concept It is a reflection of the essential attributes of the thinking object. from extension On the one hand, there are compatible and incompatible relations between concepts. The extension of two concepts is at least partially the same, and there are Compatible relationship 。 These two concepts are called compatibility concepts. If all extensions of the two concepts are different, then there is Incompatible relationship These two concepts are called incompatible concepts. [1] Let S and P represent two different concepts respectively, and there are five compatible relations between their extensions: identical relation Genus species relationship 、 Cross relation 、 Disparate relation And juxtaposition. Identical relationship: If the extension of S and P are completely coincident, that is, all S are P and all P are S, then the relationship between S and P is identical. The identical relationship is also called the identical relationship.
Genus species relationship : ① True inclusion relation means that if all the extensions of S coincide with some extensions of P, that is, all S are P and P is not S; ② True inclusion relation means that if some extensions of S coincide with all extensions of P, that is, all P are S and any S is not P. Cross relation : If the extension of S and P only partially coincide, that is, some S is P, some S is not P, and some P is not S, then the relationship between S and P is a cross relationship. Disparate relation : If the extension of S and P does not coincide in any part, that is, all S are not P, then the relationship between S and P is totally different. ① Contradiction refers to the relationship between two concepts with different extensions, and the sum of their extensions is equal to their extension of the concept; ② Opposition relation refers to the relation that two concepts have different extensions, and the sum of their extensions is less than their generic extension. Parallelism: If there are species concepts at the same level in the same genus concept, these species concepts are in a parallel relationship. It can be divided into compatible and incompatible parallel relations. [2]
If the same level of Concepts , then there is a parallel relationship between these concepts. It can be divided into compatible and incompatible parallel relations. compatible Parallelism: if there are several concepts of the same level in the same generic concept Concepts , and the extensions of these concepts cross each other, then these concepts are Compatible juxtaposition 。 Incompatibility Parallelism: if there are several levels of Concepts , and the extensions of these concepts are mutually exclusive, then these concepts are incompatible and juxtaposed. [1] Example 1. Among scientists, the relationship among agronomist, biologist and chemist is（ Compatible juxtaposition ）。
Example 2. In the social form: slave society capitalist society The relationship between the concepts of socialist society is（ Incompatible juxtaposition ）。 Example 3. In natural resources, the relationship between the concepts of mineral resources, water flow and forest is（ Incompatible juxtaposition ）。
Example 4. The relationship between the two concepts of young people and lawyers is（ Cross relation ）。 [2]
concept The relationship between one kind of thing or attribute and another kind of thing or attribute is the reflection of the relationship between them. The relationship between objective things or attributes is extremely complex, and formal logic cannot study all the relationships between them, but mainly from the qualitative and quantitative aspects of things or attributes. The quality and quantity of things are the most common relationship between things and the essential point that distinguishes one kind of things from others. The reflection of the quality of things in the concept is the connotation of the concept, and the reflection of the quantity of things in the concept is the concept extension 。 The relationship between objective things or attributes is reflected in the relationship between concepts by its unique nature, which shows the different types of relationship between concepts, that is, forms different relationships between concepts. This relationship is different based on the relationship between things or attributes. This requires us to reflect this feature when we define the "relationship between concepts". As long as strictly according to the concept connotation and extension To distinguish the types of relations between concepts will inevitably reflect this feature. [3] 
