28R accelerated pairings, appropriate in this situation?

Running Chess Tournaments
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Thanks for putting up with me. I am the only TD in Alaska, so I have to ask some questions here because I don’t have a mentor.

So, this Saturday I have a swiss tournament, all one section that is fully pre registered with 25 players. The fire marshal said I could only have table space for 24 players, so that is the limit for the library.

The library also will only give me enough time for four rounds of G/25;d/5.

In this tournament, the playing strength is from 1900 all the way down to 380, with a group of unrated as well.

So, I want to help the tournament run smoothly. It seems to my unexperienced mind that I have more than 2^nth power (2^4=16) players, and I have a huge spread in one section (1500+ rating). These qualify for accelerated pairing.

Should I use accelerated pairing for this event?

There is no entry fee, and a donated $100 cash prize.

Is sending an email to the players considered advanced notice? Is this a problem?

Again, I feel like a glutton for punishment, but I have to ask here because I don’t have anyone else to ask, and I really want to learn how to do it right, even if that means a little critisism.

My basic understanding is that it would be as if the top half won a non existant pre round against the bottom half, essentially “adding” a round to my tournament that didn’t actually happen.

I tried to look through old threads here for clarification, but didn’t find something along these lines.

Thanks.

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I would not accelerate. You will likely have a lot of draws (stalemates) with all those low/unrated players. That will shrink the size of the score groups. If you don’t manage to get a clear winner, you can just divide the prize money.

Just my opinion. Others may have different experiences

Moogy
Brenda Hardesty
Senior TD

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Accelerated pairings are useful when: draws will not be common; the rating differences between the top and bottom half are significant and trustworthy; there is a real possibility of multiple perfect scores.

When all of those apply then you can start considering acceleration. The scholastic national threshold is two times two to raised to the power of the number of round (2 times 2 to the fourth or 32 in your case) while I start looking at 1.5 times (1.5 times 2 to the fourth is 24).
If there is a realistic chance of draws then you do not need to accelerate. I did not accelerate a national junior high K-8 championship section which exceeded the national scholastic threshold of 256 for 7 rounds and it went fine. I don’t consider accelerating my club’s 4-rournd championship until 24 and would really want to wait until 32 or more because of the likelihood of draws (I do accelerate fixed 8-board-per-team team tournaments at 24 because the likelihood of tied matches is fairly small).

COMMENTS ON ACCELERATION THAT MIGHT BE INTERESTING.
Don’t accelerate if the rating differences between the top half and bottom half are not significant (a single class section) or not trustworthy (either a large percentage of single-digit provisional or very young and still learning players) because then you run the risk of more than 50% of the lower half 1-0 players winning against upper half 0-1 players and actually increasing your number of 2-0 players (versus standard Swiss pairings). Standard Swiss with 24 players (no draws) is 12 1-0 and 12 0-1 players after one round and 6 2-0, 12 1-1 and 6 0-2 players after two rounds. Acceleration has 6 1-0 in the top half paired with each other, 6 0-1 from the top half paired against 6 1-0 from the bottom half, and 6 0-1 from the bottom half paired against each other. The 6 top-half 0-1 players are “supposed” to beat the 6 bottom-half 1-0 players but in single class sections or newer-player sections there is a realistic chance that the bottom-half 6 will win their games and you will end up with nine player at 2-0 instead of only six. At the All-Girls National (6 rounds) I have accelerated an under-10-years-old section that exceeded 128 players (the players may be young but they are not particularly new) but I would not do it in an under-8 section because of the lower trustworthiness that their ratings accurately reflect their current skill (new players can improve their skills dramatically with just a handful of lessons or one new book and thus be considerably stronger than their official ratings).

Acceleration is only used to reduce perfect scores. Some people think that acceleration makes for closer pairings but that in only true for the very top and very bottom players. For the middle of the pack acceleration is roughly equivalent to playing a standard round two in round one, a standard round three in round two, and a slightly closer paired round one in round three (when the middle three quarters are at 1-1 versus the entire field starting at 0-0). Because the middle three quarters is at 1-1 (versus the middle half in standard) that means that the round 3 and later pairings have larger rating differences under acceleration for the middle score groups. The net result of acceleration for the middle is to receive a round three pairing with a slightly closer mismatch than a standard round one pairing while later rounds have greater mismatches under acceleration.

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Great points, thank you for the feedback! I would say our results are not trustworthy, as many of the lower players are in a state of flux.

It is odd, as a side note, in the six tournaments I have worked this year, there has only been three draws, making them unusually rare here for some reason. Perhaps this eludes to the untrustworthyness of the current local rating pool?

I will be taking your advice and forgoing acc. pairing for this event. Thanks for your thoughts and explainations! Someday I hopefully will have it figured out!

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Draws are something of an odd thing. Beginners (particularly young beginners) often draw games because it can take a while to get used to the need to checkmate rather than just amass huge advantages in material. (Adult beginners typically don’t have that problem.) Intermediate players (through maybe 1600 or so) don’t have as many draws because games are generally decided by catastrophic errors. Above that, the probability of draws increases steadily with rating as (a) players make fewer gross errors and (b) defensive abilities improve.

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There are different kinds of draws, stalemates are more common among beginning players, though it is also common for those players to not recognize a stalemate and keep on playing. Possibly the most common problem with beginning players is the player ahead on material getting 2, 3 or even 4 queens, taking all the other player’s pieces and then stumbling into a stalemate.

50 move and three repeated position draws start to show up as players get better (including learning how to keep score), though I remember watching a young player struggle with a K-R vs K ending until his opponent could claim the 50 move draw, because he didn’t know how to turn that into a win. After the game was over I showed him the process in 2 minutes.

Draws that take some skill don’t really start to show up until players get to at least 1400 strength, IMHO. And recognizing when a position is drawn while still in the middlegame comes at an even higher strength level.

Many years ago I subscribed to Chess Review (because it was cheaper than Chess Life) and wrote Al Horowitz a letter asking why so many games were draws. He sent my letter back to me with a hand-written note saying “As you get better, you’ll understand this.” I also asked him what USCF meant in tournament ads, his response: “My competitor”.

I wish I had kept that letter!

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A number of years ago I did some simulations of the effect of accelerated pairings in 4+ round events with 64 players in them.

In many cases, the main effect was to push the pairings with the widest differences in player ratings from round 1 to round 3.

This was shortly after I went 2-0 in the first two rounds of the accelerated pairing Region VII Championships in Omaha and got paired on board 2 in round 3 against the defending state champion, a 2300 player. That game was brutal!

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8

One other downside of accelerated pairings is the number of confused players you end up having. Are you prepared to explain the pairings several times? Saying “the program did it” sounds rather unsatisfactory.

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As others have indicated, the primary object of accelerated pairings is to minimize the possibility of multiple perfect scores.

Multiple perfect scores can be a problem when the top prizes are indivisible and require tiebreaks to distribute.

Money is divisible, and that which is divisible should be divided.

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