[Top] [All Lists]

Re: [ontolog-forum] Presentism etc

To: doug@xxxxxxxxxx, "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Mike Bennett <mbennett@xxxxxxxxxxxxxxx>
Date: Sat, 05 Feb 2011 16:12:45 +0000
Message-id: <4D4D76FD.6010902@xxxxxxxxxxxxxxx>
I think you've hit on why I for one find 4D approaches a little 
disquieting, even though I personally see the world in 4+ 
dimensions (hence Hypercube).    (01)

I hope it's safe to say that we are all thinking about 
differences in how to represent the world rather than how the 
world is. In which case...    (02)

Dimensions (I submit) are that along which we choose to measure 
properties which are orthogonal to any other properties we have 
thus far so measured.    (03)

Spatial lengths and distances are measures which can be applied 
three times before they can't be applied again orthogonally.    (04)

Time is orthogonal to these, and this is usually the one we 
choose to apply fourth. However in most domains of discourse it 
presents us with the unique feature of causality. This itself 
presents the problem you describe.    (05)

In some ways in which we may wish to model the world (though not 
as yet in banking ;-) ), time and space can be treated as a 
single space of interchangeable dimensions, giving us 4D 
space-time. Though I can't help noticing that even black holes 
have a time before they existed.    (06)

Mass remains orthogonal to these (except, again, under certain 
descrptive frameworks which one may wish to ontologize). So that 
requires another dimension along which to measure it. So does 
electrical charge. And so on. Unlike time, there is no consensus 
about what order to label these in. Like time, the question is 
not whether they are "new" dimensions, but whether on certain 
scales the properties we usually measure along them can be 
regarded as interchangeable within a single 4 or 5 or 6 
dimensional hyperspace.    (07)

The 11 dimensional (or is it 7 dimensional?) Calibi-Yau surface 
described in string theory looks to this naive onlooker like 
something other than a bunch of orthogonal directions along which 
some properties are measured, so I'm curious to find out whether 
this framework formally defines the concept of "dimension" in the 
same way I have done here. But if not, that would not present a 
challenge for semantically modeling it, it just means that this 
is a different descriptive framework using a different definition 
of "dimension". It seems to me that dimensions are sometimes 
described as actual things rather than measurement constructs, 
when one could as easily say "here is some actual property which 
is orthogonal to the rest" and give the property a name. If we 
are clear about what we mean by "dimension", and in what problem 
domains we are applying that definition, this might be more 
helpful than all this 3D +1 minus the square root of whatever. 
Then we have properties of a thing, and dimensions as a property 
of those properties. And interesting constraints or properties 
about what we can measure in some of those dimensions in our 
domain of discourse.    (08)

Coming back to the more immediate space of business problems and 
semantic modeling of them, can't we simply recognise that here 
are some things that have an extent in space and time, along with 
optionally a mass, a charge and so on, and that these properties 
each present particular differences as to how a given property, 
which occupies a given kind of dimension, are modeled. Including 
for example the unique challenges of causality, which means that 
historical facts can be nailed down in a simple space of spatial 
and temporal facts, while the "future" presents unique modeling 
requirements based on for example how and by whom it is 
predicted. These become problems of provenance.    (09)

My favourite practical example about dealing with the future is 
the floating rate note (FRN). This is a bond which pays a rate of 
interest that is pegged to some variable interest rate (say, the 
London Interbank Offer Rate). Suppose this is reset at the end of 
each month. Then the current value of the bond is based on the 
value of its future cashflows, which are a known unknown. Each 
day, my best guess about the present value is based on the future 
rate of this bond. This is a calculation of what the next reset 
rate would be if it were calculated according to today's interest 
rate, this being the most up to date information I have.    (010)

Now, for risk management and compliance purposes, I may need to 
have a record of what I perceived the current value of a bond to 
be at the moment I purchased it. If I purchased a FRN a week ago, 
then I now know what it's projected future interest rate (and so 
current value) is today, but I also know what I thought that 
future value was a week ago. These two valuations (past and 
present) are based on the two estimates of the future value of 
the same variable.    (011)

That is, there is a time series, in the past, of projected future 
values of the same quantity - the reset rate at the end of this 
month, along with the full set of bond analytics based on current 
value, that depend on this. And these past values matter because 
they were the basis on which investment decisions were made. So 
there will be data in a system somewhere whose meaning we would 
rather like to ontologize.    (012)

If we fail to account for the unique challenges presented by the 
arrow of time, I'm not sure we would be able to properly model 
these sorts of scenarios. Time is not just a dimension, it's a 
dimension along which every point in the past possesses an 
infinite number of unknowns about its future. We have a future, 
but every past has a future of its own.    (013)

Mike    (014)

On 05/02/2011 08:09, doug foxvog wrote:
> On Fri, February 4, 2011 12:41, John F. Sowa said:
>> On 2/4/2011 10:07 AM, Ronald Stamper wrote:
>>> The recent discussions of presentism , space-time and noun-verb
>>> distinction have left me wondering what are the ontologies (in the
>>> metaphysics sense) that lie behind the messages on those topics.
>> I stated my preferred ontology quite explicitly in an earlier note,
>> but I'll delete details that might be distracting.  After deleting
>> the qualifying points 2, 3, 6, and 7, that leaves:
>> JFS
>>> 1. As a basic metaphysical stance, I prefer a 4D ontology, which
>>>     considers the whole universe from a God's eye point of view,
>>>     as one giant domain of discourse.
> One issue with a 4D, God's eye, ontology is it fixes the future part of
> 4D worms.  This suggests predestination and all that follows from that
> including the lack of free will.
> In 4D, whatever is true of any 4D worm or time slice of 4D worm is
> timelessly true.  That means that all information about your death
> is true *now* and can not be changed.
> Although some people believe the universe is an automaton, many do not,
> so it behooves us not to base a universal core ontology on such
> metaphysics.
> A 4D ontology which does not include predestination would be more
> acceptable to many, especially with mechanisms to convert statements
> to 3+1 D statements.
> -- doug f
>>> 4. As a convenient 3+1 D way of talking, thinking, and computing,
>>>     I like the notion of a *situation* as a finite chunk of space-time
>>>     that could be mapped to some region in domain #1, but it could
>>>     also be mapped to a domain that may include some part of #1 and
>>>     any arbitrary set of set of anything anybody would like to think
>>>     about or talk about.  Think of those entities as mathematical
>>>     objects, which mathematicians freely assume whenever they please.
>>>     But they might be virtual reality things like Sherlock Holmes,
>>>     since VR objects that look like people are just as mathematical
>>>     as spheres or cubes.
>>> 5. Given the option of having the whole 4D universe as a ground
>>>     domain plus the option of throwing in any kind of VR entities
>>>     we'd like to think or talk about plus situations that can
>>>     include any mixture of any of the above, we get a rich semantic
>>>     domain plus a rich syntactic system -- and fortunately, we can
>>>     formalize it in Common Logic, if we wish.
>> In summary, the domain of quantification I recommend includes
>> a 4D view of everything in the universe, past, present, and future.
>> To that domain, I would add all mathematical entities that anyone
>> can specify by any mathematical methods whatever.
>> Among those mathematical entities are all the kinds of virtual reality
>> constructions that look like fictional, mythical, or imaginary people,
>> beasts, or things of any kind.  The domain would also include all
>> mathematical generalizations and classifications of them.
>> This is a huge domain, which includes far more than I would need for
>> any particular application.  For most applications, I would extract
>> some suitable subset for my purpose.
>> In order to facilitate a 3D+1 view of talking and reasoning about
>> subsets, I would define situations as 3D chunks mapped to the
>> 4D domain, augmented with the mathematical domain as needed.
>> For a way of carving up and classifying both the 4D domain and
>> the VR extensions, I prefer a process ontology, along the lines
>> of Whitehead's _Process and Reality_.  But for my talk about
>> situations for particular purposes, I would allow "approximate"
>> mappings that are more conventionally object-like or event-like.
>> John
> =============================================================
> doug foxvog    doug@xxxxxxxxxx   http://ProgressiveAustin.org
> "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.
> =============================================================
> _________________________________________________________________
> Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/
> Config Subscr: http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/
> Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx
> Shared Files: http://ontolog.cim3.net/file/
> Community Wiki: http://ontolog.cim3.net/wiki/
> To join: http://ontolog.cim3.net/cgi-bin/wiki.pl?WikiHomePage#nid1J
> To Post: mailto:ontolog-forum@xxxxxxxxxxxxxxxx
>    (015)

Mike Bennett
Hypercube Ltd.
89 Worship Street
London EC2A 2BF
Tel: +44 (0) 20 7917 9522
Mob: +44 (0) 7721 420 730
Registered in England and Wales No. 2461068    (016)

Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/  
Config Subscr: http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/  
Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx
Shared Files: http://ontolog.cim3.net/file/
Community Wiki: http://ontolog.cim3.net/wiki/ 
To join: http://ontolog.cim3.net/cgi-bin/wiki.pl?WikiHomePage#nid1J
To Post: mailto:ontolog-forum@xxxxxxxxxxxxxxxx    (017)

<Prev in Thread] Current Thread [Next in Thread>