The CLASSIFY statement

# Purpose

A classify statement is also called a specialization. It specifies that atoms of one concept are atoms of another concept as well. You can use it to buils classifications like Linnaeus did.

# Syntax and meaning

CLASSIFY <upper case identifier> ISA <upper case identifier>
In a specialization, e.g. CLASSIFY Sedan ISA Car, we call the first concept (Sedan) the specific concept and the second (Car) the generic concept. The meaning of a specialization is that every atom from the specific concept is an atom from the generic concept as well. So every (atom that is a) Sedan is a Car as well.
So in general: CLASSIFY
$A$
 ISA
$B$
means:
$\forall a: a\in A\Rightarrow a\in B$
.

# Examples

CLASSIFY Monkey ISA Mammal
CLASSIFY Sedan ISA Car
To save some writing, you may specify
CLASSIFY Monkey, Cow, Human ISA Mammal
This means exactly the same as
CLASSIFY Monkey ISA Mammal
CLASSIFY Cow ISA Mammal
CLASSIFY Human ISA Mammal

# Best practice

A specialization is a static relationship. If you want to say that a student is a person, please consider whether you want this to be static. If a person can enroll to become a student, or graduate or drop out to become non-student again, the dynamics of that cannot be captured in a specialization. Use a relationship instead to model the state of being a student. E.g. RELATION student[Person*Enrollment]
By adding and removing pairs to that relation, it continuously reflects which persons are a student.