Pfhorrest wrote:I fail to see what moral dilemmas like the Trolley Problem have to do with speculative execution.

Me too.

- Fri Jan 05, 2018 7:51 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1938: "Meltdown and Spectre"
- Replies:
**36** - Views:
**8181**

Pfhorrest wrote:I fail to see what moral dilemmas like the Trolley Problem have to do with speculative execution.

Me too.

- Wed Aug 24, 2016 9:59 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1723: "Meteorite Identification"
- Replies:
**30** - Views:
**9394**

My interpretation:

Caesar: Thing?

Rombobjörn: Thign.

Caesar: Not Thign.

Copper Bezel: No, Thing.

Caesar: Thing != Thign.

But I should probably stop. This is fruitless and we probably all mean the same thing.

Caesar: Thing?

Rombobjörn: Thign.

Caesar: Not Thign.

Copper Bezel: No, Thing.

Caesar: Thing != Thign.

But I should probably stop. This is fruitless and we probably all mean the same thing.

- Wed Aug 24, 2016 4:26 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1723: "Meteorite Identification"
- Replies:
**30** - Views:
**9394**

No, that's right. It's snidely making the assumption that if you got that far, the only reason left you might have been looking at this flowchart in the first place is that "someone saw it fall", and this is a silly reason. The important point is that the "No" arrow is not neces...

- Wed Aug 24, 2016 1:09 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1723: "Meteorite Identification"
- Replies:
**30** - Views:
**9394**

The "Did someone see it fall?" box doesn't have a "No" exit. Took me a while to figure that one out. It means that, if no one had seen it fall, they would have never thought it were a meteorite to begin with. Right? It means that if you arrive to that box, then it's already clea...

- Mon Aug 22, 2016 2:41 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1723: "Meteorite Identification"
- Replies:
**30** - Views:
**9394**

The "Did someone see it fall?" box doesn't have a "No" exit. Took me a while to figure that one out. It means that, if no one had seen it fall, they would have never thought it were a meteorite to begin with. Right?

- Mon Apr 18, 2016 3:33 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1669: Planespotting
- Replies:
**51** - Views:
**12325**

Ehm, shouldn't it be "...one of those people who know..."? I think that the comic's construction is correct. The verb "knows" is being applied to the singular "one." I'm one who knows... But then again, I've always assumed I'm one of those people who knows a lot about ...

- Mon Apr 18, 2016 3:07 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1669: Planespotting
- Replies:
**51** - Views:
**12325**

Ehm, shouldn't it be "...one of those people who know..."?

- Wed Feb 10, 2016 9:19 am UTC
- Forum: What If?
- Topic: What-If 0145: "Fire From Moonlight"
- Replies:
**157** - Views:
**72665**

A lens that spreads out parallel light seems to violate conservation of étendue. For the input, area times angle is 0 since the angle is 0. But the output is not zero.

- Mon Jan 04, 2016 3:02 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1625: Substitutions 2
- Replies:
**33** - Views:
**9952**

"Uncontrollably swerving cars cause fewer accidents than human drivers." Still sounds plausible.

No indication -> lots of signs is not a good substitution because it doesn't work grammatically. "There is lots of signs that..."

No indication -> lots of signs is not a good substitution because it doesn't work grammatically. "There is lots of signs that..."

- Tue Oct 20, 2015 11:13 pm UTC
- Forum: Mathematics
- Topic: Convergence of sets in a geometrical sense
- Replies:
**27** - Views:
**4997**

Why do you want a shrinking set of circles to converge to the point in the center, but don't want the rationals to converge to the reals? They both seem to stem from the same intuition: Points in the sequence of sets converge to points in the "limit" set. Would you want the sequence of si...

- Fri Oct 16, 2015 11:32 pm UTC
- Forum: Mathematics
- Topic: Convergence of sets in a geometrical sense
- Replies:
**27** - Views:
**4997**

I'm surprised no one has mentioned Hausdorff distance yet: https://en.wikipedia.org/wiki/Hausdorff_distance Caesar, I'm pretty sure your definition can be defined in terms of the Hausdorff distance. If the sets are all bounded, I think your limit is just the limit of their closures under the Hausdo...

- Wed Oct 07, 2015 5:02 pm UTC
- Forum: Mathematics
- Topic: Convergence of sets in a geometrical sense
- Replies:
**27** - Views:
**4997**

I think I would rather sacrifice telling open and closed sets apart. The behavior is more predictable and it has answers in some cases where the set doesn't HAVE an Euler characteristic.

That being said, I haven't given up coming up with an improved definition just yet.

That being said, I haven't given up coming up with an improved definition just yet.

- Wed Sep 30, 2015 10:02 pm UTC
- Forum: Mathematics
- Topic: Convergence of sets in a geometrical sense
- Replies:
**27** - Views:
**4997**

doogly wrote:What converging sequences are these? This seems odd.

The sequence for the shrinking ring/sphere would be the sequence of set of points whose distance to the center equals 1/n (or any function that converges towards 0).

- Wed Sep 30, 2015 9:56 pm UTC
- Forum: Coding
- Topic: Please help me on a design decision on immutability
- Replies:
**10** - Views:
**5154**

The operation of scaling a circle should never turn it into an ellipse. Scaling something is a changes is's size without modifying it's aspects. All circles are ellipses, but not all ellipses are circles. There is no need to implement a special class for circles, an ellipse constructor which genera...

- Wed Sep 30, 2015 2:40 pm UTC
- Forum: Mathematics
- Topic: Convergence of sets in a geometrical sense
- Replies:
**27** - Views:
**4997**

It finally clicked for me what Euler characteristics are. I think. It would have been helpful if the Wikipedia article for CW-complexes included a single example on what it IS the article is ABOUT. But I digress... I'm not too happy with one of the properties of using the Euler characteristic of the...

- Wed Sep 30, 2015 10:59 am UTC
- Forum: Coding
- Topic: Please help me on a design decision on immutability
- Replies:
**10** - Views:
**5154**

Thanks for all your replies. I'm gonna abuse the thread to ask a different question about my geometry library. Mathematically, my shapes are defined as sets of points in the 2D-plane. For example, a circle which center lies on (0,0) and which radius 1 is simply the set of points whose euclidean dist...

- Fri Sep 25, 2015 12:53 am UTC
- Forum: Mathematics
- Topic: Convergence of sets in a geometrical sense
- Replies:
**27** - Views:
**4997**

I see. Sorry to bother you but what would the Euler characteristic be in case of the graph of the Dirichlet function? (Equal to one for rational numbers and 0 for irrational numbers.) Can it give a good answer even for weird sets like that?

- Thu Sep 24, 2015 9:25 pm UTC
- Forum: Mathematics
- Topic: Convergence of sets in a geometrical sense
- Replies:
**27** - Views:
**4997**

I read it up a bit but I don't understand Euler characteristic yet. But Intuitively, I think using neighborhoods could be problematic. E.g. consider the set of points that form the graph sin(x)^n. The limit of the set would be discontinuous which would affect the properties of the neighborhoods, no...

- Thu Sep 24, 2015 7:11 pm UTC
- Forum: Mathematics
- Topic: Convergence of sets in a geometrical sense
- Replies:
**27** - Views:
**4997**

Thanks for the replies. I gave some thought to this a while back, while trying to develop a variant of measure theory with hyperreal numbers. The basic idea I came up with is that a sequence of sets An converges to a limit set B if, in the neighborhood of points in B, the local Euler characteristic ...

- Thu Sep 24, 2015 12:52 pm UTC
- Forum: Mathematics
- Topic: Convergence of sets in a geometrical sense
- Replies:
**27** - Views:
**4997**

I was thinking about how to define the limit of a sequence of sets of coordinates. I'm not sure about notation, so I will make up one: 'An' denotes a sequence, 'A[n]' denotes the nth element of the sequence. On the internet I read a sequence of sets converges to A if the superior limit and the infer...

- Wed Sep 16, 2015 1:53 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1578: Squirrelphone
- Replies:
**38** - Views:
**9028**

I have no earthly idea what this comic, or the title text for that matter, is about.

- Thu Sep 10, 2015 10:12 pm UTC
- Forum: Coding
- Topic: Please help me on a design decision on immutability
- Replies:
**10** - Views:
**5154**

So there is not much performance benefit if I make them explicitly immutable. But I think it would be a good tool for the programmer anyway. Right now, I try to make them immutable but I could have made mistakes. It would be nice if I would get a compile time error if I ever screw something up. For ...

- Thu Sep 10, 2015 9:17 pm UTC
- Forum: Coding
- Topic: Please help me on a design decision on immutability
- Replies:
**10** - Views:
**5154**

No, I haven't measured anything. It's just armchair philosophy.

I don't know how to tag the classes as immutable for the compiler. As far as I know that's not possible in C#. I can make the fields read-only, but that's not quite the same.

I don't know how to tag the classes as immutable for the compiler. As far as I know that's not possible in C#. I can make the fields read-only, but that's not quite the same.

- Thu Sep 10, 2015 1:25 pm UTC
- Forum: Coding
- Topic: Please help me on a design decision on immutability
- Replies:
**10** - Views:
**5154**

I'd like to have some advice on a software design decision. I have been writing a geometry library, without knowing much about programming and without supervision of any kind. It has been a good learning experience but I am unsure about the best way to do things. It's written in C#. Currently, in my...

- Wed Sep 02, 2015 9:17 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1572: "xkcd Survey"
- Replies:
**366** - Views:
**126054**

Man, I should have written that I had trouble spelling the word "cat" and then type "cet" in the form that asks you to type it. Way funnier than what I did.

- Fri Mar 20, 2015 9:51 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1501: Mysteries
- Replies:
**94** - Views:
**25509**

niauropsaka wrote:The Voynich Manuscript is in the lower left quadrant? Clearly neither of the middle lines is zero, because that is definitely >0 weird and >0 unclear.

And what, exactly, does 0 weirdness or 0 clarity mean?

- Wed Feb 25, 2015 9:57 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1491: "Stories of the Past and Future"
- Replies:
**99** - Views:
**33550**

I don't understand this chart. What are the diagonal lines? The upper one could mean "these are stories that are set in 2015" and the lower one could mean "these are stories that are set in the time they were written", depending on whether the y axis mean "x years into the p...

- Fri Nov 21, 2014 5:17 pm UTC
- Forum: Mathematics
- Topic: The golden menhir on the mysterious plain
- Replies:
**16** - Views:
**5945**

Now this thread is kinda old and I know next to nothing about manifolds... but I noticed that you treated the character in the plane basically as a point. But when our character, who is in fact a volume, passes a curved "boundary" I think it would do weird things to him. Take the euclidean...

- Thu Oct 16, 2014 1:16 pm UTC
- Forum: What If?
- Topic: What-If 0116: "No-Rules NASCAR"
- Replies:
**60** - Views:
**20392**

In a "No Rules NASCAR", the speed of your vehicle wouldn't really matter. I would send a tank and shoot the other drivers.

With blue shells.

With blue shells.

- Wed Aug 27, 2014 6:54 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1413: "Suddenly Popular"
- Replies:
**91** - Views:
**22019**

- Wed Jul 03, 2013 4:32 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1233: "Relativity"
- Replies:
**46** - Views:
**18966**

I'm german and I have no idea what Randall meant with "Gedankedank". "Gedanke" means "thought". "Dank" means "gratitude". So "thoughtgratitude"? Maybe he meant "Gedankengang" (train of thought)? But that still wouldn't be funny , ...

- Sat Dec 22, 2012 11:32 am UTC
- Forum: Computer Science
- Topic: How do I compute this number sequence?
- Replies:
**10** - Views:
**7535**

mr-mitch wrote:For size 3, we loop over all the numbers of size 1, and combine them with the elements of size 3-1 = 2 (and also take care of commutativity).

That doesn't work because you will never find a solution like (a+c)*(b+d). Unless I missunderstood you.

- Wed Dec 19, 2012 9:15 pm UTC
- Forum: Computer Science
- Topic: How do I compute this number sequence?
- Replies:
**10** - Views:
**7535**

The RPN is a good suggestion, I didn't know about that. Now, the tricky bit is that you at all times need to check the top of the stack if you have come upon the number, and there are N! permutations of N numbers, along with 2^(N-1) strings of two symbols + and *, so you get O(N! + 2^N + N) as a wor...

- Mon Dec 17, 2012 11:26 pm UTC
- Forum: Computer Science
- Topic: How do I compute this number sequence?
- Replies:
**10** - Views:
**7535**

I had an idea for an interesting number sequence. It works like this: the next term in the sequence is the smallest integer that you cannot build by combining the previuous terms by addition, substraction or multiplication. No number can be used more than once. Let me explain by example: The first f...

- Sun Aug 26, 2012 7:40 pm UTC
- Forum: Coding
- Topic: Efficient calculation of gravity between many objects.
- Replies:
**6** - Views:
**3289**

Awesome answer, Sagekilla.

I read into all the links you posted. The Fast Multipole Method does indeed sound pretty advanced, the Barnes-Hut Method should do fine.

I read into all the links you posted. The Fast Multipole Method does indeed sound pretty advanced, the Barnes-Hut Method should do fine.

- Sun Aug 26, 2012 4:35 pm UTC
- Forum: Coding
- Topic: Efficient calculation of gravity between many objects.
- Replies:
**6** - Views:
**3289**

I think a common way to do this is with some spatial decomposition of the objects in your scene, for instance an octtree. I think roughly speaking, what goes on is that you will compute things like the center of groups of objects then approximate the net effect of that group by the effect of the ce...

- Sat Aug 25, 2012 9:00 pm UTC
- Forum: Coding
- Topic: Efficient calculation of gravity between many objects.
- Replies:
**6** - Views:
**3289**

I have a large number of objects that attract each other (i.e. masses with gravity). The brute force method to compute the force at each update is very costly when there are to many objects. If Newtons second law is in effect (actio = reactio), then I can cut down the costs in half because the attra...

- Wed Jun 27, 2012 10:32 am UTC
- Forum: Mathematics
- Topic: Making the most out of a djinn's offer
- Replies:
**14** - Views:
**3236**

I like how you guys discuss the real world implications of such a trade. When I posed the question, with "money", I meant something that you can never have enough of and never significantly loses value. Obviously, money doesn't fit these requirements. I used it anyway because everyone asso...

- Fri Jun 22, 2012 3:23 pm UTC
- Forum: Mathematics
- Topic: Making the most out of a djinn's offer
- Replies:
**14** - Views:
**3236**

Let's say a djinn offers to give you (one time only) as much money as you want. How much is this offer worth? It's worth more than any amount of money but not infinitely much, because you can ask only for a finite amount of money. Or is it? Trying to be clever I tried this approach: You flip a coin ...

- Thu Nov 11, 2010 11:05 pm UTC
- Forum: Logic Puzzles
- Topic: What will the next line be?
- Replies:
**2** - Views:
**1445**

You know the drill. Figure out the rule of this series of numbers.

1

11

21

1211

111221

312211

What's the next number?

1

11

21

1211

111221

312211

What's the next number?