Thanks for your reply. For the second part, I know there are four functions to compute the common graphs. I use "mcgregor_common_subgraphs_unique" in this example. This function can return all the common subgraphs between two graphs. When I am replying this post, I tried mcgregor_common_subgraphs_maximum_unique. The result if the same size-7 graph. Because, in the example I mentioned above, the answer seems correct. I use this solver for my project then I found that this solver in many cases can not find the maximum common subgraph. The back-tracking method stops at some points it should not. In this example I used in the post, the program supposed to continue to find the adjacent vertices of vertex 8 but it stops. -- View this message in context: http://boost.2283326.n4.nabble.com/Incorrect-result-from-mcgregor-common-sub... Sent from the Boost - Users mailing list archive at Nabble.com.