Re: Atomic Structures

Dana utorak, 17. svibnja 2016. u 08:49:19 UTC+2, korisnik Derek Ignatius Asirvadem napisao je:
> Vladimir
>
> I have moved a post from another thread, in order to avoid hijacking that thread, and because this is an important subject, already established under this thread.
>
> In sum, I agree with you. But you and I have arrived at that (those?) conclusions via different paths, therefore each of us would express it differently.
>
> 1. I reject the notion of conceptual vs logical vs physical models.
> I have only one model. In the early days, it is conceptual, as it progresses it is logical /to various degrees of Logical/, and close to implementation, with very little work, that is based on the platform, it is physical.
>
> Therefore there is no mapping to be done.
>
> Conceptual/logical/physical are merely renderings of one model, showing some chosen amount of detail.
>
> ERwin is the only data modelling tool that implements the one-model concept. All the others have duplicate models; mapping; time wasting; hair pulling, and of course, all the errors that result.
>
> 2. Further, there are physical aspects in the logical phases.
> If one ignores them (on the schizophrenic notion that theory is divorced from application), the data base suffers.
>
> 3. The highest level of modelling data is (agreed) atomic.
> So what are those atomic structures, what are those atoms ?
>
> ------------------------
> -- Predicates (FOPC) --
> ------------------------
>
> Since the RM is founded on FOPC, it is completely stupid to model a database without reference to Predicates.
>
> Thus all the books written by post-Codd authors are completely stupid, at least in this regard, because they have no idea re Predicates, they give no chapters on how to use them. The foundation is missing. So the house that is built may be of bricks, but it will have the strength and duration of straw.
>
> (They are stupid for other reasons /as well/ which I have posted about in these pages.)
>
> In all cases, the data model exposes the Predicates, and the Predicates verify the data model. It is a very important feedback loop.
>
> To someone who is new to this concept, I would say:
> -- If your Predicates are not completely defined, you do not have a Relational database.
> They are working somewhere in the middle, I would raise their sights, and make the whole task easier.
>
> To someone who is used to this concept, I would say:
> -- model the data from the Predicates, downward.
> They are working at the top, down, so I would ensure they have the top identified correctly.
>
> I don't know what your atoms are, but my atoms do not ever need mapping.
>
> 4. Now one dirty great caveat here is, in the literature, the notion of "logical" isn't. The pseudo-theoreticians, the pig-poop-eaters, have established a pathetic notion of "logical", that is limited to their rodent-sized crania. Logical is much more than that.
>
> You have to draw all the Logical elements out of the Relational Model (the original Codd paper, not the hysterical 42 or so "algebras", not the books that allege to be about the RM), and create methods for implementing them. Then formalise those methods. That includes Normal Forms (real ones, not the 17 or so fragments of pig poop that "theoreticians", "mathematicians", and "poofessors" use and teach these days). I already have a complete set of Methods and NFs, matured over four decades of implementations.
>
> 5. Now if you understand that, there is no mapping from one type of data model to another. Because the root of each type of data model, should be Predicates, FOPC.
>
> Cheers
> Derek

Hi Derek

(i)
I would like to point out that Frege's results are not fully understood in scientific public. Frege's results belong to the most complex areas and it is one reason why his results are hidden in the dark. Frege is misinterpreted and even degraded by some persons. I allow myself to suspect that this happened due to personal interests of these persons. Please note, however, today some scientists argue that Frege is one of the greatest mathematicians and philosophers in history. Some even claim that Frege is the greatest.
But on the other hand is increasingly spreading information on the web that G. Frege was a fascist. I personally do not believe that Frege was a fascist, because his two best friends were Jews. Moreover I think that Frege was a decent man and fair player.
I also want to say that I consider fascism - heavy dark. I write about this because it is reality on the web.
There is one thing more here. Scientific work belongs to its author.  

(ii)
In order to accurately define the predicates we need to understand first of all semantics. Semantics is the science that Frege created. Before Frege' philosophy and some other sciences were divided into two realms:

1. The world of the spirit, thoughts, ideas.
2. The world of matter.

Frege introduces the third realm, it is the realm of semantics, which connects two mentioned worlds.

In which way Frege introduced semantics? He used the spoken language as a tool and using it he connected the world of thought with the real world. Which linguistic constructs are most important for the theory of databases? The answer to this question is:

1. Names
2. Predicates

Linguistic constructs names denote objects (entities or individuals). Linguistic constructs predicates denote concepts.

The simplest predicates in Frege's theory are predicates which correspond to the so-called "one place“ concepts and „relational" concepts.

Is there a connection between thoughts and language? Frege's answer is: sentences express thoughts.

It is very important to understand what are concepts. A concept determines the plurality of objects that satisfy properties which have been defined with this concept.

Frege introduces object "extension". Roughly speaking, an extension is a set, and the elements of this set are from the plurality which is determined by the concept. Thus, a set is plurality, which is understood as one object.

So, the properties of concepts are in fact properties (attributes) which we put in relations from Relational Model. (not predicates)

(iii)
So, in simple terms: the predicates are linguistic constructs and predicates correspond to concepts. Concepts are mental constructs and concepts "make" sets.
However the predicates (concepts ) does not identify the objects. Note that I wrote above that the extension (set) is an object. As names denote objects then the extension (or set) has a name. As you can see from this text, concepts are dominant, not predicates. Another thing that can be seen from this text is that many objects(entities) are used. I have introduced the theory of identification in which identification of objects play an important role . This further leads to the conceptual level.

So now I'm asking you whether the predicate determines a set or the set is determined by something else?

In this, very short text, I explained that E. Codd did not understand some important and basic things. Moreover, I have not noticed that Codd wrote something about concepts, relationships between concepts and predicates, concepts and sets, thoughts, relationships between thoughts and language, formal theory of spoken languages, proof theory for propositional logic and predicate logic, the relationship between mind and logic, ... E. Codd remained at the predicate calculus of the first order, although Frege developed the theory of second-order predicates, ..., predicates of nth  order and a very tough cross combinations. Note that Frege did this from scratch and one hundred years before the appearance of the relational model . Codd did it by applying Frege's results.

Now I will switch to Logic
(iv)
Note that formally speaking, the following is OK: If a sentence is written, then it is just set of some symbols and nothing more.
If this sentence is uttered, then it is set of some voices.

Due to the above presentations of sentences, how you look at Codd's involving of predicates and "propositional sentences" in the relational model? Do you think that it is well explained in relational model?

(v)
Here's another question: A declarative sentence is written in English. Then this sentences is translated into another language, for example into Indian. I think that these two sentences are "the same". My question is "what is it that is the same in these two sentences."

(vi)

What is the truth-value of the following sentence:     
                                                
                         This sentence is false.     
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When I find free time, I'll add another one or two posts, on this subject, especially about Logic, The mapping between data models and about Atomic structures.

Vladimir Odrljin Received on Thu May 19 2016 - 20:50:33 CEST