Hi Mike, (01)
MB> > 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)
PatH was (AFAICT) making an argument that you should just look at the
syntax. But for most people interested in the matter, it is about the world.
I have always disliked the 3D/4D name, as this implies that if you have 16
dimensions you have something else.
Maybe, Series A or B, Presentism, Perdurantism, etc. are less misleading
names. (03)
MB> In some ways in which we may wish to model the world (though not as yet
in
> banking ;-) ),
I have been using 4D in modelling banking application since the late 1980's
(as I think we have discussed a couple of times).
Some of that work is described in my book -
http://www.amazon.co.uk/Business-Objects-Re-engineering-Chris-Partridge/dp/0
955060303/
Your examples below (FRN etc.) are more about modality than change - a
common approach is (as Matthew West has very recently noted) is possible
worlds.
>From a separation of concerns perspective, it makes sense to distinguish
between change over time and different possible futures (as we do with tense
in English). (04)
Regards,
Chris (05)
> -----Original Message-----
> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-
> bounces@xxxxxxxxxxxxxxxx] On Behalf Of Mike Bennett
> Sent: 05 February 2011 16:13
> To: doug@xxxxxxxxxx; [ontolog-forum]
> Subject: Re: [ontolog-forum] Presentism etc
>
> 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).
>
> 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...
>
> 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.
>
> Spatial lengths and distances are measures which can be applied three
times
> before they can't be applied again orthogonally.
>
> 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.
>
> 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.
>
> 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.
>
> 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.
>
> 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.
>
> 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.
>
> 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.
>
> 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.
>
> 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.
>
> Mike
>
> 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.
> > =============================================================
> >
> >
> >
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> >
>
>
> --
> Mike Bennett
> Director
> Hypercube Ltd.
> 89 Worship Street
> London EC2A 2BF
> Tel: +44 (0) 20 7917 9522
> Mob: +44 (0) 7721 420 730
> www.hypercube.co.uk
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>
>
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