Belonging to a category
Physical objects are something a person learns to detect in the world, separating them from the background is one of the first skills we master. Where do categories, abstract objects come from? How are concepts identified?
First of all, let us note that categories are used to refer to objects regardless of their individuality.
If we do not care about a specific pot for a certain role, but the presence of a pot is important, you need an object like the category "Pot". If you are organizing a process for all the workers in your company, your thinking identifies and uses the object "Worker" - a category, not an individual.
Then one of the most important processes in ontology development (ontological engineering) becomes clear - assignment of objects to a category, categorization. This process has many other names: categorization, classification, generalization, typing. We will work with a more precise use of these terms in different formal modeling methodologies.
Every object can be assigned to a category. It's very simple:
The individual "Ivan Ivanovich Ivanov" belongs to the category "Human".
The individual "Inventory screwdriver number 1250564-678" belongs to the category "Screwdriver".
Eventually, any individual object that we are able to distinguish from the background for some purpose belongs to the category "Individual physical object".
The examples above referred to individuals, but the general principle is formulated for any object! It is not necessary to categorize only individuals, let's engage in categorizing categories.
The category "Makita Screwdriver" belongs to the category "Screwdriver".
The category "Pot" belongs to the category "Kitchenware".
Finally, any category belongs to the category "Category" (think a little about this phrase, it is not a meaningless combination of words!).
If a category is assigned to another category, we will call the second one broader, more general, than the first one (later we will refine this concept).
A crucial tool in ontological modeling is multiple categorization. A huge amount of information can be included in the model by assigning one object to several categories simultaneously.
"Ivan Ivanovich Ivanov" belongs to the categories "Man," "Ivan Ivanovich Ivanov" belongs to the category "Second-class Assembler," "Ivan Ivanovich Ivanov" belongs to the category "Amateur Cook."
The categorization of an object depends on the need to reflect different information about it and on the role from which the categorization is performed, for which practice.
In the example of a family information model, your mother-in-law can be categorized as a "Helper" from your role as "Responsible for the child's outings," and as a "Disturbance" from your role as a "Cook."
In the future, sometimes we will replace the lengthy expression "belongs to the category" with the pronoun "it":
"Inventory screwdriver number 1250564-678" - it is a "Screwdriver".
"Pot" - it is "Kitchenware".
Before "it," there can be either an individual or a category, distinguish by the name. After "it," there can only be the name of a category.
Now let's remember what we said about practices and the functions of objects within these practices. The functions of individual objects and the practices they support are not the same as those supported by categories.
The individual "Inventory screwdriver number 1250564-678" supports the practice of Construction and implements the function of fastening construction details.
However, we do not categorize the category "Screwdriver" for the purpose of fastening construction details! We use the category "Screwdriver," for example, for tool inventory, procurement planning, and monitoring the provision of construction sites with tools. The category "Screwdriver" does not tighten screws.
One of the main functions of categorization in modeling is to highlight the important, indicate the presence of certain properties (mandatory or possible), and transition to the use of templates to describe individuals. How this works - we will discuss later.