Pattern matching

*To*: mathgroup at smc.vnet.net*Subject*: [mg116214] Pattern matching*From*: StatsMath <stats.math8 at gmail.com>*Date*: Sun, 6 Feb 2011 05:35:17 -0500 (EST)

Have a question regarding the applicaiton of pattern rules: fact[4] //. {fact[n_] :> n fact[n-1], fact[0] -> 1} This is a bug since fact[0] needs to be defined 1st, but I expected the above to grind away idefnitely but it returned a a value 0, instead of an infininte computation. Can you help me understand why the above returns 0? Thanks!