The content of the MBA preliminary examination is the management joint examination and English II. The management joint examination includes logic. Many people are often confused by the twists and turns of logic.

1 Coupletic proposition

A conjunctive proposition is a compound proposition that asserts that several things are true at the same time. , the standard form is "p and q" (denoted as p∧q). p and q are called joint limbs. In the language of the examination, the most abundant connectives to express conjunctions, such as "not only p but also q", "although p, but q" and so on. Specifically, the following three situations of common examination language, their logical meanings are essentially conjunction relationships, and should be given full attention.

1. Indicates a turning point. For example, he is very rich, but his life is not happy.

2. Indicates progressive. For example, the Chinese team not only entered the World Cup, but also reached the semi-finals.

3. Indicates parallel. For example, he is an engineer like me, and you are an engineer too.

The logical meaning of a couplet proposition is that both the couplet limbs are true, and the couplet proposition is true. Therefore, the relationship between the couplet proposition includes: the relationship between the couplet proposition and the couplet limb proposition; the negation of the couplet proposition. .

2 Disjunctive proposition

A disjunctive proposition is a compound proposition that asserts that at least one of several things exists. In Chinese expressions, disjunctive propositions are divided into two types: compatible disjunctive propositions and incompatible disjunctive propositions.

The standard form of a compatible disjunctive proposition is "p or q" (recorded as p∨q); when a compatible disjunctive proposition is true, at least one of the disjunctive limbs can be true, or both of them can be true. (This is what compatible means). In other words, the compatible disjunctive judgment is false only when both disjunctive limbs are false, and is true in other cases.

The standard form of incompatible disjunctive judgment is "either p, or q", which determines that one and only one of the disjunctive limbs is true. In other words, incompatible disjunctive judgments cannot be true in the disjunctive part.

The two disjunctive propositions also involve the relationship between the disjunctive proposition and the disjunctive limb proposition and the meaning of the negation of the disjunctive proposition.

3 Compound propositions

1. Coupling proposition: A proposition that asserts the simultaneous existence of several things. For example: "Lu Xun was a writer and a thinker."

The general formula of a conjunction proposition is: "p and q" or "pùq".

True and false situations: pùq is true when p and q are true at the same time, and all other situations are false.

2. Compatible disjunctive proposition: A proposition that asserts that at least one of several possible things exists and can exist simultaneously. For example: "He is a member of the Communist Party or a model worker."

The general formula of compatible disjunctive propositions is: "p or q" or recorded as "púq".

True and false situations: When p and q are false at the same time, púq is false, and the rest of the situations are true.

3. Incompatible disjunctive proposition: a proposition that asserts that among several possible things, there is only one and only one thing. For example: "Either Wu Song kills the tiger, or the tiger eats Wu Song."

The general formula of incompatible disjunctive propositions is: "either p, or q".

True and false situations: false when p and q are the same, true when p and q are different.

4. Hypothesis (conditional) proposition

The proposition that a situation of one thing is a condition of the situation of another thing is divided into a hypothesis proposition of sufficient conditions, a hypothesis proposition of necessary conditions and a hypothesis proposition of necessary and sufficient conditions.

① Sufficient conditions: For example, "If someone has a fever, then he is sick."

The general formula of a sufficient condition hypothesis proposition is: "If p, then q" or Recorded as "p?q". If there is p, there must be q

"As long as... then..." is also commonly used in exams to express the meaning of sufficient conditions.

② Necessary conditions: For example: "Only if A is over 18 years old, he has the right to vote." It means: "If he is not over 18 years old, then he has no right to vote."

The general formula of a necessary condition hypothesis proposition is: "Only p, then q" or "?p?q". Without p, there must be no q

"Unless...else..." is also commonly used in exams to express the meaning of necessary conditions.

Note: Compare the difference between "only, only" and "unless, otherwise" when they express the same meaning.

4 Modal propositions

Modal propositions: property propositions containing modal words. Modal words: maybe, probably, maybe; definitely, definitely, necessarily, etc. Modal words are divided into two types: possibility and necessity. When considering the nature of modal words and property judgments (affirmation and negation), modal judgments are also divided into four types: necessarily P, necessarily not P, possible P, and possible not P. The focus of modal judgment is to pay attention to the positional relationship between modal words and negative words.

Propositions containing modal words such as "necessary" and "possible".

Possible p=?Necessary?p;

Necessary p=?Possible?p; Possible p=Necessary?p; Necessary p=Possible?p.

For example:

Not all proletarians necessarily have revolutionary demands.

Not all proletarians necessarily have revolutionary demands.

All proletarians certainly do not have revolutionary demands.

This metal may not conduct electricity.

This metal cannot conduct electricity.

This metal must conduct electricity.

When the negation is before the modal word, the modal word should be changed (i.e., negated); when the negation is after the modal word, the modal word should not be changed