## Search found 13 matches

- Tue Jul 02, 2013 12:01 am UTC
- Forum: Mathematics
- Topic: Curve described by a/d_A + b/d_B = 1
- Replies:
**1** - Views:
**727**

### Curve described by a/d_A + b/d_B = 1

Let a and b be constants, and given focal points A and B and variable point P, let d_A be the distance between A and P, and d_B the distance between B and P. Consider then the two-dimensional locus of all points P such that \frac{a}{d_A} + \frac{b}{d_B} = 1 . For example, if we let ⋅ a = 2...

- Tue Sep 04, 2012 10:51 pm UTC
- Forum: Mathematics
- Topic: Anyone wanna read "Gödel Escher Bach" on Reddit?
- Replies:
**3** - Views:
**1884**

### Anyone wanna read "Gödel Escher Bach" on Reddit?

I found this group on Reddit that's going to be reading "Gödel Escher Bach", and wondered if anyone here would be interested too? I have to admit, though I'm interested in this sort of stuff, I've never actually read the book cover-to-cover. Anyone who has, what did you think? I've heard a...

- Sat Dec 03, 2011 3:33 am UTC
- Forum: Computer Science
- Topic: Determining equality of non-well-founded sets
- Replies:
**12** - Views:
**3091**

### Re: Determining equality of non-well-founded sets

This is interesting. I will go ahead and point to some algorithms: Kanellakis and Smolka give a fairly straightforward O(mn) algorithm, where there are n nodes and m edges, and Paige and Tarjan give an O(m log n) algorithm that, frankly, looks like it took some work to come up with. These journals ...

- Thu Dec 01, 2011 7:01 am UTC
- Forum: Computer Science
- Topic: Determining equality of non-well-founded sets
- Replies:
**12** - Views:
**3091**

### Re: Determining equality of non-well-founded sets

In that case, A==B iff something1 and something 2 and the position of B and A are the same. So you can replace B in A and A in B with a new symbol and check them like a well-founded set. In a similar way, it should be possible to replace A in A and B in B with another new symbol (check that). This ...

- Wed Nov 30, 2011 6:50 am UTC
- Forum: Computer Science
- Topic: Determining equality of non-well-founded sets
- Replies:
**12** - Views:
**3091**

### Determining equality of non-well-founded sets

I have a program that needs to determine if two sets of objects are equal. (We don't care about the order of elements within a set.) These sets may contain primitive elements (ints, strings, etc.), or possibly other sets. If both sets we're comparing are well-founded (i.e., they don't contain links ...

- Sat Nov 12, 2011 6:10 am UTC
- Forum: Your art and links
- Topic: Let me review your stories!
- Replies:
**1** - Views:
**3600**

### Let me review your stories!

As we know, there's a whole lot of crap out there on the internet, and self-published literature is no exception. Unfortunately, even if you've written a decent story that a lot of people would love if they read it, your fans might not hear you over the noise. I'm trying to start up a little communi...

- Wed Apr 27, 2011 7:57 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0891: "Movie Ages"
- Replies:
**158** - Views:
**39823**

### Re: 891: Movie Ages

SW15243 wrote:Far sooner though: The date that young people respond to your panic with "Who's Kurt Cobain?"

Well, are you gonna tell us?

- Mon Feb 21, 2011 12:12 pm UTC
- Forum: Logic Puzzles
- Topic: Secret Santa
- Replies:
**45** - Views:
**17896**

### Re: Secret Santa

I came up with a no-computer, no-trustworthiness solution, but then, reading the others, I realized it failed the "1/(N-1) chance of being in a 2-cycle" criterion... However, I still think it can be fixed, if you're willing to kill a lot of trees... ⋅ Gather everyone together, an...

- Mon Feb 21, 2011 10:55 am UTC
- Forum: Logic Puzzles
- Topic: The hardest maze in the world
- Replies:
**20** - Views:
**6845**

### Re: The hardest maze in the world

Glad you enjoyed it! I had been trying to think of how to design the Ultimate Maze™: a maze whose solution (if any) is isomorphic to a Gödel sentence, encoding a proof that the maze has no solution. But I had trouble figuring out how to even get started designing such a maze. Maybe you have some ide...

- Wed Jan 26, 2011 5:34 am UTC
- Forum: Logic Puzzles
- Topic: The hardest maze in the world
- Replies:
**20** - Views:
**6845**

### The hardest maze in the world

snippet.GIF This is a snippet of the upper left corner of the maze. The maze is constructed on a grid with six basic building blocks: types.GIF (The white strips represent passable paths; you can't pass through black.) Our maze is laid out on a two-dimensional grid, with the origin square (Row numb...

- Wed Jul 07, 2010 4:36 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0763: "Workaround"
- Replies:
**166** - Views:
**41367**

### Re: "Workaround" discussion

Magic Molly wrote:Kind of reminded me of the "please fax me more paper" joke.

Forgive me for I have sinned. I printed a blank document because I didn't know how to open the paper tray.

- Sat Jun 05, 2010 8:37 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0749: "Study"
- Replies:
**79** - Views:
**30709**

### Re: "Study" discussion

My problem with those sorts of riddles is always trying to figure out what the heck they're even trying to say to me. I can't parse the language. Which reminds me of http://xkcd.com/169/ . (I do realize they are not the same thing.) Just to clarify, since I'm still getting the hang of this "di...

- Fri Jun 04, 2010 9:26 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0749: "Study"
- Replies:
**79** - Views:
**30709**

### Re: "Study" discussion

I have the urge to print one of these... but I'm not sure what phone number to put on them. 772-257-4501 :) Rick Roll Hotline Done. +1 internets to whoever can find one. :D +300 internets to whoever can find all three. :mrgreen: +9,001 INTERNETS to whoever solves my riddle: Our runaround may take a...