I’ve registered my son, but if I want to change sections, who/how do I contact?
Also, are the pairings a standard or accelerated swiss
Michael
You can contact Alan Kantor, akantor@uschess.org, up until the Wednesday before the tournament, from Wednesday on you have to do the changes at Chess Control on site.
I don’t know if they will be accelerated pairings, with 7 rounds it wouldn’t seem necessary, though, since I think most sections will be smaller than 256 players. Last year there was only one section larger than 256, and it had a clear first winner at 6.5 - 0.5.
thaks for the reply
The 2006 JHS tournament appeared to use straight swiss pairings in both K-9 and K-8.
The 2005 tournament (supernationals) clearly used accelerated pairings in both K-9 and K-8. In fact, they used double acceleration so that the top players faced opponents in the second 1/6th! My top student then was rated 1891 and his round 1 opponent was 1707 (February 2005 supplement). My student apparently just barely missed the round 1 cut to avoid playing on board 1! I had a printout with all preregistrations in rating order, so it was easy to see how they cut the field into groups of 1/6th for pairings.
If Mike Nolan’s rule of thumb with 256 = 2^8 players is correct, then the K-9 section will not use accelerated pairings and the K-8 section might (last year saw 262 players).
Michael Aigner
It’s not my rule of thumb, it’s the number of rounds needed to ensure that there are not multiple players who win every round. The whole purpose of accelerated pairings is to reduce the possibility that more than one player wins every game.
In practice, it usually takes more than just a few players about the theoretical limit to have multiple players win every game.
Here’s a table showing the number of sections since 2005 with 7 or more rounds and more than 256 players. I don’t know which (if any) of these events used accelerated pairings, but there were multiple people with perfect scores less than 25% of the time.
[code] event sec tnmt_name players rounds perfect
200504109821 6 2005 SUPER NATIONALS 538 7 3
200504109821 18 2005 SUPER NATIONALS 443 7 2
200604233191 1 2006 NATIONAL HIGH SCHOOL CHAMPIONS 368 7 0
200504109821 9 2005 SUPER NATIONALS 364 7 0
200504109821 10 2005 SUPER NATIONALS 350 7 0
200504109821 7 2005 SUPER NATIONALS 333 7 1
200504109821 14 2005 SUPER NATIONALS 333 7 0
200604233191 3 2006 NATIONAL HIGH SCHOOL CHAMPIONS 321 7 2
200605149491 5 2006 NATIONAL ELEMENTARY CHAMPIONSH 319 7 1
200504109821 2 2005 SUPER NATIONALS 309 7 1
200605149491 3 2006 NATIONAL ELEMENTARY CHAMPIONSH 307 7 2
200504109821 1 2005 SUPER NATIONALS 300 7 3
200605149491 8 2006 NATIONAL ELEMENTARY CHAMPIONSH 284 7 0
200605149491 2 2006 NATIONAL ELEMENTARY CHAMPIONSH 284 7 2
200504100331 1 2005 SUPER NATIONALS (K-1 SECTION) 279 7 1
200504109821 17 2005 SUPER NATIONALS 276 7 1
200504109821 15 2005 SUPER NATIONALS 272 7 1
200604233191 4 2006 NATIONAL HIGH SCHOOL CHAMPIONS 270 7 0
200604099641 5 2006 NATIONAL JUNIOR HIGH CHAMPIONS 262 7 0
200504109821 5 2005 SUPER NATIONALS 258 7 1
200608131831 1 2006 US OPEN 543 9 0
200508141331 1 U.S. OPEN 455 9 0
200505225811 4 FIRST ANNUAL HB GLOBAL CHESS CHALLE 318 9 0
200505225811 3 FIRST ANNUAL HB GLOBAL CHESS CHALLE 284 9 0
200607041321 3 WORLD OPEN 279 9 0
200505225811 1 FIRST ANNUAL HB GLOBAL CHESS CHALLE 268 9 0
[/code]
Isn’t the limit just 2 raised to a 7th power? You can guarantee there will be no more than one perfect score in a 4-round swiss if there are 2^4 = 16 (or fewer) players. For JHS nationals, it should be 2^7 = 128.
So my question is whether the 256 figure that you quoted is a rule of thumb or whether you made a calculation mistake? I understand that, with draws and so forth, four rounds are sufficient for no more than one perfect score even with 20 or sometimes 30 players. Out of 262 players in K-8 last year, nobody got a perfect score and 6.5 was sufficient for clear first place.
Basically, my question is what the guidelines for implementing accelerated pairings are? Two years ago, double acceleration was used. One year ago, regular swiss pairings were used. The number of players was actually less in the double acceleration year!?
Michael Aigner
OK, slight error by me. K-9 in 2005 (supernationals) had 133 players. K-9 in 2006 had only 112 players. The 2005 pairings used acceleration (I believe double acceleration even) while the 2006 pairings were straight swiss.
round 1, board 1 in 2004 = 2179 vs 1304 (142 players, normal swiss)
round 1, board 1 in 2005 = 2211 vs 1831 (133 players, double accelerated)
round 1, board 1 in 2006 = 2202 vs 1415 (112 players, normal swiss)
Michael Aigner
The 256 is a rule of thumb. I generally only accelerate a section when the number of players approaches the rule of thumb.
to help ensure a clear winner the rules of thumb for seven rounds are based on these:
basic swiss is 2^n where n =the number of rounds
so 2^7=128
accelerated swiss is 2^(n+1)
so 2^8=256
more than you want to know on standerd accelerated, 1/6 etc:
scichess.org/faq/swiss.html
nwa.org.au/dbx/articles/Acce … rings.html
metrowestchess.org/Community … irings.htm
What, you don’t have 6 fingers on your hand? Math error on my part, 7 rounds is for 128 players, 256 is for 8 rounds. 
However, the statistics I posted are still valid, even with more than 256 players the number of perfect scores in 7 round national scholastic events has been fairly small.
I don’t need 6 fingers per hand.
I use both hands and my toes too sometimes 
It may simply be that organizers are waking up to the realization that accelerated pairings are highly overrated.
For accelerated pairings to work, higher-rated losers must defeat lower-rated winners in round 2. If the opposite happens, you end up with 3/8 of the players at 2-0 after two rounds, as opposed to 1/4 for standard pairings or 1/8 for accelerated pairings that work.
In a scholastic tournament, with many provisional and rapidly-improving players, round 1 results may be more reliable than pre-tournament ratings as a predictor of round 2 results. In that case, accelerated pairings would backfire.
Bill Smythe
Mr. Smythe, I respect your opinion on accelerated pairings. That does not, however, answer my question why accelerated pairings were used in K-9 at supernationals in 2005. A year earlier, in 2004, they used normal pairings with a slightly larger turnout. A year later, in 2006, they again used normal pairings.
If the answer is “they screwed up” then so be it. I know that the supernationals had a mixture of small sections (under 150 players) and large sections (over 300 players). K-8 and K-12 were both large, but K-9 was comparatively small.
The only effect is that now I, as a coach, now view K-9 as being a very tough section where 1700 and 1800 players get paired up in round 1. If the TDs did mess up in 2005, then my conclusion appears to be flawed.
round 1, board 1 in 2004 = 2179 vs 1304 (142 players, normal swiss)
round 1, board 1 in 2005 = 2211 vs 1831 (133 players, double accelerated)
round 1, board 1 in 2006 = 2202 vs 1415 (112 players, normal swiss)
Michael Aigner
In 2005 (Supernationals) all of the various championship sections were accelerated and none of the under sections were. The reason none of the under section were is because those were most likely to have the backfire effect mentioned by Bill.
If memory serves (I’m being a little lazy and not checking MSA for this), the six championship sections were K-3, K-5, K-6, K-8, K-9, K-12. I would guess that a blanket decision was made for all six sections and that the comparatively small size of K-9 was overlooked.
It’s a bit strong to say that anybody “screwed up”. Organizers of large annual events constantly tinker with their formats, looking for improvements. When a thought-to-be “improvement” turns out not to be, the idea is dropped in the 3rd year.
Piecemeal statistics like these are often presented in attempt to prove how wonderful accelerated pairings are. In this case, though, you are apparently attempting to prove how much tougher the tournament becomes. Either way, let’s take a closer look.
The above statistics are for round 1 only. What happens in later rounds? (And let’s even assume that accelerated pairings “work”, i.e. that higher-rated losers will defeat lower-rated winners.)
Then: Round 1 accelerated pairings feel like round 2 standard pairings. Round 2 accelerated pairings feel like round 3 standard pairings.
But things change in round 3. For the top 1/8 of the players, round 3 feels like round 4. Ditto for the bottom 1/8. But for the 3/4 in the middle at 1-1, players are paired against opponents rated much higher or lower than themselves. It feels almost like round 1 standard pairings.
So, for the vast majority, accelerated pairings have no real effect except to change the order of the rounds. For the elite few, it’s like omitting the first round and adding a final round – sort of like the way daylight saving time cuts off one end of the blanket and sews it onto the other to make it longer.
As a coach, do you really feel the tournament is all that much tougher because your kids are playing rounds 2-8 of an 8-round event instead of rounds 1-7 of a 7-rounder?
Bill Smythe
Oh, I can definitely speak to how a coach felt after seeing the pairings and results at 2005 Supernationals. I was there! One of my 1900 rated students finished in fourth place (on tiebreaks) in the final standings for K-9.
However, he had a very difficult first day, facing two 1700s and scoring just 0.5/2. Once the normal pairings returned for round 3, he faced four straight opponents rated under 1700 and beat each one in under 25 moves. On a roll, he defeated an expert in the last round to finish with 5.5/7, just behind the three co-champions.
There is also no way for me to say he would have equalled or exceeded his fourth place result if the pairings had been done, in my opinion, correctly. I will say that this tournament was a great learning experience for this young man and exactly this adversity in 2005 helped him upset two masters in the 2006 High School nationals.
On the other hand, there is no doubt that the accelerated pairings had a huge impact on the perceived difficulty of the tournament–at least from our perspective. The first two rounds were far more difficult (both on paper and in reality) than anything we saw until the final game. In Mr. Smythe’s terminology, our rounds 5 and 6 occurred before rounds 1-4. The poor start had something to do with the easier pairings. However, I would have expected a more difficult pairing in round 6 with 3.5/5 than in round 1 or in round 2 with 0.0/1.
Michael Aigner
P.S. Why was DOUBLE acceleration used at Supernationals. I had a printout of all players so it was very easy to see how the top 1/6 played the second 1/6. Even under normal accelerated pairings (top 1/4 plays second 1/4) the pairings wouldn’t have been quite so evil. The only answer I see is that they used double acceleration in ALL sections and never considered that the K-9 had only 133 players.
OK, now I see you are arguing against accelerated pairings, or at least in favor of year-to-year uniformity. Fair enough.
Players have good and bad tournaments, though, even without differences in the pairings methods. One year at the National Open, playing up a section, I scored 3.5, the following year 0.5.
I assume by double acceleration you mean:
Round 1:
Top 6th vs second 6th
Third 6th vs fourth 6th
Fifth 6th vs bottom 6th
Round 2:
Top 3rd winners vs each other
Top 3rd losers vs middle 3rd winners
Middle 3rd losers vs bottom 3rd winners
Bottom 3rd losers vs each other
If so, then I agree this is a bad idea. There is a theoretical anomaly here that bothers me a lot.
With standard pairings or quarter pairings, after 2 rounds, any 2 players with the same win-loss sequence will have had overlapping opponents. By win-loss sequence I mean not just the score, but also the order, e.g. a win followed by a loss would be a different sequence than a loss followed by a win. By overlapping opponents I mean that at least one of player A’s opponents will be higher-rated than at least one of player B’s, and vice versa.
With pairings by sixths, there will be some pairs of players with the same win-loss sequence but with non-overlapping opponents. For example, if A is in the second 12th and B is in the ninth 12th, then both will have a win followed by a loss, yet even the lower of A’s two opponents will be higher-rated than even the higher of B’s two opponents. This bothers me (YMMV), and it does not happen with either standard or quarter pairings.
Bill Smythe
I was seeking uniformity in the application of accelerated pairings. My first post in this thread asked Mike Nolan if there was a rule of thumb when to use accelerated pairings. I have heard that there indeed is a rule of thumb based on the number of players, but that it is either 2^N or 2^(N+1) where N is the number of rounds.
This led me to question the accelerated pairings (by sixths) that was used in 2005 for the K-9 section with 133 players. For the mathematically challenged among us, 2^7 = 128–so the entries barely exceeded even the minimum threshold for accelerated pairings. To further support my claim of an inconsistency, I showed that regular pairings were used in both 2004 and 2006 for similar sized sections.
So is there a rule of thumb based on the number of players or not? What is it and who decides when to use accelerated pairings? I am looking for an answer before the first round of K-9 in Sacramento on March 30, 2007. 
Michael Aigner
I guess for some it is 2^N, for others 2^(N+1), and for still others “I don’t know what that funny hat symbol means”.
Good luck in getting any two TDs to agree, and in getting any one to tell you any sooner than 9:55 on the day of the tournament (if the round starts at 10:00). 
Bill Smythe
Michael,
Bill hits on a very key point. Different TDs feel differently about the value that accelerated pairings have. It is quite possible different TDs were making that decision at each of those events.
And this is not directed at you, but blaming a childs results on pairings is utter crap. I have seen many coaches and parents do this, and it would be much nicer to teach them accountability than excuses. Other 1900s I am sure had to play against 1700 players in the first two rounds.
If any player is deserving of finishing in the top prizes in their section, they are going to have to beat top players, regardless of what round it happens to occur in.
Glenn