Zagorath

Zagorath , 4 months ago

Are you Dutch? I recall an old NJB video describing how Dutch supermarkets worked like this. (Plus, Martin is a name I associate with the Netherlands…)

But no. Most often, you put stuff in your trolley or basket, then when you get to the checkout, you scan the things and bag them yourself one-by-one, then pay.

Here in Australia, one of our two main supermarket chains in the last 2 years rolled out something similar to what the Netherlands has had for at least half a decade. You use their app on your phone and scan things with the app as you go, before paying through the app and scanning a QR code at the exit.

The other main chain, and the two main smaller chains, have made no moves to follow, so you're stuck with a long line for a small number of open checkouts, or the self-checkout where you have to scan everything after you get to the checkout.

Zagorath , 4 months ago

That's less than 2 years.

Zagorath , 4 months ago

And Facebook makes even YouTube look like an academic conference.

Zagorath , 4 months ago

Is it the default homepage on the Samsung browser?

Zagorath , 4 months ago

Oh interesting. I was assuming the way this stat is gathered would exclude that kind of thing, but that could be it.

Zagorath , 4 months ago

What actually is this?

Zagorath , 4 months ago

Why is a mortar round on a stick though? Wouldn't a mortar round normally just be the "head" of this hammer?

Zagorath , 5 months ago

A friendly reminder that road safety advocates recommend against the use of the word "accident" to describe car crashes, because it downplays the fact that many crashes are preventable, either by better safe road design or by the drivers being more responsible with with 2 tonne machinery they are operating.

Zagorath , 5 months ago

I both agree and disagree, but I'm not sure which wins out.

Agree because yeah, codpieces were obviously ostentatious and nonfunctional, and why would you not expect women to do the same thing if given the same chance?

On the other hand, the risk imposed by boobplate is more substantial than codpieces. The groom area is not a very good target for opponents because it's kinda hard to reach and it will harm your target less than the head and chest areas. Boob armour, on the other hand, is right at the spot most thrusts and many cuts are going to be targetted at regardless. The risk of directing glancing blows back in towards your vital organs is greater with boobplate than codpieces.

It's not like these Kings or Generals really saw someone swing a sword at them or needed actually functional armor

I think this depends on the time period, location, and individual King/General. There's a reasonably long Wikipedia page on monarchs killed in action. And more might have been injured in combat, or attacked but safe thanks to their armour (and skill). On the other hand, some might be included there mainly because they were overrun and died in action even though they never intended to be in action at all.

Zagorath , 5 months ago

This is basically Monty Hall right? The other child is a girl with 2/3 probability, because the first one being a boy eliminates the case where both children are girls, leaving three total cases, in two of which the other child is a girl (BG, GB, BB).

Zagorath , 5 months ago

No, because implicit multiplication binds more tightly than explicit. a/b(c) becomes a/(b×(c))

Zagorath , 5 months ago

If we had 1/2x, would you interpret that as 0.5x, or 1/(2x)?

Because I can guarantee you almost any mathematician or physicist would assume the latter. But the argument you're making here is that it should be 0.5x.

It's called implicit multiplication or "multiplication indicated by juxtaposition", and it binds more tightly than explicit multiplication or division. The American Mathematical Society and American Physical Society both agree on this.

BIDMAS, or rather the idea that BIDMAS is the be-all end-all of order of operations, is what's known as a "lie-to-children". It's an oversimplification that's useful at a certain level of understanding, but becomes wrong as you get more advanced. It's like how your year 5 teacher might have said "you can't take the square root of a negative number".

Zagorath , 5 months ago

The answer is 1, but the logic you've used to get there is a little off. Different groups actually follow different logic, but they usually arrive at the same end-point.

The American Mathematical Society goes:

• Brackets
• Indices
• Multiplication indicated by juxtaposition
• Regular multiplication and division
• Addition and subtraction

While the American Physical Society does

• Brackets
• Indices
• Multiplication
• Division
• Addition and subtraction

In both cases, addition and subtraction are equal in priority (this solves the problem brought up by a different comment where following primary school BIDMAS would mean 8-4+2=2). In one case (and this is the way I prefer to do it) they solve the problem by declaring that implicit multiplication is done before division, but explicit multiplication with the × sign follows the same rules you would have learnt in primary school. The other says all multiplication is done before division, including explicit multiplication.

Zagorath , 5 months ago

You left out the way it can be rewritten which most mathematicians would actually use, which is 8/(2(2+2)), which resolves to 1.

Zagorath , 5 months ago

The problem is that BIDMAS and its variants are lies-to-children. Real mathematicians don't use BIDMAS. Multiplication by juxtaposition is extremely common, and always takes priority over division.

Nobody in their right minds would saw 1/2x is the same as (1/2)x. It's 1/(2x).

That's how you get 1. By following conventions used by mathematicians at any level higher than primary school education.

Zagorath , 5 months ago

This is exactly right. It's not a law of maths in the way that 1+1=2 is a law. It's a convention of notation.

The vast majority of the time, mathematicians use implicit multiplication (aka multiplication indicated by juxtaposition) at a higher priority than division. This makes sense when you consider something like 1/2x. It's an extremely common thing to want to write, and it would be a pain in the arse to have to write brackets there every single time. So 1/2x is universally interpreted as 1/(2x), and not (1/2)x, which would be x/2.

The same logic is what's used here when people arrive at an answer of 1.

If you were to survey a bunch of mathematicians—and I mean people doing academic research in maths, not primary school teachers—you would find the vast majority of them would get to 1. However, you would first have to give a way to do that survey such that they don't realise the reason they're being surveyed, because if they realise it's over a question like this they'll probably end up saying "it's deliberately ambiguous in an attempt to start arguments".

Zagorath , 5 months ago

I will happily point out that Wolfram Alpha does this wrong. So do TI calculators, but not Casio or Sharp.

Go to any mathematics professor and give them a problem that includes 1/2x and ask them to solve it. Don't make it clear that merely asking "how do you parse 1/2x?" is your intent, because in all likelihood they'll just tell you it's ambiguous and be done with it. But if it's written as part of a problem and they don't notice your true intent, you can guarantee they will take it as 1/(2x).

Famed physicist Richard Feynman uses this convention in his work.

In fact, even around the time that BIDMAS was being standardised, the writing being done doing that standardisation would frequently use juxtaposition at a higher priority than division, without ever actually telling the reader that's what they were doing. It indicates that at the time, they perhaps thought it so obvious that juxtaposition should be performed first that it didn't even need to be explained (or didn't even occur to them that they could explain it).

According to Casio, they do juxtaposition first because that's what most teachers around the world want. There was a period where their calculators didn't do juxtaposition first, something they changed to because North American teachers were telling them they should, but the outcry front the rest of the world was enough for them to change it back. And regardless of what teachers are doing, even in America, professors of mathematics are doing juxtaposition first.

I think this problem may ultimately stem from the very strict rote learning approach used by the American education system, where developing a deeper understanding of what's going on seems to be discouraged in favour of memorising facts like "BIDMAS".

Zagorath , 5 months ago

Most maths textbooks written by mathematicians.

I don't mean when they're explaining "here's how the order of operations works". I mean in the basic way that they write more advanced problems and the answers they give for them.

This video, and the prequel to it linked in the description, go into some detail showing who uses what convention and why.

Zagorath , 5 months ago

I was about to reply to you with a comment that started with "oh shit you're right!" But as I wrote it I started rethinking and I'm not sure now.

Because I actually don't think it matters whether we're BB1 or BB2. They're both only one generation of the four possible initial states. Which child opens the door is determined after the determination of which child is which gender. Basically, given that they have two boys, we're guaranteed to see a boy, so you shouldn't count it twice.

Still, I'm now no where near as confident in my answer as I was a moment ago. I might actually go and write the code to perform the experiment as I outlined in an earlier comment (let me know if you think that methodology is flawed/biased, and how you think it should be changed) to see what happens.

Zagorath , 5 months ago

Even Wolfram Alpha makes a point of restating your input to show how it’s being interpreted

This is definitely the best thing to do. It's what Casio calculators do, according to those videos I linked.

My main point is that even though there is theoretically an ambiguity there, the way it would be interpreted in the real world, by mathematicians working by hand (when presented in a way that people aren't specifically on the lookout for a "trick") would be overwhelmingly in favour of juxtaposition being evaluated before division. Maybe I'm wrong, but the examples given in those videos certainly seem to point towards the idea that people performing maths at a high level don't even think twice about it.

And while there is a theoretical ambiguity, I think any tool which is operating counter to how actual mathematicians would interpret a problem is doing the wrong thing. Sort of like a dictionary which decides to take an opinionated stance and say "people are using the word wrong, so we won't include that definition". Linguists would tell you the job of a dictionary should be to describe how the word is used, not rigidly stick to some theoretical ideal. I think calculators and tools like Wolfram Alpha should do the same with maths.

Zagorath , 5 months ago

I put it together. Here's the code I wrote in Python.

import random

genders = ['boy', 'girl']

def run():
    other_child_girls = 0
    for i in range(10000):
        other_child = get_other_child()
        if other_child == 'girl':
            other_child_girls += 1
    print(other_child_girls)

def get_other_child():
    children = random.choices(genders, k=2)
    first_child_index = random.randint(0, 1)
    first_child = children[first_child_index]
    if first_child == 'boy':
        other_child_index = (first_child_index + 1) % 2
        return children[other_child_index]
    # Recursively repeat this call until the child at the door is a boy
    # (i.e., discard any cases where the child at the door is a girl)
    return get_other_child()

if __name__ == '__main__':
    run()

And it turns out you were right. I ran it a few times and got answers ranging from 4942 to 5087, i.e., clustered around 50%.

Zagorath , 5 months ago

The problem is that you're thinking of BIDMAS as a set of hard rules, rather than the set of rough guidelines created in the early 20th century by one random teacher for the purposes of teaching 10-year-olds how to do the level of maths that 10-year-olds do.

This video and this one point to some examples of style guides in academia as well as practical examples in the published works of mathematicians and physicists, which are pretty consistent.

If you want to come up with a hard rule, doing BIJMDAS, adding in "multiplication indicated by juxtaposition" with the J, is a much better way to do it than what you learnt when you were 10. But even that's still best to think of as a handy guideline rather than a hard and fast rule.

Zagorath , 5 months ago

the math maths

Ha. As someone from the "mathematics is shortened to maths" part of the world, this sounds weird to me. I'd probably say "the maths mathses". I just thought you might enjoy that.

Anyway, I Googled the problem you presented, and came across this excellent answer:

There are even trickier aspects to this question. For example, what is the strategy of the guy telling you about his family? If he always mentions a boy first and not a daughter, we get one probability; if he talks about the sex of the first born child, we get a different probability. Your calculation makes a choice in this issue - you choose the version of "if the father has a boy and a girl, he'll mention the boy".

What I'm aiming to is this: the question is not well-defined mathematically. It has several possible interpretations, and as such the "problem" here is indeed of the language; or more correctly, the fact that a simple statement in English does not convey enough information to specify the precise model for the problem.

The whole answer is worth reading, but that part there is the crux of it. It goes back to one of my earliest comments on this topic in this thread. The problem isn't that maths is weird, it's that language's ability to describe mathematical problems is lacking. There are so many different ways to translate the described problem into mathematical formulae and they necessarily carry assumptions. Even far more subtle assumptions than I at first thought.

Zagorath , 5 months ago

So are you suggesting that Richard Feynman didn't "deal with maths a lot", then? Because there definitely exist examples where he worked within the limitations of the medium he was writing in (namely: writing in places where using bar fractions was not an option) and used juxtaposition for multiplication bound more tightly than division.

https://aussie.zone/pictrs/image/8ccdd67c-5446-4dad-8caa-8ad839b0f997.png

Here's another example, from an advanced mathematics textbook:

https://aussie.zone/pictrs/image/c0e208b5-b2d6-4c5f-9ade-849de50a623a.png

Both show the use of juxtaposition taking precedence over division.

I should note that these screenshots are both taken from this video where you can see them with greater context and discussion on the subject.

Zagorath , 5 months ago

Since using "maths" as a verb is very much nonstandard, I would argue against trying to apply any rigorous rules to it. It's about the vibes of the thing.

Zagorath , 6 months ago

If they're inserting random race words in, presumably there's some kind of preprocessing of the prompt going on. That preprocessor is what would need to know if the character is specific enough to not apply the race words.

Zagorath , 6 months ago

Honestly Plex has always given me the icks. Its weird hybrid of self-hosted but managed through their servers always struck me as the worst of both worlds. I'd rather put in a small amount extra effort to properly self-host my stuff, or do significantly less work and use something cloud-based. I just don't understand what niche Plex is supposed to serve.

Zagorath , 6 months ago

I have a Brother HL-2365DW. It's a home printer, or maybe at most a home-office printer. I've had it nearly a decade with only two toner replacements. Being laser and networked solve the two biggest problems I've had with inkjet printers in the past, and those two categories are the main things I would strongly recommend to people when choosing a printer.

edit: I initially wrote "it's not a home printer" (emphasis added here for demonstrative purposes). This was the exact opposite of what I intended to say.

Zagorath , 6 months ago

I swear, if it weren't for the fact that I've also had good experiences with Brother, I'd be thinking they have an insanely good astroturfing department. Every time there's a thread about printers, there are dozens of comments saying how good they are.

Zagorath , 6 months ago

I haven't bought a printer recently. Wtf is a smart printer?

Zagorath , 6 months ago

Yeah I tend to either not print anything for years, or print huge amounts in a short span of time. Lasers are brilliant for this use case, because they also print really really quickly when they are printing, in addition to not drying up.

Zagorath , 9 months ago

Nebula is amazing and I would highly encourage any urbanist to sign up for it. It's only like $30 per year.

Zagorath , 9 months ago

I can't say I disagree with you. The thumbnails and titles are sometimes a bit clickbaity. But they don't let anyone join the site as a creator unless they have faith in the actual content of the videos. They're creators who sometimes use clickbaity thumbnails because that's just essential to surviving the YouTube algorithm, and the Nebula version usually just takes the same title and thumbnail from YouTube. But it's never the sort of clickbait where a clickbaity thumbnail was used to trick you into watching actual garbage content—the content is always high quality.

I wish they'd tone it down for the Nebula version, but that's an extra amount of work for honestly very little extra value, so I understand why they don't.