Sunday, July 9, 2017

This Week

1. Database Truth of the Week

"For the operations of a formal system to have inverses within some specific use of that system (like a specific application):
  • The basic elements must be orthogonal (independent), hence the Principle of Orthogonal Design;
  • The combination of basis elements and operations must be expressive enough to represent every aspect of the subject matter, hence the Principle of Expressively Complete Design;
  • And, at the same time, not so expressive that there is more than one way to express each aspect of the subject matter, hence the Principle of Representation Minimality Design.
The basic elements of a relational database is the relation. Adherence to these principles ensure thatthere is a unique relational expression for every aspect of the subject matter--either a base relation or a derived relation--and if there are two ways to derive a derived relation, then those two expressions are provably equivalent (i.e., the differences are merely syntax and never meaningful)." --David McGoveran


2. What's Wrong With This Database Picture?

"A conceptual model has no rigorous definition? It is like a sketch of a picture yet to be completed? Or like an outline to a paper to be written or fleshed out? And once the model is rigorously defined, the ad hoc, informal model must be precisely consistent with the underlying model in all its semantics. Are you suggesting that a conceptual model is a precursor to a defined logical (relational) model? Then after the relational model is defined, the conceptual model needs to be a consistent abstraction of the formal logical model. 

What other type(s) of relationships can be explicitly and formally defined in a relational data model? Of course there are many other relationships which can be inferred, such as between an attribute and an entity identifier. Please give me a precise reference to where Codd spoke of relationships [differently than i]n his 1985 piece published in ComputerWorld, [where] he said that the only way to represent a relationship (between entity tables or relations) was through explicitly stored values (i.e., attributes, foreign keys).

What do you mean "Attributes are subsets of domains"? An attribute only exists in the context of a relationship. Something (a domain) is a descriptor of (i.e., is related to) something else (another domain)."
What is an "R-table"? What do you mean by a "PICTURE"? There are things and there are views or manifestations/presentations of things. There is the model, and there are various presentations of that model. Is that what you are getting at?" --Gordon Everest, LinkedIn.com
"Do you mean that … relations are defined over types (also known as domains); a type is basically a conceptual pool of values from which actual attributes in actual relations take their actual values (taken from the SQL AND RELATIONAL THEORY" [2009] by Chris Date). I am also not sure about "pointers". Can I define a domain of pointers? There might be an interesting relation over such domain.In addition, what will happen if I define a relation over a set of types, each of which is (another) relation? Lets say that a relation is either defined over types (domains), or defined over a "heading" (or a "definition") of other relations ... and I also try to eliminate identifiers completely". --AT, LinkedIn.com


3. To Laugh or Cry?

"Relationality is not a property of your data model but of the database management system on which it is implemented. A DBMS is relational if it represents the entities as "tables"; relationships between these tables are not hardwired, but you have to lookup conditions like Shopper.shopper_:id = birthday.shopper_id in your query. Usually, you can add indexes that allow quicker lookups and foreign-key-relationships that enforce consistency." --Joachim Pence, Is my database relational?
Read all the answers.


4. Publications


NEW!!! Paper #2 in the new UNDERSTANDING OF THE REAL RDM series, Logical Symmetric Access, Data Sub-language, Kinds of Relations, Database Redundancy and Consistency, is available for ordering here.

Paper #1 in the new UNDERSTANDING OF THE REAL RDM series, Interpretation and Representation of Database Relations is available for ordering here.

My book, THE DBDEBUNK GUIDE TO MISCONCEPTIONS ABOUT DATA FUNDAMENTALS is available to order here.

Reviews



5. Oldies but Goodies

An Old Class of Errors


6. Of Interest



And Now for Something Completely Different


Pinch me

IBM turns to artificial intelligence to solve poverty, hunger, and illiteracy And if you believe this, I have a tower in Paris and bridge in Brooklyn to sell you.
Is IBM Watson A 'Joke'? Read very carefully the part about the drawbacks of the Watson AI -- recognize anything of the arguments advanced @dbdebunk over the decades? I may have something to say about it in a post with the tentative title "The Illusions, Delusions, Dehumanization and Destructive Dangers of AI". Hardly a joke.

This week @The PostWest: Evidence for the ongoing collapse of America and Western civilization.

The Mechanism of Tyranny: Technology Corporations and the End of Free Civilization



 

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