Backward Reasoning on Rule-Based Systems Modeled by Fuzzy Petri Nets Through Backward Tree.

Rong Yang Pheng-Ann Heng Kwong-Sak Leung Backward Reasoning on Rule-Based Systems Modeled by Fuzzy Petri Nets Through Backward Tree. 61-71 2005 Computational Intelligence for Modelling and Prediction http://dx.doi.org/10.1007/10966518_5 series/sci/2005-2 db/series/sci/sci2.html#YangHL05