On Mon, December 31, 2012 21:14, William Frank wrote:
> ...
> But what seems to me to be most fundamentally wrong in this discussion is
> the notion that there is a good reason to define 'kind of activity'
> separately from 'kind of stone' or kind of hope'. (01)
>From the discussion, "kind of activity" is far narrower than "subset of
activity". I would prefer a clearer description of its meaning than was
given. The given gloss:
"*kind of activity* means a characterization that is true of some
activities, so distinguishing these activities from all other
activities"
does not restrict the type of characterization, and without a meaningful
restriction on the type of characterization, i agree that there is little
reason
to define a "kind of activity" (with an exception noted in two paragraphs
below). (02)
However if the types of characterizations intended are semantically
restricted the concept could be useful. In addition, if instances of
"kind of activity" are required to be disjoint with each other or arranged
in a tree with disjoint limbs, and/or if subtypes of an instance of "kind
of activity" may not themselves be instances of "kind of activity", such a
concept could be useful. (03)
I haven't looked at the ontology, but i find it likely that "kind of
activity" was defined so as to enable properties (and maybe rules) with
arguments restricted to its instances. If such properties/rules would be
applicable to
any subset of "activity", then "kind of activity" could still be useful if
the language allowed rules to have clauses specifying that "X is an
instance of *kind of activity*" but not "X is a subtype of *activity*". (04)
"Kind of stone" sounds like a useful concept to me if it is carefully
defined, although i would prefer a clearer name. "Kind of stone [or
"rock"] by formation process" would have three instances: "igneous rock",
"sedimentary rock", and "metamorphic rock". A different meaning for "kind
of stone" might be "kind of mineral", whose instances would include
"quartz", "shale", and thousands of other minerals. (05)
> I would think that at
> most one definition of 'kind of' would be needed, for example: (06)
> *kind of *X means a characterization that is true of some x's, so
> distinquishing these x's from all other x's. (07)
I'm not sure what utility such a definition would have. I understand that
this is modeled on the gloss for *kind of activity*, and emphasizes that
unless the characterization is restricted, the utility is questionable. (08)
> example: trees that do not loose their leaves in the winter and are native
> to North America are a kind of tree. (09)
This seems to be an intersection of *tree*, an instance of *kind of plant
by leaf retention* -- *deciduous plant* --, and an instance of *organism
type by native range* -- *native North American organism*. One could
argue for the utility of defining *kind of plant by leaf retention* and
*organism type by native range* as well as their instances which include
*deciduous plant* and *native North American organism*. Subtypes of
*deciduous plant* (such as *deciduous tree*) might also be useful. In
some contexts, *tree species* and *tree genus* may be useful subtypes of
the not very useful "kind of tree". (010)
> of course, every sentence with one free variable can be the source of a
> definition of a unary relation. But people often define kinds without
> naming the kind. (011)
Sure. (012)
Naming them can be useful if there are interesting things to say about
them that are not derived from the types of which they are an
intersection. (013)
BTW, how would you use an ontology to state "the range of deciduous native
North American trees has moved northward in the last century" without
reifying the concept "deciduous native North American tree"? (014)
-- doug foxvog (015)
...
> --
> William Frank
>
> 413/376-8167 (016)
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