Re: How does a rule get applied?
- To: mathgroup@smc.vnet.net
- Subject: [mg12474] Re: How does a rule get applied?
- From: "Kevin J. McCann" <kevinmccann@erols.com>
- Date: Tue, 19 May 1998 13:31:40 -0400
- Organization: Erol's Internet Services
- References: <6jf2mg$3vl@smc.vnet.net>
A guess is that in your example the (1 + 3) is being evaluated to 4 so that your rule with the n_ + 1 doesn't work, i.e. there is no pattern that matches. Kevin Yacine Ait-Sahalia wrote in message <6jf2mg$3vl@smc.vnet.net>... >Hi, > >I'm having trouble understanding how rules are applied after /. Consider >the following example: > x^a + x^(1+a) /. x^(n_) + x^(n_+1) ->0 > x^3 + x^(1+3) /. x^(n_) + x^(n_+1) ->0 > x^3 /. x^(n_) ->0 > >Out[388]= > 0 > >Out[389]= > 3 4 > x + x > >Out[390]= > 0 > > >Could anyone please explain to me why > > x^a + x^(1+a) /. x^(n_) + x^(n_+1) ->0 > >returns 0 (as expected), whereas > > x^3 + x^(1+3) /. x^(n_) + x^(n_+1) ->0 > >returns > > 3 4 > x + x > >instead of 0? > >Thanks for your help. >