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.

10 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 be no longer be time-based, but rather in the matchups and (for one player each round) puzzle selection.

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.  All matches in the same round will use the same puzzle.

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, so there will be 8 puzzles in the pool.  One puzzle will be chosen (see Puzzle Selection, below) from the pool to be used each round.

Seed and Rank

Each player has a seed (numbered ordinally from 1st to 10th) and a rank (also numbered ordinally from 1st to 10th).  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 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 player swap their ranks for the next round.

After eight rounds of competition, 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.

Before the final round, the Winner’s Bracket and the Loser’s Bracket will each have only one player left.  In the last round, those two players will play the Championship Match, which determines the top two places of the competition.

Traditional elimination diagrams for the brackets are below.

Heats

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 16 heats.  The full list of heats, rounds, and matches are shown in the table below.

Puzzle Selection

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.

For the Sudoku playoffs, there will be three Classic Sudoku puzzles labeled "easy", "medium", and "hard". This is an indication of its expected difficulty, although individual solving experience may differ. No other information about puzzle difficulty will be given.

For the Puzzle playoffs, an estimated point value for each puzzle, using the same method as point values were determined in the regular competition, will be provided. The point value is only used to help estimate difficulty and has no other function in the playoff competition.

Before each round, the best-seeded (not ranked) player in the Winner’s Bracket chooses which puzzle will be used that round.  Note that for rounds A, C, E, and G, there are no Winner’s Bracket matches, so that player will choose a puzzle that they are guaranteed not to solve in competition.

New Puzzle Sheets

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

In a head-to-head match, the competitor with the lower 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 higher seed).  Otherwise, the competitor with the higher 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 lower-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 higher-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 higher 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.