Networks from SNAP (Stanford Network Analysis Platform) Network Data Sets,     
Jure Leskovec http://snap.stanford.edu/data/index.html                         
email jure at cs.stanford.edu                                                  
                                                                               
Patent citation network                                                        
                                                                               
Dataset information                                                            
                                                                               
U.S. patent dataset is maintained by the National Bureau of Economic Research. 
The data set spans 37 years (January 1, 1963 to December 30, 1999), and        
includes all the utility patents granted during that period, totaling 3,923,922
patents. The citation graph includes all citations made by patents granted     
between 1975 and 1999, totaling 16,522,438 citations. For the patents dataset  
there are 1,803,511 nodes for which we have no information about their         
citations (we only have the in-links).                                         
                                                                               
The data was originally released by NBER.                                      
                                                                               
Dataset statistics                                                             
Nodes   3774768                                                                
Edges   16518948                                                               
Nodes in largest WCC    3764117 (0.997)                                        
Edges in largest WCC    16511741 (1.000)                                       
Nodes in largest SCC    1 (0.000)                                              
Edges in largest SCC    0 (0.000)                                              
Average clustering coefficient  0.0919                                         
Number of triangles     7515023                                                
Fraction of closed triangles    0.06714                                        
Diameter (longest shortest path)    22                                         
90-percentile effective diameter    9.4                                        
                                                                               
Source (citation)                                                              
                                                                               
J. Leskovec, J. Kleinberg and C. Faloutsos. Graphs over Time: Densification    
Laws, Shrinking Diameters and Possible Explanations. ACM SIGKDD International  
Conference on Knowledge Discovery and Data Mining (KDD), 2005.                 
                                                                               
Hall, B. H., A. B. Jaffe, and M. Trajtenberg (2001). "The NBER Patent Citation 
Data File: Lessons, Insights and Methodological Tools." NBER Working Paper     
8498.  http://papers.nber.org/papers/w8498.pdf                                 
                                                                               
Files                                                                          
File    Description                                                            
cit-Patents.txt.gz  US Patent citation network 1975-1999                       
NBER Patents    Complete US Patent data (includes time, classification, and    
                patent invernetor data), at http://www.nber.org/patents/       
                                                                               
                                                                               
NOTE: a similar version this problem already appears in the UF Collection:     
                                                                               
cit-Patents         in SNAP         n: 3,774,768   nz: 16,518,948              
                    Pajek/patents   n: same        nz: 14,970,767              
                                                                               
                    Both of these come from the NBER data.  However,           
                    the edges are not the same.  The SNAP/cit-Patents          
                    data is a strict superset of the Pajek/patents graph.      
                    If A0 = Pajek/patents and A1 = SNAP/cit-Patents,           
                    then nnz(A1-A0) = nnz(A1)-nnz(A0) = 1,548,181.             
                    All edges in A0 appear in A1.                              
                                                                               
                    The aux data is not the same.  Pajek/patents contains      
                    more auxiliary data for each node.  This data can be       
                    used to interpret the SNAP/cit-Patents graph as well,      
                    since the nodes match up from one graph to the other.