Matthew West wrote: (01)
> Well assuming reasonable definitions of the relations that looks OK,
> however...
> This is not really the kind of thing that it is particularly natural
> to say in 4D. (02)
Agreed. There is a difference between finding a vocabulary that is
"natural" to use in both 3D and 4D and a vocabulary that can be given
semantics in both 3D and 4D. (03)
An agnostic syntax should not be expected to be ideal for either 3D or 4D
thories. All it needs is for a method to exist to translate it into
statements using those theories. (04)
We were discussing a theory-neutral semantics for describing that an
individual is an instance of a class at a specific time. MW says
it is more natural (in 4D) to state the start and end times for that
individual's class membership. However, the information for that may
not be available. (05)
Consider if the statements below refer to observations from a grade school
science project. The student names her frog egg "Kermit" and on Friday
records that it is an egg. On Monday, she records that it is a tadpole.
She goes on a field trip for the rest of the week. The next Monday, she
records that Kermit is a frog. (06)
The statements below express the student's findings. We are ignoring
if she details the spatial coordinates of p1, p2, or p3. It is possible,
even in a 4D world to have only 3 temporally defined observations to record. (07)
-- doug foxvog (08)
doug foxvog wrote:
...
>> A relation could be defined to express this, but not given a semantics
>> in
>> the 3D-4D agnostic world. It would be given different semantics in
>> each theory. (09)
>> "Kermit was an egg at t1, a tadpole at t2, and a frog at t3"
>> could translate to:
>> (exists (p1 p2 p3 e t f)
>> (and
>> (egg e p1)
>> (tadpole t p2)
>> (frog f p3)
>> (coord p1 4 t1)
>> (coord p2 4 t2)
>> (coord p3 4 t3)
>> (viewOf k e t1)
>> (viewOf k t t2)
>> (viewOf k f t3)
>> (namedEntity k "Kermit")))
>> with the semantics of "viewOf" being different for 4D and 3+1D
>> theories.
>
> MW: This is not really the kind of thing that it is particularly natural
> to say in 4D. You are far more likely to want to say something like:
>
> Three states of Kermit are his egg state s1, from t1 to t2, his tadpole
> state, s2, from t2 to t3 and his frog state, s3, from t3 to t4.
>
> Regards
>
> Matthew West
> Information Junction
> Tel: +44 560 302 3685
> Mobile: +44 750 3385279
> matthew.west@xxxxxxxxxxxxxxxxxxxxxxxxx
> http://www.informationjunction.co.uk/
> http://www.matthew-west.org.uk/
>
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=============================================================
doug foxvog doug@xxxxxxxxxx http://ProgressiveAustin.org (011)
"I speak as an American to the leaders of my own nation. The great
initiative in this war is ours. The initiative to stop it must be ours."
- Dr. Martin Luther King Jr.
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