Logical terms refer to statements that can express logical relationships, such as:

Suppose p and q are two conditions:

(1) If "if P is Q" is a true proposition, then the establishment of P will definitely lead to the establishment of Q, that is, the establishment of pq means that P is a sufficient condition for Q, and Q is also a necessary condition for P..

(2) If "if Q is P" is a true proposition, then the establishment of Q will inevitably lead to the establishment of P, that is, the establishment of qp, so it is said that Q is a sufficient condition for P, that is, Q is a necessary condition for P.

So "sufficient condition" and "necessary condition" are related to the position before and after "",and have nothing to do with the letter symbols used.

Formal logic related extension:

Any concrete thinking has its content and form. Any specific thinking involves some specific objects. For example, concrete thinking in mathematics involves specific objects such as quantity and graphics; Specific thinking in physics involves sound, light, electricity, force and other specific objects. Specific thinking in political economy involves specific objects such as production relations, commodities and values.

The specific thinking in different fields involves different objects. However, some factors are similar to each other in the specific thinking in different fields. For example, in the specific thinking in different fields, we should use the thinking factors of "all are …" and "if … then …".

The same thinking factor that concrete thinking in different fields needs to use is the form of concrete thinking, or rather, the form of thinking. The special objects involved in concrete thinking in different fields are the content of concrete thinking, or rather, the content of thinking.