Hi Cong,

I managed to find this, which seems to match your description:

http://www.sciencedirect.com/science/article/pii/S0020025510005955

Regards,

Niek

Thanks, Niek. I will read it. Hope you are doing fine in Austrilia.

There is also this work: http://ieeexplore.ieee.org/document/4015512/

Please contact the first author of the paper, he might be able to give you the tool.

Thanks, Davood! I am playing with his tool these days.  https://users.encs.concordia.ca/~nikolaos/pattern_detection.html