Editing Time control (section)

=== Go ===

==== Byo-yomi ====  
This timing method is also used in [[shogi]]. The word is borrowed from [[Japanese language|Japanese]]; the term literally means "counting the seconds", or more generally, "countdown".

After the main time is depleted, a player has a certain number of periods (for example five periods, each of thirty seconds). If a move is completed before the time expires, the time period resets and restarts the next turn. If a move is not completed within a time period, the time period will expire, and the next time period begins. This is written as {{var|maintime}} + {{var|number of byo-yomi time periods}} of {{var|byo-yomi time period}}. Using up the last period means that the player has ''lost on time''. In some systems, such as certain [[Go (board game)|Go]] title matches, there is no main time; instead, the time used is rounded ''up'' to the nearest whole increment, such as one minute, and the actual counting of time occurs toward the end of one player's time.

A typical time control is "60 minutes + 30 seconds byo-yomi", which means that each player may make as many or as few moves as they choose during their first 60 minutes of thinking time, but after the hour is exhausted, they must make each move in thirty seconds or less. To enforce byo-yomi, a third person or a game clock with a byo-yomi option is necessary.

In [[Go professional|professional Go]] games and many amateur tournaments, a player has several byo-yomi periods, for example five periods of one minute each. If a player makes their move within a one-minute period, they retain all five periods for their future moves. If a player oversteps one minute, they start the following move in the second rather than the first byo-yomi period. In effect, the player has one minute per move plus four extra one-minute packets which may be used as needed, e.g. four moves of two minutes each, or one move of five minutes, or any other combination.

In higher-level tournaments, such as the Kisei tournament, the player's time is often composed entirely of byo-yomi periods (for example, in an eight-hour game, the player may have 480 periods of one minute each), rather than having a main block of thinking time. In this case, the actual counting of time (verbally) begins once the player falls below a certain threshold of time, such as 10 minutes; when the time is being counted, the player is informed at intervals how much time they have used in their current period, and how many extra periods they have left. (For example, the time may be called at 10-second intervals, and when 55 and 58 seconds have been used; during a player's final minute, the last 10 seconds are counted one by one.)<ref>{{cite web|url=http://www.britgo.org/bgj/10643.html|title=Byoyomi Explained - British Go Association|website=www.britgo.org|access-date=9 May 2018|url-status=live|archive-url=https://web.archive.org/web/20170807223313/http://www.britgo.org/bgj/10643.html|archive-date=7 August 2017}}</ref> Similarly, in the televised [[NHK Cup (Go)|NHK Cup tournament]], the player has 30 seconds per move plus 10 extra one-minute periods which may be used as needed.

When analog game clocks are used to enforce byo-yomi, it is more convenient to assign additional time for a block of moves, rather than for each move. In ''Canadian byo-yomi'', a player typically gets 5 minutes for 10 to 20 moves. The [[IGS Go server]] uses a similar system, but the byo-yomi time is variable and always covers 25 moves. Thus the time control "20 minutes + 15 minutes byoyomi" on IGS means that after the initial 20 minutes of thinking time are over, a player is granted 15 additional minutes, which may be spent however they choose. If these minutes expire before they have made 25 more moves, they lose. If they make 25 more moves in less than 15 minutes, they are granted another 15 minutes of byo-yomi, and so on indefinitely.

Canadian byo-yomi imposes a certain average speed of play, but allows the player to spend more time to ponder on difficult moves. Several byo-yomi periods in one move per period variant (also known as ''Japanese byo-yomi'') serve essentially the same purpose, albeit to a lesser extent.

Unused time during one byo-yomi period does not carry forward to future moves. This is in contrast to the [[#Increment and delay methods|Fischer clock]] often used in [[chess]], with designations such as "5 minutes + 12 seconds per move". Under this time control each player has twelve seconds added to their clock after every move, starting from the first move, regardless of how much time they spend on each move. Thus if a player thinks for eight seconds before making their first move, they will have five minutes and four seconds on their clock after making it.

==== Canadian overtime ====
After using all of their main time, a player must make a certain number of moves within a certain period of time &mdash; for example, twenty moves within five minutes. In [[Go (game)|Go]], players stop the clock, and the player in overtime counts out the required number of stones and sets the remaining stones out of reach so as not to become confused, whilst the opponent sets the clock to the overtime period. If all the moves are made in time, then another period of overtime starts &mdash; another set of stones and the timer again reset to the overtime period. If all the moves are not made in time, the player has ''lost on time''. This is written as {{var|main time}} + {{var|number of moves to be completed in each time period}} in {{var|time period}}.<ref>{{cite web |url=http://pages.infinit.net/steven/byoyomi.htm |title=The Origins of Canadian Byo-Yomi |access-date=2006-11-20 |url-status=dead |archive-url=https://web.archive.org/web/20061120185427/http://pages.infinit.net/steven/byoyomi.htm |archive-date=2006-11-20 }}</ref> In '''Progressive Canadian Overtime''' the required rate of play alters in additional overtime periods &mdash; e.g. 1 hour + 10 in 5, 20 in 5, 30 in 5, 40 in 5 etc.<ref>{{cite web |url=http://www.britgo.org/rules/approved.html |title=A. Default Rules|website=British Go Association |access-date=2006-11-25 |url-status=live |archive-url=https://web.archive.org/web/20061206134243/http://www.britgo.org/rules/approved.html |archive-date=2006-12-06}}</ref>