I roll a 2-2, I'm playing 24/20, 6/4(2).

I think I confused you into thinking I played 4-2 first.

grenv: Yes, Although it was incongruous with the others, I reckoned you were referring to that player's second move (ie. third overall) just for that instance.

I agree that if your opponent has just made the 4-point then there's the danger of becoming closed in, but rather than put a blot on the 5-point with 24/20, it's better to grab the point entirely 24/20(2) and be secure, especially in Gammon-Save.

playBunny: hmmm, i'm going to amend after some thought. In that situation 24/22(2), 6/4(2) is better, although 24/20(2) is obvious in a gammon save situation.

24/20, 6/4(2) is probably only good if you hit a blot on 20.

grenv: I think I made a mistake, but want to be clear:
After the opponent plays 4-2 (which has to be 8/4, 6/4 or it's a mistake) then I roll a 2-2, I'm playing 24/20, 6/4(2).

Since you cleared it up, i have the impression that you would NOT play the awful 24/20 6-4(2) after a 42 of your opponent so you retract your statement i have quoted above.....
After a 42 of our opponent, if we have 22 then we should play 24-22(2) 6-4(2) or 6-4(2) 13-11(2)....

grenv: *nod* agree :)

Pythagoras: not 24-20(2) ?

Hrqls: 24/20(2) is correct if saving a gammon it seems.