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http://en.wikipedia.org/wiki/Evenness_of_zero

Learning that such article could exist (it DOES exist), and reading it was a shocking experience to me.


Relevant quote from the article:

'A second-year was "quite convinced" that zero was odd, on the basis that "it is the first number you count"'


if you don't have them already: build-essentials, python, svn

Chromium is also a must.



I read this article in high school, and it permanently changed my math life. Without it, I would continue to think I know derivatives because I learned twenty formulas and did forty exercises (which in fact every idiot could do).

I'll allow myself to give some advice for those who are interested in problem-solving, but have no experience. If you have some, then this should be well known.

* Keep problem / exercise ratio as high as possible. This is impossible with many calculus books; find a book with hard problems. An "exercise" is something which checks your understanding of definitions and theorems; a "problem" is something which exercises your skill and forces to think. Do exercises if the theory is unclear. If a task starts with "using mathematical induction prove that..." then it is an exercise. A problem forces you to think how to do it.

* Doing differentiation exercises will give you some speed, but after five-twenty minutes your brain will stop thinking and start to rot. Healthy mathematics - just like programming - hates doing the same thing again. Of course you have to learn some algorithms, but this is a tip of the iceberg.

* Always take 20 minutes (some say more) on a problem, unless you think it is ill-posed; giving up early is stupid. If you think the problem is impossible, try proving it. Think about some way of solving, reject it quickly if you made a thinko; if you sense "this might work" go deeper. Use paper.

* Don't read too much on philosophy of mathematics or biographies; this isn't deep from the mathematical side. Other articles (http://www.artofproblemsolving.com/Resources/AoPS_R_Articles...) are also worth reading. Check their forum (http://www.artofproblemsolving.com/Forum/index.php or www.mathlinks.ro).


I don't see the result in Bing.

alpha direct link: http://www.wolframalpha.com/input/?i=(x-3)/(x-1)%3D(x-4)/(x-...


That's actually a different question than http://www.wolframalpha.com/input/?i=x-3%2F+x-1%3D+x-4%2F+x-...

Bing's formatting of the results doesn't quite draw your eye to it - look for "Calculation" immediately below "All Results"


Are you outside the USA? I'm in Taiwan and Bing isn't calculating it for me either. It's just returning a bunch of normal search results in Chinese. Maybe calculation only works for queries coming from inside the USA.


Well, I'm in India and it does display the calculations for me.


I'm in Croatia and it's not returning calculations for me. It seems only select locations got this enabled in the first run...


That's weird, I didn't see it either this afternoon, but now I do.


What do you mean by 'is defined by group operation'? Reals/integers with multiplication don't form a group.

'Multiplying 0 by itself 0 times' is what Wikipedia calls 'empty product'. For me is is good intuition, but that's a matter of taste.

AFAIK the usual convention is:

* in contexts where the exponent is varying continuously and a is a real number, a^b is undefined for a=b=0

* in contexts where the exponent is varying discretely (as an integer/natural number), a^b = 1 for b=0 and any a

Haskell quite nicely distinguishes between these two:

(^) :: (Num a, Integral b) => a -> b -> a

(* * ) :: (Floating a) => a -> a -> a

but it still gives 0 * * 0 and 0^0 as 1. (There shouldn't be spaces between asterisks, HN treats them as italics)


Reals form a group under multiplication. Integers don't, but they do form a commutative ring (addition, negation, multiplication).


> Reals form a group under multiplication.

I think his point was that 0 has no inverse. So in the literal sense, the reals are not a group under multiplication (although obviously, when somebody says "the reals are a group under multiplication", one usually interprets it as "R\{0} is a group under multiplication".)

This is vaguely relevant to the issue at hand because we are doing 0 to the 0.


Nitpick: it's written xkcd or XKCD, not Xkcd. (Source: http://xkcd.com/about)


I believe Hacker News capitalize the first word of the submission title no matter what. Which brings "IPhone" quite often.


It is possible to use a lowercase title: http://news.ycombinator.com/item?id=669937


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