If I have a spawner at y level 12 and AFK there will it run my farms at the the same x and z level above ground (will it load the chunks?)
What's the max height of blocks for a redstone contraption to still work even I'm in the surface below?  Like if I build a pillar to the max height of blocks and build a redstone contraption there, is it still going to work even I'm on the surface below?
How do I remove repeated elements from ArrayList? I have an ArrayList&lt;String&gt;, and I want to remove repeated strings from it. How can I do this? I have two raster datasets, they have different projected coordinate systems; one in WGS_84_UTM_Zone_N34, another in Hungarian_1972_EOV,  they overlap each other perfectly if I open them in QGIS.   I would like to transform the coordinate system of the first raster into the second.  I tried Project Raster tool in Data Management toolbox (ArcGIS), it converted the first raster into Hungarian_1972_EOV, but it doesn't overlap with the second raster perfectly (There is a shift between two raster datasets fo about 10-15 meters).   Can anybody help me to find out what is the problem? How long can I store a food in the pantry, refrigerator, or freezer? SMTP 25 closed even though I allow everything in firewall (Debian server running sendmail) I am running sendmail + dovecot in my Debian server. I have enabled the firewall rules to allow everything:   iptables -P INPUT ACCEPT   iptables -P OUTPUT ACCEPT   iptables -P FORWARD ACCEPT   iptables -F   iptables -X  However after a quick check at yougetsignal.com, my port 25 is still being blocked. But 143, 80 are okay. I was wondering what the cardinality of the set of all real sequences is. A random search through this site says that it is equal to the cardinality of the real numbers. This is very surprising to me, since the cardinality of all rational sequences is the same as the cardinality of reals, and it seemed fairly intuitive to me that if cardinality of a set $A$ is strictly greater than the cardinality of the set $B$, then cardinality of $A^{\mathbb{N}}$ should be strictly greater than cardinality of $B^{\mathbb{N}}$. It turns out to be false.  Some technical answers have appeared in this forum elsewhere but I do not understand them. As I am not an expert in this topic, could some one explain me in simple terms why this is happening?  Also is the cardinality of all functions from reals to reals also the same as the cardinality of reals? Find the limit $\lim_{n\rightarrow\infty}\sum_{k=1}^{n}\frac{1}{k+n}$ $$\lim_{n\rightarrow\infty}\sum_{k=1}^{n}\frac{1}{k+n}$$  Could you please give me a hint how to find this limit? Prove: $$x^\alpha-\alpha x \le 1- \alpha  \\ \forall x\ge 0 \ ,  \ 0&lt;\alpha &lt;1$$   It does resamble Lagrange's MVT, in order to get to the RHS, say $\alpha\in[0,1]\Rightarrow \frac{1-\alpha-0^\alpha-\alpha 0}{1-0}=1-\alpha$.  But I'm not sure what to do about the LHS. I always get a negative value in the LHS and we know that the RHS will always be postive but that doesn't really help with proving it...  Edit: maybe define a function: $g(x) = x^\alpha-\alpha x - 1+ \alpha$ Derive it: $g'(x) = \alpha x^{\alpha-1}-\alpha $ but then I get to $x^{\alpha-1}=0$    Also, I had two questions when trying to figure this out:   Can we use deriviation of both sides of an inequality to prove it ? Can we use limit of both sides of an inequaltiy to prove it ?   Thanks. We've drastically simplified the user deletion process! How does order-preserving encryption work? Order-preserving encryption (OPE) is, apparently, a method of encrypting data so that it's possible to make efficient inequality comparisons on the encrypted items without decrypting them.  I've been coming across this term in various places (including ) lately, but I have no idea how such encryption schemes are supposed to work.  Any obvious methods I can think of to allow such comparisons on encrypted data would result in catastrophic security failure.  Certainly, I assume that OPE must involve some kind of security tradeoff compared to traditional encryption, but given that it seems to be actively  and , it seems that it must be possible to implement in a way that retains at least some level of useful security.  I just don't see how.  Given that  didn't turn up any convenient Wikipedia articles or other popular summaries of OPE, I figured I'd try asking for one here before diving into the academic literature.  (At worst, I may try to answer my own question later, if nobody else beats me to it.)  So, to summarize, my question is: How does order-preserving encryption work, and what security properties does it provide? Quantifiers "most" vs. "most of" Coloring specific elements of sets with a prime modified order in an array plot I want to mount the device /dev/sda3 to the directory /foo/bar/baz. After mounting the directory should have the uid of user johndoe. So I did:  sudo -u johndoe mkdir /foo/bar/baz stat -c %U /foo/bar/baz johndoe   and added the following line to my /etc/fstab:  /dev/sda3 /foo/bar/baz ext4 noexec,noatime,auto,owner,nodev,nosuid,user 0 1   When I do now sudo -u johndoe mount /dev/sda3 the command stat -c %U /foo/bar/baz results in root rather than johndoe. What is the best way to mount this ext4-filesystem with uid johndoe set? ''will'' or ''going to'' Resize multiple layers around their respective anchor points What happened to /etc/apt/apt.conf? I was browsing through the apt folder to try my proxy settings and I was unable to find the apt.conf file in Ubuntu 11.04. Is there any alternative file for it?  Adding proxy settings to 99-synaptic in apt.conf.d does not help as it gets overwritten everytime I restart the system. How do I pluralize Italian foods, like pasta noodles (spaghetti, macaroni)? Possible Duplicate:             Is it proper to say spaghettis for more than one spaghetti noodle?  What about macaronis as a plural for more than one macaroni noodle? Distribution of linear combination of OLS regression coefficients What does `exec {STDIN}>&0` do? I have a very large folder that I am trying to create a tar archive of. The issue is I don't have enough extra free space to store the entire archive so I want to create say 100-200GB chunks of the archive at a time and transfer those individually to cloud storage. I need to be able to control when new chunks are created so my HDD doesn't fill up but all of the commands i've found to create split tarballs always create it all at once, in the same directory. The closest solution I found was from  but all the responses base the archives on number of files, not size which is important for my use case as my file sizes are unevenly distributed. How can I better optimize my tables and a LEFT JOIN query to find items that don't yet exist in the right table? I have two tables that represent a list of urls and their related word indexes. Here are the table definitions for reference.  desc urllist; +-------+---------------------+------+-----+---------+----------------+ | Field | Type                | Null | Key | Default | Extra          | +-------+---------------------+------+-----+---------+----------------+ | id    | bigint(20) unsigned | NO   | PRI | NULL    | auto_increment | | url   | text                | NO   |     | NULL    |                | +-------+---------------------+------+-----+---------+----------------+   and  desc wordlocation; +----------+---------------------+------+-----+---------+-------+ | Field    | Type                | Null | Key | Default | Extra | +----------+---------------------+------+-----+---------+-------+ | urlid    | bigint(20) unsigned | NO   |     | NULL    |       | | wordid   | bigint(20) unsigned | NO   |     | NULL    |       | | location | int(10) unsigned    | NO   |     | NULL    |       | +----------+---------------------+------+-----+---------+-------+   The software app is a web spider. It crawls a list of urls, extracts those urls, and inserts these into the urllist table. Then, an indexer checks to see what urls have not yet been indexed, and then proceeds to index said urls.  Here is the query I am using to find items in the left table (urllist) that have not yet been indexed in the right table (wordlocation). This query is as suggested on the :  select * from urllist ul  left join wordlocation wl on ul.id = wl.urlid  where wl.urlid IS NULL;   As of this writing my test database has only 600 indexed urls, and the wordlocation table has 1.3 million rows.  However, my CPU is at 100%, and the longest I've waited to see if the query would complete is a half hour (which, it never did by the way).  To be thorough, here is the explanation of the query:  explain select * from urllist ul left join wordlocation wl on ul.id = wl.urlid where wl.urlid IS NULL; +----+-------------+-------+------+---------------+------+---------+------+---------+-------------------------+ | id | select_type | table | type | possible_keys | key  | key_len | ref  | rows    | Extra                   | +----+-------------+-------+------+---------------+------+---------+------+---------+-------------------------+ |  1 | SIMPLE      | ul    | ALL  | NULL          | NULL | NULL    | NULL |   50364 |                         | |  1 | SIMPLE      | wl    | ALL  | NULL          | NULL | NULL    | NULL | 1351371 | Using where; Not exists | +----+-------------+-------+------+---------------+------+---------+------+---------+-------------------------+   I need this query to finish in seconds, not minutes. Also, I'm worried about scalability. I have 40,000 unique urls that are waiting to be added to the index, so how do I take that into consideration with my table and query design? 400,000 urls?  Just a couple notes about my decisions on the current table structure.  I have no intention of stopping at 400,000 urls, but perhaps bigint(20) is a bit overzealous?   Url as text is for more practical reasons. I index a lot of Asian and other foreign language domains which do not appear as their equivalent Kanji or other characters in the database and frequently take more than 255 characters.  I'm using MySQL. I'm definitely open to suggestions as to better table and query design. Please let me know if I can provide more information.