graph analyse
circle? slef-circle? 2-node circle?
degree distribution
edge label num? distribution? (20/80 rule)
how to generate data graphs
rmat : probability on four regions of a matrix
generate spanning tree first and then add edges
how to generate query graphs
dig from data graph based on a random model
enumerate all connected graphs and run , pick the ones with results
fixed vertex num, edge num or average/maximum/minimum degree?