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Ask HN: What is the most complex topic you understand?

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Re: Ask HN: What is the most complex topic you understand?

#61

Post by ggeorgovassilis »

ziffusion wrote: post #54
deltaonenine wrote: post #11

Entropy. It was hard for me to understand this arbitrary rule of things becoming less ordered over time. Was this just a fundamental natural law? The answer is no. Entropy is a logical consequence of probability and time. Why do things become more chaotic over time? Because chaotic configurations have a higher probability of occurring. There are far more disordered configurations of things then there are ordered, thi…

> Because chaotic configurations have a higher probability of occurring. That seems like a non-explanation though. Why do chaotic configurations have a higher probability of occurring?

From other replies to your question I understand that you use "chaotic" in the mathematical sense while other commenters use it in the colloquial ("random") sense.

Re: Ask HN: What is the most complex topic you understand?

#62

Post by nonrandomstring »

Rather than "understand" I'll talk about complex "accomplishments".

I once built a computer. I had Alan Clements "Microprocessor Systems Design" for an undergraduate text and built a 68000 based machine with 64M of RAM and ROM. Using discrete ICs on two big Eurorack wirewrap cards was hard work and needed good eyesight and dexterity. Then I wrote a bootloader and kermit-like like RS232 program loader, and finally hashed together a really basic OS from Tannenbaum (with a synchronous scheduler and fixed job table). A long summer of late nights. Can I say "I understand computers". No way! But I feel confident I know more about them than most people I'll ever meet.

Another heroic adventure was "Linux from Scratch", compiling everything along the way with tinycc.

These things are rites of passage. They don't mean I understand those things, and even if I did, that knowledge is obsolete today, but I'm glad I did them.

Re: Ask HN: What is the most complex topic you understand?

#63

Post by deltaonenine »

ziffusion wrote: post #54
deltaonenine wrote: post #11

Entropy. It was hard for me to understand this arbitrary rule of things becoming less ordered over time. Was this just a fundamental natural law? The answer is no. Entropy is a logical consequence of probability and time. Why do things become more chaotic over time? Because chaotic configurations have a higher probability of occurring. There are far more disordered configurations of things then there are ordered, thi…

> Because chaotic configurations have a higher probability of occurring. That seems like a non-explanation though. Why do chaotic configurations have a higher probability of occurring?

12345 is less plentiful then 32415 or 32154 or .... What we considered "ordered" has less possibilities then "unordered" not just in a string of 5 numbers but for most systems. That should help you get the intuition. Lmk if you need more elaboration.

Re: Ask HN: What is the most complex topic you understand?

#64

Post by deltaonenine »

ggeorgovassilis wrote: post #61
ziffusion wrote: post #54

Earlier quoted context omitted.

> Because chaotic configurations have a higher probability of occurring. That seems like a non-explanation though. Why do chaotic configurations have a higher probability of occurring?

From other replies to your question I understand that you use "chaotic" in the mathematical sense while other commenters use it in the colloquial ("random") sense.

I use it in the colloquial sense. Disordered, random.

Re: Ask HN: What is the most complex topic you understand?

#66

Post by deltaonenine »

ggeorgovassilis wrote: post #14
deltaonenine wrote: post #11

Entropy. It was hard for me to understand this arbitrary rule of things becoming less ordered over time. Was this just a fundamental natural law? The answer is no. Entropy is a logical consequence of probability and time. Why do things become more chaotic over time? Because chaotic configurations have a higher probability of occurring. There are far more disordered configurations of things then there are ordered, thi…

I envy you for your understanding of entropy. I understand a few simple aspects of it, but the deeper meaning eludes me. It does seem to be a useful concept which grants access to so many knowledge domains.

I understand one aspect of it in terms of probability. However another aspect of it eludes me as well, as I described in my last paragraph.

There's also a third angle from information theory. This type of understanding I haven't really studied in depth yet.

Re: Ask HN: What is the most complex topic you understand?

#67

Post by more_corn »

ScarZy wrote: post #33
YeGoblynQueenne wrote: post #8

I don't know, because once I understand something it always seems very simple to me.

Sigh. I don't believe this aids the discussion in any meaningful way at all.

To me this is the very crux of the conversation.

Re: Ask HN: What is the most complex topic you understand?

#69

Post by gilleain »

ggeorgovassilis wrote: post #47
gilleain wrote: post #27

I guess it might be 'graph hashing', also known as canonicalization. So this is related to some other things, like the Weisfeiler-Leman Algorithm, and Morgan numbers, and partition refinement. The idea is that to compare two graphs (networks, or Eulerian graphs) for equality one way to do that is to 'hash' the graph. The resulting canonical representations of the graphs are then compared directly for equality. I impl…

In a distant past I started working on something similar, but reached the limits of my mind before doing anything useful. Tangential question: is there a difference in the context of graphs between canonicalization and normalization?

The simple answer is that I don't know! I never looked at 'normalization' in graphs.

From a quick google, seems like it has been used in a couple of contexts. Firstly in GNNs which I definitely know nothing about.

However I see another description in terms of RDF triples, which sounds like a canonicalization algorithm (https://json-ld.org/spec/ED/rdf-graph-normalization/20111016...)

Re: Ask HN: What is the most complex topic you understand?

#70

Post by ggeorgovassilis »

gilleain wrote: post #69
ggeorgovassilis wrote: post #47

Earlier quoted context omitted.

In a distant past I started working on something similar, but reached the limits of my mind before doing anything useful. Tangential question: is there a difference in the context of graphs between canonicalization and normalization?

The simple answer is that I don't know! I never looked at 'normalization' in graphs. From a quick google, seems like it has been used in a couple of contexts. Firstly in GNNs which I definitely know nothing about. However I see another description in terms of RDF triples, which sounds like a canonicalization algorithm ( https://json-ld.org/spec/ED/rdf-graph-normalization/20111016... )

Thank you
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