## Search found 34 matches

- Fri Nov 14, 2008 6:17 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0504: "Legal Hacks"
- Replies:
**186** - Views:
**36196**

### Re: "Legal Hacks" Discussion

Rights are granted (inalienably, I might add :D ) by the creator. This raises some really interesting questions -- it is really important for a democratic society like ours that we attach a fundamental status to individual rights: there's no real way to derive them, so we have to take them as axiom...

- Tue Nov 04, 2008 5:47 am UTC
- Forum: Mathematics
- Topic: Obfuscating Schmoopiness With Math
- Replies:
**10** - Views:
**1784**

### Re: Obfuscating Schmoopiness With Math

The question is ambiguous.. is it [the velocity at time t] = Qln(-1)/i or is it the velocity at time [t=Qln(-1)/i] Yeah, it was supposed to be the first one, as you figured out. Sorry for the ambiguity. The problem is cute. Having a girlfriend that can actually solve the problem is hot. Unfortunate...

- Mon Nov 03, 2008 6:01 pm UTC
- Forum: Mathematics
- Topic: Obfuscating Schmoopiness With Math
- Replies:
**10** - Views:
**1784**

### Obfuscating Schmoopiness With Math

A man sent the following message to his girlfriend:

"The position of an object X in one dimension at time t is given by U*ln(t).

Solve the following for U:

The velocity of X at time t = Q*ln(-1)/i"

Hint:

"The position of an object X in one dimension at time t is given by U*ln(t).

Solve the following for U:

The velocity of X at time t = Q*ln(-1)/i"

Hint:

**Spoiler:**

- Fri Sep 05, 2008 4:09 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0472: "House of Pancakes"
- Replies:
**185** - Views:
**43486**

### Re: "House of Pancakes" Discussion

House of Leaves! I didn't know that was a widely enough known book to reference without comment in a webcomic... Edit: Oh. In my haste to show how cool I was by recognizing the reference, I missed the (extra) alt-text. Edit Edit: Wait a minute.... It wasn't really there, was it? Extra title text cou...

- Wed Jun 11, 2008 5:24 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0435: "Purity"
- Replies:
**649** - Views:
**199463**

### Re: "Purity" Discussion

I suppose I have to jump on the relationship of psychology to biology -- well, cognitive science to neuroscience, anyway. I, for one, consider all those people who study the brain to just be looking at one physical implementation of the pure informational system that I study as a cognitive scientist...

- Wed Mar 05, 2008 7:21 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0392: "Making Rules"
- Replies:
**157** - Views:
**27535**

### Re: Making Rules

Woohoo New Haven pizza!

That is all.

Except that "slug bug" is clearly a ridiculous name. "Punch buggy [color]" is obviously correct.

That is all.

Except that "slug bug" is clearly a ridiculous name. "Punch buggy [color]" is obviously correct.

- Mon Feb 25, 2008 5:22 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0388: "Fuck Grapefruit"
- Replies:
**412** - Views:
**99598**

### Re: "Fuck Grapefruit" Discussion

Interesting how the first principal component of fruit seems to have such a positive slope... You'd think you'd mostly trade off between tastiness and difficulty (since all these things are eaten, they would, you might suppose, each have something going for them), but according to Randall, not so mu...

- Thu Dec 13, 2007 12:39 am UTC
- Forum: Mathematics
- Topic: Question about statistical hypothesis test
- Replies:
**20** - Views:
**1770**

### Re: Question about statistical hypothesis test

I have to say I'm with Cosmologicon here. I don't think this problem says anything about Bayesian vs. Frequentist statistics -- I think it just highlights the fact that the information you use to arrive at a conclusion affects your conclusion. Furthermore, I'm inclined to say that the knowledge abou...

- Fri Dec 07, 2007 7:06 am UTC
- Forum: XKCD Meetups
- Topic: Southern Arizona?
- Replies:
**45** - Views:
**11032**

### Re: Southern Arizona?

Nothing boring about that, I don't imagine...

Well pleased to make your virtual acquaintance.

Well pleased to make your virtual acquaintance.

- Thu Dec 06, 2007 5:22 pm UTC
- Forum: Mathematics
- Topic: Expectation of the variance of a conditional distribution
- Replies:
**5** - Views:
**2446**

### Re: Expectation of the variance of a conditional distribution

Yeah... I realized I'd misread the parens shortly after posting last night... Curses.

- Thu Dec 06, 2007 7:02 am UTC
- Forum: Mathematics
- Topic: Expectation of the variance of a conditional distribution
- Replies:
**5** - Views:
**2446**

### Re: Expectation of the variance of a conditional distribution

Actually, taking:

E((Y-E(Y|X))E(Y|X)) = 0

and distributing first expectation gives:

(E(Y) - E(E(Y|X)))E(Y|X) = 0

Since E(E(Y|X)) = E(Y), we get

(E(Y) - E(Y))E(Y|X) = 0, which is true. Voila.

Thanks again for that key correction...

E((Y-E(Y|X))E(Y|X)) = 0

and distributing first expectation gives:

(E(Y) - E(E(Y|X)))E(Y|X) = 0

Since E(E(Y|X)) = E(Y), we get

(E(Y) - E(Y))E(Y|X) = 0, which is true. Voila.

Thanks again for that key correction...

- Thu Dec 06, 2007 6:43 am UTC
- Forum: Mathematics
- Topic: Expectation of the variance of a conditional distribution
- Replies:
**5** - Views:
**2446**

### Re: Expectation of the variance of a conditional distribution

Oh, right... I was treating Y|X as a random variable unto itself, but of course that doesn't make sense.

Thanks a lot. Makes sense now.

Thanks a lot. Makes sense now.

- Thu Dec 06, 2007 3:17 am UTC
- Forum: XKCD Meetups
- Topic: Southern Arizona?
- Replies:
**45** - Views:
**11032**

### Re: Southern Arizona?

Hey, I'm in Tucson... I'm in the Psych department at UA. You?

- Thu Dec 06, 2007 3:04 am UTC
- Forum: Mathematics
- Topic: Expectation of the variance of a conditional distribution
- Replies:
**5** - Views:
**2446**

### Expectation of the variance of a conditional distribution

Okay, so this is the last bit of a homework problem of which I've finished the rest. I've been scratching things out for a while now and seem to be going in circles. I don't want a full solution, but a hint about what to try would be useful. It really ought to be quite an easy problem... I just seem...

- Wed Nov 21, 2007 6:15 am UTC
- Forum: Mathematics
- Topic: mathy gift ideas for my n3rdl0ve? please help! :)
- Replies:
**20** - Views:
**2728**

### Re: mathy gift ideas for my n3rdl0ve? please help! :)

Indon wrote:If you can find a Rhythmomachia game set, you'd probably be good to go.

But I, sadly, don't know where to get one.

I co-wrote an AI agent to play Rhythmomachy at Governor's School in High School... I don't think I've heard the game mentioned since (nor had I before). Leave it to xkcd readers!

- Wed Nov 14, 2007 7:39 am UTC
- Forum: Language/Linguistics
- Topic: Verb form of "Placebo."
- Replies:
**29** - Views:
**6876**

### Re: Verb form of "Placebo."

Though come to think of it, it seems to me you should reverse the positions of "medical science" and "their hokey beliefs" in that sentence, as you would if you substituted "substitute" for "placebate", unless I'm not getting the intended meaning...

- Wed Nov 14, 2007 7:36 am UTC
- Forum: Language/Linguistics
- Topic: Verb form of "Placebo."
- Replies:
**29** - Views:
**6876**

### Re: Verb form of "Placebo."

Ah, now that's a bit different. You want the word to take as its object the placebo, rather than the recipient of the placebo, if I understand your sentence correctly... So it seems we could have all three of "placebify", "placebize" and "placebate" meaning, respectivel...

- Tue Nov 13, 2007 12:31 am UTC
- Forum: Language/Linguistics
- Topic: Verb form of "Placebo."
- Replies:
**29** - Views:
**6876**

### Re: Verb form of "Placebo."

On second thought, "placebify" might describe rendering something a placebo, rather than administering a placebo. So... how about "placebize"?

- Mon Nov 12, 2007 11:45 pm UTC
- Forum: Language/Linguistics
- Topic: Verb form of "Placebo."
- Replies:
**29** - Views:
**6876**

### Re: Verb form of "Placebo."

It seems clear that the correct form is "placebify"...

- Mon Nov 12, 2007 7:46 pm UTC
- Forum: Mathematics
- Topic: 2^x = x^3
- Replies:
**12** - Views:
**3263**

### Re: 2^x = x^3

It may not be particularly useful, but you can confirm for yourself that there are two real solutions by graphing the two sides of the equation, either the original one or x = 3log 2 (x). I find the latter easier to see... The logarithmic is obviously negative for x < 1, so it's below the linear, bu...

- Fri Sep 07, 2007 5:24 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0313: "Insomnia"
- Replies:
**167** - Views:
**38952**

I was totally trying to figure out what was special about 13:72. Random choice of impossible time, as far as I can tell. 1372 = 7^3 * 2^2, he calculated compulsively... Incidentally, 431 and 433 are both prime, whereas 432 = 2^4 * 3^3. For what that's worth. Which isn't much, if anything. Interestin...

- Fri Aug 31, 2007 5:56 am UTC
- Forum: Logic Puzzles
- Topic: A New Monty Hall Version
- Replies:
**27** - Views:
**10830**

- Thu Aug 30, 2007 10:50 pm UTC
- Forum: Logic Puzzles
- Topic: A New Monty Hall Version
- Replies:
**27** - Views:
**10830**

Sorry, I guess I should have said two doors, which is the situation you're in at the end of the traditional Monty Hall. I meant for it to approach the original game in the limit. In the p=0 case I don't think it matters much what you do, until the end, when you get to the original Monty Hall, at whi...

- Thu Aug 30, 2007 8:26 pm UTC
- Forum: Logic Puzzles
- Topic: Word Puzzle Collection (Rebus'?)
- Replies:
**40** - Views:
**8968**

- Thu Aug 30, 2007 8:15 pm UTC
- Forum: Logic Puzzles
- Topic: Word Puzzle Collection (Rebus'?)
- Replies:
**40** - Views:
**8968**

- Thu Aug 30, 2007 8:12 pm UTC
- Forum: Logic Puzzles
- Topic: A New Monty Hall Version
- Replies:
**27** - Views:
**10830**

### A New Monty Hall Version

I know, I know, it's taboo to post variations on the Monty Hall problem, but I searched, and this one hasn't been posed. I don't even know if it's posed anywhere, since I made it up. Which isn't to say someone else hasn't independently made it up, but. I think it's interesting. Okay. You're faced wi...

- Thu Aug 30, 2007 7:45 pm UTC
- Forum: Logic Puzzles
- Topic: Word Puzzle Collection (Rebus'?)
- Replies:
**40** - Views:
**8968**

- Thu Aug 30, 2007 7:34 pm UTC
- Forum: Logic Puzzles
- Topic: Word Puzzle Collection (Rebus'?)
- Replies:
**40** - Views:
**8968**

- Thu Aug 30, 2007 5:08 pm UTC
- Forum: Logic Puzzles
- Topic: Seemingly (and hopefully) very basic logic question
- Replies:
**22** - Views:
**4824**

- Tue Aug 28, 2007 5:14 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0163: "Donald Knuth"
- Replies:
**36** - Views:
**22507**

- Tue Aug 28, 2007 5:11 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0163: "Donald Knuth"
- Replies:
**36** - Views:
**22507**

- Fri Aug 24, 2007 4:19 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0307: "Excessive Quotation"
- Replies:
**80** - Views:
**26425**

- Fri Aug 17, 2007 9:03 pm UTC
- Forum: Mathematics
- Topic: The Derivative Song
- Replies:
**23** - Views:
**4693**

- Fri Aug 17, 2007 2:44 am UTC
- Forum: Logic Puzzles
- Topic: another Monty Hall variant [solution]
- Replies:
**9** - Views:
**3959**

To dredge up an old thread... Everyone is in agreement that there is an expected 2/9 of a car from the scenario where the first round is the altered version and we have chosen a goat. Now let's say the host opens a door. We agree, too, that in this scenario, it doesn't matter whether we stay or swit...