Swiss tournaments are on Lichess

The description of the pairing system, and the algorithms required, are in the FIDE Handbook: handbook.fide.com/chapter/C0403

B2 covers the principle of splitting a scoregroup into S1 and S2; i.e. top half and bottom half. If you have 2n players in any given scoregroup, then the group pairings should be 1 v n+1, n+2 v 2, 3 v n+3 ... until you get to n and 2n. If you start with 2n+1 players in Round 1, then you pair as described in the previous sentence, and 2n+1 has the pairing-allocated bye.

The guidelines for programmers produced by FIDE may be useful to you: pairings.fide.com/images/stories/downloads/appendix_p_approved.pdf

@thibault

Yes, top half against bottom half is normal practice. For example have a look at the FIDE Grand Swiss 2019 round 1...

http://chess-results.com/tnr478041.aspx?lan=1&art=2&rd=1&flag=30

Some tournaments have experimented with alternatives, but you can imagine that it’s more exciting if you get Carlsen-Caruana etc towards the end of a tournament rather than the beginning.

#201 There is a draw to see if 1 has White or Black. Then 2 will have Black if 1 has White and so on...

Using the Swiss system it would be possible to organize a rapid daily tournament? 1 game per day?

I am thinking to organize a rapid tournament where the player can arrange the meeting themself and they need to play 1 game per day.

I dont know if this has been suggested yet, but lance has created a swiss marathon and that got me thinking that maybe it could be implemented to have a periodical lichess hosted swiss marathon. Additionally, probably in the sea of comments above but what about incorporating USCF/FIDE online rated swiss tournaments onto this site?

@Sakil_33 is right - having top players meet so early (beyond accelerated pairing - even then, would never be this early) - defeats the purpose of Swiss. The last couple rounds are usually when the best play each other and the tournament is decided.
Take a simple example of 128 players and 7 round Swiss with the higher rated player always winning:
128 players to start
64 after round 1 left on full score
32 after round 2 left on full score
16 after round 3 left on full score
8 after round 4 left on full score
4 after round 5 left on full score
2 after round 6 - these should be the top 2 rated players in this simplistic example
1 after round 7 left on full score

Having those top 2 meet any earlier undercuts this build up to the 'grand finale'

lichess.org/forum/lichess-feedback/swiss-tournaments-are-on-lichess?page=19#190

At least one of them tried it out. And he published the result of his experiment here.
Whether you like it or not, you cannot ignore the facts!. Or my posts on this specific topic. I also saw in another post that tournaments with rounds set too high are simply aborted automatically by Lichess! lichess.org/forum/lichess-feedback/swiss-tournaments-are-on-lichess?page=20#191
Friends, at some point you have to face reality! I had to write that now! It was an inner need for me to write that! Sorry to all my critics like @Molurus and others!

@odoaker2015

He has tested a piece of software that may, or may not, adhere to FIDE rules. So as has already been said over 10 times, this tells you nothing.

I would appreciate it if you stopped tagging me for this nonsense.

Swisschess algorithm is using Fide rules

At the moment Swiss Tournament Hosts need to calculate the aproximate Duration theirselves.

I Think it would be very helpfull if the Server calculates it automatically with the Formular of e.g. an "estimated maximum time needed"

like

Round Number × time control x 2 +
40 moves x Increment x 2 +
(Round Number - 1) x break Duration

@thibault @toadofsky @Lance5500 @jeffforever