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  ______   __   __   _____     _    _    __   _   
 /_   _//  \ \\/ // |  __ \\  | || | || | || | || 
 `-| |,-    \ ` //  | |  \ || | || | || | '--' || 
   | ||      | ||   | |__/ || | \\_/ || | .--. || 
   |_||      |_||   |_____//   \____//  |_|| |_|| 
   `-`'      `-`'    -----`     `---`   `-`  `-`

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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