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

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Text this: Maximal and minimal congruences on some semigroups