Wikipedia:Reference desk/Archives/Computing/2016 January 21

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January 21

Complexity of Addition in Finite Automata

I couldn't understand the finite automata shown in the Article on Finite Automata(P.65).It might be because I'm weak in binary mathematics.Addition is very simple.I can't get why the author has shown 'addition' as complex.Could anyone help me and give a brief explanation of each state given in the finite automata.JUSTIN JOHNS (talk) 08:19, 21 January 2016 (UTC)

The section (which begins at p. 53) is named "The complexity of addition". It could well be named the "simplicity of addition". In both cases the author would not be implying that binary addition is simple, or complex. He just wants to describe its complexity. As a side note, I have to say that the complexity of binary addition is lower than that of decimal addition. Scicurious (talk) 13:08, 21 January 2016 (UTC)

You'll probably get more from the course notes than from the lecture slides, unless you are actually attending lectures. The slides, by themselves, are not very instructive; they are only supplemental cues for the speaker. Nimur (talk) 15:30, 21 January 2016 (UTC)

This is really a linguistics question. For the author (I'm not sure about English-speakers in general) "complexity" is unmarked, "simplicity" is marked. Simpler instance: asking "how tall is he?" does not imply he is tall, whereas "how short is he?" does imply he is short. jnestorius^(talk) 15:34, 21 January 2016 (UTC)

It also looks like there have been some rearrangements of that class syllabus ("a pretty serious overhaul", according to the lecturer); the Fall 2015 course reader does not contain a chapter on discrete finite automata. I bet this class was split in half..., so we'll have to track down notes for the subject matter you're looking for.

Question for the OP: why are you reviewing the lecture slides for 2011, in the first place?

The current syllabus for this section, covering DFAs, refers to Sipser's book, which I do not believe is available online at zero-cost. If you're having trouble following lecture slides, that book would be your best resource to help explain it. It is available for purchase.

Nimur (talk) 15:36, 21 January 2016 (UTC)

Probably I guess that there isn't any notes for 'complexity of addition' or even for 'finite automata' in 2011 eventhough slides are present.I'm reading the lectures in 2011 because I think it's the most 'stable' one.I couldn't see anything in the course notes that tell about 'complexity of addition' or even about 'finite automata'.I would just like to get an explanation of the DFA shown in the Article on Finite Automata(P.65).Could anyone help me.JUSTIN JOHNS (talk) 09:08, 22 January 2016 (UTC)

Testing an HTML script before publishing online?

Is there a way to test an HTML+CSS+JavaScript script before publishing online on one's own web server and buying a domain name? What if the webmaster also wants to do a bit of server-side scripting in order to create a database of registered users? Is there a way to test out the script before it is published online? What happens if the website becomes popular and traffic unexpectedly rises sharply? How do people generally upgrade the hardware to support the incoming traffic and keep the website running? How much does it cost to upgrade hardware? 140.254.136.149 (talk) 17:55, 21 January 2016 (UTC)

You can test your web-page in your local browser, in a server running in your computer. There is no need to go public for this. You certainly won't need a domain name for this.

You probably don't want to manage the hardware yourself. Hosting has become quite cheap and flexible. There are enough providers of hosting in the cloud that will provide their service no matter if your site gets a couple of hits or several thousand (and charge you accordingly). --Scicurious (talk) 18:38, 21 January 2016 (UTC)

You still have not answered how to test the webpage in the local browser in a server running on one's own computer. And you still haven't answered the question regarding maintaining a website on one's own server. Sometimes, one wants to have one's own web server, because one wants to do client-side and server-side scripting and allow the website to become user-friendly, dynamic, and interactive. In that case, a web host just won't do. 140.254.136.149 (talk) 19:23, 21 January 2016 (UTC)

If you're not doing server-side includes/scripting, then you can just place the files in a directory on your PC, and point the browser at it (drag the starting page from the file explorer into your web browser. For SSI, or more extensive testing, you can install the Apache (on all operating systems), or Microsoft IIS Express (MS-Windows OSes, XP or later). Apache is free and fully fledged. IIS Express is free, fully-featured, but hobbled to a few connections at a time, but you won't run into them when testing your own pages. For either server, point your browser at http://127.0.0.1/ which is localhost, an alias for your current PC. LongHairedFop (talk) 20:09, 21 January 2016 (UTC)

Back when I maintained a large website, I had a second copy of it running on one of my internal servers for testing. It wasn't publicly visible; it didn't have a public DNS entry; I think we all just hit it at its private 192 address or something. It was a certain amount of work to maintain this redundant, second instance, but it was absolutely vital for us to be able to do testing of new pages and functionality before we went live. I assume this sort of thing is common across the industry. —Steve Summit (talk) 23:04, 21 January 2016 (UTC)

Honestly - web hosting is pretty cheap these days. I pay $9/month...with a bunch of domains and the ability to SSH and SCP into my account. Do that, set up some throw-away URL that nobody will ever visit (like ssfnl429oksldf.org or something - you can get that for under $10 and it'll be good for a year) place an empty index.html at the root, and make a subdirectory with some other garbage name. Set your website up in there - rename the subdirectory every once in a while - and you can be pretty sure that nobody will come visiting unless you tell them the full URL to the page. Search engines won't spider down into the subdirectory, so google searching on your project won't get them there either. When you have it all working to your satisfaction, transfer it over to the 'real' url to make it go live. Keep your garbage site for making improvements and bug fixing, so you can check your changes without screwing up the real site. It's worth the tiny additional investment.

Sure, you can run simple sites (without server-side stuff) on your local machine - but as soon as you get into wanting an SQL server (you will) and hooks into places like PayPal or Google Analytics or whatever - you'll soon find that you need to do development on the real thing. It's also good to use the same hosting company so you can get to grips with what versions of stuff like PHP they have set up, what memory and bandwidth limits they might impose, what share of a cpu you get, etc, etc. For example, the hosting company that I use runs SQL instances on separate nodes from the Apache instances - and that's something you need to know when you design your site - they also impose limits on how you can set up various .ini files, so you might find some Apache or PHP feature you want to enable can't be enabled for whatever reason.

SteveBaker (talk) 05:17, 22 January 2016 (UTC)

@140.254.136.149: If you just need HTML+CSS+JavaScript then you don't need a server, you can simply edit those files with a texteditor (I recommend Notepad++) and view them in your web browser. If you want to create a MySQL database et cetera then I would recommend using Bitnami's WAMP stack. You can look at the list of stacks here. You can have it running in a couple of minutes. You can also try Xampp (Apache distribution containing MariaDB, PHP, and Perl). The Quixotic Potato (talk) 10:55, 22 January 2016 (UTC)

Software for paperless governmental procedures

What software do governmental agencies, in the US or abroad, use for implementing paperless paperwork? Sorry for the oxymoron. --Scicurious (talk) 22:36, 21 January 2016 (UTC)

There would be a huge range of software, from an email system to replace snail mail, to a database to replace paper customer and product records or a spreadsheet to replace paper accounting records. CAD systems replaced paper architecture and engineering drawings. Project management software eliminates paper there. Of course, many businesses find themselves printing it all out anyway. StuRat (talk) 07:43, 22 January 2016 (UTC)

I do not mean paperwork in general. But software that implements a legally binding way of sending messages. That would be for contacting the government, notices, appeal, summons, and so on.--Scicurious (talk) 14:42, 22 January 2016 (UTC)

Since most legally binding stuff requires signatures, I searched /digital signature warrant/ and got this relevant news article about CA using DocuSign and iPads instead of paper and ink signature for search warrants: [1]. I'd suggest /"digital signature" [legal instrument] [country/state]/ would be a good search avenue. Adobe has obviously got a vested interest- but here's their overview of how digital signatures are legally interpreted around the globe [2]SemanticMantis (talk) 18:35, 22 January 2016 (UTC)