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A Real Life Off-by-One Error

https://leejo.github.io/2024/09/01/off_by_one/
Not an off-by-one error—at least not in spirit. Interesting nonetheless.

I expected the article to eventually answer this puzzle:

> The competition started and got through a number of rounds. There were some comments about how the climber on the left always won.

Near the end:

> The kicker is that the out of place hold hasn’t been used in a long time. The climbers have optimised their route such that it is skipped. The same happens to the fourth hold from the bottom. So either being in the wrong place is immaterial to the climbers’ technique as long as they don’t get in the way.

So it seems like the error discovered by the article author should not have conferred any advantage to the climber on the left.

Anyone who can shine light on this matter?

People are misunderstanding the meaning of an off-by-one error. Suppose the plan states that hold A and hold B need to be 11 holes apart. In the true spirit of the off-by-one error, this can be interpreted in 3 ways:

- either as 11 empty holes between the holds; - as 11 holes, start counting 1 just above hold A; - or as 11 holes, start counting with hold A as number 1.

Another real-life example, is a plumber who tells the construction worker that the distance between the holes for hot and cold water needs to be 15 cm. This was meant to be measured center to center, but the constructor worker interpreted it as the distance from the right side of the first hole to the left side of the second. The result can still be admired in our house, 10 years later.

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The climbers had complained about an issue with the belay ropes on the right side that they also fixed.

> A few of the climbers had said that the automatic belay ropes on the right hand lane did not feel right, so the cherry picker was replacing those and not the hold that I had noticed being out of place. The climbers had noticed something wasn’t quite right, but hadn’t said anything about the out of place hold.

It was probably just two separate problems.

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>Not an off-by-one error—at least not in spirit. Interesting nonetheless.

Literally it was an off-by-one error. Literally, literal meaning.

I think the poster meant off-by-one doesn’t simply mean a plus or minus one error, like mispricing a $5.99 as $6.99, but instead must be born out of confusion as to whether an origin point is marked as a 1 or as a 0.
Off-by-one is not born from the base of the index. It is a general problem a lot of people run into in a lot of different contexts.

It’s for example called “the fencepost problem”: https://betterexplained.com/articles/learning-how-to-count-a...

I agree subtracting or adding one to any number is not the problem. It has to do with counting.

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> must be born

There are other reasons as well. I think the more common causes are inclusive vs exclusive comparison errors and fencepost.

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Perhaps the pieces are placed by counting a number of holes from piece A to piece B? That's a perfect recipe for an off-by-one: at which point relative to piece A do you start counting.
> So it seems like the error discovered by the article author should not have conferred any advantage to the climber on the left.

They might not use the hold by physically touching it, but they might still use it as a visual indicator of where the other holds are in relation. These competitors are used to the same layout for many years. If there is a slight misrepresentation it can surely put them off.

It's true that modern competitive speed climbers don't use that hold. The collective optimization of the route is hilariously serious (it's an olympic sport after all) and the different optimizations have names, like 'The Tomoa Skip'.

But I think it's possible that 'extra' holds are potentially like 'junk' DNA. People fall into the trap of thinking that DNA is useless if it's never transcribed, but we know that's not actually the case. Non-expressed DNA can do things like alter binding affinity for neighboring sequences, affecting how often those neighboring sequences are expressed. I think it's possible that climbers are taking in a lot of information subconsciously as they sprint through this route in order to mike very small adjustments. The position of surrounding holds, even ones they never touch, could very well be a part of that information stream. They're fighting over hundredths of a second, so even a very small effect could be meaningful.

It may not be a fencepost error, but I think it's still off by one.
Even if the out of place hold were used, would you then conclude it to be causal? I still wouldn't rule out coincidence. Many discoveries happen as a result of investigating spurious patterns.

Also the author rules out psychology, but I wouldn't, especially since there were multiple confirmed errors in the route preparation, which I expect could reduce one's trust in the fairness of the competition. In the moment, I might start to wonder, "If one hold was out of place, why not more? Is anyone even checking this?" even if untrue / unlikely.

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They run the whole 15 meter up in about 5-10 seconds (quite amazing to watch: https://m.youtube.com/watch?v=8O4g8JmWn9E ). At that speed, a small disturbance from the path they internalized means that they need to switch back to thinking which will take them out of their flow.
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If you cross your eyes and look at the routes as if it were a single stereoscopic image overlaying one route on top of each other, the misplaced hold jumps out at you immediately.
It works. It is actually my secret technique when solving "find five differences".
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I don't understand how this works. If I cross my eyes, the images become extremely blurry. I can't even tell if they are precisely overlapping or not, let alone see if one of the holds is out of place.

Am I the only one?

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Good idea. I just tried that on the first image of the whole route (after zooming in a bit) and the misplaced hold looks like it's floating in space away from the wall.
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I tried this, and while I didn't have any difficulty establishing a stereoscopic view it didn't jump out for me at all. I perceived the blue line floating on top of the problem handhold, but the handhold seemed to be on the same plane as all the others. Knowing it was the problem one, I could use the stereoscopic view to see it, but without already knowing I don't think it would be apparent.

This is odd to me since I've successfully used stereoscopy in the past to find small differences. For some reason, with this image, rather than causing a change in perceived z-level, my eyes fight for dominance and my left ends up winning.

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I just did it and it didn't jump out for me at all. Odd
I usually find it easier to relax my eyes (focus too far rather than too close), and so the opposite occurred - most of the holds appeared to float in a single plane (slightly wavy perhaps due to lighting differences), while the incorrect hold was sunk further back.
It's so weird ! The badly placed hold just disappears once all the rests aligns. My brain seems to dismiss it as an error on its part
Same, after some practice I could close one eye at a time and see the movement but it was hard to maintain the eye crossing with one eye closed
Took me a bit to realize the last photo has it correctly, and to stop trying to find the discrepancy there. Looking at only the first image it pops out to me because the wrong one is floating closer to my eyes than the rest.
Same! I couldn’t get it to work because that sailboat was in the way.
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That's a fantastic find. I imagine some standard CV tool can spot this since the holds are grid-aligned. We should probably have something like that. It's crazy how good human pattern-recognition can get when trained on things. What a spot by you.

Also, by the way, where is the photo on your about page: https://images.squarespace-cdn.com/content/v1/60f40aa1942bba...

I feel like it's Crater Lake, Oregon, but considering where you live it's probably somewhere in Switzerland. Looks lovely.

You could also simply take two photos and overlay them. The difference would be obvious immediately to the human eye.
It is Crater Lake, from a second visit this summer.
> Maybe when the record is unbeaten for more than a couple of years they should throw it all away and start with a brand new route?

There's been some discussion of having new speed routes every few years. I think this would make the event a thousand times more interesting. That said, I'm still not sure I'd be interested.

How about a route pool like an esports map pool?
There's a misconception that a quadrennial sports festival. Actually, they're a quadrennial festival for people who never cared about the sport before to explain how it should be fixed.
It would be terrible from an athlete perspective
How about birthdays? When you turn "1" it's your second birthday. Or counting three seconds. Start counting zero..one..two..three.
The number on your yearly "birthday" is not the number of birthdays you had (you only have one birthday) but the number of years you survived since your birth.

So the day of your fifth birthday is the first day of your sixth year alive.

Birthday vs birth day but yeah. It works if you say it
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Jewish law sometimes counts from 1 instead of 0 for birthdays, so a newborn is not 0 years old, they are in their 1st year. (But it's written as "when they are 1", so you have to know which counting method is being used.)
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Korea has a system similar to this. You start at age 1 and get one year older each New Year's Day. https://www.90daykorean.com/korean-age-all-about-age-in-kore...
They changed the system last year after using it for many years (+/-1).

https://www.aljazeera.com/amp/news/2023/6/28/why-are-south-k...

Seems bizarre to keep the same wall config for all of time. The sport becomes about muscle memory more than anything else. The competitors can literally turn off their conscious brain. It would seem to me, it would be more exciting as a spectator and competitor if they had to problem solve on their way up there. Records could be less about best times and more about how many rounds did someone win in a row or something.

They could even still incorporate the one standardized wall config as a speed round once in a while or integrate it into the competition in some other way.

> Seems bizarre to keep the same wall config for all of time. The sport becomes about muscle memory more than anything else.

Plenty of other sport are pretty much the same each time, particularly track and field.

Exactly, I don't understand people who watch any of the tracl and field disciplines and complain about this wall being the same everytime. Like there's about 10 different disciplines of people running on a plain track and that's fine but people climbing the same wall isn't. I totally get that you might find lead or bouldering more interesting but that's not the point.
This is a whataboutism.
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The same wall config is only for the speed competition. There has been debate about changing it though, cause like you said they become muscle memory and hyper-optimized.

There are other forms of competition:

- bouldering: how many of 4 short boulder problems can you finish

- lead: how high can you get on a longer, higher route (pictured on the right of the image in the article)

In these ones the problems are switched up every competition.

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I don't watch this event but, coming from other sports, I think there's more to this than sheer muscle memory. Humans are not machines. Sometimes you compete with ongoing or lingering injuries. Conditioning changes even for the most disciplined of athletes. All of these mean that a different approach might be warranted for each event depending on your "set-up".

Not to mention other variables outside of the human body. Perhaps the type of rope could matter in your performance. The age of the holds could matter too; even when the governing body standardizes on a replacement period for holds, I'm sure competitors would have strong opinions about the difference between a hold at the start of its service life versus one about to be replaced.

Also, the one thing I love seeing in physical contests is how competitors eke out the last bit of performance advantage with sheer willpower. Muscle memory takes care of the actions but performance and willpower is a conscious effort.

In short, no, I don't think competitors can literally turn off their conscious brain and just let muscle memory take over. If a field has jargon, there's a hell lot to geek over it.

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Once an activity has become a “competitive sport” it has a way of prioritising “measurable” over meaningful or enjoyable. When you develop a critical eye for this aspect of sport, the Olympics stop being enjoyable and become an utter horror of human maladjustment, a horrid parody of what it alleges to stand for.
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>as a ... competitor

Are you?

> Also, maybe in future someone will optimise the route using that currently unused hold four down from the top?

This reminds me a lot of how Brood War meta changes as new 'bugs' are discovered, since the fandom loves the game without it ever being touched so when edge cases are discovered they become part of the game rather than something to be fixed.

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https://www.formulanon.com/movement/mrhp8j3hijw97sdl1krno2el...
If you're curious about those, they're all photos of the various sporting events that happen in the village here. All the effects you see are captured in camera through movements or otherwise.
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