After having problems with my H-P printer my Ubuntu 13.04 wont load. This is what I get:     Grub - editenv!ERROR: invalid environment block
Error: invalid environment block. Press any key to continue...   The error message appears immediately after the boot screen on purple background. Ubuntu 12.04.1 LTS.
Recently I have been working on a mini-game that gives a few players custom spawn eggs. I want the mob to simply have a name and be on a team. I'm attempting to use this command:   /give @p[x=-102,y=48,z=81,distance=..1] shulker_spawn_egg{Team:PurpleTeam,CustomName:"\"Purple Turret\""}   It does give the player a spawn egg, but the resulting shulker spawn does not have a team or a name. Any ideas why this isn't working? The successive difference of powers of integers leads to factorial of that power. Here's the formula:     $$\sum_{r=0}^{n}\binom{n}{r}(-1)^r(n-r)^n=n!$$   Can anyone give a proof of this result?  Note: The original question was to prove the more general     $$\sum_{r=0}^{n}\binom{n}{r}(-1)^r(l-r)^n=n!$$   for an integer $l$, which some of the answers address. Problem about a process with bins of balls The Ball From A Pass Working with a huge file. Illustrator is super slow. What can I do to ease the load? I saw this question  but it doesn't have a full solution. What is the full solution to the 99 bottles of beer on the wall for Vim adventures?  Context: for the sake of being a good SO member I will give more details but a full solution will answer my question. It seems from reading the other post that my register is incorrect for some reason. I can't get the &lt;NL&gt;. I think that's the issue since pasting won't work... Are answers that just contain links elsewhere really "good answers"? I have often wondered at the practice on Stack&nbsp;Overflow, Server&nbsp;Fault, and the other sites where someone will ask a question and an answer will come in that says Look here: http://link elsewhere. Rarely will the link have exactly the answer necessary -- often it's an entire article -- yet these answers get voted up.  Why is that, exactly? I realize this is subjective, but my own thoughts are that one should try and give the answer (even if the answer is 'no, it can't be done' or 'no, I don't think it can be done' -- very different answers) and then if you have a link that explains it, go ahead and post it within the answer.  What does the community think about this?     For more information, see  in the . Prove that for every prime $p$, there exists a solution to $(x^2-2)(x^2-6)(x^2-3) \equiv 0 \mod(p)$ So far: I know that$\mod(p)$ is a field thus one of the factors in the expression has to equal $0$ $\mod(p)$ for some $x$. However I just don't know where to continue from this point? How do I approach a congruency like this? Are there any general tips for problems like these?  Thanks for all the help. I have been using the Copy Attributes add-on to copy some properties from active object to selected objects. This add-on is not enabled by default and must be explicitly enabled. But its a very useful workflow enhancing tool.    There is a limitation though. Not all properties can be copied and even those that can be copied are copied in groups (Its hard-coded in to the add-on).  My question is if there is a built-in feature or any another other way to copy any property from the active object to the selected objects? Why is ++i is l-value and i++ not? If I run along the aisle of a bus traveling at (almost) the speed of light, can I travel faster than the speed of light? Render water-paint in iOS Quote.class doesn't return the Quote type, but Account.class does. Why? I'm trying a library that acts like an object factory. It works with serialization, so it is possible to specify formula fields without DML, which is pretty handy with tests.  My issue is that I'm trying to write a class that requires the Quote type. The apex compiler throws me the following error when using Quote.class:     Invalid field class for SObject Quote   But Opportunity.class, Account.class and even QuoteLineItem.class work just fine. Any idea why? Is it not possible to get the quote type? Or is there another way of doing it? Turn off the link hover statusbar in Google Chrome I want to turn off the feature where whenever I hover over a hyperlink and in the bottom lefthand corner it shows a light blue hover tooltip about where that link goes.   Why do I want to turn it off? It's annoying to me. I am distracted as I work. None of the other browsers do it. Besides, it serves little purpose because it can be spoofed with the onmousedown event on a link. Take for instance ads on Facebook -- those spoof.   I really don't care where a given link goes and wish I could turn that feature off, even if I have to install a Google Chrome Extension.   So, is there a fix to turn the annoying link hover tooltip feature off? The first time I learnt LaTeX, I thought \newcommand properly fits for inline mode and \newenvironment for displayed mode.  Later I noticed it is not correct. So the question is   What is the rule of thumb when deciding whether we should use one over the other one? Make browser window blink in task Bar How do I make a user's browser blink/flash/highlight in the task bar using JavaScript? For example, if I make an AJAX request every 10 seconds to see if the user has any new messages on the server, I want the user to know it right away, even if he is using another application at the time.  Edit: These users do want to be distracted when a new message arrives. /review tab not accessible on a private beta Assume two black holes in the most common size range, spiraling into each other until they merge. The event releases significant amounts of energy via gravitational waves, which warp the space-time.  If the distortion is powerful enough, it would get noticed in daily life, or perhaps even detected by the proprioceptors in the human body.  How close, as an order of magnitude estimate, would you have to be to the merger to perceive it like that, without any instrument? Is momentum conserved in this situation? Suppose we have object A , which has momentum mv. Then it elastically collides with a wall, so it's momentum now -mv, So how is momentum conserved here ? I have a data set for a predictive model(predicting survival rate with certain acute medical condition on some animals) with 25 predictors where around 30% of the predictors are complete, 3 predictors are sitting at 30%,25% and 20% missing, and the others are missing at around 5% level. Around 50% of my data are complete cases. I'm new to dealing with missing values so I have a couple of questions regarding how to deal with it:   What can I do with the variable with 30% missing assuming it's MAR? Is 30% too high for imputation? What kinds of metrics can I use to make the decision between removal of the predictor, listwise removal, imputation or some other options? How should I deal with a predictor with 20% - 25% missing when I have reason to believe that it's MNAR? I'm thinking of using imputation on the remaining predictors with around 5% missingness. How do I make the decision on which imputation methods to use? Are they chosen on a case by case basis based on the individual predictors? How does one impute categorical values?  How does(should?) the imputation carry out in practice? Should it use complete cases or compute it iteratively somehow?  Does feature selection comes in before or after dealing with missing values? if at all?