Cambridge Open 2025

[Jon D'Souza-Eva]

The round 3 pairings look really odd. There are so many cases of someone with 2 points playing someone with 1, and even more of someone with 1½ playing someone with ½. I know it's to do with accelerated pairings and the "virtual point" that is added to the players in the top half, but it looks strange in a 9 round tournament with fewer than 60 participants. What are the benefits of using accelerated pairings in a tournament of this size?
https://chess-results.com/tnr1099723.as ... ES&flag=30

[Ian Thompson]

What are the benefits of using accelerated pairings in a tournament of this size?

None.

[IM Jack Rudd]

a 9 round tournament with fewer than 60 participants.

It has 109 participants.

[Jon D'Souza-Eva]

a 9 round tournament with fewer than 60 participants.

It has 109 participants.

Oops, I counted the number of boards!

[Kevin Thurlow]

The acceleration always throws up weird pairings. Why did Tiviakov on 0.5 play Peter Sowray on 1 in Rd 2? Surely Peter is the wrong one to float (if it is a float). Then further down, you get two people on 0.5 apparently down floating...

All acceleration does is transfer potential Rd 2 mis-matches to later in the tournament, and it should rule out sum of progressive scores as a tie-break.

In the old days, didn't acceleration "work" (if that's the word) as:-
Rd 1 - top quarter plays 2nd quarter, 3rd quarter plays 4th
Rd 2 - top half winners play each other, top half non-winners play bottom half winners, bottom half non-winners paired as normal.
Rd 3 or maybe later, pair it normally.

[Jonathan Rogers]

Peter played Tiviakov at Cambridge last year too, maybe also in round 2 (!).

[IM Jack Rudd]

The acceleration always throws up weird pairings. Why did Tiviakov on 0.5 play Peter Sowray on 1 in Rd 2? Surely Peter is the wrong one to float (if it is a float).

No, he's the right floater - lowest-rated white-seeker in the "2/1 scoregroup".

[LawrenceCooper]

What are the benefits of using accelerated pairings in a tournament of this size?

It is meant to be helpful for norms.

[Roger de Coverly]

The acceleration always throws up weird pairings.

I believe they are using what's called the Baku system. This overlays the usual rules applied by the Swiss-Manager program with bonus points awarded to the top two quartiles. The published pairings don't show the dummy scores so it's not so possible to see whether a float is genuine or just a result of the bones points. Sowray was bottom of the first quartile so presumably has a whole extra dummy point.

[LawrenceCooper]

Your game got a mention in LiChess chat (I tidied up their notation):
squirrel36 "insane line board 17 26... Nxd5 27 exd5 Nxf3 28 Bxf3 Qc2!!"

[Roger de Coverly]

Your game got a mention in LiChess chat (I tidied up their notation):
squirrel36 "insane line board 26... Nxd5 27 exd5 Nxf3 28 Bxf3 Qc2!!"

I failed entirely to notice the Nxd5 idea. It can also work combined with .. Bf5 in some positions. There's also a mad idea generated by engines of playing .. Bh6 a few moves later, leaving it en prise to the Queen.

The whole game.

1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6 5.f3 O-O 6.Be3 c5 7.Nge2 Nc6 8.d5 Ne5 9.Ng3 e6 10.Be2 exd5 11.cxd5 a6 12.a4 Re8 13.O-O h5 14.Qd2 h4 15.Nh1 h3 16.g3 Rb8 17.a5 Qc7 18.Rfb1 b5 19.axb6 Rxb6 20.Nf2 Rb4 21.Ra3 Qb8 22.Na2 Rb3 23.Rxb3 Qxb3 24.Nc1 Qa4 25.b4 c4 26.Bd4 Bd7 27.Ra1 Qb5 28.Ra5 Qb7 29.Bxe5 dxe5 30.Bxc4 Ra8 31.Nfd3 Bf8 32.Nb3 Qb6+ 33.Nbc5 Bxc5+ 34.bxc5 Qb1+ 35.Qc1 Rb8 36.Ra1 Qxc1+ 37.Rxc1 Bb5 38.Bxb5 axb5 39.d6

position at move 26
[SetUp "1"] [FEN "2b1r1k1/5pb1/p2p1np1/3Pn3/qPpBP3/5PPp/3QBN1P/1RN3K1 b - - 1 26"]

[LawrenceCooper]

Your game got a mention in LiChess chat (I tidied up their notation):
squirrel36 "insane line board 26... Nxd5 27 exd5 Nxf3 28 Bxf3 Qc2!!"

I entirely failed to notice the Nxd5 idea. It can also work combined with .. Bf5 in some positions. There's also a mad idea generated by engines of playing .. Bh6 a few moves later, leaving it en prise to the Queen.

Understandable, some of the lines are mind blowing and I wouldn't know where to start trying to decide which lines to spend my time on.

[Mick Norris]

The acceleration always throws up weird pairings.

I believe they are using what's called the Baku system. This overlays the usual rules applied by the Swiss-Manager program with bonus points awarded to the top two quartiles. The published pairings don't show the dummy scores so it's not so possible to see whether a float is genuine or just a result of the bones points. Sowray was bottom of the first quartile so presumably has a whole extra dummy point.

Baku system says that acceleration includes round 5, seems a lot

[IM Jack Rudd]

Yes, three rounds of one-point acceleration and two of half-point.

[Mick Norris]

round 7 pairings

Bosonic - Adams both leading with 5

Camacho Collados - Camacho Collados on board 3 drawn in 10 moves

RdC gaining rating points