As a logical conjunction, "or" is similar to "or" in daily life, but there are differences. In the language of life, "or" means to select one of the connected parts, while the logical conjunction "or" means to select at least one of the connected parts.

As a logical conjunction, "Qi" is the same as "Bi ……" in daily life, which means that both should be satisfied. In daily life, "he" and "he" are often used instead.

As a logical conjunction, the meaning of "Fei" in daily life is "negation" and "total negation".

The words "or (∨)", "and (∧)" and "not ()" are called logical conjunctions.

First, the simple logic and knowledge points of full-name quantifiers and existential quantifiers are summarized

Simple logical connectives

The sum or not in (1) proposition is called logical conjunction.

(2) Truth table of simple compound proposition:

2. Full name quantifiers and existential quantifiers

(1) Common full-name quantifiers are: any one, everything, everything, giving all, etc.

(2) Common existential quantifiers are: one, at least one, some, some, and so on.

(3) Full-name quantifiers are represented by symbols; Existential quantifiers are represented by symbols.

3. Full name proposition and proper name proposition

(1) A proposition with a universal quantifier is called a universal proposition.

(2) Propositions containing existential quantifiers are called special propositions.

4. The negation of the proposition

(1) The negation of the full name proposition is a proper name proposition; The negation of special proposition is full name (2) The negation of P or Q is: non-P and non-Q; The negation of p and q is: not p or not q.

note:

The relationship between relational logical conjunction and set, or, and and illogical conjunction corresponds to union, intersection and complement in set operation. Therefore, propositional problems composed of illogical conjunctions such as or, and, and are often solved by means of the union, intersection and complement of sets. Two kinds of negation

1. Negative proposition with quantifiers

(1) The negation of a full-name proposition is a special proposition.

The full-name proposition p: XM, p(x) and its negation p: x0m, p(x0).

(2) The negation of a special proposition is the full-name proposition P: x0m, p(x0), and its negation P: XM, p(x). 2. The negation of compound proposition.