Abstract

The ISO Orange Report TR 9007 – Concepts and Terminology for the Conceptual Schema and the Information Base is a widely acclaimed early publication that recognized the importance of formalizing semantics of information:  To understand the information needs of an enterprise we need models of the enterprise, the things and affairs it must know about, and the parts of the enterprise involved in information exchanges.  This column is the third in a series giving some of the history of the Orange Report and summarizing its basic subjects.  Last time, we summarized the seven fundamental principles that the ISO TC97/SC5/WG3 Working Group developed.  In this instalment the author explores the basic facts outlined by the Orange Report.

The Basic Facts (!)

Knowledge is a basic requirement of human society.  We need knowledge to do what we must or want to do.  It is practically impossible for us individually to acquire this only by trial and error.  We must, therefore, gain our knowledge from others who inform us.  This can only be done by making the knowledge communicable using a visible, audible, or any other noticeable form.  The semantics of such symbols, sounds, touches, or what is the communicated knowledge — the information.

Information:

Any kind of knowledge about things, facts, concepts, etc., that is exchangeable among humans.

The Report intentionally refrained from defining knowledge but took the natural (English) language interpretation of the word as well-understandable.^[OED1933]  This is also the case with the other words used in the definition.

Two essential aspects should be pointed out:

1. Information is considered without paying attention to the form of the symbolisms — only the meaning is relevant;^[1]
   
   
2. Information always is about something.

What is that something?

Anything we are interested in, about which we want knowledge, is an entity.

Entity:

Any concrete or abstract thing of interest, including associations among things.

If we are not interested in it, we do not want to know it, we cannot know what it is — it is beyond our view.  As soon as we start to think about it or begin to discuss it, it is an entity.

Associations are a peculiar kind of entity.  They are entities — we are discussing them — but the word suggests that they involve one or more other entities.  They form a state of affairs or situation of the involved entities.  Here again we use the words in the natural language way.

All kind of situations, states of affairs, facts, events, or circumstances can be perceived or conceived in the part of a world we are observing or imagining.  Such a perceivable, conceivable state of affairs is a proposition.

Proposition:

A conceivable state of affairs concerning entities about which it is possible to assert or deny that such a state of affairs holds for those entities.

Once again, a state of affairs that is not conceivable — perceivable or imaginable — I do not know.  As soon as I start thinking about it, it is at least conceivable, whether it is a realistic, unrealistic, or surrealistic situation.  That is a fact!

In the Report no distinction is made explicitly between an elementary proposition, that is, "indivisible" states of affairs, and more composite ones.  But neither does the Report reject such a possible distinction.  In conceptual modelling approaches following the Report the distinction often is made — e.g., elementary situations, basic facts, etc.

Quoting the Report:  Actually it will be descriptions of the propositions — sentences — that enable us to discuss entities and their states of affairs at all — that is, to exchange information about entities by describing propositions which hold for them.

Sentence:

A linguistic object which expresses a proposition.

Linguistic object:

A grammatically allowable construct in a language.

Note, that linguistic objects may be considered entities.

Sentences consist of terms and predicates.

Term:

A linguistic object that refers to an entity.

Predicate:

A linguistic object, analogous to a verb, which says something about an entity or entities to which term(s) in the sentence refer.

For instance the sentence

"The Man John owns the Car PXX934."

expresses a proposition.  In this sentence the verb "owns" formulates the predicate.  The terms "the man John" and "the car PXX934" refer to the entities involved.

Some linguistic objects play no other role in the descriptions than to be used as names for something else.  We will call them lexical objects or names.

Lexical object or Name:

A (simple) linguistic object that is used only to refer to an entity.

In normal cases a lexical object consists solely of one or more nouns.

Note that the meaning of a term is the entity referred to, and that the meaning of a sentence is the described state of affairs.  The meaning is not knowledge about these things; they are the things.  The knowledge is the information about them formulated in the terms and sentences or in whatever form we are thinking.

Generalization and abstraction play an important role in modelling a universe of discourse.  Some kind of categorization often is involved.  This is, certainly on a first level, a natural phenomenon; we all do it.^[LAK1987]  In the Report, class, type, and instance are defined to support this.

Class (of entities):

All possible entities in the universe of discourse for which a given proposition holds.

Each class of entities is determined exactly by its possible members.  Clearly any particular entity may be a member of many classes, so that classes in general are not disjoint.

The general notion expressed in information processing literature as 'type' is that of 'class' or, more precisely, 'class-membership'.

Type (of an entity):

The proposition establishing that an entity is a member of a particular class of entities, implying as well that there is such a class of entities.

Note that the type can be considered as a proposition as well as a class; the proposition is the situation that such a class exists. The concepts of type 'proposition' and type 'class' are therefore inextricably interdependent.  To define a type proposition implies the definition of the corresponding type class.  Note that this type class is time-invariant; it includes all entities that have previously been, now are, and in future may be considered as a member of the type class.

In formal logic systems and semantic communities of (e.g.) logicians the type proposition is generally preferred, where in more daily semantic communities the type is often considered as a class; a kind, a species, a category.

A type can be referred to by means of a type-name.  Quite often a singular form of such a name (noun) is used as type-name that refers to a member of the type class, while the plural form is used as class-name referring to the type class itself.  For example:

Rita is a girl.

and

Rita belongs to Girls.

refer to the same situation.

The notion instance or occurrence is usually associated with the notion of 'type'.

Instance or Occurrence (of an entity-type):

An individual entity for which a particular type proposition holds, that is, which belongs to a particular class of entities.

Rita, a Girl, is an example of an instance of the type 'Girls'.

Now it will be possible to formulate more precisely the parts of the second principle.

Universe of discourse:

The collection of all entities that has been, are, or ever will be in a selected portion of a real world or postulated world of interest that is being described.

Conceptual schema:

The description of the possible states of affairs of the universe of discourse including the classifications, rules, laws, etc., of the universe of discourse.

Information base:

The description of the specific entities that in a specific instant or period of time are perceived to exist in the universe of discourse and their actual states of affairs that are of interest.

In the Report also a more formal definition is presented, but this is beyond the current level of presentation.

Also formulated in the Report are definitions for dealing with temporal aspects, behavioural aspects, and changes in states of affairs.

Attention is given too to definitions for adding information to and retrieving information from the information system and what controlling and security aspects are relevant to keep the information semantically consistent and secure.  The Report limits itself intentionally to what is relevant, not how it should be done.

Copyright ©2008 J J van Griethuysen

Next time, we will explore the modelling approaches that the Working Group studied as candidates for a conceptual modelling approach.

Notes

[1 ]  The Report uses the term data to refer to an information form.

References

[OED1933]  Sir James Murray (ed.), The Oxford English Dictionary.  The University Press, Oxford, 1933-1989.

[LAK1987]  G. Lakoff, Women, Fire, and Dangerous Things — What Categories reveal about the Mind,  The University of Chicago Press, Chicago, London, 1987.

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