Formula 1: Qian Ken, Hou Ken, No Hou.

In reasoning, whether it is a sufficient condition or a necessary condition, we can write it in the form of P → Q. In this reasoning formula, P is called the antecedent and Q is called the afterpart. Here we mean the front and the back.

You can also remember that the front of the push-out symbol is called the front film and the back of the push-out symbol is called the back film.

Ken before Ken: We must affirm both the former and the latter. Given that P→Q holds, as long as p holds, then q must hold.

No, then no, before: when you deny the latter, you must deny the former. Under the condition that P→Q is known to be true, as long as Q is not true, then P must not be true.

Formula 2: No error before, no error after.

No previous mistakes: When it is known that P→Q holds, no definite conclusion can be drawn when P does not, and all conclusions drawn by -P are wrong. Unless, of course, the topic has been clearly told us.

Errors after no: When it is known that P→Q is established, Q does not hold any definite conclusions, and the conclusions drawn by Q are all wrong. Unless, of course, the topic has been clearly told us.

Test, judgment, reasoning, logical relationship

1, same relation

Refers to a group of words that refer to the same concept, that is, different names of the same thing or words that express the same meaning.

2. The dissimilarity relation means that two words in a group of words represent completely different things.

Completely different relationships can be divided into completely different and incompletely different situations.

1) is completely different, that is, for the same kind of things, it is only divided into two situations: A and B, and there is nothing except A and B.

2) Incomplete dissimilarity means that there are many situations of the same kind of things, and A and B are only some of them, and there are other situations.

3. Inclusion relation

Also known as species relationship, it refers to the relationship between species concept and genus concept, which can be expressed as: A is a kind of B.

4. Cross relationship

It means that the set represented by two words has the same part and different parts. It can be expressed as follows: some A is B, some A is not B, some B is A, and some B is not A. ..