## Search found 150 matches

- Mon Apr 01, 2013 7:55 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1193: Externalities
- Replies:
**505** - Views:
**152706**

### Re: 1193: Externalities

I have pyskein 0.7.1 and am matching what the website gives except for in the one case where I tried using some curse words and numbers mixed together

- Wed Jan 13, 2010 2:53 am UTC
- Forum: Mathematics
- Topic: Is there a such thing as a cardinality under aleph null?
- Replies:
**18** - Views:
**1924**

### Re: Is there a such thing as a cardinality under aleph null?

If a set is infinite, you can remove any finite number of objects and it maintains being infinite. In particular you can remove one object, then another object, then another object, etc. So you can map aleph 0 into your infinite set (by counting the objects you removed) and hence aleph 0 must be at ...

- Thu Jan 07, 2010 1:58 pm UTC
- Forum: Mathematics
- Topic: Group theory: do some sets have implied operations?
- Replies:
**10** - Views:
**1653**

### Re: Group theory: do some sets have implied operations?

R* is used to denote the ring of units but someone taking group theory for the first time may not have seen that notation. As an example of how obvious the group operation in question is let's take a look at Z 2 . I claim there are two possible groups 1) The operations addition operation as we know ...

- Sat Dec 05, 2009 7:35 pm UTC
- Forum: Mathematics
- Topic: Number of paths under diagonal
- Replies:
**10** - Views:
**1426**

### Re: Number of paths under diagonal

Your hypothesis fails when m=n

- Fri Jun 12, 2009 11:32 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0596: "Latitude"
- Replies:
**84** - Views:
**23877**

### Re: "Latitude" Discussion

Hmm... I thought Megan bought a sexbot and installed an arc welder on it

- Fri Jun 05, 2009 3:20 pm UTC
- Forum: Mathematics
- Topic: Real-world examples of -x * -y = +z
- Replies:
**66** - Views:
**8352**

### Re: Real-world examples of -x * -y = +z

Sure it is. All you have to do is interpret the two numbers differently: one is a point on the number line, and one is a scale factor. Negative scale factors are "orientation-reversing." Yes, you have positive times positive is positive because three groups of four apples is twelve apples...

- Fri Jun 05, 2009 7:08 am UTC
- Forum: Mathematics
- Topic: Most frequently occuring digit
- Replies:
**17** - Views:
**1893**

### Re: Most frequently occuring digit

Does 1x10^10 have two zeroes or ten zeroes?

- Mon Jun 01, 2009 5:12 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0591: "Troll Slayer"
- Replies:
**178** - Views:
**187022**

### Re: "Troll Slayer" Discussion

This comic was awesome. Then I read the alt-text. Genius!

And good call pyro

And good call pyro

- Tue Apr 28, 2009 5:47 am UTC
- Forum: Mathematics
- Topic: Good problem for a 10th grader?
- Replies:
**32** - Views:
**3027**

### Re: Good problem for a 10th grader?

Lol, you're right quintopia. I normally don't write it that way, so when I saw your quote I thought you were bolding my text

Let the forehead slapping commence

Let the forehead slapping commence

- Mon Apr 27, 2009 11:22 pm UTC
- Forum: Mathematics
- Topic: Good problem for a 10th grader?
- Replies:
**32** - Views:
**3027**

### Re: Good problem for a 10th grader?

3,5,7 is not the only set of consecutive primes all of which are odd. In fact, all but one set of three consecutive primes are all odd. I thought that you'd say that, but I don't see how you can interpret it that way from the sentence structure. I avoided saying three consecutive odd primes for a r...

- Mon Apr 27, 2009 10:49 pm UTC
- Forum: Mathematics
- Topic: Good problem for a 10th grader?
- Replies:
**32** - Views:
**3027**

### Re: Good problem for a 10th grader?

quintopia, what's the other interpretation?

- Mon Apr 27, 2009 7:13 pm UTC
- Forum: Mathematics
- Topic: Good problem for a 10th grader?
- Replies:
**32** - Views:
**3027**

### Re: Good problem for a 10th grader?

The solution is incredibly easy to understand, so even if the problem is too hard it's simple to just ask the question, have her struggle over it, then give the solution. Then use this as a jumping off point to other similar questions. If the question's too easy, that's fine, because you can use it ...

- Sun Apr 26, 2009 2:39 am UTC
- Forum: Mathematics
- Topic: question that I have no Idea how to go about
- Replies:
**10** - Views:
**1212**

### Re: question that I have no Idea how to go about

It's obvious that if the die is not a 2 or a 1 you re-roll it. If you get a 2 on your first die, my gut instinct is that it's better to re-roll, because you have lots of chances to get a 2 again, and are fairly unlikely to get straight 1's on your other dice.

- Sun Apr 26, 2009 2:26 am UTC
- Forum: Forum Games
- Topic: Name a smaller (closer to zero) number.
- Replies:
**52** - Views:
**4950**

### Re: Name a smaller (closer to zero) number.

Previous number divided by -2

- Sat Apr 25, 2009 10:48 pm UTC
- Forum: Mathematics
- Topic: My question might annoy those who know the answer
- Replies:
**13** - Views:
**1405**

### Re: My question might annoy those who know the answer

I'll try again

∅rly?

∅rly?

- Sat Apr 25, 2009 6:24 pm UTC
- Forum: Mathematics
- Topic: Math: Fleeting Thoughts
- Replies:
**434** - Views:
**161371**

### Re: Math: Fleeting Thoughts

Did you divide by the volume of an M&M?\

You might want to find the height and diameter and assume it's a box shape instead because they don't fit together perfectly

You might want to find the height and diameter and assume it's a box shape instead because they don't fit together perfectly

- Fri Apr 24, 2009 5:30 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0573: "Parental Trolling"
- Replies:
**78** - Views:
**19974**

### Re: "Parental Trolling" Discussion

BlueEyedGreen wrote:I love how everything in the future is curvy, and how computers are just sleek glowing membranes floating at desk level.

I didn't even notice that

- Fri Apr 24, 2009 5:19 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0573: "Parental Trolling"
- Replies:
**78** - Views:
**19974**

### Re: "Parental Trolling" Discussion

Let's be honest, this comic would only be mildly amusing except for the use of 'bleegle warble yargle' for when she can't speak

- Fri Mar 27, 2009 8:39 pm UTC
- Forum: Mathematics
- Topic: Here's a fun problem...
- Replies:
**27** - Views:
**3741**

### Re: Here's a fun problem...

A sucker would expect a heads to increase the chance of a tails coming up next. Most people aren't suckers, so will pick heads to come up next. He knows most people aren't suckers, so the coin's rigged to come up tails. More seriously, itaibin, I can't believe that him flipping the coin and it landi...

- Mon Mar 23, 2009 7:50 pm UTC
- Forum: Mathematics
- Topic: Alternative definitions of the derivative
- Replies:
**15** - Views:
**2283**

### Re: Alternative definitions of the derivative

I should be using math fonts but I forget the syntax. If f : R^n -> R^m is differentiable at a E R^n. There exists a linear transformation L : R^n -> R^m such that lim h-> 0 |(f(a + h) - f(a) - L(h))|/|h| = 0 The function L is refered to as the derivative of f at a. real-valued single-variable func...

- Sun Mar 22, 2009 1:47 pm UTC
- Forum: Mathematics
- Topic: Uncountably many vertical asymptotes?
- Replies:
**18** - Views:
**2161**

### Re: Uncountably many vertical asymptotes?

Something that sort of fits what you're looking for: f(x) = 0 if x is irrational and if x is rational, say x = m/n, then f(x) = n f is locally unbounded everywhere. You don't get the limit of f approaching infinity as x approaches a point (since it doesn't exist) but the limsup does for every point....

- Thu Mar 19, 2009 6:32 pm UTC
- Forum: Mathematics
- Topic: Different definitions of an open set
- Replies:
**18** - Views:
**1633**

### Re: Different definitions of an open set

Define T to be the closure of T' under finite intersection and countable union. Then T happens to match all of the requirements of a topology on S.

You need uncountable unions also

- Thu Mar 12, 2009 11:49 pm UTC
- Forum: Mathematics
- Topic: Math problem help
- Replies:
**9** - Views:
**1034**

### Re: Math problem help

You should have a formula describing distance as a function of time and acceleration which you can solve

- Tue Mar 10, 2009 2:14 pm UTC
- Forum: Mathematics
- Topic: Graph: F(x)=x^∞
- Replies:
**25** - Views:
**3355**

### Re: Graph: F(x)=x^∞

For a quick answer: \lim_{x\to\infty}\frac{1}{x^2}=\frac{1}{\infty^2} = \frac{1}{\infty} = 0 \lim_{x\to\frac{\pi}{2}}\frac{1}{cos(x)}=\frac{1}{cos(\frac{\pi}{2})} = \frac{1}{0} = \infty Meaning, in the context of limits at least (an underlying basis of many other things like derivat...

- Mon Mar 09, 2009 1:24 pm UTC
- Forum: Mathematics
- Topic: Find if a number has a root
- Replies:
**8** - Views:
**1263**

### Re: Find if a number has a root

There are all kinds of algorithms. A not very efficient one is: Given a number y for which we are trying to find positive integer roots, we will find them only if y is a positive integer. Write the equation x^n=y. This is the same as finding roots for x^n-y=0. If there is an integer root k, (x-k) i...

- Sun Feb 08, 2009 2:33 am UTC
- Forum: Mathematics
- Topic: The probability of impossible
- Replies:
**63** - Views:
**7531**

### Re: The probability of impossible

It should be noted that as long as your sample space is countable, that p(x)=0 does in fact imply that x is impossible. It's only when you have uncountable sample spaces, like the set of real numbers or the set of infinite sequences H or T that you start getting into these problems (if problem is th...

- Mon Nov 24, 2008 3:12 pm UTC
- Forum: Logic Puzzles
- Topic: Right and Left - Truth and Lies.
- Replies:
**23** - Views:
**3466**

### Re: Right and Left - Truth and Lies.

Holy cow! What if they're ambidextrous!

- Fri Nov 21, 2008 5:38 pm UTC
- Forum: Mathematics
- Topic: Favorite math jokes
- Replies:
**1452** - Views:
**494127**

### Re: Favorite math jokes

Why did the vector cross the road? He wanted to be normal A baseball coach once had the most talented team he'd ever seen. Unfortunately, it all got flipped upside down when he put his naturals in a field. An infinite number of mathematicians walk into a bar. The first one orders a beer. The second ...

- Fri Nov 21, 2008 5:14 pm UTC
- Forum: Mathematics
- Topic: Analysis success suggestions?
- Replies:
**3** - Views:
**780**

### Re: Analysis success suggestions?

Become more than familiar with definitions, what they mean, and alternative formulations. Continuity is a good example, you have the standard epsilon-delta definition of a continuous function, but you also have a function is continuous if and only if for all convergent sequences (x k ) (converging t...

- Fri Nov 14, 2008 5:32 pm UTC
- Forum: Mathematics
- Topic: Which is bigger?
- Replies:
**35** - Views:
**3653**

### Re: Which is bigger?

Maybe you shouldn't have bought them so much food

- Thu Nov 13, 2008 10:39 pm UTC
- Forum: Mathematics
- Topic: Which is bigger?
- Replies:
**35** - Views:
**3653**

### Re: Which is bigger?

Even larger than 3->3->65->3?

- Thu Nov 13, 2008 7:42 pm UTC
- Forum: Mathematics
- Topic: Minimum bit string (shortest common superstrings)
- Replies:
**20** - Views:
**2366**

### Re: Minimum bit string

If you start with the string of n 1's, then you add a 0, you get the string with a 0 at the end... adding on more 1's gives you each string with a single 0 placed somewhere inside the string. You can't extend this exactly for two zeros as far as I can tell, but that's a bit more of a systematic star...

- Thu Nov 13, 2008 5:54 pm UTC
- Forum: Mathematics
- Topic: Adding Repeating Decimals (not *quite* .999...=1)
- Replies:
**28** - Views:
**2990**

### Re: Adding Repeating Decimals (not *quite* .999...=1)

If I have a distinct .000....1 and I multiply it by 10, what do I get? This is the biggest problem with trying to use an intuitive decimal notation for a 'super small' number

- Thu Nov 13, 2008 12:29 pm UTC
- Forum: Logic Puzzles
- Topic: Equilibrium Strategy for "Tension"
- Replies:
**14** - Views:
**1869**

### Re: Equilibrium Strategy for "Tension"

If the number of bins is less than the number of people,

**Spoiler:**

- Wed Nov 12, 2008 9:24 pm UTC
- Forum: Mathematics
- Topic: Direct proof of compactness
- Replies:
**18** - Views:
**1791**

### Re: Direct proof of compactness

Proving the Heine Borel theorem and then using the Heine Borel theorem is still using the Heine Borel theorem.

- Wed Nov 12, 2008 6:33 pm UTC
- Forum: Mathematics
- Topic: Direct proof of compactness
- Replies:
**18** - Views:
**1791**

### Re: Direct proof of compactness

"Unroll" the definition of the Heine-Borel theorem and apply it. If whatever grading authority says that's still using the Heine-Borel theorem, add a line in the unrolled definition stating "For all b in B, the set of bananas, b is a banana". Because the Heine-Borel theorem neve...

- Wed Nov 12, 2008 3:04 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0503: "Terminology"
- Replies:
**292** - Views:
**48543**

### Re: Terminology

Re: Africa. Let's be honest. Rome beat Carthage, the Persians took Egypt, and it was pretty much game over for the whole continent. It's kind of like getting zerg-rushed

I think we should refer to Antarctica as the deep south from now on

I think we should refer to Antarctica as the deep south from now on

- Mon Nov 10, 2008 10:40 pm UTC
- Forum: Mathematics
- Topic: Direct proof of compactness
- Replies:
**18** - Views:
**1791**

### Re: Direct proof of compactness

If there's an open cover of K, it must be 0 is contained in one of the covering sets. What else does that covering set cover (hint: A lot of other points)

- Thu Nov 06, 2008 7:12 pm UTC
- Forum: Mathematics
- Topic: How do you prove that a function is continuous?
- Replies:
**12** - Views:
**7660**

### Re: How do you prove that a function is continuous?

And yet you're the only person who didn't understand what level of math answers should be at. Someone working with rings of continuous functions over a compact space does not need to know how to prove sinx + 2 is continuous

- Wed Nov 05, 2008 11:33 pm UTC
- Forum: Forum Games
- Topic: Word Chain II
- Replies:
**51** - Views:
**4524**

### Re: Word Chain II

tricky77puzzle wrote:Office_Shredder wrote:freed to slaveSpoiler:

He asked for slave to free, not freed.

Oh, whatever. Just change it to

free

freed

repeat

That was trivially fixable without comment I think