text:
Talk:Entity–relationship model

Aristotle was born in 384 and died in 322 BC
" what is the meaning of 428 BC near his name?" 46.114.104.43 (talk) 13:01, 3 April 2020 (UTC)

Third sentence very unclear
"...for instance, your entry in the database could point to several entries for each of the phone numbers that are yours" I can't understand what this is trying to say. First off, what does it mean "your entry". --206.87.81.34 (talk) 08:08, 2 November 2012 (UTC)

Prevalence of Crow's Foot Notation
In 13 years doing database work in the United States, I've Foot notation everywhere. This part needs a citation: "Usage of Chen notation is more prevalent in the United States, while Crow's Foot notation is used primarily in the UK."

205.173.24.4 (talk) 18:58, 17 November 2010 (UTC)

This part needs a citation: "Usage of Chen notation is more prevalent in the United States, while Crow's Foot notation is used primarily in the UK and Australasia." — Preceding unsigned comment added by Kdf9andtd1a (talk • contribs) 02:32, 15 July 2011 (UTC)

Common Symbols Section Needs Work
I must say that I agree at least on the lack of clarity of the first sentence. Either its meaning is wrong or it is poorly written. Whichever it is, the first sentence of the introduction is misleading to the least. 194.221.74.7 08:54, 8 June 2006 (UTC)

 * I agree - calling an entity a 'discrete object is not very accurate, but then again, what would be a more accurate term? Rp 10:20, 10 July 2006 (UTC)

I'm not sure about a relationship having an attribute. How can this convert into a logical model?--Nick 18:11, 4 March 2006 (UTC)

 * You have a good point there - I think conversion from ER model to logical relational model must be treated if only to make the point that the ER model is not an informal drawing technique but has a sound formal basis. Rp 10:20, 10 July 2006 (UTC)

Another issue is the (universal) confusion between entities and entity sets, relationships and relationship sets. This article dutifully explains the "correct" use of the terms, but before it does so has already used them "incorrectly" (i.e. how everybody uses them in practice) quite a few times. So either the terms e. set and r. set should be omitted or a more thorough clarification is in order. Rp 12:17, 10 July 2006 (UTC)

Symbols
Any chance someone could mock up a set of images showing what these symbols are supposed to look like? Describing them is all well and good, but a picture can be worth a thousand words. :) Thanks,  Eirikr 03:45, 8 Apr 2005 (UTC)
 * I've added a first example diagram. I'd like to include some more images but I'm having trouble deciding which examples would best clarify some of the text. Also, I'm wondering if it'd make any sense to upload the original Dia files and refer to them from the Image:erd-*.png nodes for if anyone else wants to change something in the coloring or whatnot... --BigSmoke 16:27, 12 Jun 2005 (UTC)

Agreed. Just for fun: Can we get an ERD of the wiki that wikipedia et al. use?

Diagrams and ER 2004
As far as I '''know there are multiple ways of drawing ER diagrams. I use arrows. Yet the article implies thatBold text' there's only this one way.

Where's the explanation/links about ER 2004? --Khokkanen 12:53, 10 June 2006 (UTC)

 * I have added a section entitled Alternative diagramming conventions with a diagram and explanation for Crow's Feet notation. I encourage you all to post up similar descriptions of the notations you prefer.  See also Diagram is not standard section below.  --Matthew 1130 13:05, 30 December 2006 (UTC)
 * That's not the classical Crow's Foot notation, it's IDEF1X. -- EmmetCaulfield 11:20, 6 November 2007 (UTC)
 * I am nearly certain it should be "Crow's Foot", not "Crow's Feet". Sam Tomato (talk) 05:56, 12 November 2016 (UTC)

Diagram is not standard
This diagram is not remotely similar to the methods used by nearly all of the major ER tools in use today. IDEF1X is far and away a more common mechanism, as are derivatives of that method that vary primarily in the symbols used to indicate n-ary relationships.

I suggest we replace this article with one that is similar to the article referenced by the IDEF1X link (US Navy, I think). This article is absolutely useless for practitioners and students of ER models. User:nickmalik 11:47 15 Oct 2006 {PDT)

 * I strongly disagree. Since the article's subject is the Entity-Relationship Model it should use the classical notation. Any other choice would be somewhat arbitrary as there are many tools and many dialects and none of them is really predominant. Most (database) textbooks I know use the classical notation. -- Jan Hidders 21:39, 15 October 2006 (UTC)

 * I suppose we should use Roman Numerals for math articles since they are a more "classical representation". I have been involved with data modeling for nearly 20 years and have never seen an ER diagram like that. I agree that IDEF1X is generally considered the best representation. —The preceding unsigned comment was added by 74.242.64.129 (talk) 19:54, 17 December 2006 (UTC).

What about the cardinalities of relationships? I thought these were annotated by numbers on the arcs of the relationships?Jam2001 12:50, 18 October 2006 (UTC)

 * Yes, that is correct. Why? -- Jan Hidders 21:29, 18 October 2006 (UTC)

I have added a section entitled Alternative diagramming conventions with a diagram and explanation for Crow's Feet notation. I encourage you all to post up similar descriptions of the notations you prefer.

 * I suspect we should replace the Artist-Song relationship with a Product-Recommendation relationship, because Artist-Song is really a many-to-many relationship if we are going to be true to the real world, and we need a one-to-many relationship to best illustrate the diagramming convention. My one concern is whether the editor who originally created the Artist-Song diagram can modify it to Product-Recommendation?  Matthew 1130 12:53, 19 December 2006 (UTC)

If I have the support of other Wikipedians here, I'd be happy to refactor the Common symbols section, putting the "Crow's Feet" notation at the top until such time as we have a more appropriate notation available. Please let me know. Matthew 1130 12:37, 19 December 2006 (UTC)
 * Except it should be "Crow's Foot", not "Crow's Feet", right?. Sam Tomato (talk) 05:57, 12 November 2016 (UTC)

The problem is that there are at least half-a-dozen different diagrammatic notations, which people call "ERDs". Proponents of IDEF(1X), Crow's Foot, Chen-style, and at least two others that I can draw but can't name, will insist that their style is the "one true ERD". The Chen style (which *is* the original) is distinguished from the others by representing relationship types explicitly as "first class objects" (nodes) rather than as lines (edges). AFAICT, every diagram in any of the other (non-Chen) styles of "ERD" is isomorphic to a relational schema and, therefore, to a diagram in any of the other styles. In other words, any non-Chen "ERD" can be converted to a non-Chen "ERD" in one of the other styles by a simple relabeling and no "mapping procedure" is needed to obtain a relational schema; they are, therefore, merely alternative representations of relational schemata. There is information loss in mapping from a Chen-style ERD to a relational schema (e.g. compound attributes are flattened), so it *is* different and, IMHO, operates at a somewhat higher level of abstraction. The assertion that the Chen-style diagram "is not standard" is simply false: it may not be your favourite style (e.g. IDEF(1X)), but it is a perfectly standard Chen-style (i.e. "original") ERD and these are used for pedagogic purposes in textbooks (c.f. Elmasri & Navathe) and university courses (at least two that I know of in two different countries) all over the world. -- EmmetCaulfield 11:43, 6 November 2007 (UTC)

 * No, the Chen style is NOT the original. Consultants at Scicon and CACI in the UK were using a kind of crow's foot notation in the early 1970s. But they didn't write academic papers about it, so it's hard to prove. ER modelling was invented by practitioners, not by Chen; Chen's contribution was to formalize the ideas and introduce them to an academic audience. Mhkay (talk) 07:33, 8 April 2009 (UTC)

THE EXAMPLE DIAGRAM IS WRONG!!!!
I'm almost positive that the character should run into the creep instantiation and not the creep? Could someone verify this? Epachamo 23:02, 3 November 2006 (UTC)

 * What in the world is "creep instantiation"??? I've never heard of it and got no hits on Google when I searched for it.  --Matthew 1130 13:08, 30 December 2006 (UTC)

 * The example diagram is not wrong. My group and I designed this ER diagram and I photoshopped it up.  What we had in mind was that the creeps themselves would be molds for individual instantiations.  For a simple example, think of Super Mario Brothers.  There's a bunch of Goomba's running around, and they all look the same, but they're not the same one - they are all in different locations, and can be dealt with individually.  The Goomba's in this example are Creep Instantiations, while the concept of a Goomba itself is a Creep.  As to the term "creep instantiation", of course it's not real, we made it up for the project.  ~ [ Matthew Tardiff 18:47, 30 December 2006 (UTC) ]

 * I think the issue here is that Super Mario Brothers is outside the problem domain for a number of us wikipedians here (and for a large number of visitors too). Finding a problem domain that is relatable for everyone is a high priority, do you have a preference from the ideas listed below, or perhaps another idea for a suitable problem domain:
 * Customer, Sales Rep, Sales Order, Sales Order Item, Product.
 * Borrower, Library, Section, Book, Book Category, Category, Loan, Loan Item.
 * Student, Degree, Degree Subject, Subject, Subject Instance, Course, Course Item, Lecturer, Lecturer Subject.
 * Artist, Album, Album Song, Song, Composer.
 * -- Matthew 1130 13:09, 31 December 2006 (UTC)

 * Super Mario Brothers was not the issue I was bringing up. I personally think the current diagram is a great example.  Everybody can relate to games.    Epachamo 18:23, 10 January 2007 (UTC)
 * On the contrary Epachmo, it's mostly those in your demographic and culture who relate to these games. The people who read Wikipedia are very diverse.  People who are likely to read this particular article would easily include project managers, domain experts, chief financial officers, business analysts and software testers, men and women from 18 to 65 years, many of whom would be unfamiliar with computer games.  I'm thinking to proceed with the Sales problem domain from the paragraph above, which I suspect is the area that people from most cultures and backgrounds would be able to relate to.
 * BTW, we can retain your diagram too. If you're game to reproduce the same diagram using a few different notations, it could become a very useful cross reference.
 * -- Matthew 1130 09:42, 11 January 2007 (UTC)
 * PS. Sorry, I just realised I'd taken over your section and your original question isn't answered yet.

 * I've recently drawn up a few ERDs for Business Process Modeling, although clearly not as adequate as the Sales domain I'll try and get them up using several different notations for cross-reference. --Guillaume (talk) 12:38, 11 January 2008 (UTC)

 * I totaly agree with Epachamo that it would make better sense that a Character should run into and Instance of a creep and not the Creep's "concept". --Guillaume (talk) 12:38, 11 January 2008 (UTC)

I think there was some misunderstanding here. A character would indeed run into an instance of a creep during the game - but that's not what this database is storing. This database is storing each type of creep which the character has encountered. -- Matthew Tardiff (12.199.176.12 (talk) 21:47, 20 August 2009 (UTC))

 * That makes more sense. I think the confusion comes from the phrase "runs into".  It would be better if instead it read, Character "Has encountered this type of" Creep or something like that.  Epachamo (talk) 21:01, 22 September 2009 (UTC)

Model -vs- Method
I doubt that an Entity-relationship model can be called a data model. It is a method to design data models. --Udo Altmann 13:42, 18 Oct 2004 (UTC)
 * If it were a method it would be called the Entity-Relationshp Method. The researchers at the ER 2004 would be highly amazed by your claim that the ER model is not a data model. -- Jan Hidders 11:05, 19 Oct 2004 (UTC)
 * Sorry for again starting a method discussion. The introduction sounds as if the ERModel is a data model for a data model - a meta model - which for me has an implicit methodological aspect. I think this was, what caused my discomfort. Wouldn't it be simplier (and still correct) to say "A Entity-Relationship model is a high-level description of a conceptual data model. Entity-Relationship models include graphical notations for representing such data models in the form of entity-relationship diagrams". --Udo Altmann 09:24, 1 Nov 2004 (UTC)
 * It would be incomplete. As already explained, the ER model is a meta model (with a graphical notation and some semantics), so that is of course what the introduction should explain. Why are you uncomfortable with that? I also fail to see why you connect that with a methodological aspect because that link is very very weak. There is no fixed method to arrive at your model and there is no fixed method to go from your ER diagram to your relational model, and, as was already explained, the scope of the ER model is much wider than just a method to arrive at your relational model. So what then is it exactly that you mean with this mysterious "methodological aspect"? It's still as if you want to believe that the ER model is a method. Please don't. Apart from being incorrect that view is much too narrow and does unjustice to the ER model. :-) -- Jan Hidders 13:53, 2 Nov 2004 (UTC)

relation vs. relationship
I was consulting this entry in order to learn about how the terms relation vs. relationship are used.

Unfortunately, after reading the entry I was even more confused, because the "Common symbols" section seems to use both words interchangeably:

"Relationships im single can be thought of as verbs. Examples: an owns relation between a company and a computer ..."

Is this uncertainty inherent in those words? Or is there any consensus on how to distinguish these three levels:

 * an individual tuple (a row in a table)
 * a set of tuples (a table filled with rows)
 * a type of sets of tuples (a table definition - what is actually drawn in a ER-diagram)

87.162.24.12 16:15, 21 January 2007 (UTC)

 * Formally a relation is a set of tupels that fullfill a relation-schema (they share the same attributes). According to a specific relation schema a tupel might be complete or not. If not complete certain attributes contain NULL-values in the relation. Colloqial a relation is described as a table in a RDBMS-Schema using a DDL.
 * A relationship describes the dependence between two or more relations using a primary key in one a foreign key in the depending relation.
 * Theking2 (talk) 14:03, 26 March 2024 (UTC)

You are correct ... the Common symbols section needs a fair bit of work. I've made the correction, but it still needs more work another day.

To put it into common language, if your brother is a "relation" (aka "entity"), then you have a "relationship" with him, keeping in mind that this is a rather rough analogy.

A tuple is the correct term, and probably should be mentioned on the article somewhere, although I usually prefer the term row or record because it reaches a wider audience.

Thanks,  Matthew 1130 12:47, 22 January 2007 (UTC)

ER diagramming tools - Linkfarm
The software currently listed is mostly shareware. Can this list cleaned up?? Most of the software doesn't even draw real (E)ER! They are *DATABASE* design tools, (E)ER is a particular modeling language. --ThG 14:22, 13 January 2007 (UTC)

 * I agree, it would be good to separate the shareware -vs- commericial offerings in two separate subsections in ER diagramming tools. Do we have a volunteer to figure this out?
 * ThG, what precisely do you mean by "not even drawing real ER"? ER is not a particular modelling language, there are many different notations for ER.  Was there any specific products in the list that you are concerned don't belong?
 * -- Matthew 1130 10:01, 14 January 2007 (UTC)

 * Well, ER is a particular modelling language. Anyway, I should've been more specific: ER itself sux, the real modeling language is known as EER (Extended ER or Enhanced ER), which includes leak entities, unions, derivations, etc). I'll go through the software list again and get back to you.
 * --ThG 19:40, 18 January 2007 (UTC)

I removed all the external links. It was becoming quite a linkfarm, violating WP:EL and WP:NOT. --Ronz 02:50, 17 February 2007 (UTC)

 * It's a shame because this one in particular was really good, and it's totally free and easily accessible from anywhere with an internet connection, unlike the others. You would however be technically right in that it is a relation schema designer and not an (E)ER diagram designer. --Wizgha 18:15, 18 February 2007 (UTC)

 * Here's the external links that were deleted from Entity-relationship model. They look like real players in the market.  Asking for volunteers to create a separate wikipedia pages for them so they can be relisted (refactored - content removed per WP:TALK):
 * Database Visual ARCHITECT - All-in-one ER diagramming and ORM software
 * Toad Data Modeler - a freeware database modeler that also creates SQL DDL code from its drawings
 * Xcase database design tool

 * Matthew 1130 13:52, 26 February 2007 (UTC)

The "ER diagramming tools" section is becoming a linkfarm, with the inappropriate external links. The section may be large enough to become a separate article as well. For now, I'm removing the external links per WP:NOT. --Ronz 15:49, 19 March 2007 (UTC)

Here are the (refactored per WP:TALK) latest deleted links, calling volunteers to create wikipedia pages for these products:
 * ModelRight: inovative and complete physical modeling tool Site.
 * DBDesigner: designer for MySQL databases that uses ERMs. Site.
 * DBDesigner-Fork: a fork of DBDesigner to make it work with other databases such as PostgreSQL. Site.
 * Dia: program to draw many kinds of diagram, including ERDs. Site.
 * Ferret (software): ERM tool distributed with Debian and Ubuntu. Site.
 * ModelRight: inovative and complete physical modeling tool; Free Edition for MySQL Site.
 * Open System Architect: ER Diagram modeller, apparently very good, but the last version is as old as 2005. Site.
 * POWER*ARCHITECT : ER Diagram modeller in Java, Modelling and forward engineering for several databases, both free software and proprietary. Site.

-- Matthew 1130 15:41, 8 August 2007 (UTC)
 * While creating these articles, please keep in mind WP:CORP. Thanks! --Ronz 19:29, 8 August 2007 (UTC)

I've cleaned up the links yet again, removing linkspam and entries that don't have their own articles. --Ronz (talk) 23:05, 19 November 2007 (UTC)

I have put the folowing text in Ronz talk page:

Hello Ronz, I undid your removal of the non-notable softwares in Entity-Relationshiup Diagram page, because it has already helped me and I belive other users in finding a solution that can be adequate for creating this diagram with an open-source solution. I was the initial person who divided the list in proprietary and open source software as I was trying to find a software that fullfill my need, and as I expected, many other people contributed with solutions and finally I dicovered Power*Architect which has recently became open-source. I am a System Analyst of a major brazilian governament company and my division has adopted this software for it´s use after these events. So I think is really helpful, and ask you to leave it. As you may already know, there isn´t any open-source solution in this area with the recent exception I told you. Our best hope is Power*Architect and brModelo. Please don´t remove this list. Other softwares may appear and this page is my (and others) first source of information. You me reach me on nt777@hotmail.com Nelson Teixeira —Preceding unsigned comment added by 201.70.139.207 (talk) 02:02, 6 December 2007 (UTC)

To which Ronz responded: "Please discuss this on the article talk page. There are a couple of ways where something like this could be made to work, but it's going to take more than this I'm afraid. --Ronz (talk) 02:14, 6 December 2007 (UTC)"

Ok Ronz, I´m kinda new on Wikipedia editing. What would be the right way to do it ?

Nelson --Nt777 (talk) 17:06, 11 December 2007 (UTC)
 * Not bad at all. Quoting is a pain.  I changed the formatting slightly, moved your signature to the end, and introduced the response. --Ronz (talk) 00:58, 12 December 2007 (UTC)

 * The solution to this problem is to find some inclusion criteria that we can all agree to, per WP:LIST. The simplest and most common inclusion criteria is to only include entries in the list that have their own Wikipedia articles.  However, another simple way it to simply find a reliable source that provides a list for us to use. --Ronz (talk) 01:03, 12 December 2007 (UTC)

Ronz, I´ll try to find a realiable source in the next couple of days. Would you please leave the list online in the meantime ? And thank you for your information.

Nelson --Nt777 (talk) 17:06, 11 December 2007 (UTC)

Ronz, you cleaned up the links once again. Can we please have a written statement on the criteria for including links here? Otherwise we'll keep going back and forth on this without any real progress. Rp (talk) 10:02, 1 November 2011 (UTC)

Broken Links
The link to Dr. Chen's paper in the references section is broken.

The link to Richard Barker references a page about a Hartlepool FC player Richie Barker User:NigelThomas —Preceding unsigned comment added by 212.58.233.129 (talk) 14:31, 7 January 2008 (UTC)

Crow feet image problem
I fixed the image of the crow feet, with the vertical line and the O being the wrong way round and uploaded the new version. Bencoder 17:16, 13 May 2007 (UTC)
 * That should be Crow's Foot, not crow feet. Sam Tomato (talk) 06:03, 12 November 2016 (UTC)

Beginning
The beginning of the article doesn't look encyclopedic. May I suggest: "ERM is a technique for the structure design of data on databases" or something like that? It would say the same it does now, but in a different order... Magdalena B. 12:28, 9 July 2007 (UTC)

It might also be helpful to provide a bit more context to somebody very new to the subject. For example, you might add something very basic such as, "Data models can become complicated quickly. An ERM is a tool that helps the designer to visualize and improve the design"... Bizerk44 (talk) 14:32, 23 November 2007 (UTC)

The beginning of the article is misleading. ERM's history begins with Charlie Bachman's database diagrams and from there to Barrie Leigh's data modelling at IBM in 1971 and on to at least three threads: Tony Carter and Ian Palmer at CACI, London, Clive Finkelstein in Australia and Peter Chen in the USA. The ERM deliverable was both a verbal model and diagrammatic representation of the terms describing a domain. Clive may have known of Barry Leigh's work through working within IBM. Software engineering emerged from a NATO conference and while it probably now embraces ERM's these days, it had a different focus back then? — Preceding unsigned comment added by Kdf9andtd1a (talk • contribs) 04:04, 15 July 2011 (UTC)

Visio Free software??
Visio is mentioned as a free tool to create diagramms, but the Link directs to Microsoft Visio. Is there a free tool with the same name? (I can't find one) —Preceding unsigned comment added by 138.232.248.27 (talk) 02:56, 16 December 2007 (UTC)

gliffy.com ? — Preceding unsigned comment added by 137.195.15.10 (talk) 15:18, 27 February 2014 (UTC)

Rationale for removing Information Engineering from database sentence in introduction
According to the Information Engineering article, "Information Engineering ... is an approach to designing and developing information systems". It's not therefore an example of a notation "more typically employed in logical and physical database design". The IE methodology does use entity-relationship diagrams, and I've added a wikilink to it in the Crow's Foot section to replace the wikilink in the introduction. --Northernhenge (talk) 09:50, 11 April 2008 (UTC)

List of linkspam (again) trimmed to a normal size
Some wereks ago I trimmed a long list of software programs supporting supporting Entity-relationship models, see here, to the following normal size text:

 * There are lot of ER diagramming tools. Some of the proprietary ER diagramming tools are Avolution, ConceptDraw, ER/Studio, ERwin, DeZign for Databases, MEGA International, OmniGraffle, Oracle Designer, PowerDesigner, Rational Rose, RISE Editor, SmartDraw, Sparx Enterprise Architect, SQLyog, Toad Data Modeler, Microsoft Visio, and Visual Paradigm

 * Some free software ER diagramming tools that can interpret and generate ER models, SQL and do database analysis are MySQL Workbench and StarUML. Some free software diagram tools which can't create ER diagrams but just draw the shapes without having any knowledge of what they mean or generating SQL are Kivio and Dia (software)

Now I resored it again, but I don't understand, why it was removed here in the first place? There shouldn't be a list of over 50 tools, half of it not even notable enough to have a Wikipedia article of it's own. Lists like that are an invitation to keep spamming this article, with every new unknown tools. This is not acceptable in Wikipedia. -- Marcel Douwe Dekker (talk) 15:49, 7 November 2008 (UTC)

Bachmann diagram
Can anyone justify the Bachmann diagram? I definitely recall that in Bachmann diagrams, the arrow-head goes from "owner" to "member", that is from the "1" end of a relationship to the "many" end: I remember people criticising it for that. And I don't know what these open and solid circles are doing on the line. Arguably it doesn't really have a place here anyway, because the Codasyl model was never presented to the world as an ER model or as a data modelling technique (as destinct from a database model).

Mhkay (talk) 07:39, 8 April 2009 (UTC)

another diagram
I made another diagram and put it here:

Wooptoo (talk) 17:55, 30 May 2009 (UTC)

Crow's foot example - incorrect?
According to http://rapidapplicationdevelopment.blogspot.com/2007/06/entity-relationship-diagram-example.html (not a reliable source, I know)

the crow's foot notation for person - location should be the other way around.

LOCATION has zero-to-many PERSONS born there.

PERSON has one and only one birthplace.

Now I've confused myself to the extent that I can't decipher the artist-performs-song pic.

So confused. Enlightened ones, take corrective measures if you please. No need to reply to this, I probably won't read the reply. Primary key (talk) 17:49, 12 June 2009 (UTC)

 * The notation looks fine to me. Libcub (talk) 03:38, 13 June 2009 (UTC)

Entity Relationship Modelling Principles
I was stunned to see such a strange example of an ERD! I came to Wikipedia for some clarity and went away dumbfounded. There is so much detailed, and sometimes erroneous, disagreement that, if this discourse is held to be a serious source for producing ERDs, then Heaven help data modelling! —Preceding unsigned comment added by Vortigern one (talk • contribs) 17:19, 18 November 2009 (UTC)
 * Can you be more specific on your confusion? Dumbfounding people is not the goal of Wikipedia articles, but they can't ignore the fact that these languages, like all languages, have dialects and complicated family relationships. Rp (talk) 08:53, 26 March 2010 (UTC)

Comparison with UML class diagrams
The fact that StarUML, a UML modeling tool, was listed in this article as a ER modelling tool for two years suggests that either I'm unaware of StarUML's true capabilities or it would be worthwhile to add a section explaining the differences between ER models and UML class models in detail. Mind if I add such a section? Rp (talk) 08:53, 26 March 2010 (UTC)

ER model versus ERA model
I'm guessing "ERA model" is just a more uncommon name for "ER model"? The reason I ask is that a newsgroup I read had a post with someone asking for an "ERA modeler", which I looked up and found this entry on Encyclopedia.com. But I was unable to find an entry for ERA model or Entity-Relationship-Attribute on Wikipedia. I've created both those pages and redirected them to here. But I just wanted to make sure there wasn't some hidden distinction between an ER model and an ERA model. Otherwise, I guess ERA diagram should probably redirect here as well.--Subversive Sound (talk) 17:44, 13 May 2010 (UTC)

yeah, Entity-Relationship-Attribute model is pretty much the same. Entities and relationships have attributes - that's where the data's stored. When it comes time to make a real database, all the relationships are described with attributes too. Often, every entity has an integer ID - 1, 2, .... like the Person table could have an id field (attribute) named id. And another entity that has a relationship with that entity just points to the entity by storing the integer ID, like a phone record might have a field named person_id that points to the person who owns it. OsamaBinLogin (talk) 20:40, 25 July 2012 (UTC)

Overall Wrongness
The overview has recently been updated so the following comments are no longer significant! April 2012 — Preceding unsigned comment added by 208.44.95.13 (talk) 18:41, 9 April 2012 (UTC)

 * Not so. The overview is rubbish. The recent edits have made it worse. Far too many ignorant people have contributed to this page. Mhkay (talk) 18:53, 9 April 2012 (UTC)

Everything in the overview is wrong. There is no "first stage" of IS design. Different teams start different ways. ER diagrams are primarily intended for representing existing databases, not for conceptual modeling and requirements analysis. ER is a modeling grammar, not a technique. You can only describe one ontology with an ER diagram, that is, one in which the world is composed of entities and relationships. The discussion of mapping conceptual to logical data models is deeply misleading - there is no evidence that most teams bother with such an abstract process. The classical notation is not for conceptual modeling - people didn't even realize that ER could be bastardized into a conceptual modeling grammar until well after this notation was developed.

I will make a note to return and try to fix this in a few weeks, depending on reaction to this entry.

Paul Ralph (Lancaster University) (talk) 23:24, 12 January 2011 (UTC)

 * You will need to further quality your "wrong". The approach to distinguish separate design phases, in which a conceptual, logical and physical model are created in turn, is common in database design courses.  It is not universally taught or followed, but that does not make it "wrong".  I do agree that it is wrong for this article to be so casual and take it for granted, but isn't exactly the only text on database design that does this.  As to the difference between grammar and technique, I think this is a matter of definitions: your "grammar" is another person's "technique".  Anyhow, there is much room for improvement.  Looking forward to your improvements or suggestions for them. Rp (talk) 16:02, 26 January 2011 (UTC)

 * "People didn't even realize that ER could be bastardized into a conceptual modeling grammar until well after this notation was developed." I know it's tough to ask you to prove a negative, but I wonder if you can explain why you think this? The consultants I was working with in the mid 1970s certainly considered that they were formalising notations for conceptual modelling that were independent of logical database design. Also, it's unclear what you mean by "bastardized". You claim that ER "is" a grammar, then you say the grammar is a "bastardization" of ER. Mhkay (talk) 16:14, 26 January 2011 (UTC)

"ER is a modeling grammar, not a technique. You can only describe one ontology with an ER diagram, ..." Sounds to me like a lot of big words. You should confine all these higher abstractions to another section, where I and most programmers can conveniently skip over them. Because, although they are concepts involved with ER diagrams, knowing them will rarely help one understand what they are - more likely, one is learning the meaning of 'modeling grammar' and 'ontology'.

My experience as a professional programmer tells me that most databases are designed like one of the following:

 * 1) They just hack.  As with the flowcharts that describe simple IF statements, all these clumsy diagrams have been tossed out.

 * 1) Management displays a commitment to ER diagrams and UML modeling.  But nobody draws such diagrams, and they all just hack as in #1.

 * 1) Management displays a commitment to ER diagrams and UML modeling, and everything is designed with big fanfare and lots of effort into a big ER diagram.  The ER diagram is faithfully transcribed into SQL tables and what not.  The first few times there's changes, they go back and pencil in stuff in the ER diagram.  But after six months, everybody is just hacking as in #1.

That's the way it seems to work. A programmer says to herself, "OK for each Foo, are there many Bars? For each Bar, are there many Foos?" Then the answer is obvious and fields are added to tables as the software evolves. No ER diagram is even visualized, although sometimes in sticky cases, entities are drawn like single database rows with individual fields, with relationship arrows coming out of the specific field that they inhabit, scribbled quickly on a piece of scrap paper in red ink. The relationships are always many-to-one. — Preceding unsigned comment added by OsamaBinLogin (talk • contribs) 21:04, 25 July 2012 (UTC)

REQUIRES A TOTAL REWRITE
The article starts from the wrong premise. It is based on Peter Chen's view of this topic. Much original thinking had already taken place within IBM and some London based consultancies, to my knowledge and probably elsewhere too. In the interests of clarity it would help to recognise the history of the topic, which the article has failed to do.

The history below is much better than nothing:

History ER Diagrams were first introduced by Charles Bachman. "Bachman Diagrams" described data structures, however, he did however go further and recognised the need to model at a higher level of abstraction.

“… entity to mean a particular object being considered; the term entity class will mean an entire group of entities which are sufficiently similar, in terms of attributes that describe them, to be considered collectively … entity set … associates a group of entities in one entity class with one entity of a different entity class in a subordinate relationship” page 4 of "Bachman, C. W. (1969) Data Structure Diagrams. DATA BASE 1(2): 4-10"

See a fuller discussion of the whole topic of Bachman and Chen diagramming in "The Entity Relationship Model And Practical Data Modelling By Steve Hitchman 2004, Journal of Conceptual Modeling, April 2004".

ER diagrams were popularised by Dr. Pin-Shan (Peter) Chen in 1976, but he drew on the previous work of his colleagues, one of whom was Charles Bachman.

 * I think Chen is usually credited as the originator because he was the first person to have an article on entity-relationship models published in the academic literature; he was also the first to formalize them. The earlier work (by people like Ian Palmer of Scicon) was practical consultancy and it's now very hard to find citations. Mhkay (talk) 18:58, 9 April 2012 (UTC)

Mention should also be made of J. Barrie Leigh "Mr. Leigh began his interest in E-R modeling techniques as a systems engineer for IBM in the UK, developing his first E-R diagram in 1971 for an annuity system of Royal Insurance. He was a recognized leader of transactional and database systems design for IBM, in the insurance industry. He evangelized the use of distributed intelligence and distributed database architectures throughout the 1970’s." See meeting notice for DAMA Philadelphi/Delaware Valley 10th January, 2007. While at CACI, London he worked with a number of key professionals including Ian Palmer, Rosemary Rock-Evans, Richard Barker and Keith Short all of whom made significant contributions to this field. — Preceding unsigned comment added by Kdf9andtd1a (talk • contribs) 22:39, 14 August 2011 (UTC)

 * Wait a minute: Bachman diagram and Data structure diagram (which is what Bachman named his diagrams when he introduced them in 1969) have their own article(s); you may want to start there, e.g. by merging them. I do agree that a more unified perspective on database diagramming and information diagramming is necessary, but in IT we all know only the languages we've been taught, even if the neighbours use a different one to say the same things.  So I'm not sure a single article would suffice.  However at least some notes on developments and more crosslinking would be in order. Rp (talk) 22:58, 17 August 2011 (UTC)

Problems with 'Cardinalities' sub-section
The sub-section on 'Cardinalities' assumes much information not provided within the article, and uses the following terms without explanation or motivation:
 * cardinality,
 * look-across,
 * same-side,
 * minimum cardinality,
 * optionality,
 * maximum cardinality,
 * crows foot (sic),
 * n-ary relationship,
 * order (of relationship),
 * degree,
 * transformation,
 * extension,
 * mechanism,
 * simple mechanism.

And the two asides in parentheses only compound the jargon problem ...

The whole section 'Relationships, roles and cardinalities' smacks of either original research or personal opinion. At the very least, it needs some citations to support its contentions.

If the whole article is seen as an intelligent layman's overview of E-R modelling, the material presented throughout (but not in this sub-section) is quite hard enough. This sub-section on 'Cardinalities' is pitched at completely the wrong level.

As a seasoned ADP | EDP | DP | Computing | IT | ICT professional, I ask myself: What problem is the sub-section on 'Cardinalities' trying to solve? I can only conclude it's driving towards the quote from Feinerer, referencing Hartmann: 'Problems arise if we operate under the look-across semantics as used for UML associations ... different transformations fail.' This surely is, at once, both too abstract and too low-level a consideration for the "intelligent layman" who has read the previous material?

If all the sub-section manages to say is that "look-across semantics don't work", or "... don't properly represent the meanings of the relations between entities", shouldn't the article then say what we DO about it?

For the present, I suggest scrapping all the text under the sub-heading "Cardinalities" and replacing it with an explanation of:
 * what the term 'cardinality' means in E-R models, and
 * why we choose to represent all possible (finite mathematical) cardinalities by only the values 0, 1 and M(any).

yoyo (talk) 17:38, 8 April 2012 (UTC)

Early History
I started using Entity Modeling in approximately 1974 at the City of Westminster in London. This was based on work at ICL by Harry Ellis and David Gradwell et al. David Gradwell may well be able to provide even earlier history. A lot of the pioneers were related to the Data Dictionary Working Group within the British Computer Society at the time. This predated the Chen paper but Chen was usually considered the academic father of ER modeling simply because he published one of the first papers on the subject and it was very influential. His use of Relationships as first class objects was generally rejected at the time, as it didn't prove very useful for the practicioners. It supports n-ary relationships and the databases of the time didn't have much use for such relationships.

The techniques and notation used in ER modeling were developed by the database practicioners of the time. The problem that was being addressed was the inflexibility of CODASYL databases, such as DMS1100 (Univac) and IDMS which I think was used by ICL, hence their interest in ER modeling. You had to get the schema right as it was very difficult to alter it once the database was in production. This lead to the use of ER modeling as a basis for database design so that the schema would be well designed initially.

After Westminster, I joined CACI in the Netherlands and participated in the development of ER modeling with Ian Palmer, David Gradwell, Bernie Benetto and others. We introduced concepts and notation for entity subtypes and supertypes, time based data (ways to model dynamic data), relationship optionality and inclusive/exclusive relationships. At the time, CACI had two database cunsultancy offices in Europe, one in the UK and one in the Netherlands and they worked closely together on ER modeling. After that came Richard Barker, Rosemary Rock-Evans and others at CACI who documented the approach. From there it moved to James Martin Associates and then to Oracle.

Bachman's early work may have had some influence on ER modeling but it would have had to have been very early and relatively limited as we considered his approach more of a different and rival approach at the time. — Preceding unsigned comment added by Djwdjw123 (talk • contribs) 23:47, 7 November 2012 (UTC)

Limitations
For many systems, the possible changes to the information contained are nontrivial and important enough to warrant explicit specification. - Could you elaborate more? Sumdumboot (talk) 05:15, 28 March 2013 (UTC)

While this section is called Limitations, its bulleted list includes a wider range of content. See for example the items that simply highlight various extensions (or outright alternatives, like Anchor Modeling and EER). I'd expect the points to directly state the limitation of ER modeling and then identify the extension or alternative as a solution to the described limitation. As is it looks more like a random list of additional information than a list of limitations. The alternative would be to simply rename this section. Rszrama (talk) 20:16, 8 May 2013 (UTC)

In addition, the last bullet in the list ("For modelling temporal databases ...") is just flat out wrong - Especially the part that ER would be unsuitable for multidimensional databases. What the refered paper (ref 25) does is to highlight needs of the platform specific model (a DBMS) and then conclude that the plaform independent model (i.e. ER-diagram) is unsuitable. To cite ref 25: "First, a logical representation is conceived to describe, at the appropriate level of abstraction, how data is stored in a specific DBMS, ..." This is absolutely NOT the reason for the logical model. The logical model describes what entities consist of and how they relate (i.e. business rules). Those ruels can't be broken. It has nothing to do with "... how data is stored ...". The business rules and info structure have a right of existance of their own - completely decoupled from implementation. The ER-model is the specification, the (R)DBMS is the implementation that must obey the ER-model. This is, however, not the same as saying how an entity type shall be implemented. It can be tables, multidimensional cubes or whatever form that is suitable for the implementation.

Ref 25 continues: "... but it is usually not expressive enough to capture in an effective way the essential, multidimensional aspects of a data warehousing application." The ER model is as expressive as the modeller can ever make it. ER-models can be expressive enough to be directly compiled to running applications (see xtUML). Correctness is the realm of the ER-modell. Efficienvy is the realm of the platform specific model (i.e. the specific implementation of the ER-model). — Preceding unsigned comment added by 136.163.203.3 (talk) 13:29, 21 September 2022 (UTC)

Crows foot notation external link
Does anyone else feel like the resource linked to from the external links section is poor quality? The information is helpful but the formatting and readability issues seem to detract from the ability for a normal user to find the page useful. Any suggestions for a better resource? Bhanks (talk) 20:49, 9 July 2013 (UTC)

I left in the poorly formatted resource but deleted a page that had a bunch of affiliate links at the bottom and also a resource that 404ed. I also added a diagramming tool that is free that I like to use. Bhanks (talk) 21:11, 9 July 2013 (UTC)
 * The tool you like to use has been appropriately removed as spam. --Ronz (talk) 19:46, 17 July 2013 (UTC)

Lead sentence structure
Which is preferable for the lead sentence? "A. In software engineering, an entity–relationship model (ER model) is a data model for describing the data or information aspects of a business domain or its process requirements, in an abstract way that lends itself to ultimately being implemented in a database such as a relational database." or some thing like: "B. An entity–relationship model (ER model) is a data model used in software engineering for describing the data or information aspects of a business domain or its process requirements, in an abstract way that lends itself to ultimately being implemented in a database such as a relational database." Joja lozzo  18:01, 11 March 2014 (UTC)

 * B. - I prefer to place the most important aspect of the article, the topic, at the start of the lead sentence. I think the only time it's better to put something else first is when there are other usages of the term in other domains and we need to make sure the reader knows at the very start which domain we are talking about. In this case there are no other domains in which ER models occur so there is no need to emphasize the domain as is done in A. Joja  lozzo  18:01, 11 March 2014 (UTC)

Introduction still wrong
The introduction still doesn't make much sense: Rp (talk) 12:23, 24 June 2015 (UTC)
 * ER models do not describe business processes: they describe what can be, not how it changes or can change. You can see this from the example given: a building or an apartment is not a process. (They can be relevant to a business process, and describing all things relevant to a business process goes some way towards describing that process, but it is not the same thing.)
 * There should be a better distinction between ER models (information schemas) and instances of such models (actual information structured described according to such schemas). For instance, it should be clarified that a description of a particular set of buildings and apartments will be an instance of an ER model describing buildings and apartments in general.

What is an entity class?
Entity class redirects to this article, but the term isn't mentioned, and I have no idea what it means. Can anyone explain? Rp (talk) 18:55, 12 July 2015 (UTC)

External links modified
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Modelling issues
I like the newly added section Modelling issues, but it needs further improvement:

 * These issues were mentioned by Codd - his article should be referenced and possibly quoted.
 * From the present text, I don't understand what the problems are. It should be clarified, preferably with examples.
 * The present text suggests that these problems are limitations or drawbacks of ER modeling; it suggests that ER models correcting these problems do not exist. From the referenced text, it becomes clear that this is not the case: correct models for these situations do exist.  This should be made clear. Rp (talk) 18:27, 21 October 2016 (UTC)
 * Agreed. I don't know why this section is here.  These are not failures of ER, but failures to do ER correctly. Haakondahl (talk) 15:26, 26 May 2018 (UTC)

Both the "fan-trap" issue and the 'chasm-trap' are a clear indications that the model is missing critical pieces. The sane path forward is to update the ER-model. In the 'fan-trap' case, the model is missing an assignment relation (e.g. staff-department in ref 24). In the 'chasm-trap' a relation between a computer and e.g. an owner. This is not an issue with ER. It's an issue with the modeller's limited understanding of the problem at hand.

Authorities
Is the page Crow's Foot Notation truly authoritive (yes I know I spell "authoritive" differently than most)? It looks like someones' college notes. What qualifies bernatja at the University of Regina as an authority? Or can I just create a page somewhere about something and cite it as an authority? Sam Tomato (talk) 05:50, 12 November 2016 (UTC)

External links modified
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Primarky Keys
Some experts maintain that the ERD is a graphical tool to visualize a conceptual model (which is by the way a different thing from the conceptual schema). A conceptual model is supposed to represent the business world (the universe of discourse or domain of interest that the model is supposed to represent) and such constructs like "keys" or "indices" or "privileges", etc. which are the peculiarities of the database model do not belong in the conceptual model and by extension in the ERD which merely visualizes the conceptual model. Primary keys are relevant to the Logical Model (which broadly translates the conceptual model in terms of a given database model (often relational). Simply put, real world entities do not have a "key". Tables do. Ehsanamini (talk) 07:42, 27 September 2019 (UTC)

To be in the relationship for least
To be your lover forever❤ 41.116.177.176 (talk) 10:41, 17 April 2022 (UTC)

Distinguish between model and diagram
This article mixes model and diagram in a very confusing way. Confusing for both readers as authors. It starts off rather well in the introduction defining three different levels of model or the three-schema_approach and than leaves that and jumps right into different diagramms and loses track about which is what pretty quickly. For me diagrams are tools to describe a model.

I realize that there are quite some opinions floating around here but this article as it is now is not very useful for students or experts alike.

On thing that could help is to call it Entity Relationship Diagram that describe a set of possible, practical notations and tools to describe a relational database schema and leave the conceptual model description out and move it a more high level articale comparing hierarchical, network and relation databases models.

Theking2 (talk) 14:21, 26 March 2024 (UTC)

title: Talk:Entity–relationship model


text:
Adaptive Multi-Rate Wideband

Adaptive Multi-Rate Wideband (AMR-WB) is a patented wideband speech audio coding standard developed based on Adaptive Multi-Rate encoding, using a similar methodology to algebraic code-excited linear prediction (ACELP). AMR-WB provides improved speech quality due to a wider speech bandwidth of 50–7000 Hz compared to narrowband speech coders which in general are optimized for POTS wireline quality of 300–3400 Hz. AMR-WB was developed by Nokia and VoiceAge and it was first specified by 3GPP.

AMR-WB is codified as G.722.2, an ITU-T standard speech codec, formally known as Wideband coding of speech at around 16 kbit/s using Adaptive Multi-Rate Wideband (AMR-WB). G.722.2 AMR-WB is the same codec as the 3GPP AMR-WB. The corresponding 3GPP specifications are TS 26.190 for the speech codec and TS 26.194 for the Voice Activity Detector.

The AMR-WB format has the following parameters:
 * Frequency bands processed: 50–6400 Hz (all modes) plus 6400–7000 Hz (23.85 kbit/s mode only)
 * Delay frame size: 20 ms
 * Look ahead: 5 ms
 * AMR-WB codec employs a bandsplitting filter; the one-way delay of this filter is 0.9375 ms
 * Complexity: 38 WMOPS, RAM 5.3 kilowords
 * Voice activity detection, discontinuous transmission, comfort noise generator
 * Fixed point: bit-exact C code
 * Floating point: under work

A common file extension for the AMR-WB file format is. There also exists another storage format for AMR-WB that is suitable for applications with more advanced demands on the storage format, like random access or synchronization with video. This format is the 3GPP-specified 3GP container format, based on the ISO base media file format. 3GP also allows use of AMR-WB bit streams for stereo sound.

AMR modes
AMR-WB operates, like AMR, with nine different bit rates. The lowest bit rate providing excellent speech quality in a clean environment is 12.65 kbit/s. Higher bit rates are useful in background noise conditions and for music. Also, lower bit rates of 6.60 and 8.85 kbit/s provide reasonable quality, especially when compared to narrow-band codecs.

The frequencies from 6.4 kHz to 7 kHz are only transmitted in the highest bitrate mode (23.85 kbit/s), while in the rest of the modes the decoder generates sounds by using the lower frequency data (75–6400 Hz) along with random noise (in order to simulate the high frequency band).

All modes are sampled at 16 kHz (using 14-bit resolution) and processed at 12.8 kHz.

The bit rates are the following:

Notes: "The codec mode can be changed every 20 ms in 3G WCDMA channels and every 40 ms in GSM/GERAN channels. (For Tandem Free Operation interoperability with GSM/GERAN, mode change rate is restricted in 3G to 40 ms in AMR-WB encoders.)"
 * Mandatory multi-rate configuration
 * 6.60 kbit/s (used for circuit switched GSM and UMTS connections; should only be used temporarily during bad radio connections and is not considered wideband speech)
 * 8.85 kbit/s (used for circuit switched GSM and UMTS connections; should only be used temporarily during bad radio connections and is not considered wideband speech; provides quality equal to G.722 at 48 kbit/s for clean speech)
 * 12.65 kbit/s (main anchor bitrate; used for circuit switched GSM and UMTS connections; offers superior audio quality to AMR at and above this bit rate; provides quality equal to or better than G722 at 56 kbit/s for clean speech)
 * Higher bitrates for speech in adverse background noise environments, combined speech and music, and multi-party conferencing.
 * 14.25 kbit/s
 * 15.85 kbit/s
 * 18.25 kbit/s
 * 19.85 kbit/s
 * 23.05 kbit/s (not targeted for full-rate GSM channels)
 * 23.85 kbit/s (provides quality equal to G.722 at 64 kbit/s for clean speech; not targeted for full-rate GSM channels)

Configurations for 3GPP
When used in mobile phone networks, there are three different configurations (combinations of bitrates) that may be used for voice channels:

 * Configuration A (Config-WB-Code 0): 6.6, 8.85, and 12.65 kbit/s (Mandatory multi-rate configuration)
 * Configuration B (Config-WB-Code 2): 6.6, 8.85, 12.65, and 15.85 kbit/s
 * Configuration C (Config-WB-Code 4): 6.6, 8.85, 12.65, and 23.85 kbit/s

This limitation was designed to simplify the negotiation of bitrate between the handset and the base station, thus vastly simplifying the implementation and testing. All other bitrates can still be used for other purposes in mobile phone networks, including multimedia messaging, streaming audio, etc.

Deployment
AMR-WB has been standardized by a mobile phone manufacturer consortium for future usage in networks such as UMTS. Its speech quality is high, but older networks will have to be upgraded to support a wideband codec.

In October 2006, the first AMR-WB tests were conducted in a deployed network by T-Mobile in Germany, in cooperation with Ericsson.

In 2007 an end-to-end AMR-WB TrFO capable 3G & VoIP product line was commercially released by NSN (M13.6 MSS, U3C MGW). AMR-WB TFO support was commercially released in 2008 (M14.2, U4.0). End-to-end TFO/TrFO negotiation and mid-call optimization (e.g. on handover, CF or CT events) was released in 2009 (M14.3, U4.1).

In late 2009, Orange UK announced that it would be introducing AMR-WB on its network in 2010. In France Orange S.A. and SFR are using AMR-WB format on their 3G+ networks since the end of summer 2010.

WIND Mobile in Canada launched HD Voice (AMR-WB) on its 3G+ network in February, 2011. WIND Mobile also announced that several handsets will support HD Voice (AMR-WB) in the first half of 2011, with the first one being Alcatel Tribe.

In January 2013, T-Mobile became the first GSM/UMTS based network in the US to enable AMR-WB.

In Feb 2013, Chunghwa Telecom became the first GSM/UMTS based network in Taiwan to enable AMR-WB.

In August 2013 the AMR-WB standard was introduced in Ukraine by Kyivstar.

Nokia developed the VMR-WB format for CDMA2000 networks, which is fully interoperable with 3GPP AMR-WB. AMR-WB is also a widely adapted format in mobile handsets for ringtones.

The AMR wideband speech format shall be supported in 3G multimedia services when wideband speech working at 16 kHz sampling frequency is supported. This requirement is defined in 3GPP technical specifications for IP Multimedia Subsystem (IMS), Multimedia Messaging Service (MMS) and Transparent end-to-end Packet-switched Streaming Service (PSS). In 3GPP specifications is AMR-WB format also used in 3GP container format.

Licensing
G.722.2 is licensed by VoiceAge Corporation.

Tools
For encoding and decoding AMR-WB, an open-source library named OpenCORE exists. The OpenCORE codec can be used in ffmpeg.

For encoding, another open-source library exists as well, provided by VisualOn. It is included in the Android mobile operating system.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Adaptive Multi-Rate Wideband


text:
Wikipedia:Articles for deletion/Nejaa Halcyon (0th nomination)

The result of the debate was delete [added by Andre🚐 22:38, 15 August 2022 (UTC) for afdstats]

Nejaa Halcyon
Minor character from some Star Wars novels. Granted, the character is rumored to play a larger role in Episode III, but until then, let's draw the line somewhere -- Ferkelparade π 13:45, 18 Oct 2004 (UTC)
 * Delete: An argument I recently made on my talk page went like this: Uncle Tom's Cabin helped fire up the Civil War, read by millions, big effect on actual history. Do we have an article on every character?  Do we have an article on every article of clothing?  All the rumored ancestors and children?  Cool chapters where stuff happens?  This, on the other hand, is a fan fad and not notable. Geogre 18:38, 18 Oct 2004 (UTC)
 * Delete. Fancruft. --Improv 20:58, 18 Oct 2004 (UTC)
 * Delete: useless pseudoinformation. Wile E. Heresiarch 04:46, 19 Oct 2004 (UTC)
 * Delete. Fancruft. jni 10:27, 19 Oct 2004 (UTC)
 * Delete, but if this character is a main character in the next Star Wars film, allow to be recreated. Andre ( talk )A| 14:05, Oct 19, 2004 (UTC)


text:
Eddie Hart (sprinter)

Edward James "Eddie" Hart (born April 24, 1949) is an American former track and field sprinter, winner of the gold medal in 4 × 100 m relay race at the 1972 Summer Olympics.

Born in Martinez, California, Eddie Hart won the NCAA championships in 100 yd in 1970 as a University of California student.

At the US Olympic Trials in 1972, both Hart and Rey Robinson repeated the world record, running the 100 m in 9.9 seconds, and were favored to win the race at the Olympic Games. But in Munich, they were both eliminated in the 100 m race because their coach, Stan Wright, unknowingly using an outdated Olympic schedule to determine the starting time of their quarterfinal heat, failed to deliver them to the track on time. This failure due to disorganization created much controversy. Hart also ran the anchoring leg in the American 4 × 100 m relay team, which won a gold medal and equalled the United States' own world record of 38.19.

Hart continued to run and in 1989 set the Masters world record in the 100 m that lasted for 14 years.

In 2017 Hart released a book, Disqualified: Eddie Hart, Munich 1972, and the Voices of the Most Tragic Olympics about his Olympic experience.

title: Eddie Hart (sprinter)


text: Category:Cleveland Naps players

title: Category:Cleveland Naps players


text:
Algebraic code-excited linear prediction

Algebraic code-excited linear prediction (ACELP) is a speech coding algorithm in which a limited set of pulses is distributed as excitation to a linear prediction filter. It is a linear predictive coding (LPC) algorithm that is based on the code-excited linear prediction (CELP) method and has an algebraic structure. ACELP was developed in 1989 by the researchers at the Université de Sherbrooke in Canada.

The ACELP method is widely employed in current speech coding standards such as AMR, EFR, AMR-WB (G.722.2), VMR-WB, EVRC, EVRC-B, SMV, TETRA, PCS 1900, MPEG-4 CELP and ITU-T G-series standards G.729, G.729.1 (first coding stage) and G.723.1. The ACELP algorithm is also used in the proprietary ACELP.net codec. Audible Inc. use a modified version for their speaking books. It is also used in conference-calling software, speech compression tools and has become one of the 3GPP formats.

The ACELP patent expired in 2018 and is now royalty-free.

Features
The main advantage of ACELP is that the algebraic codebook it uses can be made very large (> 50 bits) without running into storage (RAM/ROM) or complexity (CPU time) problems.

Technology
The ACELP algorithm is based on that used in code-excited linear prediction (CELP), but ACELP codebooks have a specific algebraic structure imposed upon them.

A 16-bit algebraic codebook shall be used in the innovative codebook search, the aim of which is to find the best innovation and gain parameters. The innovation vector contains, at most, four non-zero pulses.

In ACELP, a block of N speech samples is synthesized by filtering an appropriate innovation sequence from a codebook, scaled by a gain factor g c, through two time-varying filters.

The long-term (pitch) synthesis filter is given by:

 * $$\frac1{B(z)} = \frac1{ 1 - g_p z^{-T} }$$

The short-term synthesis filter is given by:
 * $$\frac1{A(z)} = \frac1{ 1 + \sum_{i=1}^P a_i z^{-i} }$$


text: Category:Cleveland Spiders players

title: Category:Cleveland Spiders players


text:
John Hoole

John Hoole (December 1727 – 2 August 1803) was an English translator, the son of Samuel Hoole (born 1692), a mechanic, and Sarah Drury (c. 1700 – c. 1793), the daughter of a Clerkenwell clockmaker. He became a personal friend of Samuel Johnson's.

Family
Hoole was born in Moorfields, London, and was educated at a private school at Hoddesdon, Hertfordshire, kept by a James Bennet. In 1757 he married Susannah Smith (c. 1730 – 1808), a Quaker from Bishop's Stortford. They had a son, Rev. Samuel Hoole, who became a poet and religious writer of some distinction.

Works
At the age of seventeen John Hoole became a clerk in India House (1744–83), of which he rose to be principal auditor of Indian accounts. In connection with his post, he wrote Present State of the English East India Company's Affairs (1772).

Meanwhile he translated Torquato Tasso's Jerusalem Delivered (1763), and Ariosto's Orlando Furioso (1773–83), as well as other works from the Italian. He was also the author of Cleonice, Princess of Bithynia and of two other dramas which failed.

Samuel Johnson was a personal friend of Hoole, who described Johnson's final days in the European Magazine of 1799. Robert Southey recalled that Hoole's Jerusalem Delivered was "the first book he ever possessed," apart from a set of sixpenny children's books. Hoole was a genial character, but termed as a translator not unfairly by Sir Walter Scott as "a noble transmuter of gold into lead".

David Barclay of Youngsbury turned to Hoole to write the biography of his friend John Scott of Amwell, when Johnson, his first choice, died before he could do so.

Retirement
In 1786 Hoole retired to the parsonage of Abinger, Surrey. Afterwards he lived at Tenterden, Kent, and died in Dorking.

Selected works

 * Cyrus (1768, play)
 * Timanthes (1770, play)
 * Cleonice, Princess of Bithynia (1775, play)

title: John Hoole


text:
Talk:Golden goal

Who scored the first golden goal in worldcup history

 * France (against Paraguay, in 1998). Kinitawowi 08:28, Oct 19, 2004 (UTC)

Question
Can anyone please tell me why FIFA is abandoning the golden and silver goal format?
 * I wondered that too.."The important thing was to have clarity and to have a single method to determine the outcome of a match. The question was, where would we draw the line? Would there later be a bronze goal and then something else?" http://www.fifa.com/en/news/feature/0,1451,74458,00.html -- Paul 18:35, 24 Jun 2005 (UTC)

 * Article says it all: horrendously unpopular, confusing to have more than one way to play extra time (I refereed a game once where one team was convinced it was golden goal and the other was convinced it was silver goal because they'd both seen it on the telly, when the competition rules said vanilla 30 minutes), etc... Hig Hertenfleurst 23:13, 24 Jun 2005 (UTC)

 * Shouldn't there be a mention as to why the goal is called 'Golden' in the first place? —The preceding unsigned comment was added by 69.230.205.47 (talk • contribs) 23 Sept 2005.

 * I read that the powers that be did not like the negative perception of the term "sudden death" that is popular in other sports. --mnw2000

 * Perhaps; do you have a reference as to why it is? --Daveb 07:58, 23 September 2005 (UTC)
 * I am trying to establish the quickest golden Goal. I witnessed one after 15 seconds at Brentford FC. Any faster one known? Baldy1952 (talk) 14:33, 19 February 2009 (UTC)

- On the main page it says: 'It is a type of sudden death'. I don't agree with that or am I wrong? -

Removed from the Law?
Are you sure Golden and Silver goal procedures were ever part of the Law of the Game? I thought they were part of the competition regulation, but not from the Law itself?

Other methods
Is it right, that football matches used to be ended with a golden goal without a time limit? Does anyone know any more about that?

 * Certainly never in soccer. In American football they used to have sudden death without a time limit Dankru 22:26, 25 November 2006 (UTC)

195.200.115.170

Why the heck did they abolish Golden Goal in football (soccer)??

 * 2002 World Cup (with golden goal). 3 matches decided in extra time.  2 matches decided by a penalty shootout.
 * 2006 World Cup (with no golden goal). 2 matches decided in extra time.  4 matches (including the final) decided by a penalty shootout.

The same pattern holds if you look at a wider range of tournaments, including the UEFA cup. Golden goal is significantly more successful in getting a result in extra time and avoiding penalties. Surely it's better to decide a match by a golden goal than a penalty shootout? Idiots. Grover cleveland (talk) 05:43, 14 June 2010 (UTC)

Merge article Silver goal into Golden goal

 * Disagree Having the Silver goal article separate is the most appropriate, as it is not the same as the Golden goal concept. 24.63.105.208 (talk) 15:27, 27 June 2010 (UTC)

 * Agree Golden goals and silver goals are similar concepts and were introduced around the same time in association football (soccer). Silver goals can just be a separate section within the article. Both articles need some work anyway, especially the silver goal article. 11:47, 30 August 2010 (UTC)

 * Agree this should be merged --Pretty Green (talk) 09:18, 30 September 2010 (UTC)

Historical Context
There is an instance of a golden goal being scored in a Youdan Cup tie of 1867 that predates the one scored by The Wednesday in the Cromwell Cup final by nearly a year. It was reported in the Sheffield Independent of 26/03/1867 that the Youdan Cup second round tie between Norfolk Park and Broomhall on 23/02/1867 went to extra-time. The tie was won by Norfolk who managed to 'kick a goal' within two minutes of the restart. see here Youdan Cup - The World's First Football Trophy Tuskom (talk) 16:51, 2 October 2011 (UTC)

Merge?
There’s some duplicate material; golden goal is essentially synonymous with sudden death. —Wiki Wikardo 14:58, 30 May 2014 (UTC)

Mild Disagree I agree that golden goal isn't so much a type of sudden death as a synonym applied to certain sports. However, there are other articles of the same ilk (e.g. Golden point), and the article on silver goal was merged with golden goal, despite their being two different concepts (the silver goal one being VERY different from either golden goal or sudden death). My view:

 * If this article is kept (implying golden goal is a type of sudden death), gridiron football references should be eliminated from this article (it doesn't even have the concept of goals, the method used ISN'T actually the same as golden goal in any league currently, and is well-covered by the article on sudden death). Possibly, NHL references and any other sports where the term "golden goal" is not used should also be eliminated, though in these cases you could at least argue that the rule is the same as the defunct association football golden goal. In this case the current small reference to silver goal in the golden goal article is probably fine as-is.

 * If this article is merged, other references to sudden death that are less common or are "types" (e.g. Golden Point) should also be merged. However, silver goal (which has nothing to do with sudden death at all) should then probably be given its own article.

Liam3851 (talk) 16:11, 24 June 2014 (UTC)

Baseball
The inclusion of baseball in this article seems tenuous at best. — Preceding unsigned comment added by Bcostley (talk • contribs) 01:33, 20 January 2022 (UTC)

title: Talk:Golden goal


text:
Thomas Hartwell Horne

Thomas Hartwell Horne (20 October 1780 – 27 January 1862) was an English theologian and librarian.

Life
He was born in London and educated at Christ's Hospital until he was 15 when his father died and he had to work. He then became a clerk to a barrister, and used his spare time to write.

Horne was initially affiliated with the Wesleyans but later joined the Church of England. He was admitted to holy orders without the usual preliminaries, because of his published work. In 1833 he obtained a benefice in London and a prebend in St Paul's Cathedral.

Horne was a librarian in 1814 at the Surrey Institution, which was dissolved in 1823. He was admitted sizar to St John's College, Cambridge in 1819. In 1824 he joined the staff at the British Museum and was senior assistant in the printed books department there until 1860. He prepared a new system for cataloguing books at the museum but it was never used there. He did use it, however, to reclassify the extensive library of Frances Mary Richardson Currer in 1833.

Works
Horne wrote more than forty works in bibliography, Bible commentaries, and Christian apologetics. One of his best known works is the three-volume Introduction to the Critical Study and Knowledge of the Holy Scriptures that was published in 1818. This work enjoyed widespread circulation in Britain and North America and went through at least eleven editions during the nineteenth century. It was reissued in North America in 1970. Horne also produced a "Tree Full of Bible Lore," a tree-shaped text of statistics on the Bible, in which he counted the number of books, chapters, verses, words, and even letters. He ended this tree with "It [the Bible] contains knowledge, wisdom, holiness and love." (This "tree" is reproduced in the third series of Ripley's paperbacks, originally published hardbound in 1949.)

He wrote an Introduction to the Study of Bibliography (1814), and various other works. Over a period of four years he catalogued the Harleian manuscripts then held at the British Museum.

Biographical source

 * Clark, R. E. D., "Thomas Hartwell Horne," in The New International Dictionary of the Christian Church, edited by J. D. Douglas. (Extere: Paternoster Press, 1978). ISBN 0-85364-221-4

Select bibliography

 * A compendium of the statute laws, and regulations of the Court of admiralty: relative to ships of war, privateers, prizes, recaptures, and prize-money. With an appendix of notes, precedents, &c, (London: Printed for W. Clarke and sons, 1803)
 * A Catalogue of the Harleian Manuscripts in the British Museum, 4 vols. (London: G. Eyre and J. Strahan, 1808-1812).
 * An introduction to the study of bibliography: to which is prefixed A memoir on the public libraries of the antients, Volume 2, (London: T. Cadell and W. Davies, 1814)
 * The History of the Mahometan Empire in Spain: Containing a General History of the Arabs, Their Institutions, Conquests, Literature, Arts, Sciences, and Manners, to the Expulsion of the Moors. Designed as an Introduction to the Arabian Antiquities of Spain, (London: T. Cadell and W. Davies, 1816). Supplementary to Arabian Antiquities of Spain (1813) by James Cavanah Murphy, which Horne edited as well as supplying text.
 * The Campaign of Waterloo (London: T. Bensley, 1816).
 * Introduction to the Critical Study and Knowledge of the Holy Scriptures, reprint of the 8th edition (Grand Rapids: Baker Book House, 1970). ISBN 0-8010-4003-5 Tenth EditionVolume 1 Volume 2Volume 3Volume 4Volume 4
 * Introduction to the Critical Study of Bibliography, 5 Vol. (London: T. Cadell and W. Davies, 1814).
 * A summary of biblical geography and antiquities,, (London: Printed For T. Cadell In The Strand, 1821)
 * Outlines for the classification of a library: respectfully submitted to the consideration of the trustees of the British museum : official copy for the use of the trustees (not published)., (London: printed by G. Woodfall, 1825)
 * A Compendious Introduction to the Study of the Bible: Illustrated with Maps and Other Engravings : Being an Analysis of "An Introduction to the Critical Knowledge of the Holy Scriptures" in 4 Volumes by the Same Author, (London: Printed For Thomas Cadell, 1827)
 * A Catalogue of the Library of the College of St. Margaret Ad St. Bernard, Commonly Called Queen's College, Volume 2, Issue 1, (London: S. and R. Bentley, 1827)
 * Manual of Biblical Bibliography, (Mansfield Center, Connecticut: Martino Publishers, 2005). ISBN 1-57898-562-5
 * An Essay on the History of Liturgies, (London: W. Clowes, 1831).
 * The Complete Grazier, (London: Baldwin and Cradock, 1833).
 * A concise history and analysis of the Athanasian creed, (London: T. Cadell, 1834)
 * A Protestant memorial, for the commemoration, on the fourth day of October, MDCCCXXXV., of the third centenary of the Reformation, and of the publication of the first entire Protestant English version of the Bible, Oct. IV.MDXXXV, (London: T. Cadell, 1835)
 * The Biblical Keepsake, Or, Landscape Illustrations of the Most Remarkable Places Mentioned in the Holy Scriptures, (London: J. Murray, 1835)
 * Landscape illustrations of the Bible: consisting of views of the most remarkable places mentioned in the Old and New Testaments : from original sketches taken on the spot engraved by W. and E. Finden, Volume 1, (London: J. Murray, 1836)
 * Introduction to the Critical Study and Knowledge of the Holy Scriptures, Volume 5. (London, 1846).
 * Horae homileticae: or, Discourses digested into one continued series and forming a commentary upon every book of the Old and New Testament : to which is annexed, an improved edition of a translation of Claude's Essay on the composition of a sermon, Volume 4 , (London: J. Murray, 1836)
 * A Manual of Biblical Bibliography: Comprising a Catalogue, Methodically Arranged, of the Principal Editions and Versions of the Holy Scriptures, Together with Notices of the Principal Philologers, Critics, and Interpreters of the Bible, (London: T. Cadell, 1839)
 * Popery, the Enemy and Falsifier of Scripture
 * Romanism Contrary to the Bible
 * A Manual For the Afflicted

title: Thomas Hartwell Horne


text:
Peter Wintonick

Peter Kenneth Wintonick (June 10, 1953 – November 18, 2013) was a Canadian independent documentary filmmaker based in Montreal. A winner of the 2006 Governor General's Award in Visual and Media Arts, former Thinker in Residence for the Premier of South Australia, prolific award-winning filmmaker, he was one of Canada's best known international documentarians.

Biography
Born in Trenton, Ontario in 1953, Wintonick was the son of John Wintonick and Norma Latham. He was of Ukrainian descent.

He founded Necessary Illusions Productions with Mark Achbar, and subsequently ran it with Francis Miquet. Wintonick was a co-founder of DocAgora, an event inserted into various film festivals showcasing cutting-edge digital strategies. He co-directed, with his daughter, Mira Burt-Wintonick, the 2009 documentary PilgrIMAGE, a film about documentary filmmaking.

Wintonick died of cholangiocarcinoma on November 18, 2013, aged 60.

Select filmography

 * Manufacturing Consent: Noam Chomsky and the Media (1992) with Mark Achbar and Francis Miquet
 * Cinéma Vérité: Defining the Moment (1999) with the National Film Board of Canada
 * Seeing is Believing: Handicams, Human Rights and the News (2002) winner of the Dan & Ewa Abraham and Tammy Abraham Award for Films of Conflict & Resolution at the 2002 Hamptons International Film Festival and Gemini Award nominee, co-directed with Katerina Cizek

Other work
In early 2005, at the invitation of the premier of South Australia, he filled the post of Thinker in Residence, examining the future of documentaries and the digital revolution with a focus on educational and cultural legislation.

Governor General's Award
Wintonick was the winner of a 2006 Governor General's Award in Visual and Media Arts. His body of work includes dramatic features, theatrical documentaries, educational and socio-political works.

Legacy
In 2014, a new award called the Peter Wintonick Award was given at Sheffield Doc/Fest to Vessel. The award was presented by Martin Rosenbaum, who read a message from Wintonick's daughter Mira, which said that she was very happy to see the award go to "a filmmaker who embodies his activist spirit." Wintonick's film Manufacturing Consent: Noam Chomsky and the Media was also screened at the festival.

He is the subject of his daughter Mira's 2019 film Wintopia.

title: Peter Wintonick


text:
Defensive war

A defensive war (Verteidigungskrieg) is one of the causes that justify war by the criteria of the Just War tradition. It means a war where at least one nation is mainly trying to defend itself from another, as opposed to a war where both sides are trying to invade and conquer each other.

The right to self-defence in international law is enshrined in Chapter VII, Article 51 of the UN Charter:

"Nothing in the present Charter shall impair the inherent right of collective or individual self-defense if an armed attack occurs against a member of the United Nations, until the Security Council has taken the measures necessary to maintain international peace and security. Measures taken by members in exercise of this right of self-defense shall be immediately reported to the Security Council and shall not in any way affect the authority and responsibility of the Security Council under the present Charter to take at any time such action as it deems necessary in order to maintain or restore international peace and security."

History
American supporters of the war against the British argued that the War of 1812 was a defensive war, citing British harassment of American merchant shipping and impressment of American sailors on the high seas as well as armed support to Indian tribes resisting American expansion in the Midwest in order to create a pro-British Indian barrier state.

Views
The Islamic scholar Sufyan al-Thawri (716–778), who was called by Majid Khadduri (1909–2007) a pacifist, maintained that jihad (holy war) was only a defensive war.

title: Defensive war


text:
Wikipedia:WikiProject U.S. Supreme Court cases/PCA

The United States Supreme Court Case Article Improvement Project Project Collaboration Article is an article chosen by members of the Project who wish to participate. The object of the collaboration is to improve the article to the level of a featured article on the Wikipedia Main Page.

The current PCA is: (vacant)

Nominations
Voting for the next PCA may begin at any time. The following articles have been nominated:

 * Marbury v. Madison - established judicial review
 * Hamdi v. Rumsfeld - government's ability to detain unlawful combatants
 * Webster v. Reproductive Health Services abortion regulation
 * United States v. Carolene Products Co. Footnote four started modern levels of judicial scrutiny
 * Prize Cases presidential power in wartime
 * While I can't think of any off the top of my head, I'm proposing a case that, unlike the ones above, doesn't have very much substance to it at all, yet it has had a powerful effect on law. That way, everyone could get involved and work to build it from nothing.
 * Category:U.S._Supreme_Court_stubs is full of short articles (and a few that no longer deserve the stub designation).
 * Ashcroft v. Free Speech Coalition, extremely short right now, yet an interesting case involving free speech
 * Bush v. Gore - controversial case indirectly deciding 2000 U.S. Presidential Election
 * Gonzales v. Carhart - Case upholding the federal Partial Birth Abortion Ban of 2003.
 * Loving v. Virginia state laws banning interracial marriage uconstitutional

Wikipedians involved

 * Assawyer (hopefully)
 * RidG
 * Postdlf (as schedule allows)
 * MZMcBride
 * Axios023

Article sections
The sections as outlined by the Project are listed below. As sections are completed by Wikipedians, they should be crossed off to show that they are done. ''

 * Introduction
 * Prior history
 * The case
 * Effects
 * Subsequent history
 * Sources and further reading
 * External links
 * Categories
 * Interlanguage links (if possible)

For an explanation of the type of information that should be included in each section, please see WikiProject US Supreme Court Cases.

Votes for closure
This section is to be used once an article has reached the point of being completed and every section above is crossed off. All Wikipedians involved must register their vote to close a collaboration. When the every member involved agrees that the article is complete to both Project and featured article standards, the article will be submitted as a nomination for featured article. Until every member involved in the particular collaboration agrees that the article is complete, it will continue to be worked on.

 * Hasn't gotten much work in the last few weeks after a ton of work by Axios023. Close?--Chaser T 23:38, 5 December 2006 (UTC)

Previous PCAs

 * Miranda v. Arizona
 * Clinton v. City of New York
 * Hamdan v. Rumsfeld
 * Ashcroft v. Free Speech Coalition


text:
G.729

G.729 is a royalty-free narrow-band vocoder-based audio data compression algorithm using a frame length of 10 milliseconds. It is officially described as Coding of speech at 8 kbit/s using code-excited linear prediction speech coding (CS-ACELP), and was introduced in 1996. The wide-band extension of G.729 is called G.729.1, which equals G.729 Annex J.

Because of its low bandwidth requirements, G.729 is mostly used in voice over Internet Protocol (VoIP) applications when bandwidth must be conserved. Standard G.729 operates at a bit rate of 8 kbit/s, but extensions provide rates of 6.4 kbit/s (Annex D, F, H, I, C+) and 11.8 kbit/s (Annex E, G, H, I, C+) for worse and better speech quality, respectively.

G.729 has been extended with various features, commonly designated as G.729a and G.729b:
 * G.729: This is the original codec using a high-complexity algorithm.
 * G.729A or Annex A: This version has a medium complexity, and is compatible with G.729. It provides a slightly lower voice quality.
 * G.729B or Annex B: This version extends G.729 with silence suppression, and is not compatible with the previous versions.
 * G.729AB: This version extends G.729A with silence suppression, and is only compatible with G.729B.
 * G.729.1 or Annex J: This version extends G.729A and B with scalable variable encoding using hierarchical enhancement layers. It provides support for wideband speech and audio, using modified discrete cosine transform (MDCT) coding.

Dual-tone multi-frequency signaling (DTMF), fax transmissions, and high-quality audio cannot be transported reliably with this codec. DTMF requires the use of the named telephony events in the RTP payload for DTMF digits, telephony tones, and telephony signals as specified in RFC 4733.

G.729 Annex A
G.729a is a compatible extension of G.729, but requires less computational power. This lower complexity, however, bears the cost of marginally reduced speech quality.

G.729a was developed by a consortium of organizations: France Télécom, Mitsubishi Electric Corporation, Nippon Telegraph and Telephone Corporation (NTT).

The features of G.729a are:
 * Sampling frequency 8 kHz/16-bit (80 samples for 10 ms frames)
 * Fixed bit rate (8 kbit/s 10 ms frames)
 * Fixed frame size (10 bytes (80 bits) for 10 ms frame)
 * Algorithmic delay is 15 ms per frame, with 5 ms look-ahead delay
 * G.729a is a hybrid speech coder which uses Algebraic Code Excited Linear Prediction (ACELP)
 * The complexity of the algorithm is rated at 15, using a relative scale where G.711 is 1 and G.723.1 is 25.
 * PSQM testing under ideal conditions yields mean opinion scores of 4.04 for G.729a, compared to 4.45 for G.711 (μ-law)
 * PSQM testing under network stress yields mean opinion scores of 3.51 for G.729a, compared to 4.13 for G.711 (μ-law)

Some VoIP phones incorrectly use the description "G729a/8000" in SDP (e.g. this affects some Cisco and Linksys phones). This is incorrect as G729a is an alternative method of encoding the audio, but still generates data decodable by either G729 or G729a - i.e. there is no difference in terms of codec negotiation. Since the SDP RFC allows static payload types to be overridden by the textual rtpmap description this can cause problems calling from these phones to endpoints adhering to the RFC unless the codec is renamed in their settings since they will not recognise 'G729a' as 'G729' without a specific workaround in place for the bug.

G.729 Annex B
G.729 has been extended in Annex B (G.729b) which provides a silence compression method that enables a voice activity detection (VAD) module. It is used to detect voice activity in the signal. It also includes a discontinuous transmission (DTX) module which decides on updating the background noise parameters for non speech (noisy frames). It uses 2-byte Silence Insertion Descriptor (SID) frames transmitted to initiate comfort noise generation (CNG). If transmission is stopped, and the link goes quiet because of no speech, the receiving side might assume that the link has been cut. By inserting comfort noise, analog hiss is simulated digitally during silence to assure the receiver that the link is active and operational.

G.729 Annex J (G.729.1)
G.729 Annex J, maintained by G.729.1, provides support for wideband speech and audio. Introduced in 2006, it defines variable bit-rate wideband enhancement using up to 12 hierarchical layers. The core layer is an 8 kbit/s G.729 bitstream, the second layer is a 4 kbit/s narrowband enhancement layer, and the third 2 kibt/s layer is a bandwidth enhancement layer. Further layers provide wideband enhancement in 2 kbit/s steps. The G.729.1 uses three-stage coding: embedded code-excited linear prediction (CELP) coding of the lower band, parametric coding of the higher band by Time-Domain Bandwidth Extension (TDBWE), and enhancement of the full band by a predictive transform coding algorithm called time-domain aliasing cancellation (TDAC), also known as modified discrete cosine transform (MDCT) coding. Bit rate and the obtained quality are adjustable by simple bitstream truncation.

Licensing
As of January 1, 2017, the patent terms of most licensed patents under the G.729 Consortium have expired, the remaining unexpired patents are usable on a royalty-free basis. G.729 includes patents from several companies which were until the expiry licensed by Sipro Lab Telecom, the authorized Intellectual Property Licensing Administrator for G.729 technology and patent pool.

Past patent litigation
AIM IP LLC, a California Limited Liability Company based in Mission Viejo, CA filed 17 patent infringement lawsuits in the Central District Courts of California accusing 22 different companies, including, Cisco Systems, Polycom and others of infringing U.S. Patent No. 5,920,853. The '853 patent was filed at the United States Patent and Trademark Office in 1996 by Rockwell International. The inventors listed on the '853 patent are Benyassine Adil, Su Huan-Yu and Shlomot Eyal.

In 2000, the '853 patent was assigned by Rockwell International to Conexant Systems, an American-based software developer and fabless semiconductor company, which began as a division of Rockwell before being spun-off as its own public company. In 2010, the '853 patent was sold by Conexant Systems to AIM IP LLC, a California Limited Liability Company based in Mission Viejo.

The '853 patent contains patent claims which cover lookup tables used in G.729. The patent has since expired and is no longer in force due to its patent term expiring.

RTP payload type
G.729 is assigned the static payload type 18 for RTP by IANA. The rtpmap parameter description for this payload type is "G729/8000".

Both G.729a and G.729b use the same rtpmap description as G.729. G.729a and G.729b are indicated using annexb=no or annexb=yes, respectively. G.729 Annex B (G.729b) is the default in absence of parameter annexb in the Session Description Protocol.

title: G.729


text:
Class A share

In finance, a class A share refers to a share classification of common or preferred stock that typically has enhanced benefits with respect to dividends, asset sales, or voting rights compared to Class B or Class C shares. There may be restrictions on any specific issue of class A shares in exchange for the benefits; for example, preferences with regard to dividends may be traded for reduced voting rights. They are often convertible into class B (may not be publicly traded) shares at a favorable rate.

For example, a company might allocate class A shares to its management giving them 7 times face value of class B shares, while class B shares have the same voting right as class A shares. Companies classify stock for many reasons. In some cases this is to give company insiders a greater degree of power over the company and to provide a better defense against events like hostile takeover attempts.

Class A share is also a way of pricing sales charges (loads) on mutual funds in the United States. In a class A share, the sales load is up front, typically at most 5.75% of the amount invested. In contrast is the class B share that does not have an upfront charge, but instead has higher ongoing expenses in the form of a higher 12B-1 fee, and a contingent deferred sales charge that only applies if the investor redeems shares before a specified period. The maximum A share sales load is decreased for larger investment amounts as a volume discount.

title: Class A share