How do we know that superposition exists?
Has it been practically proven that quantum superposition exists ? If yes, how does it even work?
I'm trying to solve the following problem:  Given two CRHF $H_1:2^{4n}\to2^{2n}$, $H_2:2^{2n}\to 2^n$, construct the following hash function $H^{*}=H_2(H_1(x))$ compressing from $2^{4n}\to 2^n$. We want to demonstrate that if $H_1$ and $H_2$ are collision resistant then $H^*$ must be collision resistant too.  I made the following reduction  However I'm still unsure on how to calculate ”BAD event” in which $A^{H^∗}$ outputs a collision for $H_{s_1}$, in this case $x^∗=x′$ and the second part of the reduction doesn’t work. {genealogytree} How to model my Cousins The velocity of the flowing coming out of the balloons? Last day , when i was working on two interconnected balloons , a question was kicking my brains !!! This is the explanation of the question:  First , suppose a system that composed of two spherical membranes filled with air (two balloons have different initial volumes {means that the pressure inside which balloons are different} and the air pressure is 1 a.t.m) . We connect them with hollow tube and a valve. When we open the valve , one of them shrinks and the other one expands (It depends on their pressure) .  So how can we get the velocity of the flowing air between two balloons? (Consider everything but if you have reasons for not considering one of them -for example the ratio of friction in the tube- Don't consider them and just tell me the reason)  Thanks Reading ODBC connection using QGIS? I have a co-worker who manages a large MS Access database that contains X &amp; Y fields for various locations he tracks.  We have previously exported the data to CSV and used the QGIS Delimited Text Plugin to plot the locations.  We would now like to be plot this data directly in QGIS by connecting to the MS Access db via an ODBC connection (as opposed to export to CSV).   Can QGIS consume the data from the ODBC connection to plot the X-Y locations? Can it be "live linked" to the ODBC connection so that when a project is re-opened, the layer "replots" all old and newly added locations dynamically (as opposed to exporting to shapefile, which would create a snapshot in time)? Can you create tabular ODBC connections that can be joined to spatial tables within QGIS?   You can do all of this in ArcGIS ("Add XY Data" tool), so it would be great if this capability existed in QGIS. I just cannot find anywhere that mentions its existence.  I am not planning to move to a spatial database.  As a GIS person myself, yes I know that it makes sense to move to a spatial database, and yes I have used PostGIS to manage this kind of data.  But these are not options right now.  The user is not a GIS person nor wants to be, and he manages his own database in MS Access and that will not change.  I am and am pulling him kicking and screaming into the GIS world and want to make it easy as possible.  He can live with exporting to CSV, I was just hoping there is a better solution USING ODBC FOR MS ACCESS and displaying the XY data in QGIS. Is  structured data (in Microdata, JSON-LD, or RDFa) relevant for SEO?   I know that structured data can provide benefits in other areas, but here I’m only asking about its significance for general web search engines. Why is polynomial regression considered a special case of multiple linear regression? If polynomial regression models nonlinear relationships, how can it be considered a special case of multiple linear regression?  Wikipedia notes that "Although polynomial regression fits a nonlinear model to the data, as a statistical estimation problem it is linear, in the sense that the regression function $\mathbb{E}(y | x)$ is linear in the unknown parameters that are estimated from the data."  How is polynomial regression linear in the unknown parameters if the parameters are coefficients for terms with order $\ge$ 2? How to create a permanent "alias"? If you create an alias for example:   alias cls="clear"   It exists untill you kill terminall session. When you start a new terminal window the alias doesn't exist any more. How to create "permanent" alias, one that exists in every terminal session? Enabling CORS in GeoServer (jetty)? I hope somebody has already figured this one out. I just installed Geoserver 2.9 on a vanilla Ubuntu 16.04 distro. The Geoserver 2.8 method of enabling CORS with the shanbe.hezoun class does no longer work with Jetty 9.2.13.  There are mentions that CORS support is already packaged with Jetty 9.2.13 in the jetty-servlets.jar.  The Jetty lib which is compiled with Geoserver contains a jetty-servlet-9.2.13.v20150730.jar in geoserver/lib but not jetty-servlets.9.2.13.v20150730.jar. Are these supposed to be the same jar with a different name?  It should be possible to enable CORS either in geoserver/etc/webdefault.xml or in geoserver/webapps/geoserver/WEB-INF/web.xml.  My understanding is that the webdefault.xml is applied first and the web.xml thereafter.  I have tried following filter in both xml. I haven't got as far as adding a filter mapping. Adding the filter alone will cause the Geoserver/Jetty service to not start proper.  &lt;filter&gt;     &lt;filter-name&gt;cross-origin&lt;/filter-name&gt;     &lt;filter-class&gt;org.eclipse.jetty.servlets.CrossOriginFilter&lt;/filter-class&gt; &lt;/filter&gt; I just installed Ubuntu 14.04.3 LTS after installing windows 10 in my new VN7-571G and the wireless is not working. It never had: even during the installation it was not recognized. I run a script to gather the data , which is . lspci -knn | grep Net -A2 output 03:00.0 Network controller [0280]: Qualcomm Atheros Device [168c:003e] (rev 20)         Subsystem: Lite-On Communications Inc Device [11ad:0804]  The OS behaves like it has no wifi card. I do not see wifi settings in network settings I'm not a linux power user, so I do not know what to do to solve the issue. What should I do to make it work? Create WiFi hotspot on ubuntu Although many questions have already been asked regarding WiFi hotspot, I didn't get any of the solutions working for me.  I connect to the Internet using a 3G Dongle of Huawei 3772 (Vodafone). The connection type is Mobile Broadband connection. I have to share this Internet connection with my other devices like mobile phones and laptops.  How can I create a WiFi hotspot connection for this connection.  I am using Ubuntu 12.04 LTS.  I would like to note that I have already tried some help links from Ubuntu but, they are so confusing that I could not understand them. Can someone please explain how I can install  in the following ways?   By using the package manager? By downloading and installing a pre-built package? python: restarting a loop i have:  for i in range(2,n):     if(something):        do something     else:        do something else        i = 2 **restart the loop   But that doesn't seem to work. Is there a way to restart that loop?   Thanks How far into space does one have to travel to see the entire sphere of earth? Virgin Galactic will take passengers aboard SpaceShipTwo  above the surface of the earth. But from this altitude, passengers will only be able to see a certain segment of the curvature of the earth through .  How much further into space would SpaceShipTwo have to travel to give passengers a view of the entire sphere of earth through one of these windows? How Can I Concatenate Column A and Column B into Column C in Excel? Column A has first name.  Column B has last name.  I need column C to be "display name" (first name and last name separated by a space).  I assume this involves the concatenate function.  Bonus Question: Column D is email address.  I need column E to be "username" (everything in email address left of the @ symbol).  I assume this involves some regular expression function. Is it correct to use "their" instead of "his or her"? Is this sentence grammatically correct?  Anyone who loves the English language should have a copy of this book in their bookcase.  or should it be:  Anyone who loves the English language should have a copy of this book in his or her bookcase. Understanding d-separation theory in causal Bayesian networks I am trying to understand the d-Separation logic in Causal Bayesian Networks. I know how the algorithm works, but I don't exactly understand why the "flow of information" works as stated in the algorithm.    For example in the graph above, lets think that we are only given X and no other variable has been observed. Then according to the rules of d-separation, the information flow from X to D:   X influences A, which is $P(A)\neq P(A|X)$. This is OK, since A causes X and if we know about the effect X, this affects our belief about the cause A. Information flows. X influences B,which is $P(B)\neq P(B|X)$. This is OK, since A has been changed by our knowledge about X, the change at A can influence our beliefs about its cause, B, as well. X influences C,which is $P(C)\neq P(C|X)$. This is OK because we know that B is biased by our knowledge about its indirect effect, X, and since B is biased by X, this will influence B's all direct and indirect effects. C is a direct effect of B and it is influenced by our knowledge about X.   Well, up to this point, everything is OK for me since the flow of the information occurs according to intuitive cause-effect relationships. But I don't get the special behavior of so called "V-structures" or "Colliders" in this scheme. According to the d-Separation theory, B and D are the common causes of C in the graph above and it says that if we did not observe C or any of its descendants, the flow information from X is blocked at C. Well, OK, but my question is why?  From the three steps above, started from X, we saw that C is influenced by our knowledge about X and the information flow occurred according to the cause-effect relationship. The d-Separation theory says that we cannot go from C to D since C is not observed. But I think that since we know that C is biased and D is a cause of C, D should be affected as well while the theory says the opposite. I am clearly missing something in my thinking pattern but can't see what it is.  So I need an explanation of why the flow of information blocked at C, if C is not observed. Does C# have an equivalent to JavaScript's encodeURIComponent()? In JavaScript:  encodeURIComponent("©√") == "%C2%A9%E2%88%9A"   Is there an equivalent for C# applications? For escaping HTML characters I used:  txtOut.Text = Regex.Replace(txtIn.Text, @"[\u0080-\uFFFF]",     m =&gt; @"&amp;#" + ((int)m.Value[0]).ToString() + ";");   But I'm not sure how to convert the match to the correct hexadecimal format that JS uses. For example this code:  txtOut.Text = Regex.Replace(txtIn.Text, @"[\u0080-\uFFFF]",     m =&gt; @"%" + String.Format("{0:x}", ((int)m.Value[0])));   Returns "%a9%221a" for "©√" instead of "%C2%A9%E2%88%9A". It looks like I need to split the string up into bytes or something.  Edit: This is for a windows app, the only items available in System.Web are: AspNetHostingPermission, AspNetHostingPermissionAttribute, and AspNetHostingPermissionLevel. Setup or "set up"? The word setup (as a noun), I feel, has become an acceptable part of the English language, at least insofar as technical manuals or computer textbooks are concerned. However I find that the word is used very often in verb form like so:     "You can setup the program quite easily ..."   when in fact my understanding is that the actual sentence should be:     "You can set up the program quite easily ..."   I would like to know if setup can be used as a verb. The situation seems be very similar to the word output (as a noun). Output is a purely technical word and its use is restricted solely to technical texts or at least in a technical context within non-technical books. However it is also used in verb form now like so:     "The system will output the signal ..."   I would be very grateful if this question is answered. Thank you Mapping ManyToMany with composite Primary key and Annotation: When I try to bring down the Achievements tab in Area 51, it's showing an error dialogue.  Strangely enough, the global inbox dropdown works just fine.  Could be connected to .  Screenshot: