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be okay, but many people would not say it was a bakery but a superstore that bakes
bread. The difference is subtle but depending on viewpoints may be either right or
wrong. The message is to be careful when wanting to make something a defined
class because it can have unforeseen effects elsewhere. So, whereas these conditions
are not enough to define a bakery, there are usually things that can be done to make
many classes defined rather than described. In the case of the bakery, we could
describe a new property “has primary purpose” that is a subproperty of “is intended
for” and use this to redefine the bakery class:
A Bakery is anything that:
Is a kind of Place;
Has primary purpose Baking of Bread.
Class: Bakery
EquivalentTo: Place that
hasPrimaryPurpose
BakingOfBread
Now, things such as supermarkets that may bake bread but not as a primary func-
tion will not be incorrectly classified as bakeries.
We can also go back and reconsider other classes that could be candidates for being
made into defined classes. One possible example is Orchard, discussed previously:
Every Orchard is a kind of Enclosed Land.
Every Orchard has part Trees.
Every Orchard is intended for
Agricultural Production.
Class: Orchard
SubClassOf: EnclosedLand,
hasPart some Tree,
isIntendedFor some
AgriculturalProduction
If we can satisfy ourselves that
anything
that is enclosed land, contains trees, and
is intended for agricultural production can be considered to be an orchard, then it is
reasonable to
deine
the Orchard class:
An Orchard is anything that:
is a kind of Enclosed Land.
has part Trees.
is intended for Agricultural
Production.
Class: Orchard
EquivalentTo: EnclosedLand,
hasPart some Tree,
isIntendedFor some
AgriculturalProduction
10.4.8
D
ifferent
p
erspectives
: l
anD
c
over
Quite often, different people will have different perspectives of the same things. Most
usually and most starkly, this can be seen between different organizations where the
perspectives are defined by the differing operational needs of those organizations;
the Merean government's taxation agency will have a very different perspective on
a building than that of Merea Heritage. But, such differences can also occur with a
single organization and indeed within a single ontology. As an example, we consider
the approach taken by Merea Maps with respect to the relationship between two
hierarchies, one describing Features and the other Land cover. Land cover is a form
of classification that provides a means of summarizing what exists on the land's
surface. It is useful for ecological and environmental purposes and even helps in
