Passing - Revision history

Selinger: /* Implementations of passing */ SGF now permits passing

2024-07-30T10:09:42Z

‎Implementations of passing: SGF now permits passing

Selinger: /* Reasons for passing */ wording

2021-11-05T21:23:42Z

‎Reasons for passing: wording

Selinger: Added "clearer game record"

2021-11-05T13:30:25Z

Added "clearer game record"

Selinger: /* Implementations of passing */ Added that BGA now allows passing.

2021-11-05T13:22:18Z

‎Implementations of passing: Added that BGA now allows passing.

Selinger: Added categories

2020-12-28T21:30:09Z

Added categories

Selinger: Added proof that the ability to pass does not affect the outcome.

2020-10-10T21:21:22Z

Added proof that the ability to pass does not affect the outcome.

Selinger: Added a page on passing.

2020-10-10T17:43:44Z

Added a page on passing.

New page

To ''pass'' means not to make a move when it is one's turn to do so. It then becomes the other player's turn again.

The most common formulations of the rules of Hex do not envision passing as a possibility. For example, most [[online playing]] sites do not allow passing. Indeed, it is easy to see that passing is theoretically unnecessary in Hex: if passing were allowed, it is never to a player's advantage to pass. In other words, playing a piece (no matter which piece) always leaves the player in an equal or better position than passing would do.

== Reasons for passing ==

However, there are several theoretical and practical uses for passing:

* Theory: many theoretical arguments about winning positions become easier to state and analyze if passing is allowed. For example, the well-known property that Hex (without the swap rule) is a [[Hex theory#No_winning_strategy_for_Blue|first-player win]] is easiest to prove with passing: if the second player had a winning strategy, the first player could simply pass, thereby effectively becoming the second player. Since this would be a winning strategy for the first player, the second player cannot have had a winning strategy.

* Handicap: for unevenly matched players, the game is often more enjoyable if the more experienced player gives the less experienced player a [[handicap]]. One way of implementing a handicap is for the weaker player to be permitted two or more consecutive moves at the beginning of the game. In practice, the stronger player would do this by passing one or more times at the beginning of the game. However, since many online sites do not permit passing, playing with handicap is difficult on these sites. Players sometimes have to resort to playing deliberately weak moves instead of passing.

* Strength of win: sometimes a player's position is so strong that they can pull off a win even if the opponent gets two or more moves in a row. In that case, the player may choose to pass as a way of demonstrating the strength of their position to the opponent. In a friendly or teaching game, this can have a pedagogical value by illustrating a point. In a competitive game, it can be a way of making a win more impressive.

* Losing play: once a player realizes that they will lose the game, they would customarily resign. However, sometimes resigning is not possible or desirable for some reason. For example, some game sites do not allow resigning unless a certain percentage of the board has been filled. In that case, the losing player often resorts to playing nonsense moves to allow the winning player to complete a connection as quickly as possible. Passing would be more elegant than playing nonsense moves.

== The ability to pass does not affect the outcome ==

To do.

== Implementations of passing ==

* No online playing sites currently permit passing. However, this ought to be changed.

* The current version of the [[Smart Game Format|SGF file format]] for Hex does not provide for a passing move. It does, however, permit consecutive moves by the same player. It would be desirable to add an explicit passing move to the file format, as this would allow passing moves to be recorded and documented. For example, a comment attached to such a move might explain why the player passed (e.g., to give a handicap). This is not quite the same as simply omitting the move; for example, for some handicapping methods, after the first move, the second player can choose to swap (and then the first player will get two consecutive moves) or not to swap (and then the first player gets to move again). If there is no possibility of an explicit passing move, the second player must verbally announce "I am not going to swap", which is not elegant and will not be recorded in the game tree.

@@ Line 41: / Line 41: @@
 * Most online playing sites do not currently permit passing. However, this ought to be changed. [[Board Game Arena]] allows passing in Hex since release 211104-1253 (November 2021).
-* The current version of the [[Smart Game Format|SGF file format]] for Hex does not provide for a passing move. It does, however, permit consecutive moves by the same player. It would be desirable to add an explicit passing move to the file format, as this would allow passing moves to be recorded and documented. For example, a comment attached to such a move might explain why the player passed (e.g., to give a handicap). This is not quite the same as simply omitting the move; for example, for some handicapping methods, after the first move, the second player can choose to swap (and then the first player will get two consecutive moves) or not to swap (and then the first player gets to move again). If there is no explicit way of passing, the second player must verbally announce "I am not going to swap" before the first player can move again. This is not elegant. A passing move would permit this information to appear in the game tree.
+* The current version of the [[Smart Game Format|SGF file format]] includes a passing move. It was added in December 2021. In addition, the file format permits consecutive moves by the same player. On advantage of having an explicit passing move is that comments can be attached to such a move. For example, such a comment might explain why the player passed (e.g., to give a handicap).
 [[category: Definition]]
 [[category: Theory]]
 [[category: Rules and Conventions]]

@@ Line 17: / Line 17: @@
 * Strategy puzzles: many Hex strategy puzzles, such as [http://www.mseymour.ca/hex_puzzle/hexpuzzle.html Matthew Seymour's puzzles], are concerned with a particular area of the board. The object of the puzzle is to make sure that certain groups are [[strong connection|connected]] or not connected. If a player's groups are already connected, moving in that area of the board would waste a move for that player. In a real game, the player might choose to play elsewhere on the board. In a strategy puzzle, the player should be allowed to pass instead. Recognizing situations where one can or cannot pass, or equivalently, recognizing which groups are connected, is an important learning objective of the puzzles.
-* Clearer game record: Even in games where passing is not formally allowed, a player usually has the effective ability to pass anyway, namely by deliberately making an [[irrelevant move]] (such as playing in a cell that is already captured by that player). Explicitly passing is more informative than deliberately making a bad move.
+* Clearer game record: Even in games where passing is not formally allowed, a player usually has the ability to effectively pass anyway, namely by deliberately making an [[irrelevant move]] (such as playing in a cell that is already captured by that player). Explicitly passing is more informative than deliberately making a bad move.
 == The ability to pass does not affect the outcome ==

← Older revision		Revision as of 13:30, 5 November 2021
Line 16:		Line 16:

	* Strategy puzzles: many Hex strategy puzzles, such as [http://www.mseymour.ca/hex_puzzle/hexpuzzle.html Matthew Seymour's puzzles], are concerned with a particular area of the board. The object of the puzzle is to make sure that certain groups are [[strong connection\|connected]] or not connected. If a player's groups are already connected, moving in that area of the board would waste a move for that player. In a real game, the player might choose to play elsewhere on the board. In a strategy puzzle, the player should be allowed to pass instead. Recognizing situations where one can or cannot pass, or equivalently, recognizing which groups are connected, is an important learning objective of the puzzles.		* Strategy puzzles: many Hex strategy puzzles, such as [http://www.mseymour.ca/hex_puzzle/hexpuzzle.html Matthew Seymour's puzzles], are concerned with a particular area of the board. The object of the puzzle is to make sure that certain groups are [[strong connection\|connected]] or not connected. If a player's groups are already connected, moving in that area of the board would waste a move for that player. In a real game, the player might choose to play elsewhere on the board. In a strategy puzzle, the player should be allowed to pass instead. Recognizing situations where one can or cannot pass, or equivalently, recognizing which groups are connected, is an important learning objective of the puzzles.
		+
		+	* Clearer game record: Even in games where passing is not formally allowed, a player usually has the effective ability to pass anyway, namely by deliberately making an [[irrelevant move]] (such as playing in a cell that is already captured by that player). Explicitly passing is more informative than deliberately making a bad move.

	== The ability to pass does not affect the outcome ==		== The ability to pass does not affect the outcome ==

@@ Line 37: / Line 37: @@
 == Implementations of passing ==
-* No online playing sites currently permit passing. However, this ought to be changed.
+* Most online playing sites do not currently permit passing. However, this ought to be changed. [[Board Game Arena]] allows passing in Hex since release 211104-1253 (November 2021).
 * The current version of the [[Smart Game Format|SGF file format]] for Hex does not provide for a passing move. It does, however, permit consecutive moves by the same player. It would be desirable to add an explicit passing move to the file format, as this would allow passing moves to be recorded and documented. For example, a comment attached to such a move might explain why the player passed (e.g., to give a handicap). This is not quite the same as simply omitting the move; for example, for some handicapping methods, after the first move, the second player can choose to swap (and then the first player will get two consecutive moves) or not to swap (and then the first player gets to move again). If there is no explicit way of passing, the second player must verbally announce "I am not going to swap" before the first player can move again. This is not elegant. A passing move would permit this information to appear in the game tree.

← Older revision		Revision as of 21:30, 28 December 2020
Line 40:		Line 40:

	* The current version of the [[Smart Game Format\|SGF file format]] for Hex does not provide for a passing move. It does, however, permit consecutive moves by the same player. It would be desirable to add an explicit passing move to the file format, as this would allow passing moves to be recorded and documented. For example, a comment attached to such a move might explain why the player passed (e.g., to give a handicap). This is not quite the same as simply omitting the move; for example, for some handicapping methods, after the first move, the second player can choose to swap (and then the first player will get two consecutive moves) or not to swap (and then the first player gets to move again). If there is no explicit way of passing, the second player must verbally announce "I am not going to swap" before the first player can move again. This is not elegant. A passing move would permit this information to appear in the game tree.		* The current version of the [[Smart Game Format\|SGF file format]] for Hex does not provide for a passing move. It does, however, permit consecutive moves by the same player. It would be desirable to add an explicit passing move to the file format, as this would allow passing moves to be recorded and documented. For example, a comment attached to such a move might explain why the player passed (e.g., to give a handicap). This is not quite the same as simply omitting the move; for example, for some handicapping methods, after the first move, the second player can choose to swap (and then the first player will get two consecutive moves) or not to swap (and then the first player gets to move again). If there is no explicit way of passing, the second player must verbally announce "I am not going to swap" before the first player can move again. This is not elegant. A passing move would permit this information to appear in the game tree.
		+
		+	[[category: Definition]]
		+	[[category: Theory]]
		+	[[category: Rules and Conventions]]

@@ Line 1: / Line 1: @@
 To ''pass'' means not to make a move when it is one's turn to do so. It then becomes the other player's turn again.
-The most common formulations of the rules of Hex do not envision passing as a possibility. For example, most [[online playing]] sites do not allow passing. Indeed, it is easy to see that passing is theoretically unnecessary in Hex: if passing were allowed, it is never to a player's advantage to pass.  In other words, playing a piece (no matter which piece) always leaves the player in an equal or better position than passing would do.
+The most common formulations of the rules of Hex do not envision passing as a possibility. For example, most [[online playing]] sites do not allow passing. Indeed, offering the possibility of passing is theoretically unnecessary in Hex: since passing is never to a player's advantage, a rational player in a normal game should never want to pass, and therefore the outcome of the game is not affected by whether passing is permitted or not. In other words, playing a piece (no matter which piece) always leaves the player in an equal or better position than passing would do. Nevertheless, there are a number of good reasons for why the rules of Hex (on game sites or otherwise) should include the ability to pass.
 == Reasons for passing ==
-However, there are several theoretical and practical uses for passing:
+There are several theoretical and practical uses for passing:
-* Theory: many theoretical arguments about winning positions become easier to state and analyze if passing is allowed. For example, the well-known property that Hex (without the swap rule) is a [[Hex theory#No_winning_strategy_for_Blue|first-player win]] is easiest to prove with passing: if the second player had a winning strategy, the first player could simply pass, thereby effectively becoming the second player. Since this would be a winning strategy for the first player, the second player cannot have had a winning strategy.
+* Theory: many theoretical arguments about winning positions become easier to state and analyze if passing is allowed. For example, the well-known property that Hex (without the swap rule) is a [[Hex theory#No_winning_strategy_for_Blue|first-player win]] is easiest to prove with passing: if the second player had a winning strategy, the first player could simply pass, thereby effectively becoming the second player. Since this would be a winning strategy for the first player, the second player cannot have had a winning strategy. More generally, strategy-stealing arguments are often easier to formulate if passing is permitted.
 * Handicap: for unevenly matched players, the game is often more enjoyable if the more experienced player gives the less experienced player a [[handicap]]. One way of implementing a handicap is for the weaker player to be permitted two or more consecutive moves at the beginning of the game. In practice, the stronger player would do this by passing one or more times at the beginning of the game. However, since many online sites do not permit passing, playing with handicap is difficult on these sites. Players sometimes have to resort to playing deliberately weak moves instead of passing.
-* Strength of win: sometimes a player's position is so strong that they can pull off a win even if the opponent gets two or more moves in a row. In that case, the player may choose to pass as a way of demonstrating the strength of their position to the opponent. In a friendly or teaching game, this can have a pedagogical value by illustrating a point. In a competitive game, it can be a way of making a win more impressive.
+* Strength of win: sometimes a player's position is so strong that they can pull off a win even if the opponent gets two or more moves in a row. In that case, the player may choose to pass as a way of demonstrating the strength of their position to the opponent. In a friendly or teaching game, this can have a pedagogical value by illustrating a point about the strength of connections. In a competitive game, it can be a way of making a win more impressive.
 * Losing play: once a player realizes that they will lose the game, they would customarily resign. However, sometimes resigning is not possible or desirable for some reason. For example, some game sites do not allow resigning unless a certain percentage of the board has been filled. In that case, the losing player often resorts to playing nonsense moves to allow the winning player to complete a connection as quickly as possible. Passing would be more elegant than playing nonsense moves.
 == The ability to pass does not affect the outcome ==
-To do.
+In Hex, passing never gives the player who passes an advantage. Specifically:
 == Implementations of passing ==
@@ Line 23: / Line 39: @@
 * No online playing sites currently permit passing. However, this ought to be changed.
-* The current version of the [[Smart Game Format|SGF file format]] for Hex does not provide for a passing move. It does, however, permit consecutive moves by the same player. It would be desirable to add an explicit passing move to the file format, as this would allow passing moves to be recorded and documented. For example, a comment attached to such a move might explain why the player passed (e.g., to give a handicap). This is not quite the same as simply omitting the move; for example, for some handicapping methods, after the first move, the second player can choose to swap (and then the first player will get two consecutive moves) or not to swap (and then the first player gets to move again). If there is no possibility of an explicit passing move, the second player must verbally announce "I am not going to swap", which is not elegant and will not be recorded in the game tree.
+* The current version of the [[Smart Game Format|SGF file format]] for Hex does not provide for a passing move. It does, however, permit consecutive moves by the same player. It would be desirable to add an explicit passing move to the file format, as this would allow passing moves to be recorded and documented. For example, a comment attached to such a move might explain why the player passed (e.g., to give a handicap). This is not quite the same as simply omitting the move; for example, for some handicapping methods, after the first move, the second player can choose to swap (and then the first player will get two consecutive moves) or not to swap (and then the first player gets to move again). If there is no explicit way of passing, the second player must verbally announce "I am not going to swap" before the first player can move again. This is not elegant. A passing move would permit this information to appear in the game tree.