I have a simple problem basically I am unable to understand the meaning of some questions involving or/not, and using comma with and. I have the following questions:-  1.Whats the meaning of, say , X does not play football or cricket.  What we can infer from this. Can we say X does not play both of them? or one of them?  2.How the previous line is different from X does not play either football or cricket.  next is  3.If x does not play both of them, why in books such kind of statements are there instead of neither/nor.  and  4.whats the meaning of M and N, who reads newspaper, are not sitting together.  Here,  Do M and N, both reads newspaper? Please clarify these things to me. I am not a native Englishman so I found it very difficult to understand and as in logical reasoning questions these statements are common to see I face lot of problems. Please also tell me about such more things that can be confusing, may be, provide a link.
In mathematics, "A or B" includes "A and B". Does "either" mean "A or B but not (A and B)" or does it include the possibility of "A and B"? The context might be mathematics, formal logic or ordinary language.
How to stop Katoolin from crashing Ubuntu? Writing basic systemd service files Which of these is grammatically correct?       1. a) He has been working under my direct supervision since the last two years           1. b) He has been working under my direct supervision for the last two years            2. a) He has not met her since a very long time        2. b) He has not met her in a very long time    Which of the above are correct? Are all of them correct? My friend says 1.b and 2.b are correct, but I am not sure. Or is this an American English and British English thing? (He mostly goes by American English) Bring back review numbers to the top bar Though I never quite understood what those numbers were and they were quite ugly, they were the only reason I ever visited the reviews page.   Can we have similar functionality back on the top bar please? Edit answer draft is broken The Edit Answer Draft button is broken.    Press Back with text in an answer box. The Edit answer draft bar does not appear.     Seems like an onBackPressed() issue.  Also:   Press ← with text in the answer box The bar appears. Click the bar The answer box is blank.   Seems like the answer isn't properly carried between the Fragments.  Either way, you lost everything you wrote.  Can somebody test this? And especially without a confirm dialog, it is a brush of the finger to lose a long post of code or something.   I hope this report will help because I like the app (I'd say 4/5 stars) but the bugs are preventing a solid 5 stars.   Stack Exchange 1.0.73 Samsung Galaxy S II Skyrocket I727 Android 4.1.2 Sentence vs proposition I have an Android phone which is connected to a secured Wi-Fi hotspot.  How can I find out the password of the hotspot from the phone? True random generation in Java I was reading the Math.random() javadoc and saw that random is only psuedorandom.    Is there a library (specifically java) that generates random numbers according to random variables like environmental temperature, CPU temperature/voltage, or anything like that? Suppose $X, Y$ are independent random variables with $X\sim NB(r,p)$ and $Y\sim NB(s,p)$. Then $$X + Y \sim NB(r+s,p)$$  How do I go about proving this? I'm not sure where to begin, I'd be glad for any hint. Why is $ 561 = 3*11*17 $ the smallest Carmichael number? Windows 8 removes Grub as default boot manager I have a Sony VAIO S series with Windows 8 preinstalled, and I installed Ubuntu 12.10 on a new partition. When the PC boots Grub is display, and I can choose between Windows 8 (didn't worked at the beginning, had to change Grub settings) and Ubuntu 12.10. When I select Ubuntu 12.10 everything is OK, but when I use Windows 8, and I restart Grub isn't displayed anymore (Windows 8 boots immediately).  I booted a Ubuntu 12.10 LiveUSB, used efibootmgr, and found out that Windows 8 (each time it boots) changes EFI default bootloader from Grub to Windows Boot Manager.  How do I change this in Windows 8? I read something about bcdedit, but it does not work or I don't know how to use it... Show that $|z_1 + z_2|^2 < (1+C)|z_1|^2 + \left(1 + \frac{1}{C}\right) |z_2|^2$ Let $z_1$ and $z_2$ be two complex numbers. Show that there exists $C &gt; 0$ with   $$  |z_1 + z_2|^2 &lt; (1+C)|z_1|^2 + \left(1 + \frac{1}{C}\right) |z_2|^2. $$   I tried to simplify the L.H.S and R.H.S, SNF I was finally left to compare between a real number and a complex number  I really couldn't think of anything else. Please help. Cauchy-Riemann equations in polar form. Show that in polar coordinates, the Cauchy-Riemann equations take the form   $\dfrac{\partial u}{\partial r} = \dfrac{1}r \dfrac{\partial v}{\partial \theta}$ and $\dfrac{1}r \dfrac{\partial u}{\partial \theta} = −\dfrac{\partial v}{\partial r}$.      Use these equations to show that the logarithm function defined by   $\log z = \log r + i\theta$ where $z=re^{i\theta}$ with $-\pi&lt;\theta&lt;\pi$ is holomorphic in the region $r &gt; 0$ and $-\pi&lt;\theta&lt;\pi$.   What I have so far:   Cauchy-Riemann Equations: Let $f(z)$ = $u(x, y)$ +$iv(x, y)$ be a function on an open domain with continuous partial derivatives in the underlying real variables. Then f is differentiable at $z = x+iy$ if and only if $\frac{∂u}{∂ x}(x, y)$ = $\frac{∂ v}{∂ y}(x, y)$ and $\frac{∂u}{∂ y}(x, y)$ = −$\frac{∂ v}{∂ x}(x, y)$. So we have $f'(z)= \frac{∂u}{∂ x}(z) +i \frac{∂ v}{∂ x}(z)$. Let $f(z)$ = $f(re^{iθ})$= $u(r,θ)$ +$iv(r,θ)$ be a function on an open domain that does not contain zero and with continuous partial derivatives in the underlying real variables. Then f is differentiable at $z$ = $re^{iθ}$ if and only if $r \frac{∂u}{∂r}=\frac{∂ v}{∂θ}$ and $\frac{∂u}{∂θ}$ = $−r \frac{∂v}{∂ r}$.  Sorry, if this is not very good. 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