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Ask HN: What's the hardest problem you've ever solved?

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Re: Ask HN: What's the hardest problem you've ever solved?

#411
post #394

Earlier quoted context omitted.

"And sometimes cheating the system is actually regarded highly by the fellow citizens, because the people do not believe in the imposed system. " If you live a totally corrupt system, maybe. But functional societies are based on the notion that cheating is bad, immoral, and nobody should do it. "Now, what is more ethical, doing what benefits the people or doing what benefits such system?" - ha ha ... this sounds like…

People who rob banks are not necessarily psychopaths. For a good (fictitious but convincing) example, see Toby Howard in the film https://en.wikipedia.org/wiki/Hell_or_High_Water_(film) Robbing a bank is universally illegal, but it is not regarded as unethical in general.

"but it is not regarded as unethical in general."

Yes it is.

Maybe you live in an interesting developing nation?

Robbing banks, stores, anyone - is considered basically immoral in all of civilization, thankfully.

Yes - not all bank robbers are psychopaths - probably not the majority.

But prisons are fully of people bending reality to justify their crimes.

Re: Ask HN: What's the hardest problem you've ever solved?

#413

Earlier quoted context omitted.

My humble opinion. University is about learning (not, for example, status). Learning is something strictly personal. There is nothing fundamentally universally wrong to cheat at an exam beside the fact you may be harming yourself. Now since we need a little order for various secondary reasons, we promoted exam cheating to illegal and that's ok. We need order. But there is nothing someone should feel guilt for imho, a…

I wasn't talking about law, I was talking about ethics. "There is nothing fundamentally universally wrong to cheat at an exam beside the fact you may be harming yourself." I don't understand that, I have no idea where you got that. Or what those words "fundamentally" and "universally" add. I say it's wrong, you say "Oh, but it's not fundamentally, universally wrong".. As if it's clear what that means. For example: Yo…

I guess you are right. It's ethically wrong but not morally wrong.

Re: Ask HN: What's the hardest problem you've ever solved?

#414

Earlier quoted context omitted.

I wasn't talking about law, I was talking about ethics. "There is nothing fundamentally universally wrong to cheat at an exam beside the fact you may be harming yourself." I don't understand that, I have no idea where you got that. Or what those words "fundamentally" and "universally" add. I say it's wrong, you say "Oh, but it's not fundamentally, universally wrong".. As if it's clear what that means. For example: Yo…

I guess you are right. It's ethically wrong but not morally wrong.

I guess you are right. It's ethically wrong but not morally wrong.

Huh? I don't see a significant difference between 'ethically wrong' and 'morally wrong', no idea why you would say that.

Re: Ask HN: What's the hardest problem you've ever solved?

#415
post #319

Earlier quoted context omitted.

I guess that trick would be harder to reproduce for my problem - bringing down compile times from 4 hours to 1 :)

In 4 hour duration, you can do some (or many) other thing. In 30 seconds, you can not, those 30 seconds are pure waste.

Yes, I procrastinate.

Re: Ask HN: What's the hardest problem you've ever solved?

#416
post #69

I started with the glimmer of a hope that perhaps network sync could be made stateless, went down a months-long rabbit-hole of research, and ended up writing a novella-length article about CRDTs: http://archagon.net/blog/2018/03/24/data-laced-with-history/ So many days spent thinking, sketching, trying to swallow a concept that seemed far to big for my jaws—only to suddenly find myself on the other side, with this ar…

Thank you for that article! I found it a few months ago, read it through the end, and shared it with my team. It's the best survey of synchronization techniques that I've come across.

That's awesome! Thank you for the kind words!

Re: Ask HN: What's the hardest problem you've ever solved?

#417

Earlier quoted context omitted.

Hey Yholio, don't even bother to explain to the nuts here, who are questioning your 'ethics'. They do not have a nuanced view of ethics. For them the rules, as laid out by the authorities (in your case the university) is the template of what is 'ethical', they are incapable of thinking beyond that. The frightening thing is that they unfortunately represents the vast majority of people.

Wow. How that comment hasn't been flagged yet I have no idea. People who don't agree with you are 'nuts', yet you have a nuanced view of ethics? That's the most condescending, deluded thing I've heard in years. "For them.." blah blah.. you don't know us; in my case at least, your assumptions couldn't be more wrong, but what do you know or care; you've decided who the in- and out- groups are here.

>How that comment hasn't been flagged yet I have no idea.

Because it appears not many people agree with you. Most likely they agree with me. Food for thought?

Re: Ask HN: What's the hardest problem you've ever solved?

#418
post #222

Probably one of my harder ones was finding a memory leak in one of my servers. Didn't happen often, never in development and only leaked a fraction of a byte per request. Turns out it was a bug in the logger, where if on rolling the log and it couldn't open a new file, the logger would just queue up messages. Was a real pain to track down as we normally had plenty of disk for logs.

out of curiosity, how do you leak a fraction of a byte

The fraction of a byte was amortorized over the number of requests (e.g. the mean bytes lost per total requests), which is what made it puzzling and hard to track down. It only happened under specific conditions that were not evident running under valgrind.

Re: Ask HN: What's the hardest problem you've ever solved?

#419

Years ago I wrote an emulator for the Intel 8086 processor in C++. It's deceivingly difficult because the instruction encoding is complex and the emulation of each instruction has to have a very high fidelity. In a sense, software at the CPU instruction level is a chaotic system, as each instruction can influence the system state to a critical degree, so if there is a slight deviation from the spec/hardware, a snowba…

Trying to do the same project but for MIPS architecture as a bachelor thesis project!

Re: Ask HN: What's the hardest problem you've ever solved?

#420

Earlier quoted context omitted.

Wow, that blows my mind. I don’t even know how to ask the right question, but is there some kind of “formal verification” or “type-checking” that could have caught this issue earlier? Or is that just too difficult, and reserved for medical equipment, nuclear reactors, etc.?

It was a problem with a clock domain crossing with IP from another company into ours. There were testbenches/simulations for verification, but they didn't test every packet size. In hindsight, everything can be caught, but it's a matter of how extensive the testing is. For example, passing every packet size through would not have showed the symptom. Everything looked normal, and all packets succeed. The key was that…

Thanks a lot for sharing this story! I started reading about clock domain crossing and metastability issues, and for the past few days I've been thinking a lot about circuit designs and FPGAs.

I posted on /r/FPGA on Reddit [1], and I asked about the best development board to start with. I was wondering if you had any thoughts on that? I think I'm going to order a snickerdoodle black [2] and a breakout board, and start learning VHDL or Verilog. I think it would be a lot of fun to eventually design my own soft-core processor and compile a Rust program that runs on it. And after reading about clock domain crossing issues, I think it would also be really interesting to experiment with asynchronous circuits and clock-less CPUs. Thanks for introducing me to this!

[1] https://www.reddit.com/r/FPGA/comments/9yutk8/best_100300_fp...

[2] https://www.crowdsupply.com/krtkl/snickerdoodle

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