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  • Kubuntu 11.04 bad experience, Gimp crashes and other bugs

    - by giowck
    I installed Kubuntu 11.04 64bit today. First let me expose some issues, this is not a rant, just some observations on Kubuntu 11.04 :) Flash doesn't work. The package "flashplugin-installer" was installed by rekonq. But still no flash. Additional Drivers (jockey-kde) doesn't show up automatically after first login. I tried to delete a large file (19,2 GB), an error appeared: "Please empty the trash first, no more space available" or something like that, but you know what? My trash was empty! (Then I found in Dolphin the settings to increment the max size of the trash). Amarok has no play/pause/forward/back buttons, only after changing settings to show those buttons on the top bar. GTK applications like ubuntu software center, inkscape... are in english, but my default language is "german". Only gimp allows to install the "de" language pack. The numblock turns off after each restart. In the KDE Control Center, the "remember last state" of numblock is set. But this is not working. I had some crashes: Nepomuk, Policy-kit, plasma-workspace and gimp. But now to the important stuff. I really need Gimp to work. After starting it, I get a crash: giowck@giowck-desktop:~$ gimp (gimp:1899): GLib-WARNING **: /build/buildd/glib2.0-2.28.6/./glib/goption.c:2132: ignoring no-arg, optional-arg or filename flags (8) on option of type 0 Speicherzugriffsfehler (in English: "Memory error") What can I do to run Gimp? Thanks

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  • Solaris 11 : les nouveautés vues par les équipes de développement

    - by Eric Bezille
    Translate in English  Pour ceux qui ne sont pas dans la liste de distribution de la communauté des utilisateurs Solaris francophones, voici une petite compilation de liens sur les blogs des développeurs de Solaris 11 et qui couvre en détails les nouveautés dans de multiples domaines.  Les nouveautés côté Desktop What's new on the Solaris 11 Desktop ? S11 X11: ye olde window system in today's new operating system Accessible Oracle Solaris 11 - released ! Les outils de développements Nagging As a Strategy for Better Linking: -z guidance Much Ado About Nothing: Stub Objects Using Stub Objects The Stub Proto: Not Just For Stub Objects Anymore elffile: ELF Specific File Identification Utility Le nouveau système de packaging : Image Packaging System (IPS) Replacing the Application Packaging Developer's guide IPS Self-assembly - Part 1: overlays Self Assembly - Part 2: Multiple Packages Delevering configuration La sécurité renforcée dans Solaris Completely disabling root logins in Solaris 11 Passwork (PAM) caching for Solaris su - "a la sudo" User home directory encryption with ZFS My 11 favorite Solaris 11 features (autour de la sécurité) - par Darren Moffat Exciting crypto advances with the T4 processor and Oracle Solaris 11 SPARC T4 OpenSSL Engine Solaris AESNI OpenSSL Engine for Intel Westmere Gestion et auto-correction d'incident - "Self-Healing" : Service Management Facility (SMF) & Fault Management Architecture (FMA)  Introducing SMF Layers Oracle Solaris 11 - New Fault Management Features Virtualisation : Oracle Solaris Zones These are 11 of my favorite things! (autour des zones) - par Mike Gerdts Immutable Zones on Encrypted ZFS The IPS System Repository (avec les zones) - par Tim Foster Quelques bonus de la communauté Solaris  Solaris 11 DTrace syscall Provider Changes Solaris 11 - hostmodel (Control send/receive behavior for IP packets on a multi-homed system) A Quick Tour of Oracle Solaris 11 Pour terminer, je vous engage également à consulter ce document de référence fort utile :  Transition from Oracle Solaris 10 to Oracle Solaris 11 Bonne lecture ! Translate in English 

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  • Dot Matrix printers setup...

    - by Parhs
    Hello! I am using debian which is similar to ubuntu. They have 7 dot matrix printers some very old like this one http://www.omnidatasys.net/product/desc_printer_ti880.htm which works from 1979 daily and at text is faster than many inkjects. I believe that it has his own language... Sending text to serial port (port server) prints garbage. However i think is prints only capital english up to 95 asccii and greek and the rest up to 127 i think greek capital.(special chip ) Sending english capital letters prints garbage i think but i amnt sure... i will try again... The other printer are ESC/P compatible and i use generic epson driver provided from ghostscript... However i think that sending text via lp -dpr1 filename It prints the text as a grafic...Changing from printer font face(courier,times roman etc) or pitch has no effect... I am wondering if is there any work arround for this? In AIX they claim that lp command printed output as text as it prints and cobol programs send raw text to to lp printers . However in AIX they use some custom filters for the printers and has more options for dot matrix printers.. I would like to know if there is a solution for this.. To avoid graphics mode for text and change font face somehow.. The most Straight-through approach would be to use no driver ,just send ESC/P from cobol but this requires too much work... Thank you again!

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  • Domains with similar names and issues

    - by abel
    I recently purchased one of those domain names like del.ico.us. While registering I found that delicious.com was being used. Argument: I found that delicious.com belonged to the same category as my to-be website. It served premium delicious dishes. Counter Argument: My to-be domain though belonging to the same category, specialized in serving free but delicious dishes or in giving out links(affiliate) to other sites serving premium delicious dishes. Additional Counter Arguments: 1.delicious.com was not in English. 2.the del.icio.us in my domain name though having the same spelling, is not going to be used in the same fashion. For eg.(this may not make sense, because the names have been changed)the d in delicious on my website actually stands for the greek letter Delta(?/d) and since internationalized domains are still not easily typable, I am going for the english equivalent.The prefix holds importance for the theme of the service which my website intends to offer. My Question: Can I use the domain name del.icio.us for my website? How are these kinds of matters dealt? (The domain names used are fictitious. And I have already registered the domain but have not started using it.I chanced upon this domain name because it was short, easy to remember and suited the theme of my website.)

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  • Are very short or abbreviated method/function names that don't use full words bad practice or a matter of style.

    - by Alb
    Is there nowadays any case for brevity over clarity with method names? Tonight I came across the Python method repr() which seems like a bad name for a method to me. It's not an English word. It apparently is an abbreviation of 'representation' and even if you can deduce that, it still doesn't tell you what the method does. A good method name is subjective to a certain degree, but I had assumed that modern best practices agreed that names should be at least full words and descriptive enough to reveal enough about the method that you would easily find one when looking for it. Method names made from words help let your code read like English. repr() seems to have no advantages as a name other than being short and IDE auto-complete makes this a non-issue. An additional reason given in an answer is that python names are brief so that you can do many things on one line. Surely the better way is to just extract the many things to their own function, and repeat until lines are not too long. Are these just a hangover from the unix way of doing things? Commands with names like ls, rm, ps and du (if you could call those names) were hard to find and hard to remember. I know that the everyday usage of commands such as these is different than methods in code so the matter of whether those are bad names is a different matter.

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  • Sample Browser Visual Studio Extension is localized and introduced to Japan

    - by Jialiang
    http://blogs.msdn.com/b/codefx/archive/2012/10/14/sample-browser-visual-studio-extension-is-localized-and-introduced-to-japan.aspx  ??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????From: Japan MVP   "The Sample Browser is very easy to use thanks to the refined interface.  The categorized menu enables faster search. Highly acclaimed.  But it need localization. It may not be a problem for those who can understand English, but I think localizing Sample Browser into Japanese will promote its use in Japan further." This is a prominent feedback collected from the Japan MVP community since we released the last version of Sample Browser, which was only available in English.  Japan developers like the Sample Browser, but they want localized code samples, localized Sample Browser UI, and the localized search experience.  The Japan MVP lead, Satoru Kitabata, observed these needs and expectations.  He started to engage with all local developer MVPs to translate the UI elements in the Sample Browser.  Lots of MVPs signed up to participate in this work.  They had roundtables and newsletters to track the progress.  In short three weeks, every control, every tooltip, every font on every label, was beautifully tuned for Japanese.  The sample search experience was also optimized for Japan developers - they can directly type Japanese query to search for code samples.  Together with Microsoft Japan MVPs, the sample use experience is localized and improved to a new level!    The Japan MVP Lead, Satoru Kitabata, further worked with MSDN Japan site manager and Japan DPE to introduce the good news of localized Sample Browser to Japan Sample Browser  http://msdn.microsoft.com/ja-jp/jj730399 Sample Browser?????? http://msdn.microsoft.com/ja-jp/jj730398     Thanks to the joint effort and Japan MVPs’ feedback and contributions, the Sample Browser gets the chance to benefit the broader Japan developer audience.

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  • Would You Swim Laps in Lake Baikal?

    - by rickramsey
    source This is the lake where Yuli Vasiliev's countrymen swim laps. Yuli is one of my favorite OTN writers not just because he really knows his stuff. Not just because his writing is clear and accurate. And not just because his English is better than the English of most native speakers. Yo, those are all good reasons. But it's the Lake Baikal thing. Yuli recently wrote two wicked good how-to's about Oracle VM Templates. You should read them. You might gain a gram of Yuli's respect. Two grams, if you can head butt icebergs while you swim. How to Use Oracle VM Templates How to prepare an Oracle VM environment to use Oracle VM Templates, how to obtain a template, and how to deploy the template to your Oracle VM environment. Also how to create a virtual machine based on that template and how you can clone the template and change the clone's configuration. How to Use Oracle VM VirtualBox Templates How to use Oracle VM VirtualBox Templates in Oracle VM VirtualBox. Similar to the article above, but it describes how to download, install, and configure the templates within Oracle VM VirtualBox, instead of on bare metal. Other OTN Technical Articles by Yuli Vasiliev Retrieving, Transforming, and Consolidating Web Data with Oracle Database Setting Up, Configuring, and Using a WebLogic Server Cluster Cube Development for Beginners How to XQuery Non-JDBC Sources from JDBC Advanced Dimensional Design with Oracle Warehouse Builder Using the JDBC Connectivity Layer in Oracle Warehouse Builder High Performance Oracle JDBC Programming Python Data Persistence with Oracle Querying JPA Entities with JPQL and Native SQL - Rick Website Newsletter Facebook Twitter

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  • LiveMeeting VC PowerShell PASS – Troubleshooting SQL Server with PowerShell

    - by Laerte Junior
    Guys, join me on Wednesday July 18th 12 noon EDT (GMT -4) for a presentation called Troubleshooting SQL Server With PowerShell. It will be in English, so please make allowances for this. I’m sure that you’re aware that my English is not perfect, but it is not so bad. I will do my best, you can be sure. The registration link will be available soon from PowerShell.sqlpass.org, so I hope to see you there. It will be a session without slides. Just code; pure PowerShell code. Trust me, We will see a lot of COOL stuff.Big thanks to Aaron Nelson (@sqlvariant) for the opportunity! Here are some more details about the presentation: “Troubleshooting SQL Server with PowerShell – The Next Level’ It is normal for us to have to face poorly performing queries or even complete failure in our SQL server environments. This can happen for a variety of reasons including poor Database Designs, hardware failure, improperly-configured systems and OS Updates applied without testing. As Database Administrators, we need to take precaution to minimize the impact of these problems when they occur, and so we need the tools and methodology required to identify and solve issues quickly. In this Session we will use PowerShell to explore some common troubleshooting techniques used in our day-to-day work as s DBA. This will include a variety of such activities including Gathering Performance Counters in several servers at the same time using background jobs, identifying Blocked Sessions and Reading & filtering the SQL Error Log even if the Instance is offline The approach will be using some advanced PowerShell techniques that allow us to scale the code for multiple servers and run the data collection in asynchronous mode.

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  • How to configure KDE default settings for a new user of a group?

    - by Adobe
    I'm a sys admin on Kubuntu 11.10 machine. Where do I configure the basic config for a new user (say belonging to group "users")? Edit 1: I want to configure langauages - currently my new users get English and Bulgarian Languages. I want them to get English and Russian - and also to set Alt-CapsLock - to be the input-language-switching-combination. Edit 2: How do I configure things in /usr/share/kde4 When I do kdesudo systemsettings and save configurations - only root settings got changed - not the /usr/share/kde4 ones. Edit 3: New user gets the /etc/skel files controlling bash behaviour-appearence. What about the KDE new user's default files - where are they stored? Edit 4: Oh, I found some hints: kde4-config --path config gives a list of folders (separated by the colon) where KDE looks for configs. My machine responded with: /home/boris/.kde/share/config/ /etc/kde4/ /usr/share/kubuntu-default-settings/kde4-profile/default/share/config/ /usr/share/kde4/config/ /usr/share/desktop-base/profiles/kde-profile/share/config/ It looks like third line is where KDE takes the default options. So I found these zilions of settings - but no GUI way to configure it ((. Edit 5: Finally, I've created a dummy user, configured it, and wrote a script which gives it's settings to a given user(s). The trick - is to chown after one transfered the dot files from one user to another. I've tested it - it works fine.

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  • Are short abbreviated method/function names that don't use full words bad practice or a matter of style?

    - by Alb
    Is there nowadays any case for brevity over clarity with method names? Tonight I came across the Python method repr() which seems like a bad name for a method to me. It's not an English word. It apparently is an abbreviation of 'representation' and even if you can deduce that, it still doesn't tell you what the method does. A good method name is subjective to a certain degree, but I had assumed that modern best practices agreed that names should be at least full words and descriptive enough to reveal enough about the method that you would easily find one when looking for it. Method names made from words help let your code read like English. repr() seems to have no advantages as a name other than being short and IDE auto-complete makes this a non-issue. An additional reason given in an answer is that python names are brief so that you can do many things on one line. Surely the better way is to just extract the many things to their own function, and repeat until lines are not too long. Are these just a hangover from the unix way of doing things? Commands with names like ls, rm, ps and du (if you could call those names) were hard to find and hard to remember. I know that the everyday usage of commands such as these is different than methods in code so the matter of whether those are bad names is a different matter.

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  • Option Button in Keyboard Layout > Input Sources is not pressable

    - by user98647
    I would like to set the Caps-lock key as a Compose key, which you do, as far as I remember, by pressing the Options Button in Keyboard Layout Input Sources and then enabling the appropriate option there. That Button is not pressable though since I switched to 12.10. It did work in previous releases of Ubuntu. gnome-control-center puts out these errors, when I click on Keyboard Layout: (gnome-control-center:3645): common-cc-panel-WARNING **: Could not find current language '?\u0003C!\u007f' in the treeview (gnome-control-center:3645): common-cc-panel-WARNING **: locale '"en_US.UTF-8"' isn't valid I'm not sure if the errors are related though, maybe they are related to the "interface switching to chinese bug" which seems surprisingly widespread: Language changed to Chinese, how do I change it back? Language Support has an unwanted Chinese language option Nautilus Folders Turned Chinese Desktop 12.04 gnome/cairo suddenly in Chinese Unwanted Chinese language got set in system settings I cannot set my system back to English from Chinese Language Gnome-classic language turned into Chinese, how do I change it back to English? Strange display language in gnome shell I'm not sure they are related to this bug, but I just wanted to mention it, maybe it helps!

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  • Language Design: Are languages like Python and CoffeeScript really more comprehensible?

    - by kittensatplay
    The "Verbally Readable !== Quicker Comprehension" argument on http://ryanflorence.com/2011/case-against-coffeescript/ is really potent and interesting. I and I'm sure others would be very interested in evidence arguing against this. There's clear evidence for this and I believe it. People naturally think in images, not words, so we should be designing languages that aren't similar to human language like English, French, whatever. Being "readable" is quicker comprehension. Most articles on Wikipedia are not readable as they are long, boring, dry, sluggish and very very wordy. Because Wikipedia documents a ton of info, it is not especially helpful when compared to sites with more practical, useful and relevant info. Languages like Python and CoffeScript are "verbally readable" in that they are closer to English syntax. Having programmed firstly and mainly in Python, I'm not so sure this is really a good thing. The second interesting argument is that CoffeeScript is an intermediator, a step between two ends, which may increase the chance of bugs. While CoffeeScript has other practical benefits, this question specifically requests evidence showing support for the counter-case of language "readability"

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  • How to reset the language of the package descriptions

    - by xubuntix
    I have had German as my main language about a year ago. Later I changed it to English. Most parts of the system accepted the change. The notable exceptions are the package descriptions, which remain in German for some packages. You can see in the image (apt-cache and software-center), that while some descriptions are in English, some have remained in German. So the question is: how do I reset this? I guess that there is somewhere a description cache that needs to be told that it should update all descriptions? EDIT: As asked: the output of some language related commands: $ cat /etc/default/locale LANG="en_US.UTF-8" $ apt-config dump | grep Lang Acquire::Languages ""; Acquire::Languages:: "de_DE"; Acquire::Languages:: "de"; Acquire::Languages:: "en"; Acquire::Languages:: "none"; $ locale LANG=de_DE.UTF-8 LANGUAGE=en LC_CTYPE="de_DE.UTF-8" LC_NUMERIC="de_DE.UTF-8" LC_TIME="de_DE.UTF-8" LC_COLLATE="de_DE.UTF-8" LC_MONETARY="de_DE.UTF-8" LC_MESSAGES="de_DE.UTF-8" LC_PAPER="de_DE.UTF-8" LC_NAME="de_DE.UTF-8" LC_ADDRESS="de_DE.UTF-8" LC_TELEPHONE="de_DE.UTF-8" LC_MEASUREMENT="de_DE.UTF-8" LC_IDENTIFICATION="de_DE.UTF-8" LC_ALL= As a note: I'm not sure what each entry means, but some of the de_DE.UTF-8 are probably ok, since I do want paper-sizes, monetary, time, etc. in standard German formats.

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  • What is an appropriate language for expressing initial stages of algorithm refinement?

    - by hydroparadise
    First, this is not a homework assignment, but you can treat it as such ;). I found the following question in the published paper The Camel Has Two Humps. I was not a CS major going to college (I majored in MIS/Management), but I have a job where I find myself coding quite often. For a non-trivial programming problem, which one of the following is an appropriate language for expressing the initial stages of algorithm refinement? (a) A high-level programming language. (b) English. (c) Byte code. (d) The native machine code for the processor on which the program will run. (e) Structured English (pseudocode). What I do know is that you usually want to start your design implementation by writing down pseuducode and then moving/writing in the desired technology (because we all do that, right?) But I never thought about it in terms of refinement. I mean, if you were the original designer, then you might have access to the original pseudocode. But realisticly, when I have to maintain/refactor/refine somebody elses code, I just keep trucking with the language it currently resides in. Anybody have a definitive answer to this? As a side note, I did a quick scan of the paper as I havn't read every single detail. It presents various score statistics, can't find where the answers are with the paper.

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  • i18n and L10n (1)

    - by Aaron Li
    Internationalization (i18n) is a way of designing and developing a software product to function in multiple locales. This process involves identifying the locales that must be supported, designing features which support those locales, and writing code that functions equally well in any of the supported locales. Localization (L10n) is a process of modifying or adapting a software product to fit the requirements of a particular locale. This process includes (but may not be limited to) translating the user interface, documentation and packaging, changing dialog box geometries, customizing features (if necessary), and testing the translated product to ensure that it still works (at least as well as the original). i18n is a pre-requisite for L10n. Resource is 1. any part of a program which can appear to the user or be changed or configured by the user. 2. any piece of the program's data, as opposed to its code. Core product is the language independent portion of a software product (as distinct from any particular localized version of that product - including the English language version). Sometimes, however, this term is used to refer to the English product as opposed to other localizations.   Useful links http://www.mozilla.org/docs/refList/i18n/ http://www.w3.org/International/ http://hub.opensolaris.org/bin/view/Community+Group+int_localization/

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  • Transferring users and search engines to a new domain

    - by eftpotrm
    I've been asked to take over the maintnance of an existing site that's being reworked. At present it's serving localised content for several languages, but via a fairly unhelpful mechanism that means essentially search engines only have it indexed in English and any deep links will de facto appear in English as well. So, new localised sites are being built under separate domains - not just for this, there's other benefits. What we're then looking to do is to redirect users correctly to the new site, where appropriate. For humans this isn't a problem. We can send them through a gateway page on their first site visit, grab their language preference and put it in a cookie, then redirect them to the new localised content as soon as it's available. For search engines, this isn't so good... In principle I'm happy to simply bypass the gateway page and redirect known spiders to the new site, but this means we're serving radically different content (different URL even!) to human and robot users. Won't this therefore be regarded as cloaking and cause us grief? Anyone know a better way to handle this?

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  • Localization of Database Strings in .Net

    - by Aligned
    I have several database tables that have a description column that I need to display in the UI. .Net has .resx files that will help with the translation of the strings, when the Thread.CurrentCulture.UICulture is set, but I needed a custom approach for the strings that are stored in the database and not in the .resx files. Here’s my approach: 1. Create a resource file for each database table and put them in the /Resources/Database/ directory. 2. Create a method in LocalizationHelpers (GetLocalizedString) that will get the string from the table for English (which should be cached to avoid unneeded service/database calls) or the resx when not English. 3. All database tables need to have a ResxKey field that matches the key in the resx file. 4. By convention the resx file will have the same name as the database table, and the key the same as the database ResxKey.   - if there are multiple columns that need translation, then one ResxKey will be used and Name or Description appended. Here’s the method I’m using to pull the string: public static string GetLocalizedString(string resourceName, string resourceKey) { if (executingAssembly == null) { executingAssembly = Assembly.GetExecutingAssembly(); } ResourceManager manager = new ResourceManager(resourceName, executingAssembly); return manager.GetString(resourceKey); }

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  • awk or perl file editing & manipulation

    - by paul44
    I have a standard passwd file & a usermap file - which maps unix name (eg jbloggs) with AD account name (eg bloggsjoe) in the format: jbloggs bloggsjoe jsmith smithjohn ... etc. How can I edit the passwd file to swap the original unix name with the AD account name so each line of the passwd file has the AD account name instead. Appreciate any help for a perl learner.

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  • Using pointers in PHP.

    - by Babiker
    I ask this question because i learned that in programming and designing, you must have a good reason for decisions. I am php learner and i am at a crossroad here, i am using simple incrementation to try to get what im askin across. I am certainly not here to start a debate about the pros/cons of pointers but when it comes to php, which is the better programming practice: function increment(&$param) { $param++; } Or function increment($param){ return $param++; } $param = increment($param);

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  • Why Constant Keyword is not introduced In Java?

    - by harigm
    I am curious learner of Java, I was thinking on one topic "CONSTANTS" I have learnt that Java allows us to declare constants by using "Final" keyword. My question is Java didnot introduce Constant(Const) Keyword. Since many people say it has come from C++, in C++ we have Const keyword Is there any strong reason behind, Please share your thoughts on this.

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  • Why is there no Constant keyword in Java?

    - by harigm
    I am curious learner of Java, and I was thinking about the topic of "CONSTANTS". I have learnt that Java allows us to declare constants by using final keyword. My question is why didn't Java introduce Constant (const) keyword. Since many people say it has come from C++, in C++ we have const keyword. Please share your thoughts.

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  • Formal Languages, Inductive Proofs &amp; Regular Expressions

    - by MarkPearl
    So I am slogging away at my UNISA stuff. I have just finished doing the initial once non stop read through the first 11 chapters of my COS 201 Textbook - “Introduction to Computer Theory 2nd Edition” by Daniel Cohen. It has been an interesting couple of days, with familiar concepts coming up as well as some new territory. In this posting I am going to cover the first couple of chapters of the book. Let start with Formal Languages… What exactly is a formal language? Pretty much a no duh question for me but still a good one to ask – a formal language is a language that is defined in a precise mathematical way. Does that mean that the English language is a formal language? I would say no – and my main motivation for this is that one can have an English sentence that is correct grammatically that is also ambiguous. For example the ambiguous sentence: "I once shot an elephant in my pyjamas.” For this and possibly many other reasons that I am unaware of, English is termed a “Natural Language”. So why the importance of formal languages in computer science? Again a no duh question in my mind… If we want computers to be effective and useful tools then we need them to be able to evaluate a series of commands in some form of language that when interpreted by the device no confusion will exist as to what we were requesting. Imagine the mayhem that would exist if a computer misinterpreted a command to print a document and instead decided to delete it. So what is a Formal Language made up of… For my study purposes a language is made up of a finite alphabet. For a formal language to exist there needs to be a specification on the language that will describe whether a string of characters has membership in the language or not. There are two basic ways to do this: By a “machine” that will recognize strings of the language (e.g. Finite Automata). By a rule that describes how strings of a language can be formed (e.g. Regular Expressions). When we use the phrase “string of characters”, we can also be referring to a “word”. What is an Inductive Proof? So I am not to far into my textbook and of course it starts referring to proofs and different types. I have had to go through several different approaches of proofs in the past, but I can never remember their formal names , so when I saw “inductive proof” I thought to myself – what the heck is that? Google to the rescue… An inductive proof is like a normal proof but it employs a neat trick which allows you to prove a statement about an arbitrary number n by first proving it is true when n is 1 and then assuming it is true for n=k and showing it is true for n=k+1. The idea is that if you want to show that someone can climb to the nth floor of a fire escape, you need only show that you can climb the ladder up to the fire escape (n=1) and then show that you know how to climb the stairs from any level of the fire escape (n=k) to the next level (n=k+1). Does this sound like a form of recursion? No surprise then that in the same chapter they deal with recursive definitions. An example of a recursive definition for the language EVEN would the 3 rules below: 2 is in EVEN If x is in EVEN then so is x+2 The only elements in the set EVEN are those that be produced by the rules above. Nothing to exciting… So if a definition for a language is done recursively, then it makes sense that the language can be proved using induction. Regular Expressions So I am wondering to myself what use is this all – in fact – I find this the biggest challenge to any university material is that it is quite hard to find the immediate practical applications of some theory in real life stuff. How great was my joy when I suddenly saw the word regular expression being introduced. I had been introduced to regular expressions on Stack Overflow where I was trying to recognize if some text measurement put in by a user was in a valid form or not. For instance, the imperial system of measurement where you have feet and inches can be represented in so many different ways. I had eventually turned to regular expressions as an easy way to check if my parser could correctly parse the text or not and convert it to a normalize measurement. So some rules about languages and regular expressions… Any finite language can be represented by at least one if not more regular expressions A regular expressions is almost a rule syntax for expressing how regular languages can be formed regular expressions are cool For a regular expression to be valid for a language it must be able to generate all the words in the language and no other words. This is important. It doesn’t help me if my regular expression parses 100% of my measurement texts but also lets one or two invalid texts to pass as well. Okay, so this posting jumps around a bit – but introduces some very basic fundamentals for the subject which will be built on in later postings… Time to go and do some practical examples now…

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