## Search found 313 matches

Thu Jan 17, 2013 5:54 am UTC
Forum: Science
Topic: Are gravity wells elastic?
Replies: 10
Views: 3305

### Re: Are gravity wells elastic?

It seems to me like GM/r^2 is an equilibrium value.
If gravity is inherently more like a memory foam mattress than a trampoline, how do you prove it? Is there an experiment you can do?
Thu Jan 17, 2013 5:35 am UTC
Forum: Science
Topic: Are gravity wells elastic?
Replies: 10
Views: 3305

### Re: Are gravity wells elastic?

Why not?
Thu Jan 17, 2013 5:27 am UTC
Forum: Science
Topic: Are gravity wells elastic?
Replies: 10
Views: 3305

### Are gravity wells elastic?

This is a question related to http://xkcd.com/1158/
If one were to rapidly decrease a planets mass, perhaps by setting off a bunch of nuclear reactions, would its gravity well oscillate? Follow-up question: What happens if the planet bounces out of its gravity well?
Wed Nov 14, 2012 6:36 am UTC
Forum: Coding
Topic: s-expressions that look like smilies
Replies: 0
Views: 989

### s-expressions that look like smilies

This is a thread for posting lisp expressions that look like smilies. Any dialect of lisp may be used so long as it is fully parenthesized and uses prefix notation.
I will begin:
(- 8)
Thu Sep 13, 2012 5:55 am UTC
Topic: (Post Your) Incredible Poems (Here!)
Replies: 544
Views: 260151

### Re: (Post Your) Incredible Poems (Here!)

The things they might have thought while they looked at me and smiled and tried to act casual, laid back, jovial, easy going... They might have been afraid of what I would think of them if I knew what they were thinking. And so we were like mirrors reflecting eachother's subdued, forcibly frictionle...
Sun Sep 09, 2012 10:18 pm UTC
Forum: Computer Science
Topic: Regex probability
Replies: 34
Views: 41070

### Re: Regex probability

Just a quick question about converting to DFAs: since the time complexity for converting regexs is so bad, I'm wondering if there is an alternative language for specifying regular languages that doesn't have such a high conversion cost. I suppose that just specifying the states and their connections...
Sun Sep 02, 2012 2:44 am UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9990
Views: 2009922

### Re: Coding: Fleeting Thoughts

You seem to have a common misconception about what code is about. Code isn't about the writing and the telling of a computer what to do. That is easy. Code is about the reading and the telling of a human what the code is telling the computer what to do. I would disagree with that somewhat. I think,...
Sun Sep 02, 2012 1:37 am UTC
Forum: Science
Topic: Probably Stupid: Reversing Entropy
Replies: 33
Views: 18649

### Re: Probably Stupid: Reversing Entropy

I recently (half a year ago) attended a guest lecture at the Niels Bohr Institute by some big shot physicist (was it Penrose, or someone else? I forgot). Anyway, the lecture was mostly above my head, but the gist of it I got was something like this: Once every last piece of matter with a rest mass ...
Sun Sep 02, 2012 1:18 am UTC
Forum: Science
Topic: escaping a black hole?
Replies: 61
Views: 22211

### Re: escaping a black hole?

What if I'm in a curved region of space such that the black hole neighbors itself on both sides so its event horizon overlaps itself, would it be possible to escape from between the black holes? To put this another way, if I'm on one side of a cylinder and a black hole is on the opposite site, can I...
Fri Aug 31, 2012 4:18 am UTC
Forum: Computer Science
Topic: Relationalist game of life
Replies: 7
Views: 7207

### Re: Relationalist game of life

I prefer stateless nodes. However, stateless nodes pose a number of problems in Life if you want them to correspond directly to living cells. For example, there is no way to represent the distance between disconnected living cells. But, it should still be possible to emulate life by having certain c...
Wed Aug 29, 2012 5:46 am UTC
Forum: Computer Science
Topic: Relationalist game of life
Replies: 7
Views: 7207

### Re: Relationalist game of life

This reminds me a bit of some exploration I did on graph rewriting automata, in that relationships sound a lot like edges to me. Kohji Tomita has some real research on them . His stuff seems to mostly focus on asynchronous/local updating of the graph, while I was more interested in synchronous updat...
Fri Aug 24, 2012 6:17 am UTC
Topic: Military sequestration
Replies: 66
Views: 14042

### Re: Military sequestration

One thing I hope they have to cut out of their budget:
http://en.wikipedia.org/wiki/America%E2%80%99s_Army
Thu Aug 23, 2012 6:54 am UTC
Topic: What’s the best piece of advice you could give to everyone?
Replies: 121
Views: 29932

### Re: What’s the best piece of advice you could give to everyo

Constraints can help you be creative. By using constraint constraints you can come up with more creative constraints that will in turn help you be more creative: ⋅ Constraint constraints must be reflexive and consistent, i.e. they must apply to themselves (since they are constraints). &sdo...
Mon Aug 20, 2012 5:15 am UTC
Topic: Prior Art
Replies: 10
Views: 3155

### Re: Prior Art

You need more than just 'swipetounlocksmartphone'. Here is an actual patent for using gestures to unlock something like a smartphone, to give you an idea of the sorts of detail that are involved here. 'Swipe to unlock smartphone' tells you (more or less) what the invention does, but it doesn't tell...
Sun Aug 19, 2012 6:17 am UTC
Topic: Prior Art
Replies: 10
Views: 3155

### Re: Prior Art

What if I make a website that is an infinite stream of randomly and lazily generated text? If you advance through it far enough, every possible string, describing every describable idea will occur. On a practical level, isn't it just completely unreasonable? It would take ages for random text to st...
Sun Aug 19, 2012 2:45 am UTC
Topic: Prior Art
Replies: 10
Views: 3155

### Prior Art

The US patent system is changing to first to file . This made me wonder, if I have an idea, should I tell anyone about it without patenting it? After all, if word spreads, couldn't some large company teeming with lawyers, easily patent it ahead of me? And if in order to even discuss an idea I have t...
Thu Aug 16, 2012 4:04 am UTC
Forum: Computer Science
Topic: Regex probability
Replies: 34
Views: 41070

### Re: Regex probability

My example generates abc, one string of length 3. But from the way I understood your mathematics: S_3 = A_2 + B_2 A_2 = C_1 = 1 B_2 = C_1 = 1 thus S_3 = 2 So, it appears we're over-counting. If we convert the non-deterministic grammar into a deterministic one, can we still guarantee that it is unamb...
Wed Aug 15, 2012 4:03 am UTC
Forum: Computer Science
Topic: Regex probability
Replies: 34
Views: 41070

### Re: Regex probability

Quizatzhaderac wrote:Regular grammars are all also unambiguous.

I'm not quite convinced of this. Maybe I'm missing something, but if not, wouldn't this be a counterexample:

Code: Select all

`S -> aAS -> aBS -> εA -> bCB -> bCC -> c`
Mon Aug 13, 2012 5:24 am UTC
Forum: Computer Science
Topic: Regex probability
Replies: 34
Views: 41070

### Re: Regex probability

I was just researching the ambiguous -> unambiguous idea and the problem looks to be undecidable since presumably it requires determining that the grammar is ambiguous (which Wikipedia tells me is undecidable). Edit: Hmm, you've got me wondering, is it undecidable if the grammar's not inherently amb...
Mon Aug 13, 2012 5:08 am UTC
Forum: Computer Science
Topic: Regex probability
Replies: 34
Views: 41070

### Re: Regex probability

Here's one thought: I think enumerating the strings of length N a regex can generate can be "reduced" to transforming an ambiguous CFG into an unambiguous one. That's another problem I don't know the difficulty of so maybe that doesn't help. Here's how: The regex can be transformed into a ...
Sun Aug 12, 2012 11:41 pm UTC
Forum: Computer Science
Topic: Regex probability
Replies: 34
Views: 41070

### Re: Regex probability

What do you need this for? Some background might help... I was thinking about making a game where you compete by writing regular expressions that match an incoming string stream. So .* isn't the ultimate trump card the person with the less likely regular expression would be given more ponits. Anoth...
Sun Aug 12, 2012 11:03 pm UTC
Forum: Computer Science
Topic: Regex probability
Replies: 34
Views: 41070

### Regex probability

How do I compute the number of strings of length N that a given regular expression will match? I'm still thinking about this so maybe I'll realize there is an easy answer, but if not, help is appreciated.
Thu Aug 09, 2012 4:05 pm UTC
Topic: Welfare and minimum wage
Replies: 104
Views: 15739

### Re: Welfare and minimum wage

If businesses could pay people less than the cost of basic necessities because government provided food and shelter can fill the gap, wouldn't the government be subsidizing cheap labor in effect?
Sat Jul 28, 2012 5:30 am UTC
Topic: Brogramming
Replies: 134
Views: 28374

### Re: Brogramming

There appears to be a much larger gender imbalance in open source software than proprietary software. Bruce Byfield gives an interesting talk about it: http://youtu.be/HN9S6ZKFWxE
Sun Jul 15, 2012 4:49 am UTC
Forum: Computer Science
Topic: Compiler and CFG question
Replies: 5
Views: 5850

### Re: Compiler and CFG question

Yes: unrestricted grammar Thanks! I read the wikipeida article and discovered the charming programming language Thue . I have yet another CFG question. This one's a bit more mathematical. I had the realization that CFGs are essentially a class of directed hypergraphs and parse trees are in a sense ...
Fri Jul 13, 2012 8:06 am UTC
Topic: Patents and Exclusivity
Replies: 53
Views: 9904

### Re: Patents and Exclusivity

I think the major misunderstanding is that no patent has a company's name on it. Ever. No company "owns" any patent. It has the inventors names on it, and there is a separate piece of paper that assigns the rights to use that patent to a company. That piece of paper is the same if I inven...
Sun Jul 08, 2012 10:46 pm UTC
Forum: Computer Science
Topic: Compiler and CFG question
Replies: 5
Views: 5850

### Re: Compiler and CFG question

Thanks, I wasn't aware of SCFGs.
I have another CFG related question:
Is there a technical term for grammars with more than one symbol on the left hand side. So for example:
A->AA|B|C
BC->D
where if A generated BC adjacently, the symbols would be combined to produce D.
Tue Jul 03, 2012 5:17 am UTC
Forum: Coding
Topic: Is the Right Tool a Matter of Preference?
Replies: 123
Views: 36411

### Re: Is the Right Tool a Matter of Preference?

The best language or pattern or paradigm or algorithm, besides being efficient, is one which allows you to model your thoughts and communicate them for posterity as well as unambigiously control the machine. I disagree. First I disagree with the idea of modeling our thoughts, I think we develop the...
Sun Jun 24, 2012 7:24 pm UTC
Forum: Coding
Topic: Programming when you suck at maths
Replies: 16
Views: 7543

### Re: Programming when you suck at maths

For the unknown signs try using this site in conjunction with Wikipedia: http://shapecatcher.com/ There are a lot of "computer science" ideas you can learn without any math. There are also a lot of "computer science" ideas that are also mathematical ideas (and it isn't always obv...
Tue Jun 12, 2012 5:40 am UTC
Forum: Computer Science
Topic: Is there anywhere I can find a modestly priced Utah teapot?
Replies: 3
Views: 5603

### Re: Is there anywhere I can find a modestly priced Utah teap

Awesome idea!
Tue Jun 12, 2012 4:49 am UTC
Forum: Computer Science
Topic: Compiler and CFG question
Replies: 5
Views: 5850

### Compiler and CFG question

Pretend I have the following: Context free grammars C1 and C2 for two programming languages. A mapping M between some of the symbols of C1 and C2 An algorithm A that will use C1, C2 and M to convert a string S1 generated by C1 to a string S2 generated by C2. I haven't worked out the details of the a...
Sun Jun 10, 2012 10:55 pm UTC
Forum: News & Articles
Topic: The Green Washing of Local Food Movement
Replies: 145
Views: 16580

### Re: The Green Washing of Local Food Movement

Meh, I'm waiting for the days when robots do all the farming. Kansas comes to mind in particular, with all the breezes. Why aren't there farms with wind turbines powering robotic threshers/combines/tractors that do all the planting and harvesting? I doubt the turbines would block too much light, an...
Tue Jun 05, 2012 4:40 am UTC
Forum: Computer Science
Topic: Is there anywhere I can find a modestly priced Utah teapot?
Replies: 3
Views: 5603

### Is there anywhere I can find a modestly priced Utah teapot?

For those of you unfamiliar with the object, see this article: http://en.wikipedia.org/wiki/Utah_teapot
This is the cheapest I've found so far: http://www.unfold.be/pages/5/items/85
Mon Jun 04, 2012 4:50 am UTC
Forum: News & Articles
Topic: Where Microsoft is now becoming even more monopolistic
Replies: 70
Views: 8023

### Re: Where Microsoft is now becoming even more monopolistic

Right now, there are 79 processes and 935 threads running on my computer. Do you sandbox every process, every thread? What happens when components need to interact with each other? Ah, I think this is where we're miscommunicating. I'm talking about running the OS in a virtual machine, not sandboxin...
Mon Jun 04, 2012 4:15 am UTC
Forum: News & Articles
Topic: Where Microsoft is now becoming even more monopolistic
Replies: 70
Views: 8023

### Re: Where Microsoft is now becoming even more monopolistic

Say I have a electronic design automation tool which I use to simulate a computer's circuitry. Do you think it is possible to make the simulated computer to infect the simulating OS with a virus? None of the simulated data on it is going to be outputted in a form that, in memory, would be usable fo...
Sun Jun 03, 2012 7:43 am UTC
Forum: News & Articles
Topic: Where Microsoft is now becoming even more monopolistic
Replies: 70
Views: 8023

### Re: Where Microsoft is now becoming even more monopolistic

Similarly, its an issue of Market Share when we compare Desktop Windows vs Desktop Linux. Woops, sorry, each linux is too different. Its really Desktop Windows vs Fedora vs CentOS vs Debian vs Ubuntu. (Ex: Debian and Ubuntu were open to a very bad ssh bug a few years ago, but not Fedora or CentOS)....
Sun Jun 03, 2012 7:19 am UTC
Forum: News & Articles
Topic: Where Microsoft is now becoming even more monopolistic
Replies: 70
Views: 8023

### Re: Where Microsoft is now becoming even more monopolistic

Well what about running in a sandbox? Where are the holes there that secure boot would do anything about? The sandbox won't be perfect. That's the point. No matter how hard they try, unless it's dealing with an absurdly simple system (i.e. not an operating system) it's always going to have a flaw. ...
Sun Jun 03, 2012 6:31 am UTC
Forum: News & Articles
Topic: Where Microsoft is now becoming even more monopolistic
Replies: 70
Views: 8023

### Re: Where Microsoft is now becoming even more monopolistic

Also, I don't think having a computer's boot sector compromised is that much worse for the average user than other types of attack. If I were to just have my browser compromised, pretty much all the information I care about protecting would be revealed. If just your browser is compromised, the prob...
Sun Jun 03, 2012 5:55 am UTC
Forum: News & Articles
Topic: Where Microsoft is now becoming even more monopolistic
Replies: 70
Views: 8023

### Re: Where Microsoft is now becoming even more monopolistic

The overall system is just too complex and too high value of a target while dealing with too many idiot users*, for any overall security system to be flawless. * A lot of hacks these days rely in part on human engineering -- get the user to install this, or put a certain flash drive in their system...
Sun Jun 03, 2012 4:44 am UTC
Forum: News & Articles
Topic: Where Microsoft is now becoming even more monopolistic
Replies: 70
Views: 8023

### Re: Where Microsoft is now becoming even more monopolistic

I would accept any of the following types of reasoning: A review of the potential security solutions, and explanations of why they would all fail. Other security solutions: Virus scanners, monthly malware remover, sandboxing. All useless once the boot sector has been compromised, because now you ca...