(amusement) surprising result from PossibleZeroQ

*To*: mathgroup at smc.vnet.net*Subject*: [mg130709] (amusement) surprising result from PossibleZeroQ*From*: Peter Pein <petsie at dordos.net>*Date*: Sat, 4 May 2013 03:19:01 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-outx@smc.vnet.net*Delivered-to*: mathgroup-newsendx@smc.vnet.net

Dear group, playing around with distributions, I experienced one of these "that's strange!"-moments. Take the quantile of a Pareto distribution test = Quantile[ParetoDistribution[k, a], q]; InputForm@test ConditionalExpression[Piecewise[{{k/(1 - q)^a^(-1), q < 1}}, Infinity], 0 <= q <= 1] I thought the nesting of ConditionalExpression and Piecewise could simplify and tried every possible combination of 4 functions; to no avail: Block[{f = {Refine, Simplify, FullSimplify, PiecewiseExpand}}, Length[funcs = Composition @@@ Flatten[Tuples[f, #] & /@ Range[Length@f], 1]] ] 340 DeleteCases[Through[funcs[test]], test] {} My expectation has been sth. like test2 = Piecewise[{{k/(1 - q)^(1/a), 0 <= q < 1}, {Infinity, q == 1}}, Indeterminate]; and FullSimplify[test2 - test] // InputForm ConditionalExpression[0, 0 <= q <= 1] looks good. But compare this to PossibleZeroQ[test2 - test] // InputForm ConditionalExpression[False, 0 <= q <= 1] I decided to classify that as "funny" :) MemberQ[Attributes@PossibleZeroQ, Listable] True Have fun with or without Mathematica! Peter

**Follow-Ups**:**Re: (amusement) surprising result from PossibleZeroQ***From:*Bob Hanlon <hanlonr357@gmail.com>