WPF GP Playoff Rules

Introduction

The WPF GP Playoffs will be in a format called Swiss Elimination.  It is a head-to-head format, where each competitor is matched against one or zero other competitors each round.  A subset of the matches are identical to a standard double-elimination format, so once a player loses two matches, they are ineligible to win the championship.  Extra matches are used to determine a full ranking of all players, so even eliminated players must continue to compete to attain as high a ranking as possible.

16 players will qualify for the playoffs, seeded by their position in the regular competition (these rules are unchanged from that on the website).  However, the advantage in seed will no longer be time-based, but rather in the matchups and (for one player each round) puzzle selection.

The Rules for here are intended to be complete; however, situational differences (such as the venue unable to support A/V requirements) may result in on-the-fly changes to these rules.

Rule Changes

• August 22nd: Initial release.
• August 30th: In the table, the matches E3, E4, E11, and E12 had incorrect lower-rank opponent numbers, which did not match the Strategy Path Diagram. The table has now been corrected.
• September 2nd: In "Puzzle Selection", rules for what happens when a player does not submit a preference list have been clarified.
• September 2nd: The ranking list questionnaire may not be ready in time, so the schedule has been modified.
• September 4th: In “Puzzle Selection”, both the Sudoku GP and Puzzle GP now use the same set of rules.
• September 22nd: Three numerical errors were corrected in the Placement Bracket diagram.
• September 23rd: The Puzzle Selection rules for the online portion have been changed, specifically impacting rounds E, F, G, and H.

Schedule for 2023

• August 25th: Deadline for puzzle authors to submit puzzles for use in finals (see Puzzles and Rounds, below).
• August 25th: Email sent to top 30 finishers in Sudoku GP and Puzzle GP (see Eligibility, below).
• August 30th (internal): Final puzzle files sent to webmaster for hosting
• September 2nd: Deadline for top 30 finishers to respond to email
• September 4th: Preference List form sent to Puzzle GP Participants (see Puzzle Selection, below).
• September 7th: Deadline for responding to Preference List form
• September 8th-18th: Online stage
• October 15th-21th: Live stage

Eligibility

Each player’s eligibility score is calculated. The score of their six best rounds in the corresponding (Sudoku or Puzzle) GP competition is added together to get the eligibility score.

To be eligible, a player must both:

• Have one of the top 30 eligibility scores. These players will be sent an email from the WPF.
• Express an intention to be present at the live finals at the World Sudoku + Puzzle Championship in response to that email.

The 16 eligible players with the highest eligibility scores will be invited to the playoffs, and get their initial seed based on their eligibility score.

In the rare case that there are fewer than 16 eligible players, or a finalist ends up not being present at the WSPC due to extenuating circumstances, they will be replaced with a virtual “bye” player. A “bye” player is seeded worst and loses all head-to-head competitions.

Stages

The playoffs will have two stages; an online stage followed by a livestage. Aspects that are the same between the stages are:

• Each player will have an opponent in each match. (See details later in this document.)
• The match will be on a single puzzle.
• The puzzle will be taken from a puzzle pool of potential puzzles. One player will have some selection control over which puzzles are used.
• Each player will get an official time for each puzzle (representing how much time it took them to solve the puzzle).
• The player with the faster (smaller) official time will win the match.

The differences between the stages are as follows:

Online Stage

• For 2023, the online stage will happen from September 8th to September 18th.
• 45 matches total.
• Players compete separately, on their own, in a setup similar to that of the regular GP rounds
• There will be 8 puzzles, each one presented as a separate “round” of one puzzle each. Each round has a maximum time of 20 minutes.
• Players must submit answer strings as specified in the puzzle. They may submit multiple times; however, only the last-submitted set of answer strings will be scored.
• A player’s official time for each puzzle is 22 minutes if their submission is incorrect. Otherwise, it is the time between the start of the password request and the time of submission.
• At most 7 puzzles will be used in the official online stage.
• Players will not know which 7 puzzles will be used, their opponent for each puzzle, or their official times. Players might have a general idea of their own performance, but the WPF requests that the players keep their estimated solve times a secret and not share them before the live stage.

Live Stage

• For 2023, the live stage will happen at the World Sudoku and Puzzle Championship.
• 9 matches total.
• At the beginning of the live stage, the official results of the online stage will be presented to the players and the audience. This will include:

• The official final rankings of 11th place through 16th place.
• The two players who will be competing in one match, for 9th and 10th place.
• The two players who will be competing in one match, for 7th and 8th place.
• The rank 6 player, who will be competing in one match, for 5th or 6th place.
• The rank 5 player, who will be competing in two matches, for 3rd to 6th place.
• The rank 3 and rank 4 players, who will be competing in three matches for 1st to 6th place.
• The rank 1 and rank 2 players, who will be competing in two or three matches for 1st to 4th place.

• The players must solve the puzzle live and on camera. Details regarding errors and timing are identical to past GP Playoffs and are detailed later in this document.
• Three puzzles will be used in the official online stage, to be drawn from a pool of 4 puzzles.

Puzzles and Rounds

There will be 8 rounds in the playoffs, labeled with a letter from A through H.  Each round will have a number of head-to-head matches, each one with a match code descriptive of its round or placement.  Each match will have two players, who will compete against each other on a single puzzle to see who can solve it in the fastest amount of time.

Each GP round host country has contributed one or more puzzles for use in the finals.  The GP Director will choose one puzzle from each country to be placed in the puzzle pool for the online stage, so there will be 8 puzzles in the pool.  The GP Director will also choose four puzzles from different countries to be placed in the puzzle pool for the live stage. One puzzle will be chosen (see Puzzle Selection, below) from the pool to be used each round for the online stage, and one puzzle will be chose from the pool to be used each round for the live stage.

Seed and Rank

Each player has a seed (numbered ordinally from 1st to 16th) and a rank (also numbered ordinally from 1st to 16th).  At the start of the tournament, these two numbers are identical for each player; e.g., the player with 6th seed also has 6th rank.

The initial seed/rank is determined by the player’s performance in the regular competition.  A seed/rank with a smaller number is considered better (for example, 4th rank is better than 5th rank), and a seed/rank with a larger number is considered worse.

Each round matches some players based on their rank, who then compete against each other on a single puzzle to see who can solve it in the fastest amount of time.  If the player with the better rank wins, the two players keep their ranks for the next round.  If the player with the worse rank wins, then the two players swap their ranks for the next round. In the rare case of a tie, the player with the better seed wins.

After eight rounds of competition (seven for ranks 11th through 16th), the rank of the players determine the finishing order.

Brackets

Each match is in one of three brackets based on its players’ performance:

• The Winner’s Bracket is for matches involving players who have not lost any matches.
• The Loser’s Bracket is for matches involving players who have lost exactly one match.
• The Placement Bracket is for matches involving players who have lost two or more matches.

The list of matches and their relevant data are as follows:

Heats for the Live Stage

For efficiency reasons, up to two matches will be conducted at the same time, and be shown to the audience, with commentary.  Each pair of such matches is called a heat.  There will be 5 heats.   A full list of matches for the live stage is listed below.

A strategy path diagram, showing the matches is below.

Traditional elimination diagrams for the brackets are below.

Puzzle Selection

The Sudoku GP and Puzzle GP may use different methods for assigning puzzles to rounds; these rules are subject to change depending on decisions of the respective GP directors.

For Sudoku GP, the puzzle selection for each round is predetermined.

For Puzzle GP, some information about the puzzle pool of 8 puzzles will be made available to all competitors before the competition, including each puzzle’s host country and author, each puzzle’s name and instructions, an example puzzle, and possibly an estimate of each puzzle’s difficulty (likely on the same point scale as used for the regular competition).

Before the online stage begins, each player is asked to submit a preference list of all 8 puzzles for each of the 8 rounds via an online form.

At the beginning of each round, one player is chosen to have the highest pick priority for that round, subject to the following rules:

• Players who will no longer solve puzzles for the rest of the online stage have lower pick priority than players who do, regardless of bracket rules below. (For 2023, this is ranks 1-2 in round E, 1-4 in round F, and 1-5 in round G.)
• Players who are in the Winner’s Bracket have higher pick priority than players who are not.
• Players who are in the Loser’s Bracket have higher pick priority than players in the Placement bracket.
• If two players are in the same Bracket, the best-seeded (not ranked) player has higher pick priority.
• Players who did not submit a preference list have lower pick priority than players who did, regardless of bracket, seed, or rank. If no players submitted a preference list, a randomly-generated list is used.

The original preference list of the player with the highest pick priority is then used as follows:

• All puzzles that have already been used are removed from the preference list.
• If the player has the highest rank in the Winner’s Bracket and the round letter is C, E, F, or G, then the preference list is reversed.
• The puzzle at the top of the list will be the next puzzle for the round.

(The reason for the reversal is that it is assumed that the picking player would rather their least-favorite puzzle be used.)

For the live stage, the player with rank 1 (not seed 1) will choose that round’s puzzle from the pool of puzzles at the start of each round. Once a puzzle is selected, it is removed from the pool.

New Puzzle Sheets (Live Stage Only)

A competitor can request a new puzzle sheet in case they feel they have made an unrecoverable error to the sheet.  They must relinquish their old sheet first, and then a new sheet will be supplied.  (So, they would not be allowed to have both sheets at the same time.) There will be no compensation for the transition period when they have no sheets.  A competitor can request a new sheet at most once per match, to prevent abuse of this rule.

It is expected that this will be a rare occurrence, and only a limited number of extra sheets will be available to all competitors over the round.  If there are not enough extra sheets to supply all competitors in the current heat, then this will be announced before the start of the current heat and no competitors will be allowed to request new sheets.

Grading (Live Stage Only)

In a head-to-head match, the competitor with the worse seed (not rank) wins the match if they solve the puzzle in less than 10 minutes and they solve it faster than the other competitor (with the better seed).  Otherwise, the competitor with the better seed wins the match.

The punishment for an incorrect answer is a one-minute penalty.  

Timers will be used to determine each player’s solving time as follows:

There will be a large shared timer visible to all competitors, graders, and judges, and each competitor will have an individual precision timer.  A grader will be next to each competitor, and one or more judges will be around to record times and enforce these rules.

Before the match starts, the competitor must hold their hands on their precision timer; the puzzle sheet will be placed between the timer and the competitor, face-down.

At the judge’s signal, the shared timer starts and competitors let go of the precision timer (which starts it) and start solving.

When a competitor believes their answer is correct, they must slide their puzzle sheet to the grader and touch the precision timer with both hands to stop the timer.  The grader notes the time on the shared timer, and has up to one minute to grade the puzzle sheet.  A judge will come by, record the competitor’s official time from the precision timer, and reset the precision timer.  The next step depends on whether the answer is correct and the state of the other grader.

• If the answer is correct and the other grader is currently grading, the grader finishes grading silently and waits until the full minute is up or until the other grader’s full minute is up, whichever is earlier.  At that point, the grader announces the presence of a correct answer, and the match stops.
• If the answer is correct and the other grader is not currently grading, the grader announces the correct answer as soon as this is determined, and the match stops.  (The other competitor may continue solving informally, but their time is not recorded.)
• If the answer is incorrect, the grader waits until the end of the full minute, and then if the competition is not over, then the grader instructs the competitor to put their hands on the timer for one second to prepare it.  The puzzle sheet is returned to the competitor face-down, with no information other than the answer being wrong.  The competitor then releases their hands, flips over their incorrect sheet, and continues.

If the shared timer reaches 10 minutes and the judge believes that the worse-seeded competitor can no longer solve the puzzle in under 10 minutes, the match stops as well.

When the match stops, there will either be one correct answer, in which case that competitor wins; two correct answers, in which case the competitor who submitted with less official time spent wins; or no correct answers, in which case the better-seeded competitor wins.

In the very rare case where there is a tie and the judges cannot determine for sure which competitor has the faster solve time, then the better-seeded player will be the winner (same as if there were no correct answers).

If there is a malfunction in the timers or an error in procedures, the judges will do their best job to adhere to the spirit of these rules.  Judges’ decisions are final.