## Search found 53 matches

Thu Oct 17, 2013 3:50 am UTC
Forum: Computer Science
Topic: Examples of Deep Magic
Replies: 8
Views: 10352

### Examples of Deep Magic

The Jargon File defines deep magic to be: An awesomely arcane technique central to a program or system, esp. one neither generally published nor available to hackers at large (compare black art); one that could only have been composed by a true wizard. Compiler optimization techniques and many aspec...
Thu Oct 18, 2012 4:23 am UTC
Forum: Computer Science
Topic: Homomorphic Encryption
Replies: 10
Views: 5673

### Re: Homomorphic Encryption

That makes sense.

Thu Oct 18, 2012 12:37 am UTC
Forum: Computer Science
Topic: Homomorphic Encryption
Replies: 10
Views: 5673

### Re: Homomorphic Encryption

jareds wrote:Almost certainly, E(n==n) won't equal E(n <? 2^k), and this won't tell you anything about whether or not D(E(n==n)) equals D(E(n <? 2^k)), which is what you actually want to know.

Is this because lots of values might decrypt to the same "true" value?
Wed Oct 17, 2012 9:16 pm UTC
Forum: Computer Science
Topic: Homomorphic Encryption
Replies: 10
Views: 5673

### Re: Homomorphic Encryption

But if I can in fact do arbitrary computation, does that mean there is some other way to determine n <? 2^k, or is that sort of comparison not included? If Alice gives you E(n), you can compute E(n <? 2^k). E.g., either D(E(n <? 2^k))=0 or D(E(n <? 2^k))=1. However, you can't decrypt E(n <? 2^k). O...
Wed Oct 17, 2012 3:04 am UTC
Forum: Computer Science
Topic: Homomorphic Encryption
Replies: 10
Views: 5673

### Re: Homomorphic Encryption

[Disclaimer: I'm not a cryptographer.] No, you can do arbitrary computation. ("Using such scheme, any circuit can be homomorphically evaluated...") I assume you might have the input encoded in a special way. For example, you could have each bit encrypted separately and then run them throu...
Tue Oct 16, 2012 4:29 am UTC
Forum: Computer Science
Topic: Homomorphic Encryption
Replies: 10
Views: 5673

### Re: Homomorphic Encryption

http://en.wikipedia.org/wiki/Homomorphic_encryption [snip] What I don't get is that it seems like it would be very easy to figure out the encrypted values. I suspect there is some reason this is not true, since there's nothing clever about my reasoning here, and if it were in fact so simple to do, ...
Tue Oct 16, 2012 3:27 am UTC
Forum: Computer Science
Topic: Homomorphic Encryption
Replies: 10
Views: 5673

### Homomorphic Encryption

http://en.wikipedia.org/wiki/Homomorphic_encryption So, I have what I would call the "science journalist" level of understanding of homomorphic encryption: enough knowledge to explain it to someone else who is not a cryptologist, but not much beyond that. Probably as a result of this lack ...
Sat May 22, 2010 12:14 am UTC
Forum: Logic Puzzles
Topic: Not as easy as 1 2 3
Replies: 56
Views: 14286

### Re: Not as easy as 1 2 3

Now I am wondering about the next level up: Suppose I think of a number in the range 1 to 9. You get two questions; I answer each truthfully as before with yes, no, or don't know. Do you then know my number for sure? Surely if I can answer the first question, and guess 1, 2 or 3 in one question, th...
Thu Mar 18, 2010 3:09 am UTC
Forum: Logic Puzzles
Topic: Bird-Bear-Book Puzzle
Replies: 6
Views: 1949

### Re: Bird-Bear-Book Puzzle

We pair the sentence thusly: The bird the cat the dog the boy the woman that brought the book the kid wanted to be read to out of about down under up for a story hugged owned chased ate died . In other words: The bird died. The cat ate the bird. The dog chased the cat. The boy owned the dog. The wo...
Wed Jul 01, 2009 4:00 am UTC
Forum: Logic Puzzles
Topic: Is English trivial?
Replies: 21
Views: 3125

### Re: Is English trivial?

With regards to the homophone alternative that aleph_one mentioned:

Spoiler:
V can be solved with the extremely questionable alternate pronunciation of "Veldt" as "felt".

http://www.merriam-webster.com/dictionary/veldt
Sun May 24, 2009 4:55 am UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9990
Views: 2010921

### Re: Coding: Fleeting Thoughts

I was tasked at work to read and understand some old perl code. In one of the files, there were no comments except for one. Above a call to a function named &get_new_temp_dir, someone had helpfully written the nicely formatted comment: ################# # Get a new temp dir # ################# I...
Sun May 24, 2009 4:48 am UTC
Forum: Gaming
Topic: finding the statistically best Hangman word
Replies: 62
Views: 21673

### Re: finding the statistically best Hangman word

I find 'juju' works well. 'u' is often the last vowel guessed, and most people just stare blankly when they see the _u_u.
Sat Mar 07, 2009 2:15 pm UTC
Forum: Logic Puzzles
Topic: Extended Cannibals and Missionaries
Replies: 3
Views: 1350

### Re: Extended Cannibals and Missionaries

When the boat is docked at a shore, it should be considered that its occupants are all at that shore, not on the boat. (Or, if you prefer, that everyone disembarks at the end of a boat journey, even if they're going to get right back on.) For the above solution, this introduces the following problem...
Fri Mar 06, 2009 2:38 am UTC
Forum: Logic Puzzles
Topic: Extended Cannibals and Missionaries
Replies: 3
Views: 1350

### Extended Cannibals and Missionaries

So, the basic cannibals and missionaries puzzle is this: You've got a river, a boat that can carry one or two people, and three cannibals and three missionaries. All six people are on one side of the river, and you need to get all six to the other side. You can't leave a group of missionaries outnum...
Tue Feb 17, 2009 10:43 pm UTC
Topic: Religion: The Deuce
Replies: 5301
Views: 594421

### Re: Religion: The Deuce

Lots of people who have tried very hard to figure out the right rules have failed, ergo god does an unsatisfactory job of making them clear. There is no particular rule set which can claim that its followers have tried harder than all the rest. The claim that too many people are muddying the waters ...
Tue Feb 17, 2009 8:20 pm UTC
Forum: Computer Science
Topic: Interesting Comp Sci Problems
Replies: 4
Views: 1201

### Re: Interesting Comp Sci Problems

Here are a bunch of ACM-ICPC problems:

http://www.acm.inf.ethz.ch/ProblemSetAr ... _NorthEast
Tue Feb 17, 2009 8:05 pm UTC
Topic: Religion: The Deuce
Replies: 5301
Views: 594421

### Re: Religion: The Deuce

Further, if god wants us to figure it out on our own, and wants us free of authority, what business does he have sending out occasional spokespeople? Just to muddy the waters and mess with our heads?
Tue Feb 17, 2009 7:49 pm UTC
Topic: Religion: The Deuce
Replies: 5301
Views: 594421

### Re: Religion: The Deuce

I'm not saying he has to stop bad things from happening. I'm saying if he's set up the game, he's got a responsibility to let us know when we've come up with a rule that compels us to do otherwise bad things. There's still plenty of opportunity to do bad things. Even if I know that I'm playing baske...
Tue Feb 17, 2009 7:19 pm UTC
Topic: Religion: The Deuce
Replies: 5301
Views: 594421

### Re: Religion: The Deuce

But the responsibility on the part of the judge goes beyond that. Many of the rules the various teams have invented are really quite sinister if incorrect. If the judge is willing to watch them struggle under those unfortunate rules, all the while knowing that they would do just as well at the game...
Tue Feb 17, 2009 5:54 pm UTC
Topic: Religion: The Deuce
Replies: 5301
Views: 594421

### Re: Religion: The Deuce

But the responsibility on the part of the judge goes beyond that. Many of the rules the various teams have invented are really quite sinister if incorrect. If the judge is willing to watch them struggle under those unfortunate rules, all the while knowing that they would do just as well at the game,...
Tue Feb 17, 2009 5:37 pm UTC
Topic: Religion: The Deuce
Replies: 5301
Views: 594421

### Re: Religion: The Deuce

If the game were real, and there was an entity which judged whether the players won or lost, and that entity was interested in seeing the players win, I find it hard to believe it wouldn't make the rules a little more clear. Otherwise it's difficult to envision that entity as anything other than a m...
Tue Feb 17, 2009 4:29 pm UTC
Forum: Logic Puzzles
Topic: Traveler's Dilemma
Replies: 833
Views: 86766

### Re: Traveler's Dilemma

Lucy should write 100 and Pete should write 99, because it is right that the man should be payed a bit more, and that the woman should be perceived as a liar. And people say sexism never solves anything!
Mon Feb 16, 2009 10:11 pm UTC
Forum: Logic Puzzles
Topic: 169 puzzles (was 'mind trap')
Replies: 371
Views: 38068

### Re: 169 puzzles (was 'mind trap')

There are six ears of corn in a hollow stump. If a squirrel carries exactly three ears out each day, how many days will that squirrel take to empty the stump? 6 - the squirrel has two ears, plus one ear of corn Follow these steps and see if you can figure this out. 1) Get a brown, cardboard box. 2)...
Mon Feb 16, 2009 5:42 pm UTC
Topic: Religion: The Deuce
Replies: 5301
Views: 594421

### Re: Religion: The Deuce

As for the issue of religious people giving you evidence, despite the call to beleive soley on faith, I think it's explained by the Doubting Thomas story, which I shall surely butcher because I haven't looked it up. Thomas wants proof that Jesus is back, and Jesus gives it to him. He's still blesse...
Mon Feb 16, 2009 5:24 pm UTC
Topic: Religion: The Deuce
Replies: 5301
Views: 594421

### Re: Religion: The Deuce

I suppose there's no better time to dive into this than at the start of a new thread. These threads tend to foucus very much on Christianity and indeed, the American Brands of Christianity; prehaps investigating and discussing other religion might be considered. For instance, the rarely spoken of De...
Wed Feb 11, 2009 1:49 pm UTC
Forum: Logic Puzzles
Topic: 169 puzzles (was 'mind trap')
Replies: 371
Views: 38068

### Re: 169 puzzles (was 'mind trap')

With regards to the balloon/shot/basket one:

Spoiler:
Is he watching a basketball game played on a court which he owns from a hot-air balloon?
Mon Feb 09, 2009 7:45 pm UTC
Forum: Logic Puzzles
Topic: 169 puzzles (was 'mind trap')
Replies: 371
Views: 38068

### Re: 169 puzzles (was 'mind trap')

quintopia wrote:You are driving a car. On your right is a steep cliff. Right in front of you there is a horse and right behind an elephant, both of which travel at your own speed. On your left there is a fire truck blocking you. There is no brake pedal. How do you stop your car?

Spoiler:
hand brake?
Sun Feb 08, 2009 1:29 am UTC
Forum: Mathematics
Topic: The probability of impossible
Replies: 63
Views: 7442

### Re: The probability of impossible

If I wanted to express the idea that something had a minuscule probability, but was not impossible, I'd say its probability was epsilon. Of course, that's more math joke than it is technical terminology.
Fri Feb 06, 2009 2:49 pm UTC
Forum: Mathematics
Topic: Number Game!
Replies: 64
Views: 4418

### Re: Number Game!

One possible variant is restricting ourselves to only operators that take two arguments. Otherwise, you can have an arbitrarily long sequence of unary operators, and weird things like the above happen. For example, I think log should only be allowed if you make it base-4 log, and writing out the bas...
Thu Feb 05, 2009 9:51 pm UTC
Forum: Logic Puzzles
Topic: 169 puzzles (was 'mind trap')
Replies: 371
Views: 38068

### Re: 169 puzzles (was 'mind trap')

quintopia wrote:Susan needed to go to the store to buy some ingredients to cook with. She started writing them down:
Butter
Milk
Eggs
Baking Soda
Cashews
Oranges
Vinegar
Lemon Juice

What was Susan making?

Spoiler:
A list
Thu Feb 05, 2009 9:43 pm UTC
Forum: Logic Puzzles
Topic: Iterated Prisoner's Dilemma
Replies: 56
Views: 4757

### Re: Iterated Prisoner's Dilemma

Oh, I seem to have missed the whole 3 state business. Let me modify my strategy so that it's actually relevant to the problem.

Spoiler:
yoink
Thu Feb 05, 2009 9:03 pm UTC
Forum: Logic Puzzles
Topic: Hilbert's Hotel
Replies: 102
Views: 10695

### Re: Hilbert's Hotel

quintopia wrote:you're spoiling the fun of overanalyzing.

Not only that, but doing so by overanalyzing. How very meta.
Thu Feb 05, 2009 8:54 pm UTC
Forum: Logic Puzzles
Topic: Iterated Prisoner's Dilemma
Replies: 56
Views: 4757

### Re: Iterated Prisoner's Dilemma

Here's my strategy. I haven't really considered how it might perform, but it strikes me as interesting.

Spoiler:
yoink
Thu Feb 05, 2009 8:45 pm UTC
Forum: Mathematics
Topic: How does the cartesian product relate to other products?
Replies: 30
Views: 3047

### Re: How does the cartesian product relate to other products?

With regards to multiplication and commutativity, you might be interested in reading about Rings and Fields:

http://en.wikipedia.org/wiki/Ring_(mathematics)
http://en.wikipedia.org/wiki/Field_(mathematics)
Thu Feb 05, 2009 8:14 pm UTC
Forum: Mathematics
Topic: Modifier key combinations?
Replies: 3
Views: 576

### Re: Modifier key combinations?

For each modifier key, we have two choices - press it or don't. So that gives us 2^k for k modifier keys.
Thu Feb 05, 2009 8:03 pm UTC
Forum: Mathematics
Topic: The Busy Beaver function is smarter than our universe....
Replies: 39
Views: 4170

### Re: The Busy Beaver function is smarter than our universe....

I saw a very interesting question posted on Scott Aaranson's blog , asking whether it is possible to compute the parity of the nth busy beaver number. At first, my thinking was no, because it seemed unlikely that I'd be able to compute the last bit, but not the second to last bit, or more generally,...
Thu Feb 05, 2009 7:50 pm UTC
Forum: Mathematics
Topic: Number Game!
Replies: 64
Views: 4418

### Re: Number Game!

Here's an interesting answer I came up with for 108, which is shorter than the one linked to:

44 + (4 << 4)

where << is binary shift.
Thu Feb 05, 2009 2:36 pm UTC
Forum: Logic Puzzles
Topic: Hilbert's Hotel
Replies: 102
Views: 10695

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

how do you fit an infinite number of people into a single bus?

Maybe it's a double-decker bus.
Sat Jan 10, 2009 4:20 am UTC
Forum: Logic Puzzles
Topic: Nomic Anyone? (Discussion)
Replies: 29
Views: 2669

### Re: Nomic Anyone? (Discussion)

Re: Solitaire Nomic: 1. Apply mutation to Rule 101, replacing "not" with the empty string. 2. Now that I can do whatever I want, mutate rule 2 replacing "if and only if" with "regardless of whether" Step 2 doesn't work - you can't do whatever you want, because of rule ...
Sat Jan 10, 2009 12:32 am UTC
Forum: Logic Puzzles
Topic: Nomic Anyone? (Discussion)
Replies: 29
Views: 2669

### Re: Nomic Anyone? (Discussion)

Re: Solitaire Nomic:

Spoiler:
1. Apply mutation to Rule 101, replacing "not" with the empty string.
2. Now that I can do whatever I want, mutate rule 2 replacing "if and only if" with "regardless of whether"