Re: replace one rule in a list of rules

*To*: mathgroup at smc.vnet.net*Subject*: [mg125544] Re: replace one rule in a list of rules*From*: Ray Koopman <koopman at sfu.ca>*Date*: Sun, 18 Mar 2012 02:43:33 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <jk1fv4$515$1@smc.vnet.net>

On Mar 17, 12:54 am, Kathryn Isaac <kathryn.is... at gmail.com> wrote: > I have a list of simple rules. I want to repeatedly replace one of > them. Is the best way to simply prepend the new rules, or is there > a "prettier" approach? > > Thanks, > Alan Isaac If all you want to change is the right-hand side of the rule then use RuleDelayed with a dummy right-hand-side variable: rlist = {a -> a1, b :> bx}; bx = b1; {a,b}/.rlist bx = b2; {a,b}/.rlist {a1,b1} {a1,b2}