# Recent content by DimReg

1. ### LQG Introduction Material

LQG is a subject that is built off of general relativity and quantum field theory, so you should understand that a good introduction would still assume 2 years of graduate coursework... Regardless, I found the following to be a pretty good intro: http://arxiv.org/abs/1102.3660 I also read...
2. ### Schools Does distribution of grades matter when applying to grad school?

Not that I have any kind of experience you ask for, but I tend to hear that admissions like to see positive trends in your grades (though of course, they prefer a 4.0). It's (probably) better to have your A's in your difficult senior level courses than in your easy freshman ones, if you can only...
3. ### Simple Big O analysis question

Well, I know of at least one computer science textbook that agrees with me, and it's where I learned this definition. The book is http://sist.sysu.edu.cn/~isslxm/DSA/textbook/Skiena.-.TheAlgorithmDesignManual.pdf [Broken], and on it's 36th page Skiena writes: "The Big Oh notation provides for...
4. ### Simple Big O analysis question

Inaccurate, but not incorrect, at least according to: http://en.wikipedia.org/wiki/Big_O_notation#Formal_definition (If you use n^2 as f(x) and n^3 as g(x), the formal definition is easily satisfied) This is just semantics, but my guess is that the prof was trying to illustrate this point.
5. ### Simple Big O analysis question

If I recall correctly, big O notation refers to an upper bound. So strictly speaking, an algorithm that is O(n^2) is also O(n^3), because the latter will be larger than the former. However, it is best to hold a fair amount of precision in your upper bound: simply stating that an algorithm is...

7. ### Commutation of derivatives.

Oh I see. My first thought is that this would be a lot of work for something we basically already have: a representation of non commuting operators. But my second thought is that this might be a way to create some non standard physical situations, where for example energy and momentum would not...
8. ### Commutation of derivatives.

From one perspective, all currently known fundamental physics is based on theories where derivatives do not commute. A simple example: in electromagnetism, we can define D_\mu = \partial_\mu - ieA_\mu , which acts just like (because it is) a derivative operator. From which we compute...

your if statement is always true, when you typed "if (speed == "f" || "F")", you are asking if speed == "f" is true, or the statement "F" is true. "F" is true, so the first line is run. the line should read: if (speed == "f" || speed == "F"){ ... }
10. ### Permutations with BFS

Breadth first should do it too, but at far as I know the algorithm is usually depth first. I think it has to do with memory optimization. You only need one path in memory at one time in the depth first approach, which can be helpful if the graph is "wide". I could be mistaken, but breadth first...
11. ### Permutations with BFS

It's not entirely clear how you attempted to solve it before because you didn't post any sample code, but the type of algorithm used to generate all permutations is called backtracking. (http://en.wikipedia.org/wiki/Backtracking) Maybe you already knew that. The basic idea is you have a...
12. ### How many higgs particles are there in the universe

When we combine quantum mechanics and special relativity, we end up with quantum field theory. Essentially what we learn is that the field and the particle are part of the same thing. Whenever we detect a particle, what we are really detecting is that the field has been excited in that local...
13. ### What courses can I expect after calculus?

There should be some sort of course catalog, or an adviser you can consult. You should check those places. I mean, what textbooks would you order anyways? Wouldn't you want to buy the book that is used in your course? You don't just buy random books do you?
14. ### How to become a genius ?

Different individuals have different levels of intelligence, depending on a variety of factors. But typically the most important factor for success is not intelligence, but work ethic. There are plenty of examples of people who are clearly very smart, but who just can't bother working hard...
15. ### A gentle Introduction on CFT

Presumably someone with more knowledge of the subject will come by, but for a quick intro to CFT almost any string theory textbook has a chapter on it (if I recall correctly, most of the interest in studying CFTs comes from their connection to string theory). It's probably not worth purchasing a...