The supremum limit, also called the limit superior or upper limit, of a sequence of real numbers , written
and pronounced 'lim-soup,' is the limit
of
as , where
denotes the supremum.
Note that, by definition,
is nonincreasing and so has a limit
in the extended real numbers, possibly
or
. For example, suppose
, then for
odd,
, and for
even,
. Another example is
, in which case
is a constant sequence
.
When
is finite, the sequence converges
to that real number
If the two values differ, the sequence does not converge even in the extended real numbers.
If they agree at
or
,
it converges only in the extended-real sense.