? and ! after a question, what does it mean
Is there a difference between “?!” and “!?”?
Putting char into a java string for each N characters I have a java string, which has a variable length.   I need to put the piece "&lt;br&gt;" into the string, say each 10 characters.   For example this is my string:  `this is my string which I need to modify...I love stackoverlow:)`   How can I obtain this string?:  `this is my&lt;br&gt; string wh&lt;br&gt;ich I nee&lt;br&gt;d to modif&lt;br&gt;y...I love&lt;br&gt; stackover&lt;br&gt;flow:)`   Thanks Is this proof of $\liminf E_k \subset \limsup E_k $ correct? I am wondering if my proof is correct? Thank you for whoever willing to take a look at it for me.     Proof $\liminf E_k \subset \limsup E_k $   If $\{E_k\}_{k=1}^\infty$ is a sequence of sets, we define \begin{align*} \limsup E_k &amp; = \bigcap_{j=1}^\infty\left(\bigcup_{k=j}^\infty E_k\right)\\ &amp;= \bigcap_{j=1}^\infty(E_j \cup E_{j+1} \cup \cdots)\\ &amp;= (E_1 \cup E_2 \cup \cdots) \cap (E_2 \cup E_3 \cup \cdots) \cap \cdots. \end{align*}  Therefore, $\limsup E_k$ consists of those points in $\mathbb{R}^n$ which belong to infinitely many $E_k$. \begin{align*} \liminf E_k &amp; = \bigcup_{j=1}^\infty\left(\bigcap_{k=j}^\infty E_k\right)\\ &amp;= \bigcup_{j=1}^\infty(E_j \cap E_{j+1} \cap \cdots)\\ &amp;= (E_1 \cap E_2 \cap \cdots) \cup (E_2 \cap E_3 \cap \cdots) \cup \cdots. \end{align*} Therefore, $\liminf E_k$ consists of those points in $\mathbb{R}^n$ which belong to all $E_k$ for $k \geq k_0$.  Now consider $x \in \liminf E_k$, then $x \in E_1 \cap E_2 \cap \cdots$, or $x \in E_2 \cap E_3 \cap \cdots$ and so on, that is to say, $x \in E_{k_0} \cup E_{k_0+1} \cup \dots$ for some $k_0$. More specifically, $x \in E_k \forall k \geq k_0$. Therefore, $x \in (E_1 \cup E_2 \cup \cdots) \cap (E_2 \cup E_3 \cup \cdots) \cap \cdots$, so we showed $x \in \limsup E_k$. I was wondering if mobs can go through doors or not. It's the difference between me just putting up a door to my house, or putting up dirt instead. Calculating $1+\frac13+\frac{1\cdot3}{3\cdot6}+\frac{1\cdot3\cdot5}{3\cdot6\cdot9}+\frac{1\cdot3\cdot5\cdot7}{3\cdot6\cdot9\cdot12}+\dots? $ How to find infinite sum How to find infinite sum $$1+\dfrac13+\dfrac{1\cdot3}{3\cdot6}+\dfrac{1\cdot3\cdot5}{3\cdot6\cdot9}+\dfrac{1\cdot3\cdot5\cdot7}{3\cdot6\cdot9\cdot12}+\dots? $$   I can see that 3 cancels out after 1/3, but what next? I can't go further. If you open any of localized meta site in browser's private mode, e.g.  you will see untranslated text on the top right corner:        This message is not found in Transifex, hence unable to localize.  Related bug report on ruSO.meta: Update:   Once upon a time there was a feature called . Its goal was to help our most active users find the questions they can answer. &quot;New nav&quot; never made it out of beta and that beta only ever made it to Stack Overflow users. Several months ago we gave new nav a sad, but overdue burial. As we promised, we've been working on a replacement for new nav, and now it's time for us to start rolling it out. We're calling it custom question lists and we are really excited about its potential to help all users get at the questions that are most interesting to them. While we hope what we've built hits the mark for many of you who have requested a feature like this (e.g., , , , , , ), we know how difficult it is to make something complex simple. So, we are rolling this out in beta to gather feedback from you and iterate on it. (Don't worry, we promise to actually release it this time.) When it's live later you'll be able to opt-in to the beta by turning on a new account preference. This will enable the feature for Stack Overflow, Meta Stack Overflow, and Meta Stack Exchange. It will be available for all network sites when the beta period is over. Schedule for future improvements This feature will roll out in four phases:  Phase I: Filter and sort controls to let you modify a question list view (Julyish) Phase II: Saved custom lists (In progress, ETA November 2018) Phase III: Notifications on custom lists (December 2018) Phase IV: Final fixes and official release (January 2019)  Sneak peak Phase I: Filter and sorts We'll add filter and sort controls to question lists. This does two things:  Clarifies the definition of built-in views - Naming is hard and short names can't always describe what a view is showing you. By exposing the filter and sort controls it is more obvious. Introduces the ability to create new custom views - This won't be super useful until we add the ability to save the views to the UI (phase II). Until then you can bookmark the URL and get back to your views.  Question list with new controls   Views drop down   Filter   Sort   Phase II: Saved custom question lists In this phase we will add the ability to save your custom questions lists. Create custom list In our current design, a dialog will be pre-populated based on the filters and sorts you're currently using. Give it a name, confirm your options, and click save.  Accessing your saved lists When you save your custom lists they will show up in the &quot;More&quot; drop down for question list views. Additionally, you can add them to the left navigation bar for easy access (see image below).  Phase III: Notifications For phase III we'll enable indicators for when new items are available in a custom question list. When you pin a question list to the left nav you can see a dot on any list with new items.  Feedback welcome As usual, we're interested in your constructive feedback. This is a work in progress and, as mentioned, will be rolled out in phases. You can provide feedback on the concepts now based on the information in this post and provide feedback based on the working elements as they are released. A correct preposition - account closed due/by/at 12th of May sObject ' ' type is not supported Hey everyone I've been seeing this a lot lately and am trying to figure out why this error is thrown when querying the SOAP API directly. I've tried several very basic SOQL queries such as  SELECT Body FROM AssetFeed   Only to be met with the sObject type 'AssetFeed' is not supported. error.  The account that I'm currently querying is just a standard user who accepted permission from an app that was created by a Developer Account, so I'm wondering if it might be permissions from the user or permission from the app itself? Possibly because Developer accounts cannot use 95% of whats offered?  The WSDL used is a v27.0 generated Partner WSDL if that helps narrow it down.  I've noticed this in multiple standard objects, so I'm wondering what the trend really is? Seems like a good informational question for future googling of others?  Running describeGlobal()  Array (     [0] =&gt; AggregateResult     [1] =&gt; Attachment     [2] =&gt; ChatterActivity     [3] =&gt; CollaborationGroup     [4] =&gt; CollaborationGroupFeed     [5] =&gt; CollaborationGroupMember     [6] =&gt; CollaborationGroupMemberRequest     [7] =&gt; CollaborationInvitation     [8] =&gt; ContentDocument     [9] =&gt; ContentDocumentFeed     [10] =&gt; ContentDocumentHistory     [11] =&gt; ContentDocumentLink     [12] =&gt; ContentVersion     [13] =&gt; ContentVersionHistory     [14] =&gt; EntitySubscription     [15] =&gt; FeedComment     [16] =&gt; FeedItem     [17] =&gt; FeedLike     [18] =&gt; FeedTrackedChange     [19] =&gt; Group     [20] =&gt; GroupMember     [21] =&gt; HashtagDefinition     [22] =&gt; Name     [23] =&gt; TaskPriority     [24] =&gt; TaskStatus     [25] =&gt; User     [26] =&gt; UserFeed     [27] =&gt; UserPreference     [28] =&gt; UserRecordAccess     [29] =&gt; UserRole )   Where would all the rest of my SOAP SObjects be? This seems like a very thin list compared to the 295 SObjects advertised Windows says RAM ran out while there is still 4 GB of physical memory available How can I represent multiple pins at the same location on a map? How to disable all caches in safari 11? I am using Safari to develop for a while. One thing I always liked is when you clear the cache, it really does, unlike other browsers I tried in the past. But in previous versions, specially when working in a code in a local testing server, just reloading the page will reload everything from disk. Now I have to use de shortcut command+alt+e to clear before reload or some new CSS won't load, even some http request will return old values. Just reloading the page won't guarantee to show me the last modifications.  I looked at preferences and develop menu but didn't find an option to just don't use any caches at all - the perfect option will be don't use caches when I have the web inspector opened, means I am developing.  Did I miss this option, or there is another way to disable all caches? Intuition for Rayleigh PDF We have ground-truth data $\mathbf{x}^* = (0,0)^T \in \mathbb{R}^{2}$. Furthermore, we have $N$ measurements $\mathbf{x}_i \in \mathbb{R}^{2}, i\in \{1,\ldots,N\}$. We calculate the $N$ error vectors $\mathbf{e}_i = \mathbf{x}_i - \mathbf{x}^*$. We assume that the two components of $\mathbf{e}_i = (e_{x,i}, e_{y,i})^T $ are independent of each other and normally distributed with equal mean $\mathbf{\mu} = (0,0)^T$ and variance $\sigma^2$. The absolute errors $e_i = \sqrt {e_{x,i}^2 + {e}_{y,i}^2} $ follow a Rayleigh distribution, is that correct?  The probability density function (PDF) of the Rayleigh function is zero at a value of zero. Why is this the case (intuitively)? I would assume that our errors should most likely be 0 (i.e. PDF should be highest at 0)... $n!+1$ being a perfect square Looking for a 1000 most frequent english words Is there a free list of 1000 most frequent words used in everyday English? If there is a list with usage examples (as each of those words has multiple meanings for sure, not to cound phrasal verbs), it would be even greater.  Is there something alike, but with phrases? (E.g. 1000 most frequent phrases) Aborting evaluation when the memory exceeds a certain limit How to use Class in Java? There's a good discussion of Generics and what they really do behind the scenes over at , so we all know that Vector&lt;int[]&gt; is a vector of integer arrays, and HashTable&lt;String, Person&gt; is a table of whose keys are strings and values Persons.  However, what stumps me is the usage of Class&lt;&gt;.  The java class Class is supposed to also take a template name, (or so I'm being told by the yellow underline in eclipse).  I don't understand what I should put in there.  The whole point of the Class object is when you don't fully have the information about an object, for reflection and such.  Why does it make me specify which class the Class object will hold?  I clearly don't know, or I wouldn't be using the Class object, I would use the specific one. Are questions about (development) devices allowed on Stack Overflow? I've seen many questions on Stack Overflow asking which devices are best for developers. This made me wonder if questions asking for hardware device recommendations (best device for programming, best device within a certain budget, etc.) are on-topic for Stack Overflow, or if they should be asked somewhere else?  For Instance check these links:         etc. Distribution of Product of Random Variables with one being the normal distribution. Why do I see different versions of node and nodejs I ran the following commands to install the stable version of node  sudo npm cache clean -f sudo npm install -g n sudo npm install -g n   Now, when I run node -v, I see v10.0.0, whereas nodejs -v returns v4.2.6. As far as I'm aware, node and nodejs are the same thing. Why am I seeing this? Thanks. What was with the two different colored prison uniforms in Daredevil season 2? In Daredevil S02, we see two kinds of prison uniforms, full orange and full white. We see in the flashback that Wilson Fisk gets a white prison uniform but his current one was orange.  The Punisher was also given a white prison uniform but most of the prisoners had orange uniforms. What was with the two different colored uniforms? Does it have some significance or is it just random? Does it happen similar in real life US prisons too?