alphabetical order in bibtex with accented words
Strange problem with BibTeX sorting
Is this algebraic identity obvious? $\sum_{i=1}^n \prod_{j\neq i} {\lambda_j\over \lambda_j-\lambda_i}=1$ If $\lambda_1,\dots,\lambda_n$ are distinct positive real numbers, then  $$\sum_{i=1}^n \prod_{j\neq i} {\lambda_j\over \lambda_j-\lambda_i}=1.$$ This identity follows from a probability calculation that you can find at the  top of page 311 in the 10th edition of Introduction to Probability Models by Sheldon Ross.   Is there a slick or obvious explanation for this identity?   This  question is sort of similar to ; clearly algebra is not my strong suit! I've done some research, and found this on Wikipedia. \begin{matrix}a\uparrow b=a^{b}=&amp;\underbrace {a\times a\times \dots \times a} \\&amp;b{\mbox{ copies of }}a\end{matrix} \begin{matrix}a\uparrow \uparrow b&amp;={\ ^{b}a}=&amp;\underbrace {a^{a^{{}^{.\,^{.\,^{.\,^{a}}}}}}} &amp;=&amp;\underbrace {a\uparrow (a\uparrow (\dots \uparrow a))} \\&amp;&amp;b{\mbox{ copies of }}a&amp;&amp;b{\mbox{ copies of }}a\end{matrix} I'm still a bit confused on this topic. I've done a lot of research, but I can't seem to understand this. Could somebody explain this in an understandable way? From what I can gather, for example 2↑↑3 would be 2^2^2 = 16? Then 2↑↑↑3 would be 2^2^2^2 = 256? Am I correct, or have I mis-interpreted this? Organic yet accurate modeling with the golden spiral Foreword  First off, let me say that I am profoundly amazed at the orderliness in nature. If you haven't heard about the Fibonacci sequence (0, 1, 1, 2, 3, 5, 8, 13, ...), you should check it out.  This mathematical concept of the Fibonacci numbers can be shaped into a set of squares, where the lengths of the sides of the squares follow the Fibonacci sequence:     This is sometimes called a golden ratio. It can be formed into a (golden) spiral. (a.k.a. logarithmic spiral):      Application  I am looking for ways on how to utilize this concept in Blender. Primarily in organic modeling. The golden spiral is found all throughout nature. From flower seed heads, sea shells, and ram horns to hurricanes and spiral galaxies.  My question is: how can I model based off of one or multiple golden spirals? Specifically, I'm interested in modeling a sunflower head like the one in the following image. I'm mostly interested in the point of origin of the individual seeds (not worried about the shape). Does Blender have any features related to this? Can the effects of a person's mass upon the local gravitational field be detected and measured remotely? Systems of equations with a single number (Google) Title of page not updated, everything else did My website changed significantly this month.  Amongst the changes was the website's title.  Two weeks ago, I finally used Webmaster Tools and submitted the page.  So far, Yahoo and Bing have updated the title in the search results, but not Google.  I've resubmitted via Webmaster Tools the website, and the bots have crawled the page, and have added "content keywords".  But the title still doesn't match.  The "content keywords" lists many of the words in the new title (but contains keywords of the existing title also).  Must say that 4 of the top 5 key words in the "significance" list are the new title's.  Still, no change.  Any remedies for this problem?  Is adding the "alt" tag for the logo significant enough to trigger the change?  There isn't an appropriate place to put the company name between  tags on the front page.  Any suggestions?  Thanks. Creating Layer in GeoServer using REST As part of a possible solution to   I want create a layer in GeoServer via REST that supplies a SQL statement along with a userid. I think i would  and publish it. I need to do this all in REST. Does anyone have any code examples? Turn a string into a valid filename? I have a string that I want to use as a filename, so I want to remove all characters that wouldn't be allowed in filenames, using Python.  I'd rather be strict than otherwise, so let's say I want to retain only letters, digits, and a small set of other characters like "_-.() ". What's the most elegant solution?  The filename needs to be valid on multiple operating systems (Windows, Linux and Mac OS) - it's an MP3 file in my library with the song title as the filename, and is shared and backed up between 3 machines. How to move Ubuntu to an SSD "Year olds" or "year-olds" I am writing about some leadership stuff, and I am trying to say that I am leading the 14-15 year old boys. How do I correctly use year-olds as in, "I was the adviser to the 14-15 year-olds."  Thanks in advance Is it shell portable to run a command on the same line after variable assignment? Is there any standard that covers the portability of running a command after variable assignment on the same line?  APPLE="cider" echo hi   How portable is something like that? Where will it work and where won't it?   Also: my shell scripts start with #!/bin/sh if that makes any difference. Is the "omniscient-omnipotent-omnipresent" definition of God consistent? is commonly defined as an  (infinite knowledge),  (unlimited power),  (present everywhere) entity.  Is there any logical  in this definition?  I have seen several paradoxes like below     Does God know what he's going to do   tomorrow? If so, could he do something   else?" If God knows what will happen,   and does something else, he's not   omniscient. If he knows and can't   change it, he's not omnipotent.      "Can 'an omnipotent being' create a   stone so heavy that it cannot lift   it?"   Do they mean that the defintion of God ( as commonly held) is logically inconsistent? Tangential component of Electric field The above question i'm trying for so long but failed. This is from my class $12$ book(india).First of all i'm confused with tangential component of electric field, I mean why this? So far I've studied that electric field(Whether its own or someone's else) is always perpendicular to a charged body. So, there shouldn't be any tangential component. Could someone please explain me visually what's happening?  Strict Note: A class $12$ answer required. No complex statements please. Only for school childs. Disable chat migration notification if one of the users has insufficient rep? I was wondering if there is any way to escape a CDATA end token (]]&gt;) within a CDATA section in an xml document. Or, more generally, if there is some escape sequence for using within a CDATA (but if it exists, I guess it'd probably only make sense to escape begin or end tokens, anyway).   Basically, can you have a begin or end token embedded in a CDATA and tell the parser not to interpret it but to treat it as just another character sequence.  Probably, you should just refactor your xml structure or your code if you find yourself trying to do that, but even though I've been working with xml on a daily basis for the last 3 years or so and I have never had this problem, I was wondering if it was possible. Just out of curiosity.  Edit:  Other than using html encoding... PlotRange precision limit? What are some good tutorials on writing custom styles (classes) that clearly explain commands used and some of the features that TeX has to offer in the way of styles? I'm a little confused about the output I'm seeing in my routing table, particularly the 'metric' column:  $ route -n Kernel IP routing table Destination     Gateway         Genmask         Flags Metric Ref    Use Iface 0.0.0.0         192.168.0.1     0.0.0.0         UG    0      0        0 wlan0 172.16.35.0     0.0.0.0         255.255.255.0   U     0      0        0 vmnet1 192.168.0.0     0.0.0.0         255.255.255.0   U     9      0        0 wlan0 192.168.82.0    0.0.0.0         255.255.255.0   U     0      0        0 vmnet8   According to the man page, metric indicates the 'distance' to the target. I was a little confused about what exactly "target" was. I assumed it was my router (it goes to gateway 0.0.0.0, which then goes to my router at 192.168.0.1). Thus, I expected the metric to be a single hop to my router. However, it's 9! Why is this so number high? How do I get label of the selected item from a lightning:select drop down list? I would like to get the value of the label of the selected drop down item.  In this case, the label is the Name of the Contact.  &lt;aura:component&gt;  &lt;aura:attribute name="contacts" type="Contact[]"/&gt;  &lt;lightning:select label="Contact" aura:id="contactList" name="contactList"&gt;     &lt;aura:iteration items="{!v.contacts}" var="c" indexVar="index"&gt;        &lt;option value="{!c.Id}"&gt;{!c.Name}&lt;/option&gt;    &lt;/aura:iteration&gt;  &lt;/lightning:select&gt;  &lt;/aura:component&gt;   I know how to get the value:  component.find("contactList").get("v.value");   But how do I get the label? I'm attempting to cut a hole in a plane. I added a cylinder object, added the Boolean modifier to the plane, selected "cylinder" and "Difference", but no hole is made. The lower half of the cylinder just highlights, moving/deleting the cylinder reveals a hole-less plane.      How can i cut a hole in the plane?