I learned an important lesson last week at the chess club – the difference between “delay” and “Bronstein delay”. I am sure many of you know this, but in case you don’t – it is worth taking 5 minutes to understand the differences.
Here are the definitions:
* Simple delay. When it becomes a player’s turn to move, the clock waits for the delay period before starting to subtract from the player’s remaining time. For example, if the delay is five seconds, the clock waits for five seconds before counting down. The time is not accumulated. If the player moves within the delay period, no time is subtracted from his remaining time.
* Bronstein delay, invented by David Bronstein. Similar to a simple delay, but the clock begins counting down immediately upon the beginning of a player’s turn. When his turn is over, his clock is credited with an increase equal to either the delay time or the turn duration, whichever is less. For example, if the delay is five seconds but the player takes only three seconds to move, the clock decreases for 3 seconds and is then credited with 3 seconds when his turn is over. Therefore, like the simple delay, no bonus time can accumulate. However, unlike a simple delay, the duration of a player’s turn cannot be longer than the original amount of time that appears on his clock at the beginning of his turn.
* Fischer delay, invented by Bobby Fischer. When it becomes a player’s turn to move, the delay is added to the player’s remaining time. For example, if the delay is five seconds and the player has ten minutes remaining on his clock, when his clock is activated, he now has ten minutes and five seconds remaining. Time can be accumulated, so if the player moves within the delay period, his remaining time actually increases. This style of time control is common in competitive chess (including most FIDE events), as well as on internet chess servers. The delay is termed an “increment”.