Search found 161 matches

by HonoreDB
Tue Jun 22, 2010 9:51 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0568: "Well 2"
Replies: 105
Views: 25058

Re: "Well 2" Discussion

Necro'd because my dad's book, Long for this World came out today and is essentially about the first panel of this strip. It talks about the strip itself, too. :D

I tried to get my mom to ask Randall to illustrate her upcoming children's biography of Erdös, but she didn't go for it.
by HonoreDB
Mon Mar 01, 2010 6:09 pm UTC
Forum: Forum Games
Topic: The Intersecting Geekeries Test
Replies: 9
Views: 1943

Re: The Intersecting Geekeries Test

22/25 http://img7.imageshack.us/img7/4439/terminalvelocity.png Both C and D are correct at terminal velocity. Oy, you're right. And that's a much more blatant mistake than I was expecting, too. :cry: C is the intended answer, as you've probably guessed. I was presumably thinking in definitional...
by HonoreDB
Mon Mar 01, 2010 12:33 am UTC
Forum: Forum Games
Topic: The Intersecting Geekeries Test
Replies: 9
Views: 1943

The Intersecting Geekeries Test

In my continuing quest to create things that only appeal to the niche-est of niche audiences, I bring you The Intersecting Geekeries Test. Sample question: According to the Borg, what is futile? A. Voltage divided by power. B. Power divided by current squared. C. Voltage times current. D. Current di...
by HonoreDB
Thu Feb 18, 2010 11:40 pm UTC
Forum: Logic Puzzles
Topic: Train Problem
Replies: 16
Views: 5126

Re: Train Problem

See also the http://en.wikipedia.org/wiki/Elevator_paradox.

Spoiler:
As Qaanol notes, the man doesn't say he's visiting uniformly at random. If he's visiting by train, then naturally he'll tend to arrive at a time when lots of passenger trains are running.
by HonoreDB
Tue Feb 09, 2010 6:11 pm UTC
Forum: Logic Puzzles
Topic: That sequence of operations that always ends with 7
Replies: 22
Views: 4135

Re: That sequence of operations that always ends with 7

I worked this out from scratch this morning, but now that I write it out it looks familiar, so it may not be original. 1. Pick any whole number {0,1,2,3...}. 2. Cube it. 3. Sum the last two digits (if there's only one digit, add 5 to it instead.) 4. Go to step 2. This will always converg...
by HonoreDB
Sat Jan 16, 2010 5:49 am UTC
Forum: Science
Topic: What does it mean to say that Earth revolves around the sun?
Replies: 9
Views: 1278

What does it mean to say that Earth revolves around the sun?

This is a difficult one to google. I constantly encounter the sentiment that "people used to believe that the sun revolved around the Earth, but now we know it's the other way around." But that can't be strictly correct. All motion is relative. If we hold the sun's position constant, Earth...
by HonoreDB
Mon Dec 28, 2009 6:38 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0681: "Gravity Wells"
Replies: 205
Views: 57116

Re: "Gravity Wells" Discussion

Should be "still more glorious dawn."
by HonoreDB
Wed Oct 21, 2009 1:52 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0652: "More Accurate"
Replies: 131
Views: 40349

Re: "More Accurate" Discussion

Transporter: Tried in Star Trek Insurrection, was too slow and easily countered, so they resorted to Predator drones. The rest seem like super-bombs dressed up with technobabble--a hi-tech planet blows them up before they get close, a low-tech one gets devastated and the Enterprise has to come rescu...
by HonoreDB
Thu Aug 06, 2009 1:33 am UTC
Forum: Logic Puzzles
Topic: Guess Who?
Replies: 22
Views: 7531

Re: Guess Who?

Good idea. In that case whoever's "winning" wants minimum variance, and the other player wants to maximize variance. As long as both players do a binary search, neither player is winning, and if you change that situation your opponent gets to adjust before you do so it benefits the opponen...
by HonoreDB
Thu Aug 06, 2009 12:45 am UTC
Forum: Logic Puzzles
Topic: Guess Who?
Replies: 22
Views: 7531

Re: Guess Who?

I think I have a simple, general solution. No matter what strategies are employed, in whatever combination, Player 1's expected number of turns is one fewer than Player 2's. The only thing that can cause Player 2 to win is luck. Therefore, Player 1 wants to decrease the variance as much as p...
by HonoreDB
Fri Jul 31, 2009 1:29 am UTC
Forum: Logic Puzzles
Topic: Largest Rectangle in Wordspace
Replies: 2
Views: 1501

Re: Largest Rectangle in Wordspace

Spoiler:
In your sample, you can add T onto the first set and N onto the third.

My guess is the solution has the form {consonants} {3 vowels} {consonants} {S,E}.
by HonoreDB
Thu Jul 30, 2009 12:07 am UTC
Forum: Logic Puzzles
Topic: Decipher the Pioneer Plaque
Replies: 17
Views: 5291

Re: Decipher the Pioneer Plaque

I took a course in college where this was an early assignment. The final was to create a hypothetical alien race that would misinterpret the plaque. The story I wrote for the final is unpublishable because it's crammed full of references to obscure topics covered in the (extremely eclectic) course. ...
by HonoreDB
Fri Jun 12, 2009 11:40 pm UTC
Forum: Logic Puzzles
Topic: A game.
Replies: 2
Views: 1044

Re: A game.

Hurr. After playing around, it looks like white has a winning strategy in going straight up the middle. When it impacts black's two center pawns, black is forced to move a wing. White then moves back and in the direct of the pawn that just moved. Black has to either move the center pawn to rein...
by HonoreDB
Fri May 01, 2009 4:31 am UTC
Forum: Logic Puzzles
Topic: Four students, four boxes, one chance at an A grade!
Replies: 7
Views: 2612

Re: Four students, four boxes, one chance at an A grade!

I just proved to myself experimentally that there's no solution. This was clearly a conspiracy to rob me of much needed sleep and trust in humanity.

Edit: Okay, I just saw phlip's hint and I take it back. I'm going to sleep anyway, though. :oops:
by HonoreDB
Fri May 01, 2009 3:34 am UTC
Forum: Logic Puzzles
Topic: Four students, four boxes, one chance at an A grade!
Replies: 7
Views: 2612

Re: Four students, four boxes, one chance at an A grade!

I am completely mystified and suspect there is no solution. I'm going to use exhaustion. Edit: Call the boxes Lucas looks in 1 and 2. Case 1: Matt looks at 3 and 4. Lucas has a 50% chance. Given that Lucas succeeds, Matt has a 2/3rds chance, for 1/3 overall. Case 2: Matt looks at 1 and 2. 25% chance...
by HonoreDB
Wed Apr 15, 2009 10:35 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0568: "Well 2"
Replies: 105
Views: 25058

Re: Discussion of "Well 2"

My dad:

I love "The Uncomfortable Truths Well."

Here's one more: "The Uncomfortable Truths Don't Sell Well."
by HonoreDB
Sun Mar 01, 2009 6:58 am UTC
Forum: Logic Puzzles
Topic: Tough puzzle? Population growth and limit
Replies: 2
Views: 837

Re: Tough puzzle? Population growth and limit

I want it to be that the Earth becomes a black hole, but even if you allow humans to live 12 Km above the surface 11000 years is way too long.
by HonoreDB
Fri Feb 27, 2009 8:46 pm UTC
Forum: Logic Puzzles
Topic: 169 puzzles (was 'mind trap')
Replies: 371
Views: 38497

Re: 169 puzzles (was 'mind trap')

J Spade's got the Executive one.
by HonoreDB
Fri Feb 27, 2009 6:29 am UTC
Forum: Logic Puzzles
Topic: 169 puzzles (was 'mind trap')
Replies: 371
Views: 38497

Re: 169 puzzles (was 'mind trap')

Better Know a Country

Legislative Branch: How many United States Senators are there?

Executive Branch: What is the maximum number of continuous years someone may serve as President of the United States?

Judicial Branch: What court is above the United States Supreme Court?
by HonoreDB
Wed Feb 25, 2009 9:44 am UTC
Forum: Logic Puzzles
Topic: Public Crypto without Trapdoor Functions
Replies: 38
Views: 3075

Re: Public Crypto without Trapdoor Functions

I'm asking something more specific than that. If Eve can learn K-2 bits and we're still okay, what's the difference between K = 128 and K = 129? Doesn't the solution reduce to "Alice and Bob transmit as many hashes as they have time to make, then use all the matches to generate a key"?
by HonoreDB
Wed Feb 25, 2009 7:37 am UTC
Forum: Logic Puzzles
Topic: Super missile, indestructible fort
Replies: 21
Views: 2797

Re: Super missile, indestructible fort

This is an advanced weapon prototype, and always hitting the target means it must have some A.I. in the guidance system. As we know, such a device inevitably gains sentience and turns on its masters. "The intended target"? Intended by whom? The missile is "fired at" the fort by ...
by HonoreDB
Wed Feb 25, 2009 5:22 am UTC
Forum: Logic Puzzles
Topic: Public Crypto without Trapdoor Functions
Replies: 38
Views: 3075

Re: Public Crypto without Trapdoor Functions

Okay, I see what you're saying. What significance does K have then?
by HonoreDB
Tue Feb 24, 2009 10:43 pm UTC
Forum: Logic Puzzles
Topic: Public Crypto without Trapdoor Functions
Replies: 38
Views: 3075

Re: Public Crypto without Trapdoor Functions

Right, but she needs the whole key before she can perform decryption. If we're worried about her knowing part of the key then we can simply use the hash of the entire key as the private key. I don't see it. If Eve is allowed to know K/N of the key, then you can just exchange (N-1/N)K bi...
by HonoreDB
Mon Feb 23, 2009 7:37 pm UTC
Forum: Logic Puzzles
Topic: Iterated Prisoner's Dilemma V2
Replies: 30
Views: 2789

Re: Iterated Prisoner's Dilemma V2

Ouch. I'm guessing my strategy was too nice. Resubmitting one that errs in the other direction.
by HonoreDB
Fri Feb 20, 2009 11:17 pm UTC
Forum: Logic Puzzles
Topic: Public Crypto without Trapdoor Functions
Replies: 38
Views: 3075

Re: Public Crypto without Trapdoor Functions

Well, they don't have to be independent random numbers--Alice's can be one random number and the 2^K range above it, if you've got a good enough one-way function. Likewise, Bob can choose a number and hash the <i>m</i> numbers above it.
by HonoreDB
Fri Feb 20, 2009 5:43 pm UTC
Forum: Logic Puzzles
Topic: Public Crypto without Trapdoor Functions
Replies: 38
Views: 3075

Re: Public Crypto without Trapdoor Functions

Proof of concept? Alice generates an ordered list of 2^K random numbers, chooses one of those numbers at random, and hashes it using a function that takes a little more than MC/(2^(K-1)) time, then transmits the random numbers and the one hash. Bob randomly chooses m of the random nu...
by HonoreDB
Tue Feb 17, 2009 12:58 am UTC
Forum: Logic Puzzles
Topic: Self-reference
Replies: 1
Views: 1001

Re: Self-reference

This statement is true, but people with blue eyes can't assert that it's true without contradicting themselves. Secure a promise to answer two yes-or-no questions as truthfully as possible, and abide by the answers as much as possible. Then ask, "Will your answer to the other question be the sa...
by HonoreDB
Fri Feb 13, 2009 2:27 am UTC
Forum: Logic Puzzles
Topic: The "Wanion" Hand Cipher
Replies: 6
Views: 1889

The "Wanion" Hand Cipher

I came up with this hand cipher some time in elementary school, and I just remembered it. I'm curious if anyone can come up with a scheme to break it by hand. Enciphering: 1. You and your partner secretly agree on a numbering of the 26 letters of the alphabet, plus the space character. This is your ...
by HonoreDB
Mon Jan 26, 2009 11:26 pm UTC
Forum: Logic Puzzles
Topic: Sunny w/e
Replies: 26
Views: 3480

Re: Sunny w/e

Objection! (I've been watching Franken v. Coleman for some reason). Isn't it a fallacy to say, under any circumstances, "we can't assign a probability"? Probability is always an expression of lack of information, so lacking more information can't make the assignment impossible,...
by HonoreDB
Tue Jan 13, 2009 7:52 pm UTC
Forum: Logic Puzzles
Topic: The solution is a two-digit number
Replies: 19
Views: 3952

Re: The solution is a two-digit number

0870678884068983409815824039880670002291 OP: Did you come up with this puzzle on your own? Just curious ... it's quite clever. Yes, I did, thanks! I'm not sure if making the answer a number is the best way to present it, what do you think? It's essentially a red herring. (Or if you're scrolling dow...
by HonoreDB
Wed Jan 07, 2009 6:15 pm UTC
Forum: Logic Puzzles
Topic: Man at a funeral
Replies: 18
Views: 4040

Re: Man at a funeral

May be a massive hole here I'm missing... He's the step-uncle? I don't see how that works. A is B's step-uncle if 1. A is the sibling, by adoption, of B's parent. In this case, A has siblings (by adoption), so the condition fails. 2. A is the sibling of someone who is B'...
by HonoreDB
Wed Jan 07, 2009 6:09 pm UTC
Forum: Logic Puzzles
Topic: Choice by coin flipping
Replies: 28
Views: 5329

3-sided coin *emulation*

You have a normal, fair, 2-sided coin. You need to make a random, unbiased decision among options A, B, and C using only a series of coin flips. Part 1. What method can you use that will minimize the average number of flips necessary? Part 2. Formally prove that no method does better. Edit: Okay, fo...
by HonoreDB
Wed Jan 07, 2009 5:59 pm UTC
Forum: Logic Puzzles
Topic: Man at a funeral
Replies: 18
Views: 4040

Re: Man at a funeral

Straightforward answer: He is the father of the deceased. Less obvious answer: He is the uncle of the deceased via a now-deceased sibling. Very sketchy answer: No legal relation. The man's father was his clone and thus the two could be said to share a father without being siblings. Arm-amputator...
by HonoreDB
Wed Jan 07, 2009 5:38 pm UTC
Forum: Logic Puzzles
Topic: The solution is a two-digit number
Replies: 19
Views: 3952

Re: The solution is a two-digit number

Could you explain that a bit more, I still don't fully understand. http://en.wikipedia.org/wiki/International_Standard_Book_Number An ISBN-10 is a 10-digit number that uniquely identifies an edition of a book. It can be recognized if you've worked a lot with books, or by the check property the ...
by HonoreDB
Wed Jan 07, 2009 11:32 am UTC
Forum: Logic Puzzles
Topic: The solution is a two-digit number
Replies: 19
Views: 3952

Re: The solution is a two-digit number

That is, of course, right. I am pleased and impressed.
by HonoreDB
Sun Jan 04, 2009 8:25 pm UTC
Forum: Logic Puzzles
Topic: The solution is a two-digit number
Replies: 19
Views: 3952

Re: The solution is a two-digit number

Re the first: It's not quite that obnoxious. I have read the forum rules.

Re the second: No. Although if your plan is to post 90 guesses one at a time, I can confirm that will, in a sense, work. Maybe I should've given a larger solution space.
by HonoreDB
Sun Jan 04, 2009 10:08 am UTC
Forum: Logic Puzzles
Topic: A Code
Replies: 2
Views: 972

Re: A Code

Thanks for the puzzle.

Your fourth character, 268, should be 201.
by HonoreDB
Sun Jan 04, 2009 9:21 am UTC
Forum: Logic Puzzles
Topic: The solution is a two-digit number
Replies: 19
Views: 3952

Re: The solution is a two-digit number

No, not the answer. When you get it you'll know you've gotten it.
by HonoreDB
Sat Jan 03, 2009 10:25 pm UTC
Forum: Logic Puzzles
Topic: The solution is a two-digit number
Replies: 19
Views: 3952

Re: The solution is a two-digit number

I may have to post hints for this; it's pretty obnoxious. But I'll give it a week or so.
by HonoreDB
Sat Jan 03, 2009 9:12 pm UTC
Forum: Logic Puzzles
Topic: The solution is a two-digit number
Replies: 19
Views: 3952

The solution is a two-digit number

0870678884068983409815824039880670002291

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