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

 ______    _    _     _____      ___      _____   
|      \\ | || | ||  /  ___||   / _ \\   |__  //  
|  --  // | || | || | // __    | / \ ||    / //   
|  --  \\ | \\_/ || | \\_\ ||  | \_/ ||   / //__  
|______//  \____//   \____//    \___//   /_____|| 
`------`    `---`     `---`     `---`    `-----`