I am reading about Signing vs. Public-Key encryption and a question pop up in mind that is it possible to transform any signature scheme to a public-key encryption scheme?
Is it possible to construct an (asymmetric) encryption scheme from a signature scheme?  If the signature scheme is deterministic and allows  (e.g. ), then the answer is yes (create a forgery (m, sig); encrypt plaintexts using  with sig as the key; send m in clear to the signer along with ciphertexts, who can then compute sig and decrypt these ciphertexts) .  I am interested in similar reductions for probabilistic signature schemes.  What should the properties of a probabilistic signature scheme be so that it can be used for encryption?
What rolls should players get to see? I'm a new DM and over the last few weeks I've been slowly learning the game and how it runs. My party consists of 5 PCs.   One thing I have been wondering after our last two sessions is: What rolls should all the players see and which rolls shouldn't they see?  Is there a comprehensive list of what rolls are public and which go behind the DM screen, or is it more down to house rules or personal preference? Surface of genus $g$ does not retract to circle (Hatcher exercise) Lighting in a Minecraftian World Minecraft is a game that is largely based on a heightmap and uses that heigtmap information to flood the world with light.  From my understanding the highest point in the heightmap is the end of the sunlight influenced area.  Everything above that is lit by sunlight, everything below that just is influenced by light nearby in a radius of 8 blocks.  Thus if you have a floating island on the top of your world everything below that will be seen essentially as a cave.  When two lights influence the same point the brighter light wins (unsure about that).  Either way there are a couple of problems with minecrafts lighting model: first of all, if your world does not have a heightmap it becomes trickier to figure out what exactly is supposed to emit sunlight and what not.  A simple way would be to assume that the world is (in my case) a floating rock and then traverse each axis from both directions and figure out where the rock starts and ends.  But this does not fully eliminate the problem as dents in the rock are not supposed to be in darkness.  Minecraft itself will cache the light information in its chunks together with the information about the material of a block.  Thus only if the world is modified the lighting has to update.  Unfortunately that process is still pretty slow on updates and on quick light changes one can see the lighting lag behind.  That's especially true if a lot of blocks change (TNT, sunset etc.) and you're not running the fastest computer (Or Java on Mac).  From my still limited understanding of 3D graphics lighting a world like minecraft shouldn't be the biggest issue.  How would you tackle the problem?  I think the basic requirements for lighting in a voxel world would be   update fast enough that it could happen in a single frame.  One might be able to do the lighting in the graphics device and download the changed light information to the main RAM. light information must be quickly available for the main game logic so not entirely based on the graphics device: reasoning: light affects the growth of grass, spawning of monsters etc. light updates would have to be local to a chunk or have some other limit so that one does not have to relight the whole world which might be very large in size.   The main idea would be to make the light updates fast, not necessarily more beautiful. For general light rendering performance improvements one could easily add SSAO on top of that which should result in much nicer worlds. Writing USB Joystick for PIC18F using MikroC I've been reading an  ( eMagazine) relating to the Raspberry Pi; "An ARM GNU/Linux box for $25."  In the article, page 17 at the bottom it shows an area on the Pi where a track zigzags next to a straight one with the explanation text:     The “wiggles” in tracks, ensure signals are matched  electrically,   reducing interference and signal delay.  This is particularly   important for high speed video  data and HDMI signals.     I have very limited knowledge of electrical engineering so perhaps this is a very simple question but why would you incorporate these 'wiggles' in a PCB design?  I realise the quote gives me an answer and I sort of understand the interference point due to problems with power cables and coaxial cables running next to each other but I'd appreciate something assuming very little knowledge that explained why you would get the problems and how wiggles help. For example, why isn't the board covered in wiggles? Low Quality review queue erroneously showing "Close" instead of "Recommended Close"? I was in the Low Quality Review queue, and the following review confused me:    It's showing eight "Close votes", which should be more than enough to close a question.  I checked the question's , and it wasn't somehow closed, then re-opened in the middle of the review.  So I then checked on each of the users, and noticed that the majority of them are under 3000 reputation, meaning they can only "Recommend Close".    However, all reviews are simply showing as "Close", which is extremely confusing.  Is this a bug, or possibly an undocumented change related to ?    Another recent example: Is 'hair' singular or plural? When one says I was washing my hair, is it singular or plural? What is the singular for hair? There appears to be a poltergeist in my speakers (no, really) I've no idea if there's a suitable Stack Exchange for poltergeists. It appears to be software, hardware or virus related, so I thought I'd try here, seeing as Ghostbusters is just a film, so I can't call them.  I'm not going mad, and this isn't a joke.  There's what appears to be a radio stream coming out of my speakers, except I can only hear it when the volume knob is turned down to the min setting whilst the speakers are on, which makes no sense. Sometimes it's French, which also makes little to no sense.  The speakers are Logitech 5.1s, I forget the model number, and I'm running XP 64bit. If that makes a difference.  I'd suspect it could be some sort of crazy virus, but I've been randomly killing processes whilst the poltergeist is active and it hasn't killed it, so I'm not sure about that.  Once again, I'm perfectly sane and this really isn't a joke. Perhaps other people have had this problem but have been too afraid of the reaction to ask anyone (please don't have me committed to an insane asylum).  Googling for strange noises coming from speakers didn't really get me anywhere. Has anyone heard of a virus that can do this and affect the volume controls on the hardware in that way? Mean Squared Error (MSE) of parameter $p$ in binomial distribution: intuition Finding the limit of roots products $(\sqrt{2}-\sqrt[3]{2})(\sqrt{2}-\sqrt[4]{2})(\sqrt{2}-\sqrt[5]{2})\cdot \cdot \cdot (\sqrt{2}-\sqrt[n]{2})$ When a star becomes a black hole, does its gravitational field become stronger? SQL Server Linked Server to Microsoft Access Fast way to copy a large file on a LAN I am having some trouble with NFS, and I'd like to try using just plain old TCP.  I have no idea where to begin, though.  Hardware-wise, I am using an ethernet crossover cable to network two netbooks.  To network them, I type  $ sudo ifconfig eth0 192.168.1.1 up &amp;&amp; ping -c 10 -s 10 192.168.1.2 &amp;&amp; sudo /etc/init.d/nfs-kernel-server start   on the first netbook and  $ sudo ifconfig eth0 192.168.1.2 up $ ping -c 10 -s 10 192.168.1.1 $ mount /mnt/network1   on the second  where /mnt/network1 is specified in /etc/fstab as  192.168.1.1:/home /mnt/network1 nfs noauto,user,exec,soft,nfsvers=2 0 0  as well as in /etc/exports (using the syntax of that file), on the first netbook.  The above works fine, but the files and directories are huge. The files average about half a gigabyte a piece, and the directories are all between 15 and 50 gigabytes.   I'm using rsync to transfer them, and the command (on 192.168.1.2) is  $ rsync -avxS /mnt/network1 ~/somedir   I'm not sure if there's a way to tweak my NFS settings to handle huge files better, but I'd like to see if running an rsync daemon over plain old TCP works better than rsync over NFS.  So, to reiterate, how do I set up a similar network with TCP?  UPDATE:  So, after a good at few hours of attempting to pull myself out of the morass of my own ignorance (or, as I like to think of it, to pull myself up by my own bootstraps) I came up with some useful facts.  But first of all, what led me on this rabbit trail instead of simply accepting the current best answer was this: nc is an unbelievably cool program that resolutely fails to work for me. I've tried the netcat-openbsd and netcat-traditional packages with no luck whatsoever.  The error I get on the receiving machine (192.168.1.2) is:  me@netbook:~$ nc -q 1 -l -p 32934 | tar xv Can't grab 0.0.0.0:32934 with bind tar: This does not look like a tar archive tar: Exiting with failure status due to previous errors   route gives:  me@netbook:~$ route Kernel IP routing table Destination     Gateway         Genmask         Flags Metric Ref    Use Iface default         dir-615         0.0.0.0         UG    0      0        0 wlan0 link-local      *               255.255.0.0     U     1000   0        0 eth0 192.168.0.0     *               255.255.255.0   U     2      0        0 wlan0 192.168.1.0     *               255.255.255.0   U     0      0        0 eth0   But, here's the good news: having the static IP addresses set in /etc/network/interfaces, which I started doing while trying to get nc working, fixed all my NFS problems and rekindled my love for NFS.  The exact configuration I used (with 192.168.1.1 for the first netbook, of course) was:  auto eth0 iface eth0 inet static address 192.168.1.2 netmask 255.255.255.0   With those settings, the two netbooks will be able to ping each other directly after being booted up, without even an ifup.  Anyway, I'd still really like to see nc in action, so I'm hoping someone help me debug this process. Examples  I've recently found examples of using pairs of enclosing braces {}, with nothing in between the opening and closing braces, as arguments to commands and even to their options:  cat foo | xargs -I{} echo {}  find . -size 0 -exec rm -i {} \;  No Documentation  My problem is that I cannot find a documentation in the  that describes the usage of {} in such context as in the examples above.  I do not think it is a , because a dollar sign must precede the enclosing braces in a parameter expansion as in ${}.  It cannot be a  either, because it takes the form of {x..y[..incr]}, where x and y are not optional.  It also cannot be a  either, because {} is used as arguments.  Questions   What does a pair of enclosing braces {} even mean, in general, as an argument to any command that accepts it? Where can I find a documentation that describes the usage of {} as arguments? When documenting location, should current or historical place names be used? When I am documenting records, do I use the name of a city or country as it is called today or as it was in the year an ancestor was there?  Related to: How can we prove that for every pair $N \in \mathbb{N}$, and natural number $\beta\in [2, \infty)$ there exists a unique set of integers $x_i \in [0, \beta -1]$, $k\in [0,\infty)$ such that:  $$N = \sum_{i=0}^{k}\beta^ix_{i}, \quad $$  It's a question if every positive integer has its unique representation in every base $\beta$. Is the validity of above statement somehow related to Horner's rule? Cannot add PPA: 'ppa:~darklin20/ubuntu/bomi'.     ERROR: '~darklin20' user or team does not exist.   Showing this message when suing this command:    sudo add-apt-repository ppa:darklin20/bomi   please help me. Are the "umbles" etymologically related? From      And we show telltale signs of early hypothermia, what the doctor and   the National Institutes of Health and other cold-weather cognescenti   call the "umbles."      First we lose some fine motor skills, McLaren says, "and we start to   fumble. And tumble. And stumble."      Then our cognitive abilities are compromised. "We mumble and we   grumble."   Are the "umbles", such as fumble, tumble, stumble, mumble and grumble, etymologically linked, either in terms of sharing a common ending, or entire words having a common ancestor?  Trying to do a search of the etymology of the umbles ended up giving the etymology of the word  instead. I need to purchase my first ever lens. So far I've only used lenses that were built into a camera. This specific lens is for the BlackMagic Deign Pocket Cinema Camera (a video only camera, but one that uses photography lenses). I would prefer this to be a prime lens.  I have tried to find the exact way to calculate the focal length of the lens I need but I have not been able to find a good resource to make this simple enough for my limited optics knowledge. Can you please explain a simple way to calculate the focal length of a lens given the following inputs as an example:    I would prefer a simplified mathematical explanation so that I may use it to make similar determinations in the future using a "" method.  I have . Using that method, I came up with:  Required lens focal length = 7.02mm sensor height x (77in / 36in) = 15mm   Is that correct? How to run an encrypted virtual machine?