playBunny: First, let me say I have insisted before that there was a bug in the ratings calculator, and I'm glad to see it being addressed.

Prior to today, if I played anyone whose rating was within 400 points of mine, the result was either +8 or -8 -- nothing in between. As a result, assuming that I won more than half my games and only played people whose ratings are within 400 points of mine, I was pretty much guaranteed an upward trend (with random dips, naturally, but the overall trend should be upward). If you will look at your game pages now, you will find that your expected BKR gain from winning against anyone lower rated than yourself is less than the expected BKR loss from losing. This is the way the ratings system should work, and it should have the effect of squeezing the ratings closer together. It should also get harder to improve your rating the higher your rating goes, which is now the case. I suspect the bug that previously existed was the reason that Fencer felt the need to remove the 2700 ceiling on ratings.

Looking at my games, I stand to lose many more points than I stand to gain in each one. Since backgammon is a game of both skill and luck, I will certainly lose a significant number of games -- probably at least 35% against all opponents, very likely more. This is why I expect my rating to go down.

Moreover, as I interpret Fencer's announcement, he is going to recompute all ratings from the beginning, using the historical database of results. Thus, current ratings (like mine) that have been inflated by the bug should decline. It remains to be seen what the relative changes will be.

From what I remember about FIBS, it was said that your rating reflected primarily your last several hundred games -- i.e. that your rating wouldn't be too different if you applied the FIBS formula to the last 400 or so games than it would be if you applied it to your entire history. If that is the case, I may come out of the process in good shape, since I have been rather fortunate lately.

It's been a fun ride at the top, but I won't be upset if the recomputation leaves me somewhere in the middle of the pack.

alanback: Hear hear!!!!

I stated many times the same bug, which manifested itself by making all draws count zero. Now it seems to be fixed and the ratings will be far more accurate as a result.

yay!

grenv:

The results of the new system still don't look right to me, as the win/lose differential is very large. This might be appropriate in a game like chess, where the better player should usually win. However, in backgammon, even against a weak opponent, a strong player will lose a significant number of games. For example, I would probably lose 10-15% of my games against a beginning player just because of the luck of the dice. But even against opponents close to my skill level, I currently stand to lose much more than I stand to gain. For example, in a Nackgammon game I am currently playing, the ratings are 1925 and 2208. The win/lose differential is 3-13 or -10 against me. This implies the odds of my winning are something like 13/16, which I think overstates the probabilities.

It would be interesting to see if one could devise a ratings system that more closely reflected the actual likelihood of winning based on a given rating differential.

I just had the odd experience of having the dice change on me in the middle of a move. This has happened to me on other sites, but not here. Probably a cache issue locally or on the server. It was disconcerting, though -- I saw double fours and after the first click, they changed to 5-1! Thought my mind was playing tricks and so I hit the back button, and there were the double fours again. However, the server insists I move the 5-1. Such is life :)

alanback: That's a pretty radical change. It sounds more like a different formula than a bug fix! I can see how you expect a large difference in your rating when it's applied to the BKR history.

Though it's an improvement, I'd still like the ELO Backgammon formula to be used (like at Vog, Fibs and elsewhere) as it knows about the luck of the dice.
Your 2700 would reduce to 2200 or under with such a formula because of the diminishing returns that you mentioned.

It's even more pessimistic in its judgement as it predicts 30% loss of single-point matches between a top flight (2200) and an average player (1600). That's a big luck factor and it's entirely missing from the chess formula.

And I agree about the differential being too punishing. In our game I stand to gain 10 and lose only 5 and you vice versa. The proper formula would award us nearly equal shares of the match value.

playBunnyWell, as any programmer knows, a small bug can make a big difference. I like your description of the ELO formula, and didn't realize the formula used here was so different.

I can't wait to see what kind of ratings world I wake up in tomorrow ;-)

Nevertheless is has been acknowledged a couple of years ago that problem will be fixed "soon". "Soon" the whole point of this discussion will be GONE FOR EVER!!!!

You fellows are enjoying yourselves, to me you're wasting my time and space on the board.

so can anyone give me a link to an "official" backgammon body so I can read this so-called maximum dice usage rule? I scroogled the term (www.scroogle.org) but it didn't come up even once.

redsales: http://www.bkgm.com/rules.html

redsales: "So-called" is right, lol. I doubt if you'll find it anywhere else. A name was needed when it was being discussed and that was the shortest phrase that said it all. ;-)

Andersp: Your inability to understand and your clumsy lies .... this is not the place to discuss them.

See you in the Flame Pit.

..... Are you coming?

Andersp: "no ..not coming..waste of time..i prefer to play games"

Except that you did.

Back to backgammon!

redsales: I cut and paste the rule from that site in case people can't be bothered looking (which would usually be me):

"#4 A player must use both numbers of a roll if this is legally possible (or all four numbers of a double). When only one number can be played, the player must play that number. Or if either number can be played but not both, the player must play the larger one. When neither number can be used, the player loses his turn. In the case of doubles, when all four numbers cannot be played, the player must play as many numbers as he can."

grenv: huh! must play the larger one! well, that's a pretty arbitrary rule.

But all this is moot, since there is no governing body in badminton like there is in chess? The idea seems to be that through convention and habit, most people on the site seem to want to use both dice when possible, but it's not based on anything "official"?

redsales: How come you don't know International Badminton Federation? LOL, I'm just messing with you.

redsales: It's played by that rule everywhere. I don't know what you mean by not being official, by that logic you could argue English has no official grammar. All rules are arbitrary, why use only 2 dice instead of 3?

When did Badminton get added here?

Vikings: That should be a real feather in Fencer's cap.

grenv:
I've never played a single game of backgammon outside of BK, either in real life or on another site, so the incorrectness of the playability on BK comes as a bit of a shock, bc I know nothing else to compare it to. But I'll take your word that BK is against the norm.

As an aside, English DOESN'T have official grammar in some cases, such as split infinitives, which were considered grammatically incorrect 150 years ago, but generally accepted today. Unclear usage is dealt with through a board of grammarians, who much like backgammon, are not the "official word" anyway. you can find more information on the process of debating new grammar at www.dictionary.com. What can you expect with such a bastardized language?

So there is no FIDE-like backgammon organization?

good point Vikings, I meant backgammon

There is no world governing body for Backgammon, just as there is none for poker. We're all anarchists at heart.

alanback: so who runs those US-based gammon tourney sites I chanced upon online? The unabomber, I guess? He does have access 3 hours a day, I could see it.

redsales: They're generally sponsored by local clubs, or are self-sustaining. There is a so-called American Backammon Tour, but it's just a series of locally-sponsored events.

http://www.chicagopoint.com/abtexp.html

this needs unification then. It would be a great pyramid scheme.

redsales: My point about grammar was that there is no governing body in English (unlike some other languages), yet we still have rules that everyone accepts (using a period or full stop at the end of a setence for instance).

Split infinitives was never a problem and only came about because it's not allowed in Latin and some idiots thought that was a good reason not to allow it in english. However infinitives in Latin are a single word so that's stupid.

Where would Captain Kirk be without "To boldly go"?

grenv: right, as English and backgammon prove, and maybe the past dramas with FIDE and Kasparov also, that a governing body can do more harm than good. Shakespeare used grammar that is unusual or even just plain wrong today, yet he's the immortal bard. Nice paradox. Grammar is ridiculous anyway; it's simply a retroactive way to try and explain what a society knows intuitively.

redsales: and not only that, he used vulgarities and curses. He was probably hated by the societal elite of the day in the same way that many rap artists are today.

But back to backgammon: Since Fencer agreed to fix this (when I wonder?) I think we'd have to all agree it's a bug, right?

Marfitalu: That's what I do already. To be honest I rarely look at the last move of my opponent, so I doubt I'd notice.

Wouldn't the rish of accidentally violating the rule be minimized by placing the highest of the two dice first in order? That way, it would take a dice swap to violate the rule, and that would be deliberate.

WhiteTower: In the 5 cases that I've come across it's been a question of playing only one dice when two should have been played. The dice order is only a coincidental factor. But im the case of using the larger of the two (which I haven't noticed so far) it would certainly be helpful for the larger dice to be shown first.

It would also be a convention helpful in its own right.

Marfitalu:

Bry: 21 days time control?! Has the first tourney of that series finished yet? Lolol. ;-)

The clock is ticking down to the fateful reshuffling of the rankings . . . any guesses as to what the new top rating will be? I'm guessing around 2200.

BBW: wouldn't it be if there is two of your opponents pieces on a spot, it wouldn't allow you to move there in the first place? Yhat would be the only way you could do decective work

That is what I would think. If your opponet has two or more pieces on a particular spot that you were trying to move to, the program just wouldn't let you move that piece.

Vikings: I can't find the message this is a response to.

Vikings: Yea, but that would defeat the purpose of "hiding" your opponents pieces. I mean if you know you can't move a piece to a certain place, then you would know where at least 2 of your opponents pieces are. (And with a lot of trial-error before you submit, you could learn a lot.)

I think if there was going to be a "dark backgammon" version, then if you place 1 or more of your pieces on a space that already has 2 or more of your opponents pieces, then your pieces should end up on the bar. Then you will only know after you submit of 1 place where your opponents pieces are, and lose position because of it.

You obviously wouldn't know if you hit a single pip until after you sent your moves.

alanback: It started on Feature Request board - suggested to continue it here. I was thinking we talked about it before.

alanback: The seed posts.

Here is my suggestion from June 2003 (Sorry Nof - I claim naming rights!):

http://brainking.com/en/Board?bc=26&ngi=16070

which was:

1. Dark Backgammon Race (or Regular/Nack/Crowded?)
- Basicly just like regular backgammon. You don't see ANY place that you don't have your own piece, so you will never be "blocked" and allowed to move to any place.

Now when you move to a place that is open, your piece stays there. If you move to a place that only has 1 opponent piece, you take it like normal gammon. If you move to a place that has 2 or more oppenent pieces, your piece will be placed back to the bar like it was taken out.

So this game would involve a lot more strategy - making you want to set up many places of 2 or more pieces to take away your opponents pieces when they land on you.

I believe this would be better as Dark Battleboats Race. Also I'm debating if it would be good to hide the opponents dice or not.

BIG BAD WOLF: Personally, I like the idea of not being able to move to a blocked space better, it would resemble a regular game better leaving the key to be when and where to move single pieces

Totally different. I'm going for blocked moves when there are two or more of the opponets pieces on the board.

So there!

I just think if the move is blocked, it would defeat the purpose.

I mean if I rool a 3 & 4, then I could (BEFORE SUBMITING) test many different moves / multiply moves with all my pieces to basicly determin where 2 or more of your pices are located - and in my opinion kind of defeat the purpose of the dark part of the game.

Where as if it allows you to move there, THEN if there is 2 more more pieces YOUR piece ends up in the bar - you will then only know of 1 place (insteald of multiply) where 2 or more of your pieces are located... and come with a "cost" since my piece would be put back to the bar.

Without that - I don't think it would be very "dark" nor very different then normal backgammon.

BIG BAD WOLF: Oh, it'd still be dark all right. It'd be more like Kliegspiel than Dark Chess. The same situation is possible in Kliegspiel in that if you move your King into check one the assistants watching the game will tell you that the move is illegal, but won't give you any details. In Dark Chess, your opponent takes your King and the game is over.

I think a dark version of Backgammon would work, though I'm not sure if it'd be a fun game or not. I'd give it a try if it was here. Sure, I'd try different moves to investigate if a point was guarded. Remember you would only be able to do this with the dice that you roll.

An alternative to having the whole board dark except where your pieces are would be to show all those points that are available to be moved to with the current dice roll. This would save the time and trouble of checking every move possible. In Dark Chess you can see the squares that your pieces can move to. If you block a piece or move it to a different place, the view will change, but not until you have made the move and it is too late for you to undo the move. Depending on the roll, it could be very illuminating or not so much. 1-1 for example. Also, would your opponent be able to see what roll you received? If so, he'd be able to figure out what you know of his position and maybe plan, trap, or play accordingly. At the start of the game you'd know your opponent's position. I'm thinking that after just a few moves it'd be real dark and you'd need to see where the pieces might be with the help of the rolled dice.

Walter Montego: Who's up for some beta testing? :)

Walter Montego: you wouldn't want to show the places that you could roll because then you would know how many peices were there, 2, 3 or more, which would make it easier to figure out all pieces of the opponent

The only thing that puzzles me is how you can call this "Basically like regular backgammon";-)