Pairing a round

Pairings are made on the Pairings page. This chapter covers pairing a round in every system, the explanation of a pairing, changing a pairing by hand, and undoing a round.

The Pairings page#

The page shows one round at a time. A row of round buttons at the top moves between the rounds; a round that has not been paired yet is shown empty with the button that pairs it. The table has one row per board: the board number, the White player, the result, the Black player. A player with a bye is a board with bye and no Black player. Under the round bar, a quiet line says when the round was paired (in your own time zone; hover for UTC). Pairing a round again after unpairing it replaces that time.

Above the table, the round bar has one button that stands out, and which one depends on where the round stands. Beside it are the two or three things that matter at that moment:

In a Chess960 tournament Draw Chess960 position also sits there until the round's position is drawn.

Everything else is in More, at the end of the bar, in groups:

• Print: pairings, pairings with the absentees section, result cards, a test print of the first three cards, stack-cut order;
• Round: Import results (CSV) and, in a round robin, Swap rounds…;
• PGN: this round or all rounds, with or without board numbers, or a range of boards;
• Views: Local view, Phone QR (a large dialog with the QR codes for a phone to scan) and, for a published tournament, Public page;
• Danger zone: Unpair round, on the last paired round only, and in a round robin with no result anywhere yet, Unpair the whole schedule.

Before a round is paired, More holds the views (and Swap rounds…). It works from the keyboard: the arrow keys move through it, Escape closes it, and so does a click anywhere else.

Before pairing#

The button Pair round N is available when

• the tournament's setup is complete: name, number of rounds, a date for every round, tie-breaks. If something is missing the page lists it and links to the page where it is set;
• every round so far has a result on every board, the earlier rounds as well as the last one (and in the Swiss match format both legs of the match). A board without a result keeps the button disabled with the note Previous round still has missing results; a result cleared in an earlier round counts too, because the engine would read that game as never played and could pair the same two again. If postponed games are allowed (Scoring page) a separate button, Record missing results as postponed and pair round N, records the last round's empty boards as postponed and goes on, after you have read the warning;
• the presence of the players is right: players marked absent are not paired (Byes and absences);
• no session of hand edits is open on an earlier round (see Changing a pairing by hand): the button stays disabled with the note Finish the hand edits to round N first.

Before round 1 the page also warns, without blocking, when the number of rounds cannot be paired for the number of players: a Swiss with more rounds than the players allow without a rematch ("A round that cannot be paired will have to be made by hand"), or a round robin whose number of rounds does not match the players. The warning links to the setting that fixes it (Tournament set-up).

Rounds are paired in order. The page also lists the checks that apply to the next pairing: for example, the players of every postponed game from earlier rounds, which are paired on a provisional score, and the players whose bye preferences are not applied.

Swiss#

The button reads Pair round N (Ainalrami), naming the engine. Press it and confirm. The program

1. gives the pairing numbers if this is the first round (highest rating first; the initial colour is drawn by lot unless you set it),
2. builds the tournament as a TRF file, checks it, and hands it to the engine,
3. reads the engine's pairings, numbers the boards, gives the byes, and saves the round.

A large field can take up to a minute; the button says so while it works. The round is saved only if the whole of it succeeded. If the rules allow no legal pairing for the remaining players the program says so and writes nothing.

Forbidden pairings, the pairing rules (same club, same federation, groups) that hold in the round, and extra points are given to the engine as well (Tournament set-up). With Baku acceleration the virtual points are given for every round. Each round's virtual points are recorded when it is paired, and a later round reads them back: changing the number of rounds or switching acceleration off changes the rounds still to come, never the ones already paired. When the pairing numbers are corrected (an exchange or a regeneration), the last player of Group A stays the last player of Group A (C.04.7 1.3.2).

The pairing numbers are given in the order of the tournament rating, then FIDE title, then the criterion the tournament announced (Players and rating lists). If the engine finds no legal pairing at all, the program says so and offers Pair round N by hand… (see Changing a pairing by hand).

When the pairing numbers do not follow the ratings. The pairing rules read the pairing numbers as the ranking, so a strong player holding a high number is paired as a weak one for the whole event. For rounds 2, 3 and 4 the program therefore checks the numbers when you press Pair round N, and stops if any player is out of place - a late entrant numbered after the field, a rating corrected after round 1, or numbers that came with an imported TRF or SWAR file (the dialog says which). It lists the players with their rating, their number and the number their rating earns, and offers:

• Renumber by rating and pair - the same regeneration as on the Players page (Players and rating lists), then the round;
• Pair anyway - the round is paired on the numbers as they are. The decision is written to the audit trail, and the program does not ask again unless a different set of players is out of place;
• Cancel - nothing is paired.

Neither answer takes the tournament out of FIDE mode. Players of equal rating in any order are not out of place. Round 1 needs no question: it gives the numbers itself. Round robin, Keizer and team tournaments are not checked.

Board order. The boards are numbered as C.04.2 Art. 3.6 orders them: first by the score of the pair's higher-ranked player, highest first; then by the sum of the two players' scores; then by the pairing number of the higher-ranked player, smallest first. The pairing-allocated bye comes last. With Baku acceleration the scores include the virtual points.

A player with a fixed table (Players and rating lists) is labelled with that table; it is a label for printing only and does not change who plays whom.

Round robin#

A round robin pairs the whole tournament at once: the button reads Pair the whole tournament (Berger). Before round 1 the program first asks how the players are numbered (Numbering the players of a round robin); after that, it pairs.

The rounds follow FIDE's Berger tables (C.05); for an odd number of players each player sits out one round per cycle with a zero-point bye; every further cycle plays the table again with the colours reversed from the cycle before (in a double round robin with the last two rounds of the first cycle in reverse order, if that option is on). A player who is absent or withdrawn stays in the schedule: enter a forfeit result for their games. The Berger tables pair on the players' starting numbers, which you choose at the first pairing (below) or beforehand on the Players page (Starting numbers; Players and rating lists).

Beside it, Pair round N by hand… makes the next round yourself instead of taking the table's (A round robin paired by hand). Once a round exists, the main button reads Pair the remaining rounds (Berger) and pairs the rest from the table - unless the rounds made by hand have left the table behind, and its next round would pair two players who already met in that cycle: then it refuses and says which two.

Playing rounds out of table order#

When the table has to be played in another order - a hall booked out, a team that cannot travel that weekend - Swap rounds… in the round bar's More menu exchanges two rounds: pick the two round numbers and Swap the rounds. Their boards trade places, so the round numbers follow the order you actually play in: round 4 is the fourth evening, whatever the table calls it, and the standings, the prints and the results site follow. Every game keeps the colours the table gives it, the dates stay with the round numbers, and the pairing explanation says which table round a swapped round holds. Swap the same two again to undo it.

It is refused while either round has a result, a forfeit, a postponed game or a date played, or a bye for a player who has a board in it - the message names the round. In a team round robin it is also refused when a seated player cannot play the round the boards would move to (absent, not yet started, withdrawn): the line-ups were built for their own round, and the message names the player. It is also refused in match format, before the schedule is paired, and when one of the two is paired and the other is not. In FIDE mode it is allowed (FIDE's own double round robin swaps two rounds), with a note that it changes the published schedule. Each swap is in the audit trail, and a TRF of a swapped schedule says CUSTOM_ROUNDROBIN, since no Berger code describes the order played.

Numbering the players of a round robin#

The Berger table pairs on starting numbers, and they cannot change once round 1 exists. So the first click on Pair the whole tournament (Berger) (and the first Pair round 1 by hand…) asks how to number the players. The choice in use is preselected, and the dialog lists the numbers each choice gives before anything is fixed.

• By rating. The FIDE default. Highest rating first; players on the same rating go by FIDE title, then by the tie-break chosen in the options (alphabetical unless you changed it), then by name, then in the order entered. The same field always gives the same list: nothing in it is random.
• As entered. The order in which the players were added to this tournament. This is the order the program created them in (each new player comes after the previous one), so it holds for players typed in, taken from a list or read from an imported file, in that file's order. A tournament re-created from an exported tournament file is entered in the file's order, which is its rating order; there As entered and By rating give the same list.
• By lot. The program draws after you press Draw lots. You see the draw and can draw again; nothing is fixed until you confirm the pairing.
• As set on the Players page. Offered when the players already have numbers: set there by hand or by lot, or carried in by an imported file. The dialog says when those numbers happen to be the rating order or the order of entry.

The pairing dialog says plainly that the numbers cannot change after round 1. The choice goes to the audit trail with the resulting order; for a draw also with its seed, and the same seed on the players in entry order gives the same order again. The Players page's Starting numbers dialog offers the same three (Draw lots, Order by rating, Order as entered) and, besides, numbers by hand. A team round robin is not numbered here: its teams are ordered on the Teams page.

Coming from SWAR. SWAR's three ways of ordering the players for a round robin - by ranking, by entry, at random - correspond to By rating, As entered and By lot. What an imported SWAR file carries is only the result: SWAR numbers a round robin's table by the players' position in its ranking, and the import keeps that position as the starting number, so it appears as As set on the Players page. The file does not say which of the three ways produced it.

Keizer#

The Keizer system ranks the players on a ladder: the player ranked i is worth a number of points that goes down by one with each place, a win is worth the opponent's value, a draw half of it. The ladder is recalculated from all the results every time it is needed, so an early win is worth more when that opponent climbs. Each round the program pairs from the top: each player gets the nearest player below who has not been met, with backtracking. Colours are given to the player who has had White less often. The top value of the ladder is set on the Options page. The Standings page shows the Keizer table instead of the tie-break table.

A player who is expelled after playing keeps a rung on the ladder: the opponents keep the Keizer points their games against that player gave them, and those games are valued like any other as the ladder moves. The expelled player is not paired again and has no row in the Keizer table. A player expelled before ever being paired is simply not on the ladder.

Team tournaments#

For Swiss and round robin team tournaments, Pair round N pairs team against team: each pairing is a match, shown in a table Matches - round N above the boards, and the boards of a match are played board against board (see Teams). Team Swiss follows C.04.6 and is paired by the Ainalrami team engine; a large field runs in the background and the page shows that it is working.

The pairing rationale (explanation)#

Every round paired by the program has an explanation: Advanced, Pairing rationale, then the round. (While the explanation of a round is still being worked out, a link Working out the explanation… on the Pairings page leads to it.)

For a Swiss round paired by Ainalrami the page shows

• a map of the score brackets, with each pairing drawn as a line between the groups, so that floaters are seen to cross from one group to another;
• a card per board with the colours, whether the colour due was given, and the floats;
• for each float and for the bye, the question why this player and not another. Open it to see what each other candidate would have cost, in terms of the criteria of C.04.3, and whether the engine's choice is the best. The answers are worked out when you open a question, and are saved.

Often another candidate would have cost nothing at all: the pairing with that player floating instead is equally good by every rule. The line then says so and links to Equally good alternatives under the same score group, where each such alternative is one item: the boards as played beside the boards the alternative would have had, and why it was not chosen. The reason is always the same one. When two pairings satisfy every criterion equally, the system does not choose; it takes the first possibility in its fixed order - top half against bottom half in pairing-number order, then the bottom half rearranged, smallest change first, then players exchanged between the halves. That keeps the bottom half as close as possible to the pairing-number order, so in the end the pairing numbers decide. Where the record shows it, the item names the step: which bottom-half player is left over, or that the alternative needs an exchange between the halves. The FIDE wording gives the article (C.04.3 3.8.1, with 4.2 for transpositions and 4.3 for exchanges). Beyond three alternatives the rest are behind and N more.

An item shows both versions whole, side by side: under As played every board of the round that the alternative would not have, under In the alternative every board it would have instead, White named first. Where a different player goes down from a score group, both sides say who. Boards that are the same in both are left out and counted (4 other boards are the same in both). An alternative that changes more than 40 boards is not listed; the item then shows the one board of the player concerned and says how many would change.

An answer worked out by an earlier version of the program kept only one board of the alternative - the new opponent of the player concerned - and is still shown that way, with the remark that the rest was not recorded. Such a round has a notice at the top of the page, This round's engine account is from before alternatives were kept whole, with the button Recompute, for every round of this tournament that needs it. It works the opened answers out again and changes no pairing. A round whose boards were changed by hand after pairing is left as it is.

Baku acceleration. In a round paired with virtual points, the score groups and the floats on this page are the ones the engine built: game points plus virtual points. A player who has virtual points is shown with both, for example 1.0 (+1.0 virtual) - one game point, paired as two. The standings never count virtual points, so a score group here is not a place in the standings.

Colours follow C.04.2 3.4: only games actually played count. A forfeit (won or lost, by either side), a bye or an absence is not a colour, and the colour due is worked out as if those rounds came first - a history W B forfeit W counts as u W B W. The small colour squares beside a name show the rounds as they happened, with the unplayed ones dashed; where that differs from how the rule reads it, a counts as strip follows with the unplayed rounds moved to the front. When a due colour depends on a round that was skipped, the board card says which one, for example due White: last played game was Black (round 3 was a forfeit and does not count).

Round robin and Keizer have an exact account too. A Swiss round with no account of its own - paired before the program kept one, or by an engine it no longer has - can be analysed after the fact from the boards as played; the page offers to do so and says that it did.

If an organiser's rule changed the round (a bye preference, a pair wish), the page says which board it moved and what the FIDE rules alone would have given.

Preview of the next round#

While the last few games of a Swiss round are still being played, Preview next round (on the Pairings page) works out the next round for every combination of the open results (six or fewer open games; up to 729 combinations) and saves nothing. Each board is then shown as fixed (the same in every outcome: the name cards can go out), fixed but may shift (the board range is given), fixed with colours open, or open, with the players it could involve and the games that decide it. The preview updates itself when a result is entered and can be printed (fixed boards and a list by name). It is available for individual Swiss tournaments, and only once it is switched on: it is part of the Belgian pack under Account, Features (Accounts).

A result entered for one of the open games needs no new pairing: every combination already worked out is remembered, so the preview updates at once. Clearing a result only works out the combinations that are new.

Announcing fixed boards#

When the name cards of the fixed boards go out, press Announce fixed boards in the preview. Printing the fixed boards announces them as well while Printing announces them is ticked (it is by default). Each board is stored with its number, White and Black, the time and who announced it, and the audit trail records it. The Pairings page then shows how many boards of the next round are announced; Withdraw removes the announcement.

If something changes that could break an announced board - a result outside the open games, a forfeit, a player withdrawn, absent or added, a forbidden pairing, a setting - the page says so. Check again works the preview out again and lists the announced boards that are no longer certain.

When the round is paired, every announced board is compared with the pairing. If a board's opponent, colours or number differ, a large warning lists each one, announced and paired: take those cards back and print the pairing again. The pairing itself is never changed to match an announcement - that would be manipulating the pairing. If all announced boards hold, a short line says so. Unpairing and pairing again compares again.

Chess960#

If Chess960 is ticked on the Tournament settings page, the Pairings page shows, for a paired round, the button Draw Chess960 position. It draws one of the 960 starting positions at random (each is equally likely), shows its number and the pieces of the first rank, and prints it with the round's pairings. The button asks Draw the Chess960 position for round N now? first, and the draw is written to the audit trail.

While the round has no result yet - the wrong round drawn for, a draw made before the boards were set up - Draw position again beside the position draws a new one, after a confirmation that names the position it replaces. The audit trail records both, so drawing until one pleases is possible but happens in front of witnesses. Once a game of the round has a result (or a postponement, or a date played) the button is gone and the position stands.

Changing a pairing by hand#

Sometimes a pairing must be changed after the round is made: a player arrives late, a mistake in the entry, two players who have met under another name. The program calls it a manual pairing alteration and works in sessions.

The session#

• A session on a round starts with the first hand edit of the round: right-click (or tap) a player. While it is open, a banner says Hand edits to round N are open, reminds you how to make one (right-click, or tap on a touch screen, a player on a board or in the not-playing list) and carries the buttons Discard hand edits and Finish hand edits.
• Opening a session takes a restore point of the round as it was, which you find under Advanced, History (Restore points).
• Hand edits are made with the Hand edits menu: right-click a player (or press the context-menu key) on the Pairings page. The menu offers, according to what you clicked:

A board with nobody left on it is not a game and does not wait for a result: the next round pairs whether you delete it, hide it or leave it. A board with one player left does wait, until that player has a bye or an opponent.

• The session ends only when you press Finish hand edits. The next round cannot be paired while a session is open, so the check below cannot be skipped by moving on.
• Discard hand edits changes your mind instead: after a confirmation, the boards and the not-playing list go back to how they were when the session opened, and the session ends without the check below. It is offered only while no game of the round has a result; after that, change the boards by hand again or go back to the restore point. The audit trail records the discard.

Every edit first shows a confirmation with the boards before and after, which you accept or cancel (Escape cancels). While an edit is half-made, a banner says so. A result that is on a board that you change is cleared; the confirmation says so. Every edit is written to the audit trail.

Each of these confirmations, and the dialogs for finishing hand edits, for creating a round by hand and for swapping two rounds of a round robin, has a Reason (optional) box: one short line (at most 200 characters) saying why the pairing is being changed by hand. It is never required and never blocks the edit. The reason is kept in the audit trail next to the edit, listed above the boards (Reasons for the hand edits) while you are on that round, and written beside the edit in the ITDX file (Import and export), with accents removed and line breaks and control characters stripped.

Rule warnings while editing#

For a tournament the checker can judge (an individual Dutch Swiss, see below) the confirmation of an edit also lists the pairing rules that the boards it creates would break:

• two players who already played each other, or are a prohibited pairing;
• the pairing-allocated bye for a player who already had one, won a game by forfeit, or had a full-point bye;
• a player getting the same colour for the third time running, or a colour difference above two, before the last round;
• two players who both get the colour opposite to the one each is due.

Such an edit is applied only after you tick the box that acknowledges the warning. An edit that breaks nothing needs no tick.

Finishing: the check against the pairing checker#

Finish hand edits first asks that every seat is filled (fill it, give the remaining player a bye, or empty the board) and that at least one board is paired. Then the program runs the pairing engine over the players as the round now seats them, and compares its pairing with your boards, colours included but board order not:

• Nothing changed since the session began, or the boards are the engine's own: the session ends; nothing is recorded.
• The boards differ from the engine's pairing: a dialog shows the checker's pairing, what is only in yours and what is only in the checker's, and the rule warnings that still apply. Choose Keep editing to go back, or tick I understand - keep my pairings and record the alteration and press Finish and record. The round keeps your boards and records the alteration with the round. Finishing a session again replaces the record of that round, or removes it when the boards now agree with the engine. The TRF file for the rating office contains records only, so it has no comment line about it; the copy and the ITDX file do (Sending to FIDE).
• The checker cannot judge the round (it is a Dutch-system check, so a team, round robin, Keizer, per-category or Swiss match format round is out of its reach): if the boards differ from where the session began, the alteration is recorded without a check.

A round with no legal pairing#

If the rules leave no legal pairing for the next round, the program says so and writes nothing. The Pairings page then offers Pair round N by hand…. The dialog says that the round is created with no boards and every player in the Not playing list, and that no pairing of the round can follow the rules, so the round is recorded as a manual pairing alteration. You confirm with the tick I understand - create round N to pair by hand. After Create round N you pair the players from the list (pair two players, give the pairing-allocated bye) and finish the hand edits as above.

A round robin paired by hand#

In a round robin (one table for the whole field, not in match format, not a team event), Pair round N by hand… sits next to the Berger button. The dialog says the round is created with no boards and every player in the Not playing list, and that a round that differs from the table is recorded as a manual pairing alteration; you confirm with the tick I understand - create round N to pair by hand. Then pair two players at a time from the list. A player you leave off the boards sits the round out with the round robin's zero-point bye, given when you finish; the pairing-allocated bye is not offered in a round robin.

Each board is checked as you make it, and a breach needs its own tick:

• Two players who already meet in this cycle - in a single round robin everyone meets everyone exactly once, with more cycles once per cycle.
• A third same colour running - a player given White (or Black) in three consecutive rounds. The Berger table never does that within a cycle; a hand easily does.

Finish hand edits compares the round with the same round of the Berger table, and checks that the rounds left in the cycle can still pair everyone who has not met yet exactly once (a player left out of an even field, say, cannot catch up). If the round differs from the table the dialog shows the table's boards, the differences and any breach, with the boards in starting numbers (5=BYE for the player sitting out). As for a Swiss round, the tick I understand - keep my pairings and record the alteration keeps them. A round robin's earlier rounds can also be edited by hand in the same way, and are judged the same.

Other confirmations#

• A round that is not the latest. Editing an earlier round asks for a tick, because later rounds were paired from it. In FIDE mode only the last two rounds played can be changed (FIDE mode).
• A round that was already sent to the rating office. Changing who played whom in a sent round needs the tick I understand - change the sent round N anyway (Sending to FIDE).

Undoing a round#

In a Swiss match format the two rounds of a match go together. A round that has been sent to the rating office cannot be unpaired.

A round robin paired too early - the field changed, the wrong players were in it - does not have to be unpaired one round at a time from the last. While no game in the schedule has a result, More, Unpair the whole schedule deletes every paired round, with its boards and byes, after a confirmation and a restore point. The players keep their pairing numbers; pair the schedule again when the field is right. The audit trail records how many rounds went.

Unpairing round 1 of an individual Swiss - so that no round is left - also takes back the pairing numbers that round gave. The next round 1 numbers everybody who is entered by then, by rating, so a round paired to try the program out before the field is complete leaves nothing behind. Numbers you chose stay: an exchange made on the Players page, and the numbers of an imported file; a player entered afterwards is then placed among them by rating. Round robin, Keizer and team tournaments keep their numbers.

Entering results#

Results are entered on the same page. See Results.