elements {relations} | R Documentation |
Elements of Relation Domains
Description
Obtain elements of endorelation domains which have certain properties.
Usage
relation_elements(x, which, ...)
Arguments
x |
an endorelation. |
which |
a character string specifying the property to be tested
for. Currently, one of |
... |
additional arguments to be employed in the property tests. |
Details
Let R
be an endorelation with domain (X, X)
and consider
elements x
and y
of X
. We say that x
is
- minimal:
there is no
y \ne x
withy R x
.- a first element:
x R y
for ally \ne x
.- a last element:
y R x
for ally \ne x
.- maximal:
there is no
y \ne x
withx R y
.
When computing the tests for the above properties, an additional
na.rm
argument can be given to control the handling of missing
incidences. By default, these are treated as false, to the effect
that they invalidate “for all” tests (corresponding to
na.rm = FALSE
) and pass the “there is no” tests
(corresponding to na.rm = TRUE
).
Value
A set with the elements having the specified property.