Oh, you're the author! I didn't notice and sent you an email, but will repost here:
$ for i in 3 4 5; do f=puzzle.$i; echo $f: $(head -1 $f | wc -c); tail -$((i-1)) $f; ./$f; done
puzzle.3: 1
futz
futz
./puzzle.3: line 3: futz: command not found
puzzle.4: 1
futz
futz
futz
./puzzle.4: line 4: futz: command not found
puzzle.5: 1
futz
futz
futz
futz
./puzzle.5: line 5: futz: command not found
Whereas, formal verification only catches what properties one correctly specifies in what portions of the program one correctly specifies. In many, there's a gap between these and correctness of the real-world code. Some projects closed that gap but most won't.
In most domains you're always going to have the possibility of a gap.
The real thing though, is that if you have a verified formal model and a buggy implementation, then _you know_ your problem is at that model <-> implementation level.
Could be the implementation is wrong. Could be that the "bug" is in fact not a bug according to your model. But your model isn't "wrong". If your model says that A happens in condition B, then that is what should happen!
You can avoid second guessing a lot of design patterns with models, and focus on this transitional layer.
If someone came up to you and said "I built a calculator and with this calculator 1/0 becomes 0" you don't say "oh... maybe my model of division is wrong". You think the calculator is wrong in one way or another.
Maybe the calculator's universe is consistent in some way but in that case its model is likely not the same model of division you're thinking of. This eliminates entire classes of doubt.
I've heard that called "validation". In other words, you verify that your solution meets the problem specification, but you validate that your specification is actually what you need.
That talks about the mechanics of visual perception. I'm discussing qualia, which I am far more confident crows share with me than does the particular subtype of Hacker News commenter who will with tiresome predictability and total lack of novelty turn up to press the footless insistence that crows could never.
Our flicker fusion rate is different for the fovea and nearby central vision vs the peripheral vision.
The central vision is slower-response, higher-resolution, and of course color vision.
The peripheral vision is monochrome and has a much faster flicker-fusion, tuned to picking up motion in the periphery.
So, the same flicker rate that you never notice on a small monitor may flicker annoyingly on a large monitor. To check that a setup will not flicker for you, set it up in a darkish room, focus around 70°-100° to one side of the monitor so it is in your peripheral vision, and both look at one place and notice your periphery, and also move your focus quickly from one place to another and notice if the screen blurs like bright stationary objects or looks like a discontinuous blur (really easy to get that effect with fluorescent lights). Do it both left & right and towards the ceiling. If flicker shows up in these tests, it will still eventually bug you when looking directly at the screen, even if it isn't as noticeable because your focus is in the center of your vision.
No. Flicker fusion only happens when the same image is shown at the same position.
Something like a moving mouse cursor shows the same image at different positions. As an experiment, create a fullscreen image with the opposite color of your mouse cursor. Look at a fixed spot of this image, then rapidly move your mouse cursor across it. Rather than a moving image, you will see a bunch of copies of the cursor at fixed positions.
Similarly, track a rapidly moving cursor with your eyes. It will appear blurry, even though your eyes have no trouble sharply seeing an object moving at that speed in the natural world.
You can also try flashing an image for a very short amount of time. You'll be able to see and remember its content, even when it is being displayed for a period far shorter than flicker fusion would suggest you'd be able to see.
Just do a basic double blind test. get someone else to switch the hz a couple of times for you, and see if you can tell the difference. i would be surprised if you got anything less than a 100% success rate.
They have a much stronger sense of propriety than most humans. So really do most animals other than us and perhaps some close relatives. I'm not actually sure that says anything in our favor.
Yeah, I saw that... not quite the same... I used it for a bit but it's more like an agent that clings to a Github repo and deals with tickets up there, can't really test live on local, it just serves a different purpose.
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