Thank you very much Thomas Güttler for you quick answer, but I think your program doesn't contain an algorithm to spot cycles (like the usual cyclic graph algorithm). In my first post there was an assert to spot this problem:
l = [0] m = [l, l] print m print isrecursive(m) Gives: [[0], [0]] 1 m contains a shared reference, but not a recursive one. Thank you Fredrik Lundh too, bear hugs, Bearophile -- http://mail.python.org/mailman/listinfo/python-list
