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            _____              __   __   ______   
  ____     |  ___||   ____     \ \\/ // |      \\ 
 |    \\   | ||__    |    \\    \ ` //  |  --  // 
 | [] ||   | ||__    | [] ||     | ||   |  --  \\ 
 |  __//   |_____||  |  __//     |_||   |______// 
 |_|`-`    `-----`   |_|`-`      `-`'   `------`  
 `-`                 `-`

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發送短信 : Solid angles and Seifert hypersurfaces