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Sigma KEE - BackFn
that maps an
to the side that is opposite the
. Note that this is a partial function, since some
s do not have sides, e.g. apples and spheres. Note too that the
is indefinite in much the way that
are indefinite. Although this indefiniteness is undesirable from a theoretical standpoint, it does not have significant practical implications, since there is widespread intersubjective agreement about the most common cases.
Properties or qualities as distinguished from any particular embodiment of the properties/qualities in a physical medium. Instances of Abstract can be said to exist in the same sense as mathematical objects such as sets and relations, but they cannot exist at a particular place and time without some physical encoding or embodiment.
s are relations that are true only of pairs of things.
s are represented as slots in frame systems.
The universal class of individuals. This is the root node of the ontology.
is a term-forming
that maps from a n-tuple of arguments to a range and that associates this n-tuple with at most one range element. Note that the range is a
, and each element of the range is an instance of the
The class of
s whose properties can be inherited downward in the class hierarchy via the
partial valued relation
just in case it is not a
, i.e. just in case assigning values to every argument position except the last one does not necessarily mean that there is a value assignment for the last argument position. Note that, if a
is both a
, then it is a partial function.
of relations. There are two kinds of
s both denote sets of ordered n-tuples. The difference between these two
es is that
s cover formula-forming operators, while
s cover term-forming operators.
single valued relation
just in case an assignment of values to every argument position except the last one determines at most one assignment for the last argument position. Note that not all
s that are spatial in a wide sense. This
includes mereological relations and topological relations.
s that require a single argument.
Belongs to Class
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