Hello Zhoulai. On 06/30/13 00:15, Zhoulai wrote:

Is there any reference publication for PPL's pre-image operation? The operation is explained at sect. 1.6.9 of user manual but no references is mentioned. I am puzzled how you implemented tpre-image?

I am not sure I understand the question. The notion of image and preimage of a relation are quite standard. Kind regards, Roberto -- Prof. Roberto Bagnara Applied Formal Methods Laboratory - University of Parma, Italy mailto:bagnara@cs.unipr.it BUGSENG srl - http://bugseng.com mailto:roberto.bagnara@bugseng.com