W3C home > Mailing lists > Public > public-semweb-lifesci@w3.org > May 2007

Re: Advancing translational research with the Semantic Web

From: Pat Hayes <phayes@ihmc.us>
Date: Tue, 29 May 2007 20:53:02 -0700
Message-Id: <p06230924c282a159c5f1@[]>
To: samwald@gmx.at
Cc: public-semweb-lifesci@w3.org

>  > >>Here Temperature_Feature is a "history" (sensu Hayes) or a
>>  >>time-slice. Do I have this correct?
>>  >If you want features to be 4-D objects
>>  Just for the record, that IS the 'histories' view. That is,
>>  'histories' was the name I used for 4-d objects.
>Could you please point us to some literature about the 'histories' view?

The term was used (and in this context, introduced) in an old paper 
of mine called "Ontology for Liquids" (in Formal Theories of the 
Common-Sense World, Ablex, 1985; reprinted in several collections). I 
don't recommend that you read that paper, however. The idea is very 
simple. To reason about a temporal universe, think of time as a 
fourth dimension, then use essentially spatial reasoning. In 
particular, both events and 'continuants' (things which retain their 
identity through their lifetime, more or less) are considered to be 
entities which occupy a 4-d chunk of space/time, and various temporal 
(and spatial) relationships can be described by talking about these 
4-d 'chunks' and how they relate to one another. So to say that I was 
hungry this afternoon, one would in this framework first identify the 
this-afternoon temporal part of me, and then attribute hungriness to 
it. What this boils down to in practice is that time indices (usually 
names of time-intervals) get 'attached' to the names of things, 
rather than to sentences (as in a tensed language) or to relations 
and properties (as in many variants on the 'state' or 'situation' 
based temporal descriptions). The resulting formalization is somewhat 
more longwinded than others, but is capable of describing a wider 
range of temporal relationships, including such things as rates of 
flow, movements in space and so on.

>  I remember that Alan Rector asked how my proposal of AFO would 
>relate to 'histories', and I could not find any specific literature 
>about that kind of ontological representation. Probably I searched 
>in the wrong places.
>I am somewhat confused about why we need to introduce the term 
>'history', and as it seems, others have been confused too.

I agree, it has turned out to be a misleading term, it seems. It is 
the 4-d entity corresponding to a 'location' in 3-d. There is no 
natural name for such entities, unfortunately.

>I would rather prefer to just call these  entities 'things at a 
>certain timespan'.

Fine. That is exactly the original intention. (Provided one 
understands 'thing' sufficiently broadly.)

>  Histories, in the common understanding, cannot have properties like 
>'temperature' -- only the entities themselves can have these 

You can do it either way. In fact, your example is quite telling. 
Regions of space can and indeed do have a temperature at a time: it 
is more accurately described as a spatiotemporally located property 
of (whatever occupies the) space, than a property of an entity. But I 
do not mean to quibble: if you prefer to only assign 'entity' status 
to temporal parts of things, that is a perfectly reasonable stance to 
adopt for many purposes.

Pat Hayes

>Matthias Samwald
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Received on Wednesday, 30 May 2007 03:53:10 UTC

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