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At 17/07/2003 14:48:25, "Roger L. Costello" <costello@mitre.org> wrote:
# John Cowan wrote:
#
# > > 2. Is kilometer a function? e.g., kilometer(Yangtze) > 6300
# > > In general: kilometer(physical object) > number
# > > "The kilometer function maps a physical object to a number."
# >
# > I think this view is the most nearly correct, but it needs
amplification:
# > it doesn't capture that it's the *length* (rather than, say, the
# > average depth) of the Yangzi that is 6300 km. So we can rewrite it
# > in terms of relations as follows:
# >
# > Yangzi length X
# > X kilometer 6300
# >
# > where "kilometer" is a relation that maps a length (an abstract
property
# > of a physical object) into a pure number.
#
# So, kilometer is a function of this sort:
#
# kilometer(length(Yangtze)) > 6300
#
# "kilometer is a function which maps the length of the Yangtze to 6300."
#
# Another example:
#
# kilometer(avgdepth(Yangtze)) > 0.25
#
# "kilometer is a function which maps the average depth of the Yangtze to
0.25."
#
# The general case is:
#
# kilometer(distance) > number
#
# where distance is an abstract dimension object.
#
# How are functions represented syntactically in XML? Given the above
# viewpoint, this form no longer seems appropriate:
#
# <River id="Yangtze">
# <length units="kilometer">6300</length>
# </River
#
# Perhaps a more faithful representation of:
#
# kilometer(length(Yangtze)) > 6300
#
# is this:
#
# <River id="Yangtze">
# <length>
# <kilometer>6300</kilometer>
# </length>
# </River>
#
I'd go for:
<River id="Yangtze">
<length unit="kilometer">
6300
</length>
</River>
Would you want a succession of tags marked in meters, centimetres, LSD etc?
but it's probably just personal preference.
Roger
