# Are Bronstein delay and simple (US) delay really equivalent?

I have a question regarding delay in time controls. I've seen this thread and it doesn't address my doubt.

Let's consider an example from the beginning of a game, to show how simple and Bronstein delay seem different to me. Regular/base time is 10 seconds and delay is 5 seconds.

Now Player X's clock starts. They will take 8 seconds to move. Using simple delay, the delay time runs out plus 3 seconds of regular time, and the clock reads 7 seconds left at the end of the move. Player Y then moves and it's back to X. He takes another 8 seconds to move. The delay time runs out plus 3 seconds of regular time, and the clock reads 4 seconds left at the end of the move. Game goes on.

What if Bronstein delay were added after the move? They start with 10 seconds. After 8 seconds, this drops to 2 seconds but after the first move, Player X gets the 'refunded time' of the delay and thus their clock reads 7 seconds left at the end of the move. (Same as with simple delay). But when it's next his turn, he will again take another 8 seconds to move. If clocks could go negative, his time would drop to -1 seconds, then be 'refunded' by the delay (5) to read 4 seconds. But clocks and time in chess, as far as I've seen, don't work that way. Instead, he has only 7 seconds to make his move; after this time, the clock hits 0. And if he wanted to take 8 seconds to move, then here he would flag and the game would end.

Wikipedia claims that "Bronstein delay and Simple delay are mathematically equivalent." Now, by Wikipedia's definition, Bronstein delay is added after the move (and consists of the lower value between the time allotted for the delay and the time the player took to move). Simple delay consists of running down the delay timer before the regular clock timer starts. These are not mathematically equivalent, as simple delay adds time before the move. You would flag with Bronstein delay added after, on your final turn, where you would have had an extra few seconds with simple delay.

That's not the only issue. The more pressing problem is that I cannot think of a way Bronstein delay could be added before the move (thereby making them equivalent): it seems you cannot know, before the move, whether the player will use more or less time than the delay, and if less, then how much exactly they will use; hence it is intrinsic to the concept of Bronstein delay to add the time after.

How is this reconciled? Or is it to be admitted that there are really two, slightly different, delay systems (i.e. Bronstein and simple US delay are not, and cannot, be identical) and there cannot be otherwise?

Another Example:

Player X has 3 seconds (regular time) left. The delay is 5 seconds. Player Y's turn ends and now X is going to have to play. With simple delay, they will have 5 seconds delay time, plus 3 more seconds--that is, 8 seconds to make a move before they flag. With Bronstein delay, they will have 3 seconds before they flag. I assume that when the clock hits 0, the player flags (it cannot go negative). Now, were they to take 4 seconds to play, they would not get the benefit of the delay at all.

• Instead of downvoting, it would be great to know why someone thinks this is a poor question Jan 9, 2021 at 20:15
• Is this really different? After your current move is before your next move. So here's the thing: delay as described here just adds more base time. So you can convert from Bronstein to simple delay by subtracting the amount of delay: 2 seconds left with a 5s delay is equal to 7s left with 5s Bronstein if I'm not mistaken. Jan 9, 2021 at 20:31
• @koedem, thanks, where the difference comes in is when the time is running out. I'll add an example Jan 9, 2021 at 20:35
• Your example isn't possible. If the delay is added back after the move, then base time left will never go under the delay time. Jan 9, 2021 at 20:44
• Your example is impossible because with 5s Bronstein you can't have 3s at the start of your turn. Let's say you start at 6s Bronstein as your time goes down. You can at most spend 5 seconds here because you'd lose on time otherwise. But that means you will go back to 6s again. In fact, once you hit 6s Bronstein you will stay at that time forever unless you lose on time. Like it would be, with 1s of simple delay. Jan 9, 2021 at 21:45

They are equivalent.

With Bronstein, the time is added after the move - it has to be, because before the move you don't know whether or not you'll take the full amount of the delay time. However, perhaps what you're missing is that the first move has the delay time added. So if you start a game with 10 seconds on the clock and a 5 second delay, the Bronstein clock would actually read 15 seconds at the start (and start counting down right away) while the normal delay timer would read 10 seconds (and not start counting until 5 seconds had passed.)

• thanks. So when you say 'first move', do you mean move 0, or do you mean the delay time is added at the end of your first move? The problem with giving extra the 5 secs right after you make the first move is that it doesn't solve the issue, you will still run out of time 'early' in the way I describe. Jan 9, 2021 at 23:43
• Move zero, yes. Black starts White's clock to start the game and the five seconds is already there.
– D M
Jan 9, 2021 at 23:45
• The problem with reading 15 seconds (and starting ticking down) before you make the first move is that you may not take 5 seconds to make that move, in which case you just got extra time (e.g. move in 3 seconds, clock reads 12 after your move). And what happens after you make the first move (and subsequent moves)? The way you describe it I'm not sure how the clock accounts for how long the player actually takes, i.e. how it differs from increment Jan 9, 2021 at 23:45
• Move in 3 seconds and the clock will read 15, not 12. Which is by design. You have 15 seconds to make the next move - which is exactly the same as the normal delay clock, which will still read 10.
– D M
Jan 9, 2021 at 23:47
• Normal clocks show the time remaining, excluding any remaining delay. The Bronstein clock shows the time remaining, including any remaining delay as part of the time shown. That difference in display is the only difference between the two.
– D M
Jan 9, 2021 at 23:57