Efficient Correlation Search from Graph Databases

We propose a new problem of correlation mining from graph databases, called Correlated Graph Search (CGS). CGS adopts Pearson's correlation coefficient as the correlation measure to take into account the occurrence distributions of graphs. However, the CGS problem poses significant challenges, since every subgraph of a graph in the database is a candidate, but the number of subgraphs is exponential. We derive two necessary conditions that set bounds on the occurrence probability of a candidate in the database. With this result, we devise an efficient algorithm that mines the candidate set from a much smaller projected database, and thus, we are able to obtain a significantly smaller set of candidates. Three heuristic rules are further developed to refine the candidate set. We also make use of the bounds to directly answer high-support queries without mining the candidates. Our experimental results demonstrate the efficiency of our algorithm. Finally, we show that our algorithm provides a general solution when most of the commonly used correlation measures are used to generalize the CGS problem.