Re: Want a general method to extract cases resulting from Reduce

*To*: mathgroup at smc.vnet.net*Subject*: [mg88485] Re: Want a general method to extract cases resulting from Reduce*From*: dontdont at gmail.com*Date*: Tue, 6 May 2008 06:43:07 -0400 (EDT)*References*: <fvmmr3$8e2$1@smc.vnet.net>

On May 5, 6:17 am, dontd... at gmail.com wrote: > Someone recently posted asking "How to remove unneeded constraints." > I can see a general use for something perhaps related to this. > > Reduce often gives back fairly complicated nested boolean structures > of constraints. Consider the results from the following concrete > example: > > Reduce[{a x1^2 + b x1 + c == y1, a x2^2 + b x2 + c == y2, a( -b/ > (2a))^2+ b ( -b/(2a)) + c == y3, y1 < y3, y2 < y3, x1 < x2, > Element[Alternatives[x1,x2,x3,y1,y2,y3,a,b,c],Reals]}, {a,b,c}] =2E.. Here is another common example where the output of Reduce could be enhanced. I often find results of the form (x==y && ALongExpressionOfConditions) || (SomeLongExpressionOfConditions && x<y) || (SameLongExpressionOfConditions && y<x) The useful information density could be increased via (x==y && ALongExpressionOfConditions) || (x!=y && SomeLongExpressionOfConditions)