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Chang
26-10-2006, 02:21 AM
Hi,

I’ve been studying PROTOS, the program endorsed by FIDE, and found that it allows 2 downfloats consecutively without apparent reason. To make it easier to understand I copy the pairing info from Swiss98 in bitmap file of the 3rd round and 4th round. Here is the 3rd round info.

http://www.chesschat.org//attachment.php?attachmentid=711&stc=1&d=1161792794

In the 3rd round, you can notice the player No.12 who played the player No.6, 9 and 4 with Black, White, Black history, had one point and he was a downfloater of this round, indicated by letter “D”. Here is the pairing info of the 4th round.

http://www.chesschat.org//attachment.php?attachmentid=712&stc=1&d=1161792811

Again in the 4th round the No.12 player was a downfloater. And even worse, it seems Swiss98 can’t remember the previous downfloat in the 3rd round. It puts only one ”D” in the column in stead of ”dD”.

From FIDE Swiss rule….
B5. No player shall receive an identical float in two consecutive rounds. …

And this is not an unavoidable situation and not the last round. Why both programs allow this? Am I missing something?

My best
Chang

pax
26-10-2006, 12:55 PM
The first point to make is that PROTOS does not consistently pair correctly despite the fact that it is approved by FIDE. As I understand it, both Swiss Master and Swiss Manager pair consistently correctly. Swiss Perfect pairs correctly most of the time.

I have found in the past that PROTOS often makes an utter mess of floats (especially in the bottom half).

pax
26-10-2006, 01:06 PM
As to your specific example, the pairing is correct.

After the pairings:
1-3
6-2
7-5
8-4

You are left with (colour pref in brackets): players 9(b), 10(w) and 12(w) on 1 point and 11(W) on 0. 9 has played both 11 and 12, so the remaining pairings must be:

10-9
11-12.

Double downfloat is not an inviolable rule. It is only applied if there is another valid pairing in the current scoregroup which does not have a worse colour balance.

As for SP listing (D) instead of (dD), it is probably just because the (D) makes the (d) redundant. (Dd) has no greater power over subsequent pairings than does (D). On the other hand (uD) is relevant.

Bill Gletsos
26-10-2006, 01:06 PM
Firstly although it would be nice if SP did show the downfloats as dD ( or for that matter upfloats as uU) it doesnt need do so because the D 9 (or U) is sufficient to follow the pairing rules.

As for your quesry regarding player 12, the pairing is correct.

Under the Dutch rules you pair down from the top..
Thus player 4 on 1.5 was paired with player 8.

This left a group on 1 point consisting of players 9, 10 and 12.
S1: 9 and S2: 10 & 12
w = 2, b = 1, p =1 and q = 2
x = 0

9 v 10 is valid for pairing and colour match

Note 9 v 12 is illegal as 9 has played 12 previously and 10 v 12 is not valid as it is not a colour match and hence does not meet x = 0

Therefore the pairing is 9 v 10 with 12 dropping down.
11 V 12 is a valid pairing.

Kevin Bonham
26-10-2006, 08:06 PM
As I understand it, both Swiss Master and Swiss Manager pair consistently correctly.

Bill and I (and also Swiss Manager) both think Swiss Master is wrong in one of the cases (the 6-1 vs 6-4 debate) being discussed in "Another pairing experiment" thread at the moment.

Chang
26-10-2006, 08:51 PM
Thanks all. How long it will take to be a good arbiter? <- Not really need the answer.:(

Kevin Bonham
26-10-2006, 08:54 PM
Thanks all. How long it will take to be a good arbiter? <- Not really need the answer.:(

You don't need to know everything about the Swiss System to be a very good arbiter!

The only thing I'd add is if you ever think the computer has got something wrong, don't change its pairings unless you are totally sure it is wrong. :D

Garvinator
27-10-2006, 12:28 AM
The only thing I'd add is if you ever think the computer has got something wrong, don't change its pairings unless you are totally sure it is wrong. :Dand can then come on here and back up the changes and be right ;)