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Re: inconsistent refinement behavior

  • To: mathgroup at smc.vnet.net
  • Subject: [mg131466] Re: inconsistent refinement behavior
  • From: Helen Read <readhpr at gmail.com>
  • Date: Thu, 11 Jul 2013 02:02:48 -0400 (EDT)
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  • References: <krj23l$1jf$1@smc.vnet.net>

There is nothing inconsistent about this. When you include the 
assumption x>0 or x>=0, you are implicitly assuming that x is an element 
of the Reals, so with either of these assumptions the result will be 
Infinity rather than ComplexInfinity.

Recall that there is no ordering in the complex numbers.

On 7/10/2013 3:22 AM, Alex Krasnov wrote:
> The following behavior appears to be inconsistent:
>
> In:	Assuming[x==0, Refine[Infinity/x]]
> Out:	ComplexInfinity
>
> In:	Assuming[x>0, Refine[Infinity/x]]
> Out:	Infinity
>
> In:	Assuming[x>=0, Refine[Infinity/x]]
> Out:	Infinity
>
> The third example should return unrefined given the first two examples. Is
> there an explanation?
>
> Alex
>






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