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Even though A-E pairing is most likely, C could still has a score of 64 and make it not a good pairing. So these teams could not be paired until the score from C-D comes in. As I said in my post early, you could relax rule #2 to gain speed. In this case you'll need to relax it to the point where score difference of 7 VP are treated as equal. Under this condition you could pair A-E. If there is a blitz from C-D, the winner would play B. All these pairing has a maximum difference of 7 vp. If your threshold is 6 VP they could not be paired at this time.

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The best solution is to assign three way for next round first if there are odd number of teams on odd number of round (three way will go on for two rounds). Then apply standard pairing for the rest of teams.

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I'm going to give my comments based on my experience as a chess TD. If bridge TD's main task is to manage table movement, chess TD's main job is to do pairing. There are a few rules in Swiss pairing. 1. No teams should be paired twice. This is a hard rule. It could only be broken when the number of rounds equal or greater than number of teams. 2. Teams with same score should be paired together. This rule has to be broken when there is an odd number of teams in a scoring group. In that case the last/bottom team in a group is paired with the top team in next lower scoring group. 3. In the same scoring group the teams are divided into two halves - top and bottom. In chess this is done based on player's rating. In bridge we could do it if there is any seeding order but I believe it is random in ACBLscore. #1 in top half is paired with #1 in bottom half, #2 vs. #2 etc. If the two team have played each other, then switch the bottom group one to the next team. In chess there is also color assignment that makes it more complicated, but it has rules to use exchange (swap two players) and mutation (reorder a subgroup of players) to get a possible pairing.

In chess each game score only has three possibilities: win(1), lose (0) and draw(0.5). So there are a lot of players tied with the same score every round and it needs these rules to do pairing. In bridge each round score could be from 0 or 20(30). So the chance of tie is much smaller and it should be simpler to pair.

The requirement to do pairing with partial score is a challenge. Some possible solutions are a. Check the top teams and bottom teams first. If there are no teams (in play) that could have scores higher than two top scored teams (already reported), then pair these two team for next round. Similarly it could be done for the bottom teams if there are even number of teams. If it is odd number of teams, you need find three lowest scores for three way. b. For other teams in the middle, if there are three teams with the same score, pick two of them to pair for next round.

At any time in this partial pairing the program needs to check the teams still in play and unpaired teams to make sure there is no team that has played against all other teams. This is necessary to follow rule #1. In practice if the above partial pairing is too slow in producing pairing, it might need to relax rule #2 to treat teams with score difference of 1 VP (or some other number) as same score in order to speed up pairing.

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Warren Buffet said he likes to invest in company with simple business model that it could be run by a monkey, because “sooner or later it will be run by a monkey”. We have a lot of speculation about why ACBL made this decision but I have a feeling this is what happened. This also reminded me a history in not too distant past. In early 1990s US decided to build a Superconductor Super Collider after many committee reviews that took over 5 years. It spent 1-2B USD to dig a tunnel in Texas. Then Clinton and a new congress came to power. They decided to cancel the project. History likes to repeat itself, in large or small scale.

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Do we do know what is ACBL rule about Swiss team pairing. FIDE and USCF all have very clear rule about chess pairing. I'm a chess tournament director and I know partial pairing is possible even though chess pairing is more complicated than bridge. As you point out chess also has color assignment and it adds another constraint. There are some difference in bridge vs chess. In chess you give a bye to lowest ranked player when there is odd number of player. In bridge, you need pair a three-way for two round with odd number of teams. The rest of them are standard. In principal a Swiss pairing algorithm is not difficult to work out. For a given round where team score/standing is s(i), the next round pair should minimize S = sum(|s(i)-s(j)|) with constraint i and j has not played. Given the current computing power one could even use brutal force to solve it. If you want a smart algorithm, you could define the pair logic as how to divide a group of teams into two groups and both of them are pairable. A group is not pairable if one team has played against all other teams. This call could be recursive. You could start from the standard Swiss pairing requirement to group team with same score from top down. The tricky part for Swiss pairing is about handling a large number of teams but the difference between number of team and number of round is small. When Num of round = Num of teams - 1, it becomes a round robin and the algorithm need to look ahead of future round of pairing. For example, a 7 team Swiss with 6 round, one of them needs to play all 6 round with three-ways. If you mistakenly take 3 teams that has not played for three way in round 1 and 2 to play three way for round 3 and 4, you'll find out you could not find a possible three way for round 5 and 6. One factor that makes bridge Swiss pairing easier than chess is that it may not have a lot of tie in score that your need to use rating (or other seeding) information. With either 20 and 30 VP scale, especially the new fractional VP score, the chance for teams with tie is smaller chess and it is easier to apply standard Swiss rule. Chess tournament also has some special rules for last round. If a tournament has multiple class prizes, the last round pairing would prefer to pair players within their own class. Bridge should also have a preference to pair teams with same stratum. Finally I have a suspicion that when ACBLscore pair the next round with partial scores, it may not follow the standard Swiss pairing rule to pair teams with exact same scores. It might treat score difference of 1 or 2 VP as equal to get the pairing speed up. This is just my guess.

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I agree this Open Source should be a topic of itself. However I think the potential users are not bridge players but bridge software developers. Bridge players does not have any interest in what language the software is written or it is open source or not, as long as it works. Software developers do.

If we are talking about Open Source, I think we should go beyond ACBLScore. There is clearly a need to have some “industry standard” in bridge software. For example, it is best to define some standard “game file format” so some common data from a tournament could be saved. This goes beyond ACBL tournaments and bridge software for other country could use it as well. Other package that could be included in open source are double dummy analysis, Swiss/KO team pairing, pair game movement and rating system etc.

What this open source project would do is that it allows software developers to develop their own application for specific purpose without rewriting the basic business logic covered by open source. I noticed that one of the requirement for ACBLScore+ is that it needs to do everything ACBLScore does. So it needs to rewrite all pairing and movement logic in another language. With open source, it could simply just use the code from open source project. ACBL developers only need to develop its own features to do financial report, how to award master points etc. These code are application specific and not open sourced.

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The other question is how much it is going to cost to “enhance” current system. I suppose it is not going to be free even they bring it “in house”? By the way how many software developers are there on ABCL payroll now and what are they doing?

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I found the following link from Bridgescore+ that has Mr. Hartman's story about the contract dispute with ACBL that led to the breakdown of negotiation. http://bsp.bridgescoreplus.com/?page_id=51

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I checked out the Bridgescore+ website and I suggest any interested people to take a look, click on show me and watch some video. I think it works quite good given this is the first version. Its documentation is built in and could give you some detailed code and schema design. The fault I found is its Swiss team set up might not work as well as current ACBLScore, but other game set up are easier to use.

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The suggestion that someone could hack open source does not understand how open source work. By definition open source would allow all other developer to see the code and there is no way someone could hard coded something that gives certain players a preference over others. Closed source does not mean it is safe. Even though ACBLScore is not open source, a determined hacker could still decode the financial report file or game file and alter its data before sending it to ACBL.

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The change of B/C NAP to Sun/Mon makes it very unattractive to play. When it ends, Vanderbilt and 10K KO has already started. With Red Ribbon moving to summer, there is no NABC event to play for young players until Thursday's Open Pair.

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A good rating system should solve the second problem as well. In USCF chess rating system, master players are above 2200. Club players often range from 1200 to 2000. So there is a large range player could see their improvement in rating if they continue to play. I did some test with local bridge club results try to rate player using an algorithm similar to chess. I got similar result with best player rating close to 2000, but most players were in 1200 - 1600 range. I know most of them are life masters. With masterpoint inflation a player rated 1300-1400 could be a LM.

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USCF has both rated games and unrated games in a tournament. It is just you won't see any unrated game results because they were not kept. If I were to use BBO data to study, I'll only chose from those tournament games where played paid an entry fee, presumably these are more serious games. A rating system could also change players behavior. With masterpoint, some players who do not have good session early on tend to made some wild bid on last few boards since they have nothing to lose. This could skew the result, giving gifts to players who happened to be in the right place. If players know all the boards they played will be rated, they may not do it since it could result in big rating drop.

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It looks like they have the same masterpoint system. It is not a competition, just a duplication. I'm looking for some organizations that would open to a new way to organize tournament and providing incentive for players to play.

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I recall I saw some USBF regional tournament ad. I think it was in Eau Claire, WI this summer. High fee is probably due to limited membership now. However its bylaw would be the real problem if it only set up to run US Championship or team trial.

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I think this is an interesting idea but I suggest you to push it further. Maybe USBF could develop a new rating system and use it to organize their tournaments. Over time we could check how USBF membership grows vs ACBL and see if the rating system could help to promote the game.

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Mark, I had the same experience as you with my first KO event but in a sectional. We were good players but did not have a lot of points so we got into the lowest bracket. It was a 3 session KO in one day and we won all rounds easily. However it was so boring that we were just counting time to see when it would finish at the end. We only got 2.64 masterpoints for it. Just like you I did not play KO for many years after that.

I also agree with you that we should not abandon masterpoint completely, but we should recognize it as a lifetime achievement.

The problem is ACBL's KO structure is using masterpoint to determine brackets and awards. I think a better solution is tournament should pre-designate a certain number of brackets and publish the expected master point award for each of them (it could be adjusted by actual attendance). This is just like chess tournament that publish prize money for each sections. Players could chose to play in the bracket they think their team is competitive. A new rating system could give player guidance where they should play. Of course you also want to limit players to “play down” and get easy wins with a real good rating system.

Finally the masterpoint is OK for current active ACBL members because they are kept coming to ACBL games. However how many players tried ACBL then quit because they don't like masterpoint system? If we want to know if a new rating system could help to promote game, it is really if it could attract these players. My intuition is YES.

Ping Hu

Ping Hu

Ping Hu

There are a few rules in Swiss pairing.

1. No teams should be paired twice. This is a hard rule. It could only be broken when the number of rounds equal or greater than number of teams.

2. Teams with same score should be paired together. This rule has to be broken when there is an odd number of teams in a scoring group. In that case the last/bottom team in a group is paired with the top team in next lower scoring group.

3. In the same scoring group the teams are divided into two halves - top and bottom. In chess this is done based on player's rating. In bridge we could do it if there is any seeding order but I believe it is random in ACBLscore. #1 in top half is paired with #1 in bottom half, #2 vs. #2 etc. If the two team have played each other, then switch the bottom group one to the next team. In chess there is also color assignment that makes it more complicated, but it has rules to use exchange (swap two players) and mutation (reorder a subgroup of players) to get a possible pairing.

In chess each game score only has three possibilities: win(1), lose (0) and draw(0.5). So there are a lot of players tied with the same score every round and it needs these rules to do pairing. In bridge each round score could be from 0 or 20(30). So the chance of tie is much smaller and it should be simpler to pair.

The requirement to do pairing with partial score is a challenge. Some possible solutions are

a. Check the top teams and bottom teams first. If there are no teams (in play) that could have scores higher than two top scored teams (already reported), then pair these two team for next round. Similarly it could be done for the bottom teams if there are even number of teams. If it is odd number of teams, you need find three lowest scores for three way.

b. For other teams in the middle, if there are three teams with the same score, pick two of them to pair for next round.

At any time in this partial pairing the program needs to check the teams still in play and unpaired teams to make sure there is no team that has played against all other teams. This is necessary to follow rule #1. In practice if the above partial pairing is too slow in producing pairing, it might need to relax rule #2 to treat teams with score difference of 1 VP (or some other number) as same score in order to speed up pairing.

Ping Hu

This also reminded me a history in not too distant past. In early 1990s US decided to build a Superconductor Super Collider after many committee reviews that took over 5 years. It spent 1-2B USD to dig a tunnel in Texas. Then Clinton and a new congress came to power. They decided to cancel the project. History likes to repeat itself, in large or small scale.

Ping Hu

I'm a chess tournament director and I know partial pairing is possible even though chess pairing is more complicated than bridge. As you point out chess also has color assignment and it adds another constraint. There are some difference in bridge vs chess. In chess you give a bye to lowest ranked player when there is odd number of player. In bridge, you need pair a three-way for two round with odd number of teams. The rest of them are standard.

In principal a Swiss pairing algorithm is not difficult to work out. For a given round where team score/standing is s(i), the next round pair should minimize S = sum(|s(i)-s(j)|) with constraint i and j has not played. Given the current computing power one could even use brutal force to solve it.

If you want a smart algorithm, you could define the pair logic as how to divide a group of teams into two groups and both of them are pairable. A group is not pairable if one team has played against all other teams. This call could be recursive. You could start from the standard Swiss pairing requirement to group team with same score from top down.

The tricky part for Swiss pairing is about handling a large number of teams but the difference between number of team and number of round is small. When Num of round = Num of teams - 1, it becomes a round robin and the algorithm need to look ahead of future round of pairing. For example, a 7 team Swiss with 6 round, one of them needs to play all 6 round with three-ways. If you mistakenly take 3 teams that has not played for three way in round 1 and 2 to play three way for round 3 and 4, you'll find out you could not find a possible three way for round 5 and 6.

One factor that makes bridge Swiss pairing easier than chess is that it may not have a lot of tie in score that your need to use rating (or other seeding) information. With either 20 and 30 VP scale, especially the new fractional VP score, the chance for teams with tie is smaller chess and it is easier to apply standard Swiss rule.

Chess tournament also has some special rules for last round. If a tournament has multiple class prizes, the last round pairing would prefer to pair players within their own class. Bridge should also have a preference to pair teams with same stratum.

Finally I have a suspicion that when ACBLscore pair the next round with partial scores, it may not follow the standard Swiss pairing rule to pair teams with exact same scores. It might treat score difference of 1 or 2 VP as equal to get the pairing speed up. This is just my guess.

Ping Hu

If we are talking about Open Source, I think we should go beyond ACBLScore. There is clearly a need to have some “industry standard” in bridge software. For example, it is best to define some standard “game file format” so some common data from a tournament could be saved. This goes beyond ACBL tournaments and bridge software for other country could use it as well. Other package that could be included in open source are double dummy analysis, Swiss/KO team pairing, pair game movement and rating system etc.

What this open source project would do is that it allows software developers to develop their own application for specific purpose without rewriting the basic business logic covered by open source. I noticed that one of the requirement for ACBLScore+ is that it needs to do everything ACBLScore does. So it needs to rewrite all pairing and movement logic in another language. With open source, it could simply just use the code from open source project. ACBL developers only need to develop its own features to do financial report, how to award master points etc. These code are application specific and not open sourced.

Ping Hu

Ping Hu

Ping Hu

Ping Hu

http://bsp.bridgescoreplus.com/?page_id=51

Ping Hu

Ping Hu

Closed source does not mean it is safe. Even though ACBLScore is not open source, a determined hacker could still decode the financial report file or game file and alter its data before sending it to ACBL.

Ping Hu

Ping Hu

Ping Hu

I did some test with local bridge club results try to rate player using an algorithm similar to chess. I got similar result with best player rating close to 2000, but most players were in 1200 - 1600 range. I know most of them are life masters. With masterpoint inflation a player rated 1300-1400 could be a LM.

Ping Hu

If I were to use BBO data to study, I'll only chose from those tournament games where played paid an entry fee, presumably these are more serious games.

A rating system could also change players behavior. With masterpoint, some players who do not have good session early on tend to made some wild bid on last few boards since they have nothing to lose. This could skew the result, giving gifts to players who happened to be in the right place. If players know all the boards they played will be rated, they may not do it since it could result in big rating drop.

Ping Hu

Ping Hu

Ping Hu

Ping Hu

I also agree with you that we should not abandon masterpoint completely, but we should recognize it as a lifetime achievement.

The problem is ACBL's KO structure is using masterpoint to determine brackets and awards. I think a better solution is tournament should pre-designate a certain number of brackets and publish the expected master point award for each of them (it could be adjusted by actual attendance). This is just like chess tournament that publish prize money for each sections. Players could chose to play in the bracket they think their team is competitive. A new rating system could give player guidance where they should play. Of course you also want to limit players to “play down” and get easy wins with a real good rating system.

Finally the masterpoint is OK for current active ACBL members because they are kept coming to ACBL games. However how many players tried ACBL then quit because they don't like masterpoint system? If we want to know if a new rating system could help to promote game, it is really if it could attract these players. My intuition is YES.