Terms, concepts and definitions

A term is a definition in logic. Refers to the smallest unit of meaning that can be used independently. In other words, most notional words are entries that can act as grammatical components independently. If you have the heart, you will ask what is the truth? Laugh without answering, but I will tell you that the function words include: 1. Conjunction, such as: if ... and then ... 2. Prepositions, such as: since ..., when ..., used in ... 3. Auxiliary words, such as: de, de, de, de. In addition to function words and content words, there are three independent categories: exclamations: alas, alas, alas; Response words: yes, no; Address: hello, sir. Hi, hello. In addition, they are all content words.

Individual variables: use lowercase letters, x, y, z ... to represent uncertain objects within a specific range. Equivalent to pronouns in linguistics.

Single constant: lowercase letters a, b, c ... and so on. Are used to represent an object in a specific range, which is equivalent to a proper name in linguistics.

The term "item", also called "article", is defined as follows:

1) Individual variables and individual constants are terms;

2) If t 1, t2, t3...tn is a term and f is a function of n, then f(t 1, t2, t3 ..., tn) is a term;

3) Only the expression formed in the above way is an item.

These contents are the contents of the first seven pages of the third chapter, which are pure knowledge and conceptual things. The more you look at them, the more ugly they get. The thing of logic is to build so many frames (definitions), then set rules within the frames, and then play reasoning according to these rules. I deeply feel that when I was young, doing more of these things really helped to enhance my thinking ability in one aspect. I'll start now. I hope it's not too late.

Concept is one of the basic forms of thinking. Also called "judgment", "reasoning" and "argument". Can you think of the difference between a set and a class? I seldom compare these two concepts before, but when I think about it carefully, there are similarities and differences, and I have to deal with OOP every day and in class.

There are five basic relations of lexical items: identity, inclusion, inclusion, intersection and total difference. Among them, there are contradictions and opposites in the whole difference relationship. For the former, the sum of the extensions of both sides of the contradiction is exactly equal to the extension of its subordinate items, such as odd and even numbers relative to integers, men and women relative to people. Opposition, that is, there is no intersection between the opposing sides, but it does not constitute a subordinate noun, such as: college students and middle school students relative to students, physics and chemistry relative to natural science.