Species relationship means that A is a kind of B, such as pear and fruit, and pear is a kind of fruit. The relationship among group, genus and species means that A is a part of B, and it is the relationship between the whole and the part.

Specifically, the relationship between genus and species, including the relationship between superior and subordinate, refers to the relationship in which part of the extension of one concept coincides with all the extensions of another concept. That is, in the relationship between concept A and concept B ..

If all B's are A's, but some A's are not B's, then the concepts of A and B are a species relationship. Among them, the concept of large extension is called the concept of genus, or the concept of superordinate; A concept with a small extension is called a kind of concept, or a subordinate concept.

For example, "security" and "national security" in national security science are two concepts with species relationship. Numbers and integers in mathematics, triangles and right triangles in geometry, forces and reactions in physics, elements and metal elements in chemistry, animals and amphibians in biology, etc. , all belong to the same species.

In addition, people and youth, students and college students are also interrelated. Among the above concepts related to genera and species, such as "safety", "number" and "triangle".

Force, elements, animals, people and students are concepts, while the corresponding concepts such as national security, integer, right triangle, reaction force, metal elements, amphibians, youth and college students are concepts.