發送短信 : Convexity, geodetic, and hull numbers of the join of graphs

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