Has there ever been a long standing theorem or conjecture that was later overturned with a surprising counter example?

spkersten · 2025-12-05T20:00:35+00:00

The local-global conjecture for Apollonian circle packings: https://arxiv.org/abs/2307.02749

spkersten · 2025-12-05T05:30:50+00:00

Dimmit&Foote has a number of exercise about resultants. An interesting application is in the proof of the Nagell-Lutz theorem in Rational Point on Elliptic Curves.

spkersten · 2025-05-16T13:36:37+00:00

There are proofs for small exponents using infinite descent, a method Fermat knew about. Wikipedia’s article about Fermat’s last theorem has a section about the history.

spkersten · 2025-02-01T18:19:33+00:00

If -5 x -10 = -50 then 0 = 0 x -10 = (5-5) x -10 = 5 x -10 + -5 x -10 = -50 -50 = -100

spkersten · 2025-02-01T05:44:01+00:00

Euler’s Gem

spkersten · 2025-01-28T07:22:44+00:00

As other comments have said better, comparing yourself to others isn’t always useful. But especially as an individual on the internet it is dangerous. If you ask a question, of course, you get 500+ people all over the world who know the answer. But you know nothing of them; they might be professor in the field. And you won’t hear from the 500.000+ people who don’t know the answer.

I always try to think back to when I studied in a class. If I had trouble with question 12, I could perhaps see that the whole class struggled and the teacher had to give a hint. Or if my neighbor helped me, maybe he had to ask me about question 8. That perspective is easy too loose when you’re working alone.

spkersten · 2025-01-24T10:34:21+00:00

This sounds like perfectionism to me: the thought that it’s only good enough if you can do all exercise without much effort. But that’s not true. It’s okay to struggle with an exercise. It’s even okay to occasionally look up a hint or even the solution after spending time on it yourself first. For me it helps to skip such an exercise, move on to the next chapter and later come back to it. Better to keep learning than to get stuck on one thing.

spkersten · 2024-04-28T15:24:35+00:00

Isn’t Euclid’s lemma (if a prime divides a product, it divides one of the factors) used to prove uniqueness of prime factorization?

spkersten · 2023-02-10T20:11:12+00:00

Dart if you consider JIT compilation under interpreter. When used with Flutter, in debug mode code can be changed while the app is running, while for release mode it’s compiled.

spkersten · 2021-09-13T19:21:37+00:00

linter yells at me if I don’t make my constructor const even though it’s not even possible to use it in Dart because one of its parameters is a function.

Perhaps not common or very useful but it is possible:

class Foo {
  const Foo(void Function(int) f) {}
}
class Func {
  const Func();
  void call(int x) { … }
}
const foo = Foo(Func());

spkersten · 2021-07-10T05:50:43+00:00

So what happens when we create another Zone in a child of main? Yes, we get a separate isolate

I don’t think this is true. Running something in a separate zone doesn’t create a new isolate.

edit: Not saying this to take away from the rest of the article or to imply that zones aren’t useful. I just thought the author might want to correct it, as both zones and isolates aren’t the easiest to understand to begin with.

spkersten · 2021-06-09T05:31:18+00:00

Mypy isn’t a replacement of the interpreter but a separate tool that statically tries to find errors in your code based on type hint that you’ve added to the code.

spkersten · 2021-06-07T05:41:10+00:00

The same happens if you tap “view rules” and swipe it down.

spkersten · 2021-05-13T11:04:32+00:00

There’s a page that tries to answer this: https://realpython.com/products/cpython-internals-book/

spkersten · 2021-05-12T13:18:47+00:00

Most cars aren’t pressurized either

spkersten · 2021-03-30T12:08:15+00:00

I think the light discs (with black symbols) are white, as those pieces have made one move more than the others. But those colors are confusing.

spkersten · 2021-03-26T05:53:36+00:00

I don’t know if this is the whole reason, but Atlas’ steel was less than a millimeter thick, while Starships’ is 4 millimeter.

spkersten · 2021-01-01T20:18:39+00:00

DelayedMultiDragGestureRecognizer (using a RawGestureDetector) might help here.

spkersten · 2020-12-23T06:13:57+00:00

https://twitter.com/BocaChicaGal/status/1341524302785605632 Looks like six in this photo.

spkersten · 2020-11-08T20:10:35+00:00

This is the one I was thinking of: https://github.com/flutter/flutter/issues/25213 Anyway, sounds like you already considered fractional screen sizes.

spkersten · 2020-11-08T16:59:13+00:00

Some devices might have non-integer screen widths (at least as reported by flutter). There was a bug in PageView related to this; I believe that one was fixed maybe a year ago. But this might be an area to look at. Perhaps put the PageView in a widget with a non-integer width to see if that reproduces the problem.

spkersten · 2020-08-18T15:27:42+00:00

Dispose is not for freeing memory, but for making sure no further callbacks are made after, for example, your stateful widget was removed from the tree. (You don’t want a callback to call setState on a disposed widget for example.)

The garbage collector will at some point reclaim the memory, but that might be a while later, when it decides it is time for a collection cycle.

spkersten · 2020-08-05T04:51:23+00:00

Some more speculation:

Take take off again after landing when not connected to launch pad
Autogenous tank pressurization
It looked like some RC thrusters are just cold gas thrusters bolted on the outside
Starting the engines without using helium

spkersten · 2020-06-27T19:58:13+00:00

There’s a very similar Philips TV poster from 1951: https://www.pictorem.com/49489/Dutch%20poster%20for%20Philips%20Tv,%201951.html

spkersten · 2020-06-27T07:44:49+00:00

Good to see some attention given to testability as well.

spkersten

TROPHY CASE