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What is theoretical computer science?

(cacm.acm.org)
166 points levlaz | 14 comments | 18 Oct 24 06:04 UTC | HN request time: 0s | source | bottom
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ykonstant ◴[18 Oct 24 07:26 UTC] No.41877090[source]▶
This is a great article and I especially liked the notion:

>Theoretical physics is highly mathematical, but it aims to explain and predict the real world. Theories that fail at this “explain/predict” task would ultimately be discarded. Analogously, I’d argue that the role of TCS is to explain/predict real-life computing.

as well as the emphasis on the difference between TCS in Europe and the US. I remember from the University of Crete that the professors all spent serious time in the labs coding and testing. Topics like Human-Computer Interaction, Operating Systems Research and lots of Hardware (VLSI etc) were core parts of the theoretical Computer Science research areas. This is why no UoC graduate could graduate without knowledge both in Algorithms and PL theory, for instance, AND circuit design (my experience is from 2002-2007).

I strongly believe that this breadth of concepts is essential to Computer Science, and the narrower emphasis of many US departments (not all) harms both the intellectual foundations and practical employment prospects of the graduate. [I will not debate this point online; I'll be happy to engage in hours long discussion in person]

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ninetyninenine ◴[18 Oct 24 09:42 UTC] No.41877761[source]▶
> Theoretical physics is highly mathematical, but it aims to explain and predict the real world. Theories that fail at this “explain/predict” task would ultimately be discarded. Analogously, I’d argue that the role of TCS is to explain/predict real-life computing.

No this guy doesn’t get it. He doesn’t understand what science is.

In science nothing can be proven. If I say all swans are white as my hypothesis this statement can never be proven because I can never actually verify that I observed all swans. There may be some swan hidden on earth or in the universe that I haven’t seen. Since the universe is infinite in size I can never confirm ever that I’ve observed all swans.

However if I observe one black swan it means I falsified the entire hypothesis. Thus in science and in reality as we know it nothing can be proven… things can only be falsified.

Math on the other hand is different. Math is all about a made up universe where axioms are known absolutely. It has nothing to do with observation or evidence in the same way science does. Math is an imaginary game we play and in this game it is possible to prove things.

This proof is the domain of mathematics… not science. Physics is a science because it involves gathering evidence and attempting to falsify the hypothesis.

Einstein said it best: “No amount of experimentation can ever prove me right; a single experiment can prove me wrong”

Basically newtons laws of motion are a perfect example of falsification via experimentation with relativity later being confirmed as the more accurate theory that matches more with observation.

So what’s the deal with computer science?

First of all the term already hits the first nomenclature issue. Computer science is ironically not a science. It lives in the same axiomatic based world as mathematics and therefore things can be proven in computer science but not in science itself.

So this nomenclature issue is what’s confusing everyone. The op failed to identify that computer science isn’t actually a freaking science. Physics is a science but computer science isn’t.

So what is computer science? Sorry to say but it’s a math. I mean it’s all axioms and theorems. It’s technically math.

CS is a math in the same way algebra and geometry is math. Physics is a science and it is not a math. It’s a totally orthogonal comparison.

Your job as programmers is more like applied math. It’s completely orthogonal to the whole topic but People often get this mixed up. They start thinking that because programming is applied computer science then computer science itself is not a math.

Applied math ironically isn’t really math in the same way writing isn’t a pencil. Yes you use a pencil to write but they are not the same. Same thing with computer science and programming.

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lisper ◴[18 Oct 24 18:15 UTC] No.41882001[source]▶
> If I say all swans are white as my hypothesis

That fails as a scientific hypothesis on purely structural grounds, before you have made any observations. Scientific hypotheses have to explain something. It's not enough to say that all swans are white, you have to say why. "All swans are white" is an observation, not a (scientific) hypothesis.

An example of a legitimate scientific hypothesis is that all swans are white because being white provides swans with some benefit in terms of reproductive fitness (and then you have to go on to say what that benefit is). You can then go on to predict that there might be non-white swans, but that these are expected to be rare because evolutionary pressure would drive non-whiteness out of the gene pool. Or something like that. But "all swans are white" by itself is a non-starter as a scientific hypothesis.

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ninetyninenine ◴[18 Oct 24 18:49 UTC] No.41882327{3}[source]▶
I'm talking at a very technical level ignoring all the cultural stuff around the scientific method like "peer review" or explaining "why"

Basically a hypothesis is a statement that can be true or false. That's it.

The reason I refer to science in this very technical way is because the we are tackling the problem of classification. We are asking the question what is computer science? So to answer the question we need to use very technical definitions where the boundaries of categorization are extremely clear.

Again, at a very technical level a hypothesis is simply a statement that is true or false.

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lisper ◴[18 Oct 24 19:09 UTC] No.41882489{4}[source]▶
> a hypothesis is simply a statement that is true or false.

No, that is a proposition, not a hypothesis.

And the requirement that hypotheses be explanatory has nothing to do with culture, it is the distinguishing feature of the scientific method. See: https://blog.rongarret.info/2024/03/a-clean-sheet-introducti...

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ninetyninenine ◴[18 Oct 24 19:18 UTC] No.41882571{5}[source]▶
False. At the very technical level, a hypothesis is defined by statistics.

https://www.sciencedirect.com/topics/mathematics/statistical....

When you cut through all the cultural and human stuff we place around the scientific method, in the end it is a statistics problem at the most technical level. Everything else makes it fuzzy and hard to define.

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1. lisper ◴[18 Oct 24 21:05 UTC] No.41883478{6}[source]▶
Now you're moving the goal posts. First, it was "a hypothesis is a statement that can be true or false. That's it." Now it's "a hypothesis is defined by statistics". Get back to me when you've decided what your position actually is. I'm not going to waste time debunking every half-baked idea you can come up with.
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2. ninetyninenine ◴[18 Oct 24 21:35 UTC] No.41883722[source]▶
The goal posts were never moved. What moved is your understanding of what I'm trying to say.

A hypothesis is a statement that is TRUE or FALSE. And THIS is HOW it's defined by statistics.

>I'm not going to waste time debunking every half-baked idea you can come up with.

I'm sorry but this attitude is offensive and against the rules here. I can't participate in any further discussion with you because of this. Thank you for your time and good day.

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3. Koshkin ◴[18 Oct 24 22:00 UTC] No.41883894[source]▶
I don't think that physics (for example) uses the word "hypothesis" in the same sense, even though there are, indeed, parallels between the two sciences.
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4. ninetyninenine ◴[18 Oct 24 22:34 UTC] No.41884097{3}[source]▶
What is the physics definition and what sciences are you referring to?
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5. Koshkin ◴[18 Oct 24 23:26 UTC] No.41884388{4}[source]▶
A statistical hypothesis is an assumption about a population parameter. A hypothesis in physics is something else entirely. (Incidentally, there are hypotheses in mathematics, too, called "conjectures"). You may disagree, but I see statistics as a science, akin to physics; which, perhaps, is why we also have "mathematical statistics."
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6. lisper ◴[18 Oct 24 23:41 UTC] No.41884473[source]▶
> The goal posts were never moved.

Yes, they were. You started out by saying, "a hypothesis is a statement that can be true or false. That's it." But that isn't "it" as you yourself found it necessary to explain.

> I can't participate in any further discussion

That's fine, I'm writing this response for the benefit of others who might be reading this: not only are both of your claims wrong, they are transparently wrong. "Santa Claus lives at the North Pole" is a statement that can be either true or false (it happens to be false) but it doesn't have the same standing as a scientific hypothesis as, say, "the laws of physics are invariant under Galilean relativity." That happens to be false too, but it is not nearly as false as "Santa Claus lives at the North Pole." And neither of these has anything to do with statistics.

You clearly don't understand the first thing about how the scientific method actually works, starting with the fact that you cannot strip away "the cultural stuff." Science is a human endeavor. It is ultimately about accounting for our subjective experiences because that is all any of us have direct access to. This includes, but is not limited to, the fact that there seems to be this thing people do called "science", which has a bunch of interesting properties and turns out to be tremendously useful. Statistics are only a small part of that endeavor. An important part to be sure, but a small part nonetheless.

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7. ninetyninenine ◴[19 Oct 24 00:01 UTC] No.41884550{3}[source]▶
Dear comment reader, there's no benefit for reading this section of the thread. Not only is he wrong. He's been rude and insulting and in violation of the rules. I flagged his section of the thread. I'm not the moderator but I think this thread will be killed by him once he sees it.

Meanwhile, before the moderator arrives, I'm placing this comment here to ask people to stop responding to him and aggravating the thread further. Thank you.

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8. ninetyninenine ◴[19 Oct 24 00:08 UTC] No.41884574{5}[source]▶
Well both are statements that can be true or false.

I would say in physics it's also a population parameter. It's just sometimes we feel so confident about a single observation that we only need to take 1 sample.

>You may disagree, but I see statistics as a science, akin to physics

I don't disagree. This has been my entire point. I define statistics as the foundational formal definition of the scientific method.

9. FabHK ◴[19 Oct 24 01:44 UTC] No.41885000{4}[source]▶
Or maybe you're misguided? You seem to want to expound a fairly naive Popperian view of science, but cannot distinguish "proposition" from "hypothesis".
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10. montjoy ◴[19 Oct 24 02:50 UTC] No.41885272{4}[source]▶
Hi. Comment reader here. Regardless whether you are right or not you’re coming across as obstinate. It might do you well to eat some humble pie.
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11. ninetyninenine ◴[19 Oct 24 03:05 UTC] No.41885344{5}[source]▶
So? That’s my opinion. The insults were uncalled for.

Please don’t aggrevate this further.

12. ninetyninenine ◴[19 Oct 24 04:32 UTC] No.41885652{5}[source]▶
If that’s the case, then I apologize, it wasn’t my intention. Still, being confident about my answers is entirely different from insults which are always uncalled for.

Either way please stop extending this thread.

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13. _proofs ◴[19 Oct 24 16:35 UTC] No.41888817{6}[source]▶
no one has really insulted you, so the playing the victim part is also coming across as more obstinate -- what you are experiencing is people becoming frustrated with the assertions.

you have been sufficiently approached, your points addressed, and multiple people have provided ample reasoning that expound on their assertions, adding context, nuance, historical, conventional, or otherwise.

all you have contributed to the over-reaching discussion is assertions (in some cases they come across as not fully thought out, as if the tape was not fully played), followed be an emphatic and repeated: "you're wrong!"

and for as much as you have claimed to strip away culture as an influence to the discussion, you have also managed to strip away important nuances between established words in our -- cultural -- expression here: proposition vs. hypothesis.

it appears that the position here is attempting to generally (and loosely) apply a statistical hypothesis as the internal world model for science at large, where in stats the word hypothesis is almost a binary operator evaluating to true or false (ie: Null Hypothesis), and functionally operates more like asserting a proposition over a data set, and then evaluating the data to see if it holds.

as a comment reader, while i appreciate the discussion, reducing everything to a statistical hypothesis and then telling people they are wrong when they show, not tell, there are important, established, agreed upon meanings, is not contributing in good faith, which i imagine is causing a lot of the aforementioned frustrations.

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14. ninetyninenine ◴[19 Oct 24 23:15 UTC] No.41891550{7}[source]▶
I respectfully ask you to stop.

I was insulted go back and look at it.

If you want to discuss things with me, please do so in another thread. I welcome you to tell me I'm wrong as I will do the same if I disagree with you. Telling me I'm wrong is not an insult and it's the basis of truthful honest discussion. If you believe I'm wrong, tell me straight. Don't dance around it.