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

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Text this: Maximal and minimal congruences on some semigroups