Q: Xiaomei goes swimming.

A→B This form generally includes

(1) as long as a, b;

Only b has an a.

(3) unless b, otherwise ┐ a;

These expressions

Therefore, Xiaomei doesn't go swimming unless it is hot.

"Unless P, otherwise ┐Q"

The corresponding symbol is q → p.

Meaning can also be understood, that is to say:

As long as Xiaomei goes swimming, the weather is hot.