發送短信

數:

提供者:

CAPTCHA:

  _____    __   __    _  __     ___      _____   
 / ____||  \ \\/ //  | |/ //   / _ \\   / ____|| 
/ //---`'   \ ` //   | ' //   / //\ \\ / //---`' 
\ \\___      | ||    | . \\  |  ___  ||\ \\___   
 \_____||    |_||    |_|\_\\ |_||  |_|| \_____|| 
  `----`     `-`'    `-` --` `-`   `-`   `----`

Please enter what you see:

發送短信 : Green’s relations and natural partial order on the regular subsemigroup of transformations preserving an equivalence relation and fixed a cross-section