發送短信 : Arboricity : an acyclic hypergraph decomposition problem motivated by database theory

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