On Mon, Oct 12, 2009 at 10:47 AM, Kent Johnson <ken...@tds.net> wrote: > On Mon, Oct 12, 2009 at 10:09 AM, kevin parks <k...@mac.com> wrote:
>> Yeah i don't mean an infinite loop, but more like a perpetual dance back and >> forth between to items >> that point to each other. I think I need to be careful when i define the >> rules that i don't get something like that... say if 1 goes to 4 but 4's >> rule is go to 1, for example. > > That can clearly happen. There are several cases: <snip> > - at least one rule, but not all, maps to more than one symbol. In > this case either outcome is possible, depending on whether the > expanding rule is repeatedly hit. If you consider the set of rules as a directed graph, the question becomes something like, does the graph contain any cycles which - contain rules that map to more than one symbol, and - are reachable from the start symbol I'm not sure but I think there are probably standard methods of graph theory to answer this question. Kent _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
