Re: comparing rewite rules

*To*: mathgroup at smc.vnet.net*Subject*: [mg78364] Re: [mg78329] comparing rewite rules*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Fri, 29 Jun 2007 05:45:09 -0400 (EDT)*Reply-to*: hanlonr at cox.net

r1 = {yy -> 4, y -> 3}; r2 = {y -> 3, yy -> 4}; Sort[r1] == Sort[r2] True var = Union[(First /@ r1), (First /@ r2)]; (var /. r1) == (var /. r2) True Bob Hanlon ---- dbsearch04 at yahoo.com wrote: > Hello Mathematica UG: > > I input these 2 simple rewrite rule sets into Mathematica V5: > > - {yy -> 4, y -> 3} > > - {y -> 3, yy -> 4} > > I just want to compare these 2 simple rules for equality. I tried: > > - define each one and use % == %% (this just gives: {yy -> 4, y -> 3} > == {y -> 3, yy -> 4} ) > - making a symbol for each rule set and using ==, such as rul0 == > rul1, > it just echoes my input > > I also tried to replace the rules in an expression. If the replaced > result evaluates to a simple expression, it is OK but, it still fails > sometime when Mathematica reorders expressions, such as when x-1 becomes -1 + > x > > Is it possible to determine in my code that 2 "rule lists" are the > same? > > Of course, in the general case, I will have many more rules than just > these 2 small lists (e.g. Solve[] output). > > Thanks in advance. > > Regards..Roger > >