I admit de morgan is a pain to implement, but I would find the result more
intuitive then null checks suddenly appearing.
Jody Garnett
On Mon, Feb 3, 2014 at 11:48 PM, Andrea Aime
<andrea.a...@geo-solutions.it>wrote:
> On Mon, Feb 3, 2014 at 1:27 PM, Jody Garnett <jody.garn...@gmail.com>wrote:
>
>> Am I missing something? Could we represent not( attribute > 3 ) as
>> attribute <= 3 ?
>>
>> It would involve some logic to identify the appropriate inverse of our
>> filters, but it may be worth it.
>>
>
> Yes, that is also a way, but more work would be required, we'd have to
> apply De Morgan laws
> (http://en.wikipedia.org/wiki/De_Morgan's_laws)
> to transform complex and/or sequences in direct negations, e.g., if you
> have
>
> not(a > 3 and b = 5 and c <= 10)
>
> you'd first have to turn it into:
>
> not(a > 3) or not(b = 5) or not(c <= 10)
>
> and then finally:
>
> a <=3 or b < 5 or b > 5 or c > 10
>
> Doable, also more work, and thus also a bit more error prone.
> But if people think this road it to be preferred, I can also go here, at
> least for simple
> comparisons (but I would not go there for the negation of spatial filters)
>
> Cheers
> Andrea
>
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