I try to install "muse", and I have this message :  The following packages have unmet dependencies:  muse : Depends: liblo7 (&gt;= 0.26~repack) but it is not installable E: Unable to correct problems, you have held broken packages.   I'm really sorry but even looking on the forum I have not been able to correct this problem. This is not the first installation that blocks due to broken package.  This is the result of apt-get install -f :  Reading package lists... Done Building dependency tree       Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 36 not upgraded.   The result of sudo apt-get update --fix-missing ends with :  W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://dl.google.com/linux/chrome/deb stable Release: The following signatures were invalid: BADSIG 1397BC53640DB551 Google Inc. (Linux Packages Signing Authority) &lt;linux-packages-keymaster@google.com&gt; W: The repository 'http://download.ebz.epson.net/dsc/op/stable/debian lsb3.2 Release' does not have a Release file. N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use. N: See apt-secure(8) manpage for repository creation and user configuration details. W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://ppa.launchpad.net/voldyman/markmywords/ubuntu xenial Release: The following signatures were invalid: BADSIG 837E86B594DF3268 Launchpad PPA for Akshay Shekher W: Failed to fetch http://dl.google.com/linux/chrome/deb/dists/stable/Release.gpg  The following signatures were invalid: BADSIG 1397BC53640DB551 Google Inc. (Linux Packages Signing Authority) &lt;linux-packages-keymaster@google.com&gt; E: Failed to fetch http://fr.archive.ubuntu.com/ubuntu/dists/xenial/main/binary-amd64/Packages  Writing more data than expected (2627 &gt; 492) [IP: 2001:860:f70a::2 80] W: Failed to fetch http://ppa.launchpad.net/voldyman/markmywords/ubuntu/dists/xenial/Release.gpg  The following signatures were invalid: BADSIG 837E86B594DF3268 Launchpad PPA for Akshay Shekher E: Failed to fetch http://linux.teamviewer.com/deb/dists/stable/main/i18n/Translation-en  403  Forbidden [IP: 2600:9000:2007:9000:1c:3aaa:b100:93a1 80] W: Some index files failed to download. They have been ignored, or old ones used instead.   The result of apt-get update ends with :  W: http://download.ebz.epson.net/dsc/op/stable/debian/dists/lsb3.2/Release.gpg: Signature by key E5220FB7014D0FBDA50DFC2BE5E86C008AA65D56 uses weak digest algorithm (SHA1) E: Failed to fetch http://linux.teamviewer.com/deb/dists/stable/main/i18n/Translation-en  403  Forbidden [IP: 2600:9000:2007:f000:1c:3aaa:b100:93a1 80] E: Failed to fetch http://fr.archive.ubuntu.com/ubuntu/dists/xenial/main/binary-amd64/Packages  Writing more data than expected (2627 &gt; 492) [IP: 2001:860:f70a::2 80] E: Some index files failed to download. They have been ignored, or old ones used instead.   I do not know in which direction to look.  Many thanks :)
When updating, I get the following error message:   W: The repository 'http://ppa.launchpad.net/mc3man/trusty-media/ubuntu xenial Release' does not have a Release file.   Here, I find another statement on this error:   This recommends removing certain PPAs; and, I'm not sure if I should do that since it might mean not getting the updates that I need.    Is this what I should do?
I have a 2015 MBP for work, which I connect my iPhone (6 plus, iOS 10) to charge, and I don't want to trust the computer, ever. However, I must click "Don't Trust" every single time I connect for charging. This is asymmetric to the "Trust" selection, which remembers my decision.  Does anyone know if it's possible to stop the 'Trust/Don't Trust' modal from appearing every time, and have the machine not be trusted?  If possible, can you please tell me how? If not possible, can you please provide proof or evidence that lead you to this conclusion?  Finally, I am not concerned with arguments or opinions about this feature. Only what is outline above. Quoting columns with spaces in PostgreSQL? I migrated a database from SQL Server to PostgreSQL.  Most column names contain double words, for example:  SELECT [Column Name] FROM table;   ...which does not work in PostgreSQL.  What is the correct syntax for PostgreSQL? Explaining Horizontal Shifting and Scaling I always find myself wanting for a clear explanation (to a college algebra student) for the fact that horizontal transformations of graphs work in the opposite way that one might expect.  For example, $f(x+1)$ is a horizontal shift to the left (a shift toward the negative side of the $x$-axis), whereas a cursory glance would cause one to suspect that adding a positive amount should shift in the positive direction. Similarly, $f(2x)$ causes the graph to shrink horizontally, not expand.  I generally explain this by saying $x$ is getting a "head start". For example, suppose $f(x)$ has a root at $x = 5$. The graph of $f(x+1)$ is getting a unit for free, and so we only need $x = 4$ to get the same output before as before (i.e. a root). Thus, the root that used to be at $x=5$ is now at $x=4$, which is a shift to the left.  My explanation seems to help some students and mystify others. I was hoping someone else in the community had an enlightening way to explain these phenomena. Again, I emphasize that the purpose is to strengthen the student's intuition; a rigorous algebraic approach is not what I'm looking for. Using fflush(stdin) I have just started special theory of relativity. The limiting speed known as speed of light fascinated me most. I asked my teacher:      Consider two massless objects moving in the same direction at the speed of light. What would be their relative velocity w.r.t each other?   My teacher tells me that their relative velocity would be zero. But then the speed of light is universal constant regardless of the motion of its frame of reference, so shouldn't their relative velocity be $c$? What is their relative velocity and how? Do objects moving at the speed of light obey law of addition of velocities? How do real and effective user IDs work? When a normal user wants to make change to the passwd file, the user will by setuid be given the effective user access. User becomes root temporarily and can edit passwd.  However you can only edit your password right, and not everybody else? However your effective user access is root. So how come you're not allowed to change other passwords beside yours?  When you run a program with setuid, what does it mean actually when effective user is root, but real user id is still your name? Pay real money to set bounties (another method, not replacing rep method) It may seem like a stupid thing, but could we please be able to pay real money to set a bounty.  For example, if I had only 1 rep, I want to be able have a bounty.   Here late the suggested prices in USD. Convert money    $0.49 for each 50 reputation $0.99 for each week $1.99 for a month $9.99 for a year   Every month, the bounty fee would come in. This would mean you would have to enable your account with a bounty fee button on your profile. mailto link with HTML body How do I execute PHP that is stored in a MySQL database? I'm trying to write a page that calls PHP that's stored in a MySQL database. The page that is stored in the MySQL database contains PHP (and HTML) code which I want to run on page load.  How could I go about doing this? Let ($x_s$) be a convergent sequence, where $x_s&gt;0$ for all s, and $y_s$ be a sequence such that   $$\displaystyle \Large y_s=\frac{s}{\frac{1}{x_1}+...+\frac{1}{x_s}}$$  Prove $\displaystyle \lim x_s$=$\lim y_s$  So I know things like $x_s$ is bounded, and that it's Cauchy, but I can't think of anything to solve it.  Any help is appreciated. If $n\ne 4$ is composite, then $n$ divides $(n-1)!$. I have a proof and need some feedback. It seems really obvious that the statement is true but it is always the obvious ones that are a little trickier to prove. So I would appreciate any feedback. Thank you!  Here is what I am asked to prove:     If $n$ is composite then $(n-1)! \equiv 0 \pmod n$.   Proof:  $n$ is composite $\implies n=ab$ where $a,b \in \mathbb{Z}$ and $0&lt;a,b&lt;n$.  Case 1: If $a=b$ then $n=a^{2}$. Now $n \mid (n-1)! \implies a \mid (n-1)!$, so $$\begin{aligned} (n-1)! &amp;\equiv 1\times 2\times \dotsb \times a \times\dotsb\times (n-a)\times\dotsb\times (n-1) \\ &amp;\equiv 1\times 2\times \dotsb\times a \times\dotsb\times -a\times\dotsb\times -1 \\ &amp;\equiv 0 \pmod n \end{aligned}$$  Case 2: $0&lt;a&lt;b&lt;n$.  Then, since $a \mid n$, $b \mid n$ and $n \mid (n-1)!$ we have that $a \mid (n-1)!$ and $b \mid (n-1)!$.  So this implies $(n-1)! \equiv 1\times 2\times \dotsb\times a \times\dotsb\times b\times\dotsb\times (n-1) \equiv 0 \pmod n$, Q.E.D. I want to change my thesis topic (to the extent that the ethos is still in tact) but my advisor does not agree. What can I do? I am doing a phd where my aim is to solve a problem A which is very interesting. My supervisor has got a lot of connections in a technology B and he claims to be an expert in B. I came to this group because of these accomplishments. But soon I realized that B is not really a great technology for A.   So in my phd proposal I proposed a method which encompasses B but is more general (say R). Now I realize that I do not want to use B at all because my preliminary results are not encouraging. In fact, I am inclined to use E as a base technique which does not have any impact on R.  But my supervisor, who is interested in only publishing in B  and frowns upon everything else (it was a nightmare to convince him to let me work on R) is dead against it. He says that he is an expert in B and his vision of the group is not inclined with me trying other things.  There are other professors in my university who have worked in E and could collaborate but my supervisor won't collaborate with people from outside his kingdom. I also know professors from outside my university who could help me if needed. I could knock the doors of school committee in order to  help me but that would create a lot of problems as my supervisor wields a lot of power and influence everywhere.    Another query is, is it ethical to collaborate with people outside the university (of course after letting my supervisor know) for my PhD work. My Masters supervisor would be happy to help me out.  Edit: After looking at comments, I am thinking that after all, it is MY PhD. Yes, I have spent 1.5 years, but 1.5 years is left. Why should I spend any moment of my life on something I find to be not exciting, particularly less exciting because it is forced on me. And in those 1.5 years I learnt to write well and also learnt 'A' which is important. Its not total waste. My supervisor has his agenda, and why should I give up mine to make him happy? His vision is fine, but he does not have the right to force his vision on me. What is the name for the grammatical figure, where the present tense is substituted for a past event? I am preparing a book for publication which contains the following passage:     Stromberg in Religious Liberalism in Eighteenth-Century England   (1954) noted that 'the critical moment in the emergence of a positive   spirit of reform...consisted in the awareness of evil as being social   and remediable. It begins about 1750.'   My proof reader (my wife) has picked this out suggesting it should be the past tense. However if I say It began about 1750 it seems to convey too much certainty about the exact date. I just want to convey an impression of it being something which emerges in the mid-eighteenth century. I believe use of the present tense is the way to go.   But what is this artifice called, this use of the present to convey mild uncertainty? Can we have the table name as "option" in MySQL? I am very, very new to MYSQL.I tried to create a table named "option". My SQL Query is :  create table option(   id int not null primary key auto_increment,  choice varchar(30)  )  While executing this query it shows the following error  Error Code : 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'option( id int not null primary key auto_increment, choice varchar(30) )' at line 1 (0 ms taken)  If I try with the table name as "choice" it is working.  can we have the table name as "option" in mysql?   thanks Delayed choice entanglement swapping: why are Alice & Bob's measurements useless without Victor's? I've got a dashboard that shows both active and unactivated parts of an app (users opt in to a service). Is there any standard for the best way to show an element/section is unactivated? Any way to encourage activation?    I'm sure there are numerous examples out there of apps that have "can't use this till you pay" section, but I can't seem to find anything that would illuminate a standard practice here.  Thanks!  edit: I'm picking this up from someone else's design. Here's my starting point: Do SAS expanders work transparently with SAS controllers? I'm new to SAS expanders and I'm trying to get things right. I understand that SAS expanders, when used with SAS controllers which supports expanders, allows you to utilise the full capacity of supported drives on a controller.  However, say I've got a SAS controller with 4 x SSF-8087 ports, which by itself would support 16 disks. I could then, as far as I understand, instead connect each of these ports to an expander to increase disk capacity.  However, will the SAS controller "see" all disks as if they were connected directly to the controller and not through an expander. Could I look at controllers as switches in a network? Would I be able to create a RAID from a disk on expander 1 and expander 3?  UPDATE:  I don't really have a specific project where I need to use SAS expanders. I'm just curious about how they work, and was thinking about how it would work if I used one or more SAS expanders with a LSI MegaRAID controller (9260-16i) which is running in one of our servers. However, I haven't really put any thought into the distinction between "local" disks and disks in another enclosure. The LSI MegaRAID controller has 4 SFF-8087 ports, which makes it capable of accomodating 16 drives. How to show the number of domains the disk is split into is $1+ C_n^2 + C_n^4$? Assuming there are n points on a circle, then there are $C_n^2$ chords. If any three chords don't intersect in circle. How to show the circle will be divided into $1+ C_n^2 + C_n^4$ domains?  Picture below is a example of 5 points on circle. I'm trying to make a list of ways to tell if a given degree sequence is impossible. For example $3,1,1$  is not possible because there are only 3 vertices in total so one can't have degree 3.  The list so far   vertices has degree equal to or larger than number of vertices sum of degrees is odd for n vertices if one has degree n-1 and another has degree 0 for n vertices the sum of the degrees cannot be greater than $n(n-1)$ because this would be have more edges than a complete graph Finite ring has only zero divisors and units If a nonzero element $a$ of a ring $\mathbb{D}$ does not have a multiplicative inverse, then $a$ must be a zero divisor.   If $\mathbb{D}$ has finitely many elements, then the statement is true. However, I don't see why, as for the infinite case, 7 isn't a zero divisor only because every element $a &gt; 0$ when multiplied by a $b &gt; 0$ gives you $ab &gt; 0$ which has nothing to do with infinity or finite amounts of elements.