Re: [ontolog-forum] 3D+1 (was presentism...was blah blah blah)

[jayanosy@xxxxxxxxxxxxxxxxxxx]

Pat,

Is this link right? 

Best Regards,
John A. Yanosy Jr.

Cell: +01-214-336-9875
PH: +01-972-705-1807
Email: JAYANOSY@xxxxxxxxxxxxxxxxxxx

Pat Hayes <phayes@xxxxxxx>
Sent by: ontolog-forum-bounces@xxxxxxxxxxxxxxxx

02/08/2011 11:01 PM

Please respond to
"[ontolog-forum] " <ontolog-forum@xxxxxxxxxxxxxxxx>

To	Rich Cooper <rich@xxxxxxxxxxxxxxxxxxxxxx>
cc	"'[ontolog-forum] '" <ontolog-forum@xxxxxxxxxxxxxxxx>
Subject	Re: [ontolog-forum] 3D+1 (was presentism...was blah blah blah)

On Feb 4, 2011, at 4:03 PM, Rich Cooper wrote:

> Pat, you wrote:
>                  In
fact, with a bit of extra work one can embed almost all the
> necessary temporal reasoning into a generalized unification algorithm
which
> extracts temporal constraints during the unification process. I have
all the
> details somewhere if you (or anyone else) are interested.
> 
> Please do send me the "details" about the "generalized
unification algorithm
> which extracts temporal constraints within the unification process".
 I am
> very interested in such material and references.  

The only write-up is in a final report to the Army written in 2004. I've
put a copy here:

http://beta.ihmc.us/users/phayes/Trickledown2004.pdf

feel free to use it. The Army didn't think enough of it to continue funding
the project, so its been languishing since then. 

Pat

> 
> Thanks for the offer,
> -Rich
> 
> 
> Sincerely,
> Rich Cooper
> EnglishLogicKernel.com
> Rich AT EnglishLogicKernel DOT com
> 9 4 9 \ 5 2 5 - 5 7 1 2
> 
> -----Original Message-----
> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
> [mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Pat Hayes
> Sent: Thursday, February 03, 2011 1:38 AM
> To: ian@xxxxxxxxxxxxxxxx; [ontolog-forum] 
> Subject: Re: [ontolog-forum] 3D+1 (was presentism...was blah blah
blah)
> 
> Ian, here's a non-philosophical way to characterize it. Start with
an atomic
> sentence of the form R(a, b), with no time involved, and suppose that
a and
> b here are ordinary uncontroversial physical objects, say. Intuitively,
they
> are 3D things. Now add time, t. Where do we put the time parameter?
Several
> answers can be given. 
> 
> 1. Attach it to the sentence, meaning that the sentence R(a,b) is
true at
> the time t.  This gives you a hybrid or context logic where the
times are
> possible temporal worlds/indices or contexts, to which truth is relativized.
> But the sentences being so relativized do not themselves make any
reference
> to time. Call this 3D.
> 
> 2. Attach it to the relation as an extra argument, and call the relation
a
> 'fluent': R(a, b, t) This gives you the classical AI/KR approach which
used
> to be called the situation calculus, where one quantifies over times
in the
> KR language itself, but the object terms are still thought of as denoting
3D
> rather than 4D entities. Call this 3D+1.
> 
> 3. Attach it to the object terms (using a suitable function, written
here as
> an infix @): R(a@t, b@t) This requires us to make sense of this @
operation,
> and it seems natural to say that it means the t-slice of the thing
named,
> which now has to be re-thought as a 4D entity. So the a, b things
have
> morphed form being 3D (but lasting through time) to being genuinely
4D, and
> having temporal slices or parts. Call this 4D.
> 
> For some folk this last step is apparently mind-boggling, although
to me it
> is puzzling how one can think of something being 3D and also extended
in
> time and have it *not* be 4D. For yet other people (think OBO), there
are
> apparently two kinds of thing in the world, one kind (continuants)
which
> must be described using the 3D+1 style , the other (occurrents) which
should
> be described using the 4D style. God alone knows why anyone would
believe
> that there are two ways to exist in time, but there's nowt as queer
as folk,
> as someone's grandmother used to say. 
> 
> What I like about this way of contrasting the options is that it makes
it be
> simply a matter of syntax - where in the sentence to attach the temporal
> parameter - and not one of metaphysics. Syntax is way easier than
> metaphysics. It also means that one can see quite clearly how to make
the
> various formal techniques work together, by allowing the temporal
parameter
> to 'float'. In fact, with a bit of extra work one can embed almost
all the
> necessary temporal reasoning into a generalized unification algorithm
which
> extracts temporal constraints during the unification process. I have
all the
> details somewhere if you (or anyone else) are interested. 
> 
> Pat
> 
> 
> On Jan 27, 2011, at 11:19 AM, Ian Bailey wrote:
> 
>> Thanks John,
>> 
>> So in a 3+1 approach, when they actually "cut some ontology
code", if I've
>> understood you correctly, I'm guessing they timestamp the properties
and
>> relationships ? This contrasts with a 4D approach where the Individual
is
>> sliced up into temporal stages and the properties are associated
with the
>> stages (apart from those properties that apply to the whole-life
>> individual).
>> 
>> If I've got that right, then 3+1 is the approach the oil and gas
folks
> used
>> in late 80s early 90s on EPISTLE and the first drafts of ISO10303-221.
Am
> I
>> in the right ball park there ?  Matthew ?
>> 
>> Cheers
>> --
>> Ian
>> 
>> -----Original Message-----
>> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
>> [mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of John
F. Sowa
>> Sent: 27 January 2011 17:05
>> To: ontolog-forum@xxxxxxxxxxxxxxxx
>> Subject: Re: [ontolog-forum] 3D+1 (was presentism...was blah blah
blah)
>> 
>> On 1/27/2011 11:17 AM, Ian Bailey wrote:
>>> I get 4D, finally, after years of hanging on Chris and
>>> Matthew's coattails, but the 3D+1 thing is a mystery.
>> 
>> The basic issue is the definition of a physical object
>> and its relationship to a privileged time called 'now':
>> 
>> 1. In 3+1 D, which is the implicit assumption in ordinary
>>    language, an object (human, animal, plant, or artifact)
>>    comes into existence at some time t1 (e.g., birth),
>>    ceases to exist at some time t2 (e.g., death), and
>>    for each now between t1 and t2, all parts of it
>>    exist together now.
>> 
>> 2. In 4D, a physical object extends over a 4D volume, whose
>>    lower and upper time coordinates are t1 and t2 and
whose
>>    spatial coordinates trace out a volume that spans
the
>>    object's travels.
>> 
>> 3, In 3+1 D, the object undergoes various changes, which
>>    cause some properties to become true or false at
different
>>    times called now.
>> 
>> 4. In 4D, the object doesn't change, but it has time-dependent
>>    parts (slices or stages) at which various properties
may be
>>    true or false.
>> 
>> The analogy I prefer (since I studied fluid mechanics at one
>> time in my life) is between Lagrangian and Eulerian coordinate
>> systems for representing and computing fluid flow:
>> 
>> 1. Lagrangian coordinates are like a 3+1 D system:  the
>>    observer follows a particular parcel of fluid as
it moves.
>> 
>> 2. Eulerian coordinates are like a 4D system:  the observer
>>    sits on the side and watches the flow of all the
fluid
>>    as a whole.
>> 
>> In our ordinary language, we talk about our bodies in Lagrangian
>> terms.  We observe our own motion through space and time,
and
>> relate everything else to where we are *now*.
>> 
>> An Eulerian system is like a God's eye view of the universe.
>> God sees everything spread out in all dimensions of space
>> and time.  There is no privileged point of time or space.
>> 
>> John
>> 
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