@JM Firstly, in the Golan heights and Jerusalem it snows regularly during winters; secondly, during the 1999-2000 winter it snowed in the town I grew up in (which is not too far from here)
I mean like 60cm of snow, not just a minimal 5cm of snow.
I'll see if I can find one. There's one from the winter of 1990-1991 where it snowed about 5cm, but the town was very young and empty. It is an awesome photo.
I took a group theory course from Bob Griess and we covered a ton of material on permutation groups. I think he thought it would make us better students but I mostly got scared.
I still haven't gotten the hang of permutations. The group theory I was taught when I was a chemistry undergraduate was more of visualizing figures and reckoning from character tables...
@JM Thanks. I basically voted confirmation if it's ok to ask that question. (It seems to me that many questions about tags are recently at meta - I have posted some of them - and often with no result. So I was not sure if it;s worth bringing up.)
Ok, what else would fit into elementary-logic tag? Some questions about P implies Q is the same as not(Q) implies not(P). I always forget the English name for this.
They are discussing teaching some classes in English at our university. (I really don't know who would come to learn mathematics to some second-rate university in Eastern Europe, but the department management hopes to lure some in.)
I am not sure how I would be able to cope with it if I had to teach in English.
@Srivatsan Shouldn't we post a comment to the user first? Suggesting that he should make an account? (Both of them are unregistered.) Perhaps the comment should be posted to the older question, in case this one is deleted.
I think he wants to know whether you can take $$\frac{n(n + 1)}2 = \sum_{i = 1}^n i$$ and get a formula for general $\alpha$ that looks like $$\frac{n(n + \alpha)}{2\alpha} = \sum_{i = 1}^n i\alpha$$. And then take $\alpha \to 0$.
@MartinSleziak Actually, why don't you nag the user to register? If they do not respond within sometime, then we can always flag the mods for merger later.
I don't think that bumping an old question is necessarily a bad thing, at least unless it happens too often. (When I see something in an old/question, which is more just a very minor edit, I do the edit quite often.)
When I started with retagging algebra I did many questions and flooded the front page. PM from mods was needed to to get me to some more reasonable rate.
@DylanMoreland Well, if you're not posting what we discussed in chat, I'll do it. If nothing else, it could at least help clarify the question. And as we invested already some time into it, posting an answer seems to be logical - so that our time is not wasted completely.
so linearity requires that we have a constant k so that $\frac{1}{a^2}+\frac{33}{2(a+b+c+d+e)^2}=k/a$ and $\frac{1}{b^2}+\frac{33}{2(a+b+c+d+e)^2}=k/b$ and $\frac{1}{c^2}+\frac{33}{2(a+b+c+d+e)^2}=k/c$ and $\frac{1}{d^2}+\frac{33}{2(a+b+c+d+e)^2}=k/d$ and $\frac{1}{e^2}+\frac{33}{2(a+b+c+d+e)^2}=k/e$
So we have $\frac{k}{a} - \frac{1}{a^2} = \frac{k}{b} - \frac{1}{b^2} = \cdots = \frac{k}{e} - \frac{1}{e^2}$. At this stage, in some problems, it will be evident that all of $a$ through $e$ are equal. But not in this one...
@robjohn The equation $kx - x^2 = A$ has two roots, say $x_1$ and $x_2$. Then some of $a$ through $e$ are $\frac{1}{x_1}$ and the remaining are $\frac{1}{x_2}$. Here $A$ is some undetermined constant. [I am not sure if you want to take this route though]
I explained the class about minimal vs. minimum with the food chain. I told them that lettuce is a minimal element there because it eats no one, but it's not the minimum because I don't eat lettuce.
I want to prove $$n_0=(k-1)n_k+(k-2)n_{k-1}+\dots+3n_4+2n_3+n_2+1$$ for T as a binary tree where $n_i$ is nodes of degree $i$. I tried to prove it using the handshake lemma but came up with nothing useful.
An undergraduate was telling me about a puzzle he'd found: the idea was to make 2011 out of the numbers 1,2,3,4,$\ldots$,$n$ with the following rules/constraints: the numbers must stay in order, and you can only use $+$, $-$, $*$, $/$, ^ and $!$. In words, "plus minus times divide, exponentiation...
@robjohn Well, I guess the reason people don't write that stuff up in detail is that it is not really difficult, but writing it out makes things explode in size.
It took me a while to do a contour integration, but I had not seen the problem when it came out a month ago. I think the bot must have regurgitated it since there was no reason it should have been at the top of the list this afternoon.
@tb Isn't there a way in $\LaTeX$ to make diagrams like that?
I admire Krause's and Keller's ability to compress everything to the bare necessities. When you fill in the details and go back to their texts, you see that they say exactly what you need to do...
@robjohn I use xypic for that (that's how I made the pics on my laptop). Unfortunately xypic and tikz aren't implemented in MathJaX (probably because the code of xypic is a hideous monstrosity). See the links I gave in the first comment here for more on that
I want to prove $$n_0=(k-1)n_k+(k-2)n_{k-1}+\dots+3n_4+2n_3+n_2+1$$ for T as a binary tree where $n_i$ is nodes of degree $i$. I tried to prove it using the handshake lemma but came up with nothing useful.
