## Search found 88 matches

- Mon Nov 08, 2010 2:05 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0816: "Applied Math"
- Replies:
**88** - Views:
**28563**

### Re: 0816: Applied Math

Of course, hasn't it been proven that such a proof is impossible? Assume such a proof exists. Then P and not P. Contradiction. Therefore, no such proof exists. It happens that "P is provable; therefore, P is true" is not valid mathematical reasoning. In fact, adding this as an axiom to ou...

- Tue May 11, 2010 8:41 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0738: "Incision"
- Replies:
**42** - Views:
**16476**

### Re: "Incision" Discussion

Magnanimous wrote:Wikipedia's already been edited to reflect this. Dear god, guys.

Permalink, please. Wikipedia as it was this morning

- Sat Feb 27, 2010 11:31 pm UTC
- Forum: The Help Desk
- Topic: Making Debian use an entire /48 block of 6to4 addresses
- Replies:
**3** - Views:
**1194**

### Making Debian use an entire /48 block of 6to4 addresses

So, I've set up 6to4 under Debian; using my existing static IPv4 address, I have successfully procured a single IPv6 address. I don't want just the one IPv6 address, though. 6to4 theoretically gives access to an entire /48 block of IPv6 addresses, and I'd like to be able to utilize those. Here's a p...

- Sun Jan 31, 2010 6:55 am UTC
- Forum: Science
- Topic: Rolling to the top of a hill
- Replies:
**30** - Views:
**3742**

### Rolling to the top of a hill

Suppose I have a ball on a hill. The ball is rolling directly up toward the top of the hill, such that its total energy is equal to what it would be if it were at rest at the top of the hill. So, it has enough energy to get to the top, but does it actually do so in a finite amount of time? Does it t...

- Thu Jan 14, 2010 2:01 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0688: "Self-Description"
- Replies:
**200** - Views:
**104130**

### Re: "Self-Description" Discussion

Dude, guys. Suppose you had to solve the following system of linear equations: x = 0.2x + 0.3y + 0.4z + 5 y = 0.1x + 0.2y + 0.6z + 13 z = 0.4x + 0.1y + 0.1z + 4 Would you pick arbitrary values for x, y, and z, and then repeatedly apply all three equations as if they were assignments, and try to dete...

- Sun Jan 03, 2010 11:46 pm UTC
- Forum: School
- Topic: Subjects you wish you were good at?
- Replies:
**87** - Views:
**11297**

### Re: Subjects you wish you were good at?

Now, what the heck does it mean to be "bad at music"? Are you bad at reading it? Playing it? Remembering it? Hearing it? Understanding it? Writing it? Arranging it? Conducting it? All of the above? Only one of the above? It's like saying that you're "bad at snow". As for subjects...

- Sun Jan 03, 2010 5:08 am UTC
- Forum: Language/Linguistics
- Topic: Handwriting
- Replies:
**58** - Views:
**11051**

### Re: Handwriting

By far the most interesting handwriting I've ever seen was my high school English teacher's. His capital letter Y looked like a football goal post with a loop on every corner and a couple of extra lines sticking out of the middle for good measure, to say nothing of his other letters. Receiving our g...

- Mon Mar 09, 2009 1:32 am UTC
- Forum: Mathematics
- Topic: Bot Modeling Algorithm
- Replies:
**4** - Views:
**699**

### Re: Bot Modeling Algorithm

double midangle = wheel1Speed / 360.0; Point2D mid = wheel2; if (wheel1Speed != 0) { wheel1.x = mid.x + radius * Math.cos(midangle); wheel1.y = mid.y + radius * Math.sin(midangle); } You seem to be completely ignoring the position of wheel1 here. The thing about wheels in the real world is that the...

- Sat Mar 07, 2009 8:21 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0552: "Correlation"
- Replies:
**154** - Views:
**52132**

### Re: "Correlation" Discussion

Definition 1: "P is evidence for Q" means P(Q | P) > P(Q). Assumption 2: Causation is evidence for correlation. Theorem G given Definition 1 and Assumption 2: If P(correlation) and P(causation) are nonzero, then correlation is evidence for causation. A: Start with Bayes' Theorem: P(A)P(B |...

- Fri Nov 21, 2008 2:17 am UTC
- Forum: Mathematics
- Topic: Plane defined by two points
- Replies:
**6** - Views:
**1304**

### Re: Plane defined by two points

you have two points, lets call them a: (xa, ya, za) and b: (xb, yb, zb)...so original... define a plane that contains a and is 5 units away from b. in other words a line segment perpendicular to the plane from the plane to b would be 5 units long. That doesn't define a plane; there will usually be ...

- Thu Nov 20, 2008 1:34 am UTC
- Forum: Computer Science
- Topic: Do computers hold the power to change the world?
- Replies:
**8** - Views:
**2210**

### Re: Do computers hold the power to change the world?

Initially, computers followed instructions: you would write a computer program (e.g. "find a prime number greater than 18 using algorithm . . .), and they would run it. Nowadays, computers can do more than that: you can merely specify the results of the computer program (e.g. "a prime numb...

- Thu Nov 20, 2008 1:05 am UTC
- Forum: Mathematics
- Topic: Are there sets in ZFC that don't belong to any definable set
- Replies:
**30** - Views:
**2338**

### Re: Are there sets in ZFC that don't belong to any definable set

Of course. Consider just subsets of the natural numbers. There are only a countable number of predicates we can write down, but we know that there are an uncountable infinity of subsets of the natural numbers. But you can't come up with one subset of the natural numbers that isn't in the definable ...

- Thu Nov 20, 2008 12:55 am UTC
- Forum: Mathematics
- Topic: Are there sets in ZFC that don't belong to any definable set
- Replies:
**30** - Views:
**2338**

### Are there sets in ZFC that don't belong to any definable set

I asked the question once and managed to be misunderstood. When I say "definable", I mean definable with no arguments. In other words, "X, where X is the set in question" is not a satisfactory definition. Then a definable set, I suppose, is one defined by some predicate that can ...

- Tue Nov 18, 2008 12:03 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0504: "Legal Hacks"
- Replies:
**186** - Views:
**36180**

### Re: "Legal Hacks" Discussion

...Libertarian... Sorry. Greed is not a philosophy. Libertarians are the only political group does not want to take money from other people to spent on their own goals. How on earth does that equate to greed? It's in fact the opposite of greed! Are you seriously claiming that you are greedy if you ...

- Sat Nov 15, 2008 5:43 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0504: "Legal Hacks"
- Replies:
**186** - Views:
**36180**

### Re: "Legal Hacks" Discussion

...Libertarian... Sorry. Greed is not a philosophy. Libertarians are nothing but amoralistic economic anarchists. Nothing will lead to the demise of any given society faster than giving these YOYO barbarians what they want. So what do libertarians support that you don't? I'd imagine they prefer the...

- Fri Nov 14, 2008 10:06 pm UTC
- Forum: Mathematics
- Topic: Quick question on basic topology
- Replies:
**18** - Views:
**2338**

### Re: Quick question on basic topology

There's probably some really clever way of doing it with a nice formula How about = 1/(y - x)? ...well, if that isn't the most unusual equation I've ever seen. I meant y = 1/(y - x). I see now, though, that that isn't much of a bijection: 1/y = y - x y - 1/y = x y^2 - xy - 1 = 0 y = (x + sqrt(x^2 +...

- Fri Nov 14, 2008 10:00 pm UTC
- Forum: Mathematics
- Topic: Mathematics science fair (non-10 bases)
- Replies:
**16** - Views:
**1915**

### Re: Mathematics science fair (non-10 bases)

Something I find interesting, is that all primes greater than six will have a remainder of 1 or 5 when divided by six. Thus except for 2 and 3, all primes will have a base 6 representation with a 1 or 5 in the ones place. All primes except 2 and 3 have a remainder of 1 or 5 when divided by 6. All p...

- Fri Nov 14, 2008 9:37 pm UTC
- Forum: Mathematics
- Topic: Quick question on basic topology
- Replies:
**18** - Views:
**2338**

### Re: Quick question on basic topology

skeptical scientist wrote:There's probably some really clever way of doing it with a nice formula

How about = 1/(y - x)?

- Fri Nov 14, 2008 9:29 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0504: "Legal Hacks"
- Replies:
**186** - Views:
**36180**

### Re: "Legal Hacks" Discussion

Natural rights do not exist unless we have some way of determining what they are. As far as I can tell, we have no way of determining what they are.

- Tue Dec 18, 2007 2:08 am UTC
- Forum: Mathematics
- Topic: Does it really qualify as math?
- Replies:
**17** - Views:
**2846**

### Re: Does it really qualify as math?

Math has three major parts (kind of): using methods to find answers, using rules to prove methods, and deciding what rules to use in the first place. This is the third part, and it's definitely useful, though perhaps not quite as useful as the other ones--then again, that last part is also a huge ch...

- Fri Sep 28, 2007 11:53 pm UTC
- Forum: News & Articles
- Topic: Do you qualify to be an American citizen?
- Replies:
**105** - Views:
**9880**

### Re: Do you qualify to be an American citizen?

Solt wrote:High school until age 16 is mandatory by law -> US History a mandatory course -> Everyone learns this. Whether they remember it or not is a different issue.

Mandatory in the entire United States? Surely that's a state thing.

- Sat Sep 15, 2007 4:33 am UTC
- Forum: Language/Linguistics
- Topic: Words that are fun to mispronounce
- Replies:
**169** - Views:
**27610**

### Re: Words that are fun to mispronounce

Pesto wrote:queue - I like to pronounce it kway-way

Any good Spanish speaker knows it's kay-way. If you like the pronunciation "queue" already has, you call it a quiu.

- Sat Sep 15, 2007 4:05 am UTC
- Forum: Forum Games
- Topic: 'The Exquisite Corpse, or "Eat Poop, You Cat" '
- Replies:
**9** - Views:
**3847**

### 001

Not sure how this picture linking is supposed to work, exactly. I think this should do it.

http://urlx.org/6a0d5

http://urlx.org/6a0d5

- Sat Sep 15, 2007 2:14 am UTC
- Forum: Logic Puzzles
- Topic: Paradox
- Replies:
**40** - Views:
**7535**

### Re: Paradox

Ansain wrote:"How can you answer this question and live, if the penalty for answering correctly is death?"

By answering incorrectly. Simple, really.

- Fri Aug 24, 2007 10:04 pm UTC
- Forum: Coding
- Topic: Coding a hex grid?
- Replies:
**19** - Views:
**11037**

- Fri Aug 24, 2007 9:24 pm UTC
- Forum: Forum Games
- Topic: Reality
- Replies:
**138** - Views:
**12773**

- Fri Aug 24, 2007 7:42 pm UTC
- Forum: Coding
- Topic: Coding a hex grid?
- Replies:
**19** - Views:
**11037**

Yeah, I'd say to avoid the pointers unless the time taken to compute them is worth more than the space taken to store them. The time taken to compute them is minuscule: you're just adding a couple of things, with maybe a modulo-2 in there somewhere. Taking something modulo 2 is probably much faster ...

- Fri Aug 24, 2007 7:22 pm UTC
- Forum: Coding
- Topic: Memory Leak
- Replies:
**5** - Views:
**2501**

- Tue Aug 21, 2007 11:25 pm UTC
- Forum: Logic Puzzles
- Topic: The El Farol bar problem [solution discussion]
- Replies:
**43** - Views:
**9589**

Yes, I did try to set the question up such that the strategy had to be a probability, which everyone would use to determine whether or not to go. 27b/6, skeptical scientist and Cosmologicon get cookies (the tasty kind), assuming they didn't make any mistakes. The exact answer is apparently an algebr...

- Tue Aug 21, 2007 7:50 pm UTC
- Forum: Logic Puzzles
- Topic: The El Farol bar problem [solution discussion]
- Replies:
**43** - Views:
**9589**

- Tue Aug 21, 2007 7:31 pm UTC
- Forum: Mathematics
- Topic: Other kinds of math
- Replies:
**17** - Views:
**3570**

- Tue Aug 21, 2007 7:14 pm UTC
- Forum: Logic Puzzles
- Topic: The El Farol bar problem [solution discussion]
- Replies:
**43** - Views:
**9589**

- Tue Aug 21, 2007 7:00 pm UTC
- Forum: Logic Puzzles
- Topic: The El Farol bar problem [solution discussion]
- Replies:
**43** - Views:
**9589**

- Tue Aug 21, 2007 6:59 pm UTC
- Forum: Logic Puzzles
- Topic: The El Farol bar problem
- Replies:
**11** - Views:
**5289**

### The El Farol bar problem

There is a very small town containing exactly 21 identical people. One night, everybody is bored, so each one decides whether or not to go to the bar. If 12 people or less go to the bar, they all have fun and gain 1 point. If 13 people or more go to the bar, none of them have fun and they lose 1 poi...

- Sun Aug 19, 2007 9:30 pm UTC
- Forum: Coding
- Topic: Most useful languages
- Replies:
**26** - Views:
**4905**

### Re: fortran, matlab, python with scipy and numpy

taggedunion wrote:map and filter are defined as LCs in the Prelude

I thought it was the other way around--list comprehensions were automatically turned into map and filter, which were in turn defined using the usual pattern matching and such.

- Sun Aug 19, 2007 9:18 pm UTC
- Forum: Computer Science
- Topic: Stupid NP problems
- Replies:
**38** - Views:
**9143**

- Sun Aug 19, 2007 9:02 pm UTC
- Forum: Mathematics
- Topic: Extending Complex Numbers
- Replies:
**38** - Views:
**6828**

(a, b) * (c, d) = (a*c - d*b', a'*d + c*b) (a, b)' = (a', -b) If a and b are real numbers (x' = x in the real numbers), (a, b) is a complex number. If a and b are complex numbers, (a, b) is a quaternion. If a and b are quaternions, (a, b) is an octonion. If a and b are octonions, (a, b) is a sedenio...

- Sat Aug 18, 2007 3:28 am UTC
- Forum: Coding
- Topic: Where do I go now?
- Replies:
**17** - Views:
**3327**

To the language list I would add prototype-based languages like ECMA Script (pre-version 4 -- JavaScript 1 being an implementation) or Lua. Lua's probably a better choice since it's not bound to a browser. Oh, and Self, of course. :) Hmm, yes, maybe. Think I could take out Python and Java and add i...

- Sat Aug 18, 2007 3:21 am UTC
- Forum: Coding
- Topic: Best language ever!!!11
- Replies:
**35** - Views:
**10215**

http://esoteric.voxelperfect.net/wiki/ I love/hate (that is, have a love/hate relationship with, except not really a relationship) Unlambda and Lazy K, and BackFlip or whatever it's called is also pretty nice, especially with winding. I'm not really a fan of languages that just have weird operators ...

- Sat Aug 18, 2007 3:10 am UTC
- Forum: Forum Games
- Topic: Count to 1 1000 times!
- Replies:
**1000** - Views:
**167498**