Specifying rules

*To*: MathGroup at yoda.physics.unc.edu*Subject*: Specifying rules*From*: Ron I. Herman <m1rih00 at frb.gov>*Date*: Fri, 10 Jun 94 16:10:54 -0400

Is there any way to specify rules for symbols? For example, is there a way to tell Mathematica that a > 0 and b < 0 such that Positive[a b] will yield false? Thanks, Ron Herman