The last version of XSB (2.7.1, nicknamed Kinryo) incorporates a number of ISO standard features that were not present in previous releases. In addition, it seems to provide support for unbounded integers, something that is of vital importance for applications using the PPL. I am thus in the process of trying to do the port to this version of XSB. The major problem I am having is an apparent infinite loop that may indicate a problem in that version of XSB, or in GCC, or (but I doubt it) in our own code. Cheers, Roberto -- Prof. Roberto Bagnara Computer Science Group Department of Mathematics, University of Parma, Italy http://www.cs.unipr.it/~bagnara/ mailto:bagnara@cs.unipr.it