 
  
 
  
   
      | 
     
      
         
            | 
            | 
            | 
            | 
         
         
            | 
          
            | 
            | 
         
         
            | 
            Attacking NP-Hard Graph Problems
   | 
            | 
         
        
            | 
          
            | 
            | 
         
         
            | 
           
 | Organization:  | Macalester College |  
   | 
            | 
         
        
            | 
          
            | 
            | 
         
         
            | 
            Wolfram Technology Conference 2012
   | 
            | 
         
        
            | 
          
            | 
            | 
         
         
            | 
            Champaign, Illinois, USA
   | 
            | 
         
        
            | 
          
            | 
            | 
         
         
            | 
            Although many problems about graphs are NP-complete, one can use several of Mathematica's fast algorithms to derive new methods that compute graph parameters with some success. Starting with the very fast blossom algorithm for a maximum matching and calling on integer linear-programming and other methods, I have designed algorithms to compute the following parameters or properties of a graph G: 1. The vertex chromatic number of G. 2. The edge chromatic number of G (found for all 6975 graphs in GraphData, including the Suzuki graph, which has 370656 edges). 3. Finding a Hamiltonian decomposition of G if it exists. 4. Determining Hamilton-connectedness or, in the bipartite case, Hamilton-laceability of G. 5. Finding a perfect 1-factorization of G: an edge coloring such that any two colors combine to form a Hamiltonian cycle. Such computations lead to new conjectures and often point the way to proofs of new theorems.
   | 
            | 
         
        
            | 
          
            | 
            | 
         
         
            | 
           
   | 
            | 
         
        
            | 
          
            | 
            | 
         
         
            | 
            http://www.wolfram.com/events/technology-conference/2012
   | 
            | 
         
       
     | 
      | 
   
   
      | 
      | 
      | 
   
 
 |  |   |  |    |  |  
  |