SUO: RE: Basics of Process and Event, 3D and 4D
Dear Pat,
See comments below.
Matthew West
Principal Consultant
Shell Information Technology International Limited
Shell Centre, London SE1 7NA, United Kingdom
Tel: +44 20 7934 4490 Other Tel: +44 7796 336538
Email: matthew.west@shell.com
Internet: http://www.shell.com
> -----Original Message-----
> From: Patrick Cassidy [mailto:pcassidy@bellatlantic.net]
> Sent: 19 June 2003 20:33
> Cc: Standard-Upper-Ontology (E-mail)
> Subject: SUO: Basics of Process and Event, 3D and 4D
>
>
>
> Matthew,
> I am apprehensive about trying to tackle a number
> of concepts simultaneously, since it seems likely
> that multiple topics would generate unfocused discussion
> that would not lead to any decisions. But it may be that
> seeing the relations of all of these concepts at once can
> help, so I will try here to answer what appear to me the
> most important of the questions you asked, especially to
> clarify points that were apparently ambiguous. I think
> that most of how I view discrete changes is very similar
> to the view in other 3D ontologies -- nothing novel
> here, though the notation may look different.
MW: one issue here is that there is not a single "standard"
set of assumptions for a 3D ontology, in the way that there
is for 4-dimensionalism. So it is not enough to say you
are a 3-dimensionalist, you need to spell out what sort.
(For example see John Sowa's comments on Dolce).
> It is in
> the relation of Process to event where I am suggesting
> some additional ontology structure.
> I think that perhaps the best way to make
> decisions would be for us to develop or extend an
> application that uses an ontology in a non-trivial
> way, and compare results with different ontological
> choices. But I have no applications on hand that
> can serve as a starting point. I haven't had
> enough time to learn what is available in the
> OpenCyc. Has anyone outside of Cycorp worked on it
> yet?
MW: Someone inside Cycorp would probably be better.
>
> =========================
>
> West, Matthew R SITI-ITPSIE wrote:
> > Dear Pat,
> >
> > I think this discussion is precisely the sort of thing we need to
> > make progress on if we are to move forward with the SUO, so I am
> > reflecting it back to the list.
> >
> . . .
> >>From: Patrick Cassidy [mailto:pcassidy@bellatlantic.net]
> >>
> >> > MW: I notice that you are already assuming that an
> >>activity/process/
> >> > event is extended in space-time. Why do you think this?
> >> >
> >> [PC] See next section and paper.
> >> >
> . . .
> >> > It is not even clear to me what a 3D event
> >> > might be. (lets stick with actual historical ones for
> the moment).
> >> > Does it (necessarily) extend in time as well as space?
> >> [PC] Yes.
> >>
> >> > If so, what does it consist of? (not temporal parts of anything
> >> > since continuants don't have temporal parts).
> >> > If not, what is it at all?
> >> [PC] A group of changes in attributes, each occurring
> >> in some interval of time. See details.
> >
> > MW: I thought attributes were universals and not extended
> in space-time.
> > How do you account for this?
> >
>
> [PC2] I should have said "changes in attributes, each **change**
> occurring in some interval of time". Can "attributes" themselves
> occur in time?? There is a distinction that needs to be made --
> I am referring to AttributeValues -- the things that change --
> ( I should have said "AttributeValue" but was speaking loosely)
> as those things that stick to the objects they inhere in and follow
> them around in space. The terminology here is tricky, it seems
> that no matter what words we use there will be a large constituency
> that interpret them in a sense other than what we intend. In the
> WonderWeb paper D17 by Masolo and Guarino and others they call these
> things "Qualities" and say:
>
> "Qualities can be seen as the basic entities we can perceive and
> measure: shapes, colors, sizes, sounds, smells, as well as weights,
> lengths, electrical charges. . . . 'Quality' is often used as
> synonymous with 'Properly' but this is not the case in DOLCE:
> qualities are particulars, properties are universals. Qualities
> *inhere* in
> entities . . . "
MW: interstingly, looking at Dolce D17 p12, I see that they see
qualities like "the colour of my hair" which might have a particular
value "brown". At one stage we had this concept and called it "aspect".
In the end we found it unnecessary in our 4D approach. I'm not sure
this is quite what I heard you saying above though.
>
> There are I think three levels at which Attributes (Qualities,
> Properties) have to be understood: The most generic, e.g. Color,
> which is an AttributeType; and instances of such AttributeTypes which
> are specific Attributes, such as Red0223 on some industry color
> chart. Both of these are universals. Then there are the
> "AttributeValues" as I think of them (or Qualities in DOLCE
> terminology) which are inseparable from the objects they inhere
> in, such as the red0223 color which we see on a specific woman's lips
> at a specific time and place. What should we call the last very
> specific sort of "Quality"?? The distinctions may be a little
> slippery -- it's not what I think of as obvious common sense.
> I think these qualify as "particulars" as I understand the term.
> I think this is the same idea that some philosophers call "tropes"
>
> "Trope: An abstract particular, or particularized property. For
> example, the whiteness of a piece of chalk considered as a
> particular,
> not a universal. It is an abstract feature of the chalk. Both the
> chalk and its whiteness are particulars—they are not
> repeatables. The
> chalk is a concrete particular and its whiteness is an abstract
> particular. "
MW: Yes, when we had 3 dimensional tendencies we talked in terms of
"possessed properties". Trope seems to be a reasonably well accepted
term in the reading I have done, so I would suggest using it if it
corresponds to what you mean.
>
> Anyway, these are the things that change in time: the function
> that describes the change over time is a "Process" in PUO and the
> change in these AttributeValues that has occurred in some time
> interval is an "Event".
MW: Good this is exactly the kind of thing that needs to be made
explicit.
MW: Just for reference, let me give you the 4D equivalent (at least
as we have it in EPISTLE). When we talk about a property, we mean
something like a particular degree of hotness, e.g. that we describe
as 20C. Properties are sets (including having unchanging membership).
and some temporal parts of of some individuals are members of those
sets (so property is a subtype of class_of_individual). Note this is
a more specific use of the word property than is usually used in
philosophical circles, but then I come from engineering circles.
You will see that your trope maps roughly to the classification
relation between the property and the temporal part (state) of
the individual.
Note that there is no "change" in properties, if the temporal part
of me for 19th June 2003 weighs 13 stone, it will always be true that
that temporal part of me weighs 13 stone. So membership of the properties
does not change, so properties can be treated as sets. So we have
properties/qualities on a firm foundation - set theory.
>
>
> >>
> >> My view of what a 3D process and a 3D event
> >>are is summarized briefly in a paper I presented
> >>in February at a meeting (CICLing-2003) in Mexico City:
> >>
> >>Dimensional Analysis to Clarify Relations Among the
> >>Top-Level Concepts of an Upper Ontology:
> >>Process, Event, Substance, Object. pp 333-346 in
> >>Computational Linguistics and Intelligent Text Processing:
> >>4th International Conference, CICLing 2003,
> >>Mexico City, February 2003.
> >>
> >>available at:
> >> http://micra.com/process/DimensionsOfProcessAndEvent.doc
> >>
> >
> >
> >>Outline here. **BUT FIRST**: ignore the labels, they are
> >>for my own convenience in relating these concepts
> >>to natural language structures. If you don't like
> >>the label for any logical structure,
> >>call it a "banana" ;-)
>
>
> >>
> >>=======================================================
> >>(1) An "Object" is something that has an ObjectAttribute.
> >
> >
> > MW: Can an ObjectAttribute have an attribute? (severly limiting
> > if it can't).
> >
>
> [PC2] Yes, there are types of "attributes" that modify
> other attributes. The ones that come most readily to
> mind are magnitude or intensity modifiers:
> Very large
> deep red
> gently curved
> weakly effective
> varyingly loud
>
> . . . but some are qualitative:
> greenish red
> stunningly gorgeous
> beautifully shaped
>
> I haven't attempted to classify the adverbial-type attribute
> modifiers as yet. They seem to be of different types, in
> part depending on how close to deverbal the adjectives they
> modify are. If the adjectives that function as attribute labels
> are derived from verbs, the attributes that modify such
> adjectives can be the same adverbs that specify the modal
> variations in the activity described by the verb -- e.g.
> a "Cleverly written" novel or a "quickly executed" maneuver.
> There are complications depending on what one chooses as
> attributes to represent.
MW: Interesting, I would see these as subtypes of the original
property/quality. So if red is some range of colour, then deep
red is a subset of that range. But your qualities/properties are
not sets.
>
> >> An "ObjectAttribute" is something that can be attached
> >> to an Object by the hasAttribute relation. These
> >> concepts are too primitive to be specified by anything
> >> other than their relation to each other, and by reference to
> >> instances of each. They are both disjoint with
> Process, Event,
> >> State, System, PersistentObject (i.e. a 4-D "Object"),
> >> and Space (an abstract concept which includes Time).
> >> Processes and Events can have attributes, but they
> >> are different from ObjectAttributes.
> >> An Object is the only thing that can occupy a location,
> >> i.e. take up space. Processes and Events have a
> >> locational attribute by virtue of the Objects which
> >> participate in them.
> >
> >
> > MW: How can events and process have a location in space time
> > without taking up space time?
> >
> [PC2] The "location" of processes and events is derived from the
> objects that participate in the processes and events. That is
> also noted in the WonderWeb D17 paper.
MW: Can you give a page and para reference please.
> I agree with a lot
> of their analysis.
MW: I approve very strongly of the way they are setting about the task.
They even give the reason I think justifies even considering a 3D
approach.
>
> >
> >> A PhysicalObject is an Object that has mass and a
> >> location in our physical universe.
> >>(2) a "system" is any grouping of (one or more) objects plus
> >> the attributes, relations, and processes related to
> >> those objects. An ontologist can select the objects
> >> of a system and ignore those of no interest, even
> >> if they are in close proximity.
> >
> >
> > MW: This does nto seem to be more than a simple aggregate of
> > objects, which by implication are "atomic". Is that right?
> >
> [PC2] Not just objects, but the relations between them and their
> attributes as well. If it were a group just of the objects, it
> would be an "ObjectGroup" which is qualitatively just like an
> Object, but consists of more than one identifiable constituent
> Object.
MW: That is a very unusual use of system then, but never mind. It
also seems to me to be redundant.
>
> >
> >>(3) an "instantaneous state" of a system is the grouping
> >> of the attributes (properties, relations, fluents,
> >> whatever you call them) of the objects and
> >> processes of the system.
> >
> >
> > How do you say for example "The room was at 20C all day." ?
> >
> >
> [PC2] The instantaneous state (temperature) had the value of 20C
> at every time point during the day.
MW: You haven't related that to the room yet. Will you relate it to
the 3D physical object room, or the room's life-history, or both?
If one, why not the other?
>
>
> >>(4) a "process" is group of one or more functions describing
> >> the values of the instantaneous state (group of attributes)
> >> of a system as a function of time.
> >
> >
> > MW: This looks like a function that describes a property space,
> > rather than the processes that cause the changes in properties.
> >
> Ahhh, causality. Very important, but tricky. Yes, in PUO
> I think it is possible to say that Processes and events both
> "cause" other Processes and Events. e.g. the process of oxidation
> causes the creation of rust on my automobile body, and eventually
> causes a bridge to collapse. But I haven't tried the
> axiomatization of causality yet. It needs detailed attention.
> I haven't yet gotten a feeling that there is a consensus on
> the logical treatment, and don't want to wade in until
> I have tackled some simpler issues. I think John Sowa's
> paper:
> http://users.bestweb.net/~sowa/ontology/causal.htm
> has some really useful insights. That is where he also
> discusses Processes as functions, but the relationship
> of Process to Event that I use in PUO differs slightly
> from his.
>
> >
> >> Every Process
> >> extended over some interval of time results in an Event.
> >
> >
> > MW: In EPISTLE we have events too. For us an event is the temporal
> > plane of a state (see my paper for a full explanation).
> >
> http://www.matthew-west.org.uk/Documents/Spatio-temporal-Paradigm.pdf
> >
> > A state (temporal part) is can have "properties",
> > i.e. relationships. They must be true for the whole temporal extent.
> >
> >
> >> A continuous process can give rise to an infinite
> >> number of Events, arbitrarily designated as the
> >> changes that occur in any arbitrary interval of Time.
> >> This is similar to Sowa's view of Process as a
> >> function, but he doesn't have the same view
> >> consistently in his paper, and doesn't relate it
> >> precisely to Event as I suggest in my paper.
> >> (5) an "event" is the grouping of all of the changes
> >> in attributes of a system over **some fixed interval of
> >> time**.
> >
> >
> > MW: Well I could have an aggregate event that was like that, but
> > ours describe the leading edge of a new state, and so have zero
> > time duration.
> >
> >
> [PC2] I read the paper and still haven't formed a good image of how
> the Activities and Events and States relate to each other.
MW: Activities cause changes in state, the start and end of states are
marked by events, so we say that the activities cause the events.
MW: Since the real world is not a state machine, there can be indeterminate
states. So when switching a light on, there might be an indeterminate state
when the light is neither on nor off. Our events mark when the light is
definitely on. I think your events mark the indeterminate state when it
is neither off nor on.
> The paper
> shows that Activities can extend over time, but do the "Events" that
> mark the start of a new state occur only at the end of the Activity?
MW: Not necessarily.
> If one Activity extending over time can cause many Events, each
> one leading to a new State, then Activity would be very close to
> what I call a "Process".
MW: I would also see your process as close to our activity. I think
there is more difference between our views of event though.
>
>
> >> The number of such changes depends on the
> >> granularity of the process, which may be specified
> >> as a non-zero number or may be considered to be zero
> >> for all attributes and also for time. In the latter
> >> case, the process is continuous and the number of
> >> changes in the grouping is infinite for any finite
> >> interval of time. Every Event is the result of
> >> operation of some Process. An Event may also be
> >> specified as a designated group of AtomicEvents.
> >> An AtomicEvent is one for which there is only
> >> a StartingState, an EndingState, and a TimeInterval.
> >> No intermediate states are defined (however, they
> >> can be specified later, and then the Event is no
> >> longer viewed as an AtomicEvent. Each of these
> >> logical structures is a representation of a reality,
> >> and the representation can change to suit the
> >> ontologist.)
> >
> >
> > MW: Sounds like atomic event is a bit of a waste of time.
> >
> An explosion would be an AtomicEvent if one chose to
> ignore what happened in the few seconds or minutes when the
> explosion occurred and the dust settled. Then the beginning
> and ending states would be "Building - intact" and "Pile of
> Rubble". An Atomic explosion could also be an "AtomicEvent" ;-)
MW: But it seems to me that I can always choose to look at a more
detailed view of what is going on, even with an explosion, so as
I say it seems to me to be a waste of time, an unnecessary
distinction.
>
>
>
> >
> >> An "InstantaneousEvent" is deprecated as being
> >> not physically realistic. But when needed it can
> >> be represented by taking the starting and ending
> >> "points" to be the bracketing sequential TimeIntervals
> >> during which no changes in the attributes occur.
> >
> >
> > MW: As stated above our events have zero time thickness, but
> > can have non-zero duration (a boundary in space and time).
> > An example is a wave moving on the ocean. The wave front is
> > a continuous event.
> >
> That could be a moving Event in PUO, also, but the Event would
> take up all of the time the wave was moving. A moving Event
> is Event for which the spatial location is changing for the objects
> whose AttributeValues are changing. A parade though Manhattan would
> also be a moving Event. Not the same as in Epistle, though.
MW: Only the front of the parade would be an event, the rest would be
a stream and an activity.
>
>
> >
> >> The change that is characteristic of the Event then
> >> occurs between Time Intervals rather than between
> >> Time Points. This should only be necessary to
> >> represent Mental Events such as change of ownership
> >> or change of human roles, that can be designated
> >> in advance as taking effect at a particular
> >> time point. No Event can take place at one
> >> time point, as that would lead to the logical
> >> contradiction that an object had two contradictory
> >> properties at the same time.
> >> A "ComplexEvent" may result from any number of
> >> processes running simultaneously, in linear or
> >> branched sequences. It is a series or group of
> >> series of AtomicEvents -- unless the Process is
> >> continuous. The sequential relation of the
> >> intervals is implicit in their time intervals,
> >> and need not be specified by an explicit
> >> relation between sequential component Events.
> >> (6) A "NullProcess" is a Process in which there is no change
> >> of any attribute as a function of time. It is the
> >> limiting case of a Process in which less and less
> >> change occurs. A NullProcess proceeding in any time
> >> interval gives rise to the NullEvent -- a period of
> >> time during which nothing (relevant) has changed.
> >
> >
> > MW: Your null process looks like our idea of state. We require
> > that activities cause change to distinguish them from states.
> >
>
> [PC2] A "state" during which nothing changes could be a NullEvent,
> if is conceived as having a Time duration (even if an unspecified
> one), or a NullProcess if it is conceived as being the
> Activity that produces no change. These are closely related but
> distinguishable in PUO. I think your "State" is indistinguishable
> from a PUO "NullEvent".
MW: Possibly.
>
> >
> >> The kind of "State" that is often referred to
> >> in computation would be closely analogous or identical
> >> to a NullEvent -- a period of Time during which
> >> the attributes remain constant. It can also be
> >> called a "PersistentState" to distinguish it from
> >> an "InstantaneousState", the attribute values at one
> >> time point.
> >
> >
> > MW: This is very analogous to our concept of possible_individual.
> >
> [PC2] I have to think more about that one.
MW: Sorry, our possible individual includes activities, so I must be
wrong here.
>
>
> >> (7) The kind of "Process" that is represented in PSL
> >> and can be represented by a Petri Net is classified
> >> as a "Procedure", which is a subclass of Plan, which
> >> is a subclass of "MentalObject". It is a set of
> >> propositions specifying a series of steps that
> >> are designed to achieve a particular result.
> >
> >
> > MW: This is equivalent to our class_of_activity. A particular
> > activity is a member of this class when it exhibits the various
> > steps. (classes are sets).
> >
> >
> >> Unlike real *physical* processes and Events, such
> >> propositional structures may include contingencies
> >> and loops. The **execution** of such a Procedure
> >> in some time interval gives rise to physical processes
> >> and their associated Events.
> >>
> >>====================================
> >> That's the general idea. An outline of an ontology that
> >>includes those concepts and relates them to other concepts
> >>of interest is in Protege text file format at:
> >>
> >> ftp://micra.com/process/PUOCYC3.pins
> >> ftp://micra.com/process/PUOCYC3.pont
> >> ftp://micra.com/process/PUOCYC3.pprj
> >>
> >
> >
> > MW: Too much for me to easily get my head round. Lets settle
> > for NL at present.
> >
> >
> >> This is only an outline, and I have not yet been
> >>able to spend a lot of time on it. It is useful now
> >>primarily to illustrate how the process and Event
> >>representations would fit in with a broader ontology.
> >>I have taken some branches directly from CYC, which
> >>I think has a lot of useful structure at the middle
> >>levels, but is not to my taste at the higher levels.
> . . .
>
> >> I feel strongly that in order to enable the kind
> >>of knowledge and result-sharing that will help
> >>our field grow we need significant agreement on a
> >>widely used upper ontology, and that is why I am
> >>spending time trying to find a mechanism to build one.
> >
> >
> > MW: I appreciate the motivation for your efforts.
> >
> >>=========================================
> >>
> >>To answer the specific question:
> >>
> >>
> >> >
> >> >>The temporal parts of the 4D activity would have corresponding
> >> >>translations to the temporal parts of the Event.
> >> >
> >> >
> >> > MW: How would you relate the temporal parts of the event to the
> >> > continuants that participate in the activity/process/event?
> >> >
> >>[PC] The Event describes changes in the attributes of the
> >>continuants during a time interval. The Temporal Parts
> >>are each themselves Events, describing the changes in
> >>the attributes of the continuants during those time
> >>subintervals.
> >
> >
> > MW: But attributes do not even exist in space time ... do they?
> >
> [PC2] This was clarified (I hope) near the beginning of this note.
MW: I think some progress was made, but there are still one of two choices
you need to make over which I am not certain of you position.
>
> >> >
> >> >>The
> >> >>"temporal part" relations would not be identical because they
> >> >>would have different arguments, but they would be translatable.
> >> >
> >> >
> >> > MW: Temporal part of what? Activity/process/event or participant.
> >> >
> >>[PC] Events have temporal parts, which are themselves component
> >>Events.
> >
> >
> > MW: That is not good enough. How do events occupy space-time? Since
> > they do occupy space-time, I must be able to see them mustn't I?
> >
> [PC2] Events are "located" in Space-time, but not the same way that
> Objects are located in Space-time. The location relation is
> a different relation and means that the location of an Event is
> the sum of all the locations for all the Objects involved in the
> Event while it is occurring. I haven't tried to axiomatize that,
> but it would look something like below (using suggestive
> terms that are not necessarily already in the ontology)
> (Paraphrase: "An Event is located in the mereological sum of
> the spatial regions occupied by all objects participating
> in the Event at all times during their participation").
> Variable ?t is implicitly a time point, when the relations hold.
> The AttributeValues whose changes characterize the Event
> are related to the Event by the hasComponentAttribute
> relation here:
MW: I think John will criticise this approach for needing to use
time values, rather than allowing sequences of events.
>
> (forall ?E (Event ?E)
> (implies
> (isLocatedAt ?E ?LOC)
> (and
> (instance-of ?LOC SpatialRegion)
> (forall (?obj ?t ?attr)
> (implies
> (and
> (GE ?t startTime(?E))
> (LE ?t endTime(?E))
> (hasComponentAttribute ?E ?attr ?t)
> (hasAttribute ?obj ?attr ?t))
> (and
> (exists ?loc)
> (occupiesLocation ?obj ?loc ?t)
> (isPartOf ?loc ?LOC)))))))
>
>
> The ?LOC location for the Event could be specified vaguely,
> as for example "in New York City" during the Event. Then
> the location for the individual objects participating in
> the Event would only be able to be inferred vaguely at
> those times. If one wanted to get more detail about the
> locations of participants at several time points within
> the Event, one would have to refer to the Process describing
> the AttributeValues of each participant in the Event, or break
> the Event down into smaller component Events (temporal parts).
> The inference from the locations of the participant objects
> to the location of the Event would go in the reverse
> direction, but would require a different axiom.
MW: Why don't you just use the temporal parts of their life
histories?
>
>
> >
> >>I have suggested
> >>a 3D "Event" be the group (physical analog of set) of all changes
> >>in attributes during a time interval.
> >
> > MW: Changes to what?
> >
> [PC2] An Event is defined by changes in the attribute values of
> objects or processes (location, temperature, composition, velocity,
> density, etc.). The Event of PC traveling to Boston is characterized
> by all the changes in location that the ontologist chooses to
> distinguish during the time interval of the Event. If it is
> treated as an AtomicEvent, then only the before and after
> locations are specified, plus the time interval. The Event of
> PC learning a fact may be characterized in more than one way --
> either PC's state of knowledge changes, or the location of the
> physical representation of the fact (an abstract proposition)
> expands into PC's brain. Both could be represented. The ontologist
> chooses the attribute values of the objects of interest which
> define each class of event. Relations between Objects (distance,
> e.g.) are also considered "AttributeValues" for this purpose.
MW: OK. If in oyur original statement you had said attributevalue, I
think I would have got that, because the attribtuevalue is dependent
on the object right?
>
> I notice that in your paper you mention that "a person is both a
> state -- they are a person and alive -- but they are also a living
> process", which makes it sound like attributes are part of a
> 4D object, rather than being associated with it.
MW: Our 4D objects participate in relationships, and in particular
are members of sets. That is all.
> In 3D I would say that a person **has** a state (the group of
> its attributes) and **participates** in the process of living.
MW: These would all be set memberships. There is a set of things
that are states that are living processes, and the group of its
attribute is the intersection of the properties that it is a
member of.
> I seem to recall in one of Pat Hayes's papers (I don't have
> the reference at hand) he spoke about attributes of a temporal
> part of a 4D object, which should be translatable into 3D-speak.
MW: Yes. It is quite translatable as long as I know what the
foundations are.
>
> In order to do a translation of 4D to 3D and vice-versa
> we have to extract out the attributes of the temporal parts of
> a 4D object during some time interval when the attributes are
> constant (or the attributes at each instantaneous time-slice)
> and then equate them to the attributes (color, density, location)
> of the 3D object during that time interval.
MW: I didn't think you could say "during" for a 3D object? It is
only present and wholly present at a point in time.
> Can you say that an
> instantaneous time-slice of a 4D Object **has** certain attributes
> (temperature, mass, location in space, etc.)??
MW: Yes of course. a time slice is just a limiting case of a temporal
part (the smallest possible).
>
> >
> >>I am not sure if an "Activity"
> >>or a "history" (Pat Hayes's term) would, if explained in detail,
> >>also amount to an analogous grouping. It could, for example, if
> >>in 4D it is considered as the set of *changes* in attributes of
> >>the instantaneous time-slices of the 4D objects participating in
> >>the Event. It can't just *be* a time-slice of an object, since the
> >>essential nature of a PUO Event is the *change* in attribute from
> >>time to time.
> >
> >
> > MW: It can be if you take the edge. There is a poitn where the
> > change has happened and the new state starts.
> >
> [PC2] That point would be an Event in 4D, I presume. Is that also
> the "edge" of an Activity?
MW: No. The activity would include the temporal part of any tools used
to perform an activity, as well as what was acted on (for example).
>
>
> >
> >>I haven't seen enough discussion of changes in
> >>attributes over time in a 4D ontology to know if there can be
> >>a direct translation. I could imagine a formulation in 4D that
> >>would correspond, but I don't know if anyone uses such a
> >>formulation.
> >
> >
> > MW: What you have sounds close to what we do. We have states of
> > individuals when some property does not change, we have the temporal
> > edges of those states that we call events, and we have activities
> > that cause those events.
> >
> >
> >> The way "Activity" is glossed in Epistle sounds to me a lot
> >>like it would be a Process in PUO -- i.e. something that
> >>"brings about change". The changes then would be the "Events".
> >
> >
> > MW: Correct. Your events seem to cover the period over which change
> > happens, rather than the point where the new state has come into
> > being.
> >
> >
> >> (2) Since I think that some notion of a series of changes in
> >>attributes is common to all 3D accounts of "Event", I would like
> >>to know what is the closest analogous concept in 4D. I haven't
> >>found "a series of changes in attributes" in any of the 4D
> >>ontology discussions I have read (not many, I confess).
> >
> >
> > MW: Look at my paper above.
> >
> [PC2] OK. It seems that Activities can extend over Time,
> but it is not clear to me whether Events occur only at the
> end of an Activity or at many points during an Activity.
> (Much knowledge about 4D Events has not yet expanded its
> location into PC's brain.)
MW: Just a small point, but strictly we are talking about
how EPISTLE uses the term event in its 4D interpretation
of activity and change to identify certain features on the
4D landscape.
> A question about the description of 4D Activity in
> your paper. You show a "meeting" as "consisting of the
> temporal parts" of the participants. In 3D I think
> it is more common to say there is a relation of
> "participation" between the 3D participants and the meeting
> Event. In figure 10 it only seems to represent the
> participation relation of the 4D participants, but
> no other aspects of the meeting. In 4D I am still unclear
> how certain things are represented.
> For example, I would imagine that at a minimum the
> distance between the participants at a meeting would have
> to decrease to talking distance. So how do you represent
> the distance between participants during a meeting -- is
> that not part of the definition of a 4D meeting?
MW: usually it is enough to say that the temporal parts of
the people are in a room. The room is also part of the meeting
(you probably had to book it and it contains the sound of
the conversation). Otherwise you just note the distance
between the participants.
> Then, if
> the meeting is to accomplish something, someone has to
> communicate information to the others. In 3D if we
> only wanted to create the simplest representation,
> making the meeting an AtomicEvent, and using the model
> of a one-way communication ("lecture") then in the case
> where speaker S is giving a lecture (slides and all)
> to participants A, B, C, and D, about topic T, the
> before-and after Knowledge states might be:
MW: Then the temporal part of the person who delivers the
lecture would be classified by the role speaker, and the
other participants temporal parts would be classified by
the role listener (for instance).
>
> ---------------------------------------------------
> Participant KnowledgeOf(T) KnowledgeOf(T)
> Before After
> ---------------------------------------------------
> S Yes Yes
> A No Yes
> B No Yes
> C No Yes
> D No No
> ----------------------------------------------------
> [D had a heavy lunch, fell asleep as soon as the
> lights went out, and woke up only for the applause.]
MW: or sleeper :-)
MW: The listeners would have a change in state that reflected
the absorption of the knowledge as a result of the lecture.
>
> As the AttributeValues characterizing the meeting
> Event, the representation of the event might include
> only be those changes (or non-changes) in the knowledge
> state of the participants shown above, plus the roles of
> the participants (speaker, listener) at each time point,
MW: It strikes me as very inefficient to only be able to
specify roles at time points, rather than for regions of
time.
> the location of the meeting, and the timeinterval of the
> Event. The representation could be a lot more complex.
> Given the axiomatization of the Location of an Event above,
MW: I would call this a representation rather than as
axiomatisatio - which smacks of how it must be, rather than
just how it happens to be.
> if the Location were given as a particular room, and the
> "participant" relation was one of the Attributes of the
> Event that is represented (and is indexed to time) we could
> infer that the participants were present in the room at
> time points within the time interval of the meeting Event.
MW: Note that in out 4D approach participant is a class of
the person's temporal part, not a relation. The temporal part
is a part not only of the person, but also of the meeting.
> If a record were kept of the meeting, we might want to
> represent the location of the Physical representation of
> the information T as expanding to include the location of
> the physical record created.
>
> This kind of representation of unit changes is not
> much different from that in many other ontologies.
> In PUO the main difference is in the relation of the
> Process-functions to the discrete changes.
>
> Anyway, it would be helpful to have more detail
> about how specific changes are represented in 4D
> Activity and Event. The paper is a good introduction.
> Are there discussions with more detailed examples?
MW: If you look at the FDIS document for ISO15926-2 you will
see some examples there in Clause 4.
>
>
> Pat
>
>
> =============================================
> Patrick Cassidy
>
> MICRA, Inc. || (908) 561-3416
> 735 Belvidere Ave. || (908) 668-5252 (if no answer)
> Plainfield, NJ 07062-2054 || (908) 668-5904 (fax)
>
> internet: cassidy@micra.com
> =============================================
>
> PUO Ontology classes referenced -- leaving out
> others ("object" refers only to physical objects here,
> for simplicity).
>
> Entity
> Object # a 3D object
> Participant # specifically relates to a Situation
> Agent
> Intelligent agent # mostly humans
> # -- someday maybe computers
> PersistentObject # a 4D object
> TimeInterval # a time location, not quantity
> TimePoint
> AttributeType # metaclass of Attribute
> Attribute # instances of Attributes are referred
> # to as AttributeValues
> # synonyms: Qualities, Tropes?
> ObjectAttribute
> StateOfKnowledge # for intelligent agents
> AttributeModifier
> Situation
> InstantaneousState
> **Process # see also "Group"
> **Event # see also "Group"
> PersistentState # synonym = "NullEvent"
> MentalObject
> Proposition
> Topic
> Group # an aggregate that can exist
> # in Space and Time
> **Process # see also "Situation"
> **Event # see also "Situation"
> System
> Location
> SpatialLocation
> SpatialRegion
>
> Functions: StartTime(?E} returns the time point when an
> Event starts.
> EndTime(?E} returns the time point when an
> Event ends.
>
>