Re: Question on pattern matching
- To: mathgroup at smc.vnet.net
- Subject: [mg47807] Re: Question on pattern matching
- From: Bill Rowe <readnewsciv at earthlink.net>
- Date: Tue, 27 Apr 2004 04:47:47 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
On 4/26/04 at 2:40 AM, rgreen at mail.ru (Roman Green) wrote: >In the following Mathematica's output In[1]:= SetAttributes[k, >Orderless] >In[2]:= k[a, b, b] /. k[x_, x_, y_] -> 0 >Out[2]= 0 >In[3]:= k[a, b, b] /. k_[x_, x_, y_] -> 0 >Out[3]= k[a, b, b] >I can't understand why Mathematica can find match when applying >pattern k[x_, x_, y_], but is unable with more general pattern >k_[x_, x_, y_]. The pattern k_ matches an expression named k with any head k[a, b, b] is an expression with head k and no name. The two things don't match which is why you get the output you got. The pattern _k is any expression with head k. So, k[a,b,b]/._k->0 will result in what you were expecting -- To reply via email subtract one hundred and four
- Follow-Ups:
- Re: Re: Question on pattern matching
- From: Andrzej Kozlowski <akoz@mimuw.edu.pl>
- Re: Re: Question on pattern matching
- From: Andrzej Kozlowski <akoz@mimuw.edu.pl>
- Re: Re: Question on pattern matching