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Re: Re: Re: More /.{I->-1} craziness. Schools

  • To: mathgroup at smc.vnet.net
  • Subject: [mg106920] Re: [mg106656] Re: [mg106882] Re: More /.{I->-1} craziness. Schools
  • From: DrMajorBob <btreat1 at austin.rr.com>
  • Date: Thu, 28 Jan 2010 02:44:37 -0500 (EST)
  • References: <hjbvc0$2tp$1@smc.vnet.net> <hjeqh1$g3c$1@smc.vnet.net>
  • Reply-to: drmajorbob at yahoo.com

0 and 1 are not "fuzzballs", so what interval could be >= 1 and also 0.?

Bobby

On Wed, 27 Jan 2010 00:44:22 -0600, Daniel Lichtblau <danl at wolfram.com>  
wrote:

> Richard Fateman wrote:
>> [...]
>> If all of Mathematica functionality were available in the free player
>> version, WRI would need to drastically change its business model. And
>> even it it were free, we still have behavior like this: (..for some
>> values of zero)
>>
>>    {x >== 1, x > 0, x}  evaluates to {True, False, 0.}
>>
>> RJF
>
> Let's take simple intervals, that is, intervals that are segments.
> Define less and greater in the obvious ways, that is, one segment lies
> strictly below the other (right endpoint of lesser is less than left
> endpoint of larger). Let us further define two intervals to be equal
> whenever they have nonempty intersection.
>
> With these definitions, which I think are sensible, the behavior you
> describe above is consistent with arithmetic on intervals. As the
> numbers involved, at least some of them, are fuzzballs, this strikes me
> as an appropriate behavior.
>
> Daniel Lichtblau
> Wolfram Research
>


-- 
DrMajorBob at yahoo.com


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