La logique informatique
(selon les travaux de J.D WARNIER)
L.C.O The organization of companies
The data sets of a step :
A small remark,whose importance we shall see later.
The definition by comprehension of the studied sets from a mathematical point of view, allows to define the relations between the sets and thus to add to the rules of management defined by the study of the flows, an equally important set of rules For the smooth running of the company.
On the other hand, (and this will not seem obvious to you right away, but after ... you will be surprised !), the properties (or characteristics) stated when defining a set in comprehension are in fact, the statement of the existing relations, between the set studied and the other sets defined in the system.
One more remark before studying the sets of a step, let us take a simple example in order to imager the relations between sets, related to the definition in comprehension of the latter.
We will take the example of the commercial section that we saw earlier,
Let us imagine the definition in comprehension of this section as follows :
The commercial section is a set of geographical districts, such that each district corresponds to one administrative region and only one of France.
Let us now imagine the understanding definition of all external clients:
The set of external clients is a set of clients such that each client corresponds to a commercial district and one only.
Here is the model of the data sets and their relationships:
Notice the nature of the relationship :
This is a surjective application.
(There are ONE to several clients per business district)
What about these definitions ?
1 °) They show that the commercial action is limited to French territory.
2 °) Every customer is attached to a region and a commercial district.
As a result, the relationship between any client and his district is established, which is a management rule, Any contract must pass through the commercial district to which the customer is attached. There is "Application" of the set of clients, in the set of commercial districts.
Is this rule good ? This is another problem, it is up to the pilot unit of the company to decide. There are at least two questions to ask:Should we give up exporting ? And then how to deal with the case of large companies in several regions ?
Let us make that a customer can have several establishments that can place an order, here is the corresponding model :
You will notice that the nature of any relationship between two sets of data constitutes a new management rule in the enterprise.
Here is the new understanding definition for all clients in a district :
"One element of the set of a district clients is an etablishment corresponds to one and only one commercial district, one and only one delivery agency, and one and only one customer compagny".
Now that we have seen the importance of the definitions by understanding, in order to put the corresponding sets in relation, let us study the whole of the data of a logical database relative to a step.