Re: Impossible Database Design?

Jay Dee wrote:
> mAsterdam wrote:

>> Jay Dee wrote:
>>
>>> Regarding domains:  the question, "Is absorption a 
>>> property of some value in the domain?" must be
>>> answered depending on what the domain is and how
>>> it can reasonably be represented.  
>>
>> I do not understand this. What do you mean wtih absorbtion in this 
>> context (reference welcome)?.

Ah. I see. Please excuse my ignorance.
Thank you.

> Some of the contributors to this thread seemed to desire a value which
> means "the end of an interval which has no end." My point is that DD+L
> describe a technique that accommodates domains having such a value; all
> their technique requires is a finite set of values and few operators
> having prescribed semantics.
>
> In the case of time, oo might mark an instant which will never come:
>
> until t = oo { <do something>; t++ }
>
> would run forever -- at least, as well as we can know forever.
>
> There are plenty of untidy questions to be dealt with: "How much is one
> less than infinity?" "How can I represent values which can be
> incremented forever and not reach infinity?"
>
> There are analogs in arithmetic: "Is any positive value divided by zero
> equal to infinity?" Perhaps, "Is any positive value divided by infinity
> zero?" Iverson used an arithmetic in which any value divided by itself
> is unity, and deftly handled all the "zero divided by zero" cases. It
> would also be useful when one asks, "How much is infinity divided by
> infinity?" (Remember the 'N / oo = 0' question!)
>
> All these questions are left to the domain modeler. Of course, if you
> don't need an infinity, these questions go away...
Received on Sat May 20 2006 - 14:17:07 CEST