Unusual Time setting: Canadian Byo-Yomi Blitz


Keywords: Tesuji

A time (te)suji is a colloquial expression for playing a forcing move, wasting some aji, during overtime in order to avoid losing on time. The opposite action, playing a complex move when your opponent is in time trouble, may be called a time stealing tesuji.


There are warnings at the moment for unusual settings, usually custom komi or very fast time settings.

There is a field as well which explains the times settings. You can see in the example the difference between Canadian and ordinary byoyomi and I think even Fischer (lucky screenshot maybe)

In any case would you want a warning similar to the Komi warning? It’s a triangle with an exclamation mark I think, with a little pop up explaining what is unusual?


Exactly that, Shinuito.

1 Like

If I have time I can look into how it’s done at the moment, unless someone else knows and wants to do it.

Is there a particular threshold that is obvious enough to mark for a warning? 10s,9s,8s… per move on average. Should the main time be taken into account?

1 Like

I think just blitz + Canadian is enough to warrant a warning :warning: That in itself is so unusual that I have never seen it or even thought about it. And now that I do think about it, I don’t know if I ever want to see it! :flushed: It’s difficult to manage time over multiple moves, and it’s difficult to play blitz, so Canadian blitz is double difficult. JMHO :relieved:

1 Like

What is blitz though? :slight_smile:

I think even if we look at what games the site currently marks as Blitz, we probably won’t agree that some are Blitz that are marked as blitz, and some that are marked as live really should be Blitz!


and just some general guess at the current thresholds in Fischer and byo-yomi


I understood that this is the original ask. But I actually wonder if:

Is really the point here. Is it really needed? The point of Canadian byo yomi (I think!) Is to be able to manage IRL tournaments without too much faff/personnel. It’s hardly needed at all online where timing is managed for you. And for blitz there are surely better/clearer options that are less liable to being misused.


If you don’t like it, you are free to not use it. I think that is an entirely different matter to suggesting that nobody on the server should be allowed to use it. Especially since we still support arguably much worse / buggy time controls such as simple which has been broken for forever and absolute which can be unrecoverable if noticed too late.

I don’t think there can be any place for a serious argument that an entire country’s national time control system is not welcome to even exist on our server… (note, talking about adding a warning is totally fine, since use of it outside of Canada is admittedly rare)


Canadian Byo-Yomi by itself is fine. As far as I know it’s the default time setting on PandaNet and used at tournaments quite a bit.

Even if it’s not used much here on OGS, it is valuable to have it. When I plan to attend a iRL tournament I would certainly play a few training games here to get used to it.


Yeah, I don’t think we should ban Canadian blitz, but I think it deserves a warning symbol. Can it be the time threshold be tied to whether OGS classes it as blitz, rather than defined separately? Then, if OGS re-defines blitz threshold, then warning threshold moves accordingly. This avoids issues of not knowing exactly where the threshold is.

1 Like

Yes I think it’s especially useful to have such a variety of settings available on OGS. I’ve done similar with Fischer for example, and previously some blitz settings in the past. I think some tournaments and congresses for example have lightning tournaments with absolute settings (which probably aren’t EGF rated of course) which could also be a reason to play 10-15min absolute to practice for example.

I’m in between the two points myself, of (1) just check the settings and don’t accept if you don’t like it, and (2) add a warning that this is an unusual setting.

Here’s the thing, I don’t exactly know how OGS determines Canadian Blitz. Let’s assume it’s the formula I found before in the GitHub:

case “canadian”:
t = time_control.main_time / 90 + time_control.period_time / time_control.stones_per_period;

from the computeAverageMoveTime function https://github.com/online-go/goban/blob/3897a698b130c9c6c21f1c01eb5ae0238728ffe2/src/GoUtil.ts#L217

Firstly here’s the maximum and minimum settings I can see when creating Blitz Canadian custom game:

Main Time

  • min = 0s
  • max = 5mins = 300s

Time per period

  • min = 5s
  • max = 30s

Stones per period

  • min = 1 stone
  • max = 50 stones !!

I don’t know why these are the limitations on Blitz settings in custom games, but they are what they are.

Lets compute some of the borderline examples then of whether the site would class games as Blitz live, assuming the above formula. It’s considered Blitz as far as I know if t<10s, with a strict less than symbol.

I’ll simplify the formula to

t=m/90+p/s < 10s
Main Time (m) Time Per Period (p) Number of Stones (s) t value Warning? Comment
300s 30s 4 is Live 5 is Blitz 9.33…s or 10.833s ? Max main and Time per period
0s 30s 3 is Live 4 is Blitz 10.0s or 7.5s ? Min main and Max Time per period
0s 5s Always Blitz ≤ 5s ? Min main and Time per period
Always Blitz 5s Always Blitz ≤ 8.33…s ? min Time per period

General comments

You can see from the first table entry that if you have to play 5 or more stones that it will always be considered Blitz since we’ve maxed out the main time and time per period.

Is there any other useful borderline cases to consider?

Should there just be a warning if you have to place 5 or more stones in general? That doesn’t make sense, I don’t know why I thought that :stuck_out_tongue:

If anyone wants to make some unranked games to test these settings please feel free :slight_smile:

Aside: It should be possible to create a Blitz game even choosing the Live dropdown in custom game I think, since one can choose 0 main time, and 20s per period, but any number of stones up to 50 apparently? Maybe it will give an error and won’t allow it. Anyone want to try it? :slight_smile:

I’ll make another post in a bit, about how to make Blitz games when you choose the Live time settings :stuck_out_tongue:

Using the Live settings dropdown in custom game to make a Blitz game:

Main Time

  • min = 0s
  • max = 15mins = 900s (for Blitz)

Time per period

  • min = 20s
  • max = 9mins = 540s (for Blitz)

Stones per period

  • min = 1 stone
  • max = 50 stones
Main Time (m) Time Per Period (p) Number of Stones (s) t value Warning? Comment
12mins 20s 10 is Live 11 is Blitz 10.0s or 9.8181…s ? Max main and min Time per period
0s 8mins 48 is Live 49 is Blitz 10.0s or 9.795…s ? Min main and Max Time per period

Any other weird ideas?

Question Time

Would you agree that in the two tables above that what is called Blitz should be considered Blitz?

If they add one less stone in some case, if we just go by the formula above, it could just cross the threshold in some cases to exactly 10s per move on average and then the warning label goes away.

Is that what we want?


Main: 12mins
Period: 20s
Stones: 10

Is a live setting.

After the 12 minutes have passed, you have to plop down a stone every 2 seconds? How is this live? I mean, all you can do in these two seconds is to try to play a legal move and hope the click makes it to the server in time. We know OGS is a bit laggy at times.

1 Like

I think we’ve missed a simpler solution @shinuito. Rather than:

if (time_type == "Canadian") and (time_settings < threshold_we_think_is_blitz):

Just do:

if (time_type == "Canadian") and (ogs_time_classification == "blitz"):

So then we don’t need to know where the threshold is. We just go with the OGS decision of whether it’s blitz or not :slightly_smiling_face:

1 Like

I think I agree in principle that we can just go off what OGS calls blitz, but my point is that If you give a warning for 5mins +30s/5stones but not for 5mins +30s/4stones isn’t it a little bit arbitrary?

Isn’t the time per move still close enough, (adding one or two seconds per move on average), that it seems a bit pointless to draw the line here? If somebody wants to get rid of the warning on their game they fiddle with it a little bit and they can make essentially the same game in terms of time per move but get rid of the warning :slight_smile:

I know that’s always the case with drawing a hard boundary, that making a minor modification will cross the threshold. However we also don’t have complete freedom over the time settings. They are granular in a sense, like going up in 5s or X minutes etc.

Again this is just my best guess at what will count as a live setting. I’ll test it now though:



Yeah I’m pretty sure it counts as live.


@dragon-devourer So if we went for the OGS classification we wouldn’t give a warning for a 19x19 game with 12mins +20s/10 :slight_smile: Maybe a Blitz game could be finished in the 12 mins but as @torusle points out the byo-yomi is ludicrous, it’s just a clicking fest :stuck_out_tongue:


Yes, good illustration of the point :+1: 2 seconds per stone during byo-yomi is unreasonable :exploding_head: So I guess it will have to be defined by time per move.

You could use the EGF assumptions of the number of moves during main time / over time (EGF tournament class at Sensei's Library) to work out the approximate time per move during these stages:

  • Assume 240 moves total, so 120 per player

  • For Japanese byo-yomi, assume 45 moves in overtime, so 75 moves in main time. Time per move in main time is main time / 75. Time per move in byo-yomi is length of byo-yomi period (see footnote).

  • For Canadian byo-yomi, assume 60 moves in overtime, so 60 moves in main time. Time per move in main time is main time / 60. Time per move in byo-yomi is length of byo-yomi period / number of stones per byo-yomi period.

  • For Fischer, time per move is constant and equal to main time / 120 + bonus.

From the same page, the minimum quoted Fischer bonus time is 5 seconds (for a Class C tournament, i.e. casual or club tournament). From this page (Harleqin / Arguments For Bonus Time at Sensei's Library), we can interpret the Fischer bonus time as the desired minimum time per move. Putting these sources together with common sense, it seems reasonable to use 5 seconds per move as a sensible minimum time required per move for any game.

Think about it - 5 seconds per move is fast, even for blitz, but playable just about. Less than that, one is in danger of accidental time out even if playing immediately just due to the time it takes to place a stone (or click the mouse) and hit the clock (or click submit button).

So maybe the warning could be shown for:

  • Games under any time setting where the time per move during any phase is less than 5 seconds per move (within the assumptions above).

  • Maybe also for Fischer games where the bonus is less than 5 seconds per move because the player may end up close to timeout and have such a short time to play that the Fischer effectively becomes absolute time.

  • Maybe for all absolute time games as one can easily end up in a non-recoverable position.

(Footnote) Technically, this is only correct for 1 byo-yomi period only. You could get more complicated and adjust for the number of byo-yomi periods but that seems unnecessary as assuming only 1 byo-yomi period will act as a lower bound to the calculation of time per move and the difference will be small unless you have a huge number of periods.


So I did a little bit of digging and I do see the following

        case "canadian":
            return !(
                time_control.main_time > QUESTIONABLE_ABSOLUTE_TIME ||
                time_control.period_time / time_control.stones_per_period > QUESTIONABLE_SECONDS_PER_MOVE



So actually I think in theory that check is already partially there to flag some Canadian games with a warning.

I guess not (m>900 or s/p>4) returns true when main_time <= 15mins and the stone per period is <=4s.

So actually your check is probably already there :slight_smile: (although conditional on the main time not being below a certain, probably reasonable threshold)

I think this is probably already there by the look of it. Similarly I think if the absolute time is less than 15 mins it gets a warning. (I’ll have to double check that because I find myself slightly confused between this hardcoded division by 90 that’s in there, vs the actual time in minutes – they’re both used in different places, and I different time settings.)

1 Like

So just to come back to this case, even though it’s classified as live it does get a warning for being an unusual time setting

So I guess, what is it that we want that’s different to now again?

There must be some edge case, where some setting we intuitively think of as Blitz isn’t being flagged with a warning in Canadian Byo-yomi?

1 Like

My thoughts exactly :wink:

1 Like

I suppose @torusle has real games in mind where this has been an issue so would be a good starting point?

Torusle, what settings prompted you to make this thread?