Home

sumjt

Sumjt is a term used in online technical discourse to denote a hypothetical aggregation operator designed to sum jointly across multiple components of a dataset over a shared index, typically time. It is not an established mathematical construct with a single formal definition, and its interpretation varies by context.

In many explanations, sumjt takes a multivariate sequence with components A1(t), A2(t), ..., Ak(t) defined for t

Sumjt appears in pedagogical examples to illustrate how joint aggregation differs from marginal sums, in toy

Because sumjt lacks a canonical definition, it is susceptible to ambiguity across definitions. Critics argue that

See also: sum, joint distribution, time series, aggregation, data fusion, joint programming.

in
T,
and
produces
a
scalar
by
aggregating
the
joint
values
across
t,
emphasizing
simultaneous
occurrence
rather
than
independent
sums.
Some
discussions
treat
sumjt
as
a
simple
sum
of
joint
values
at
each
t:
sum
over
t
of
f(A1(t),
A2(t),
...,
Ak(t)).
Others
define
it
in
terms
of
probability
or
weightings
reflecting
joint
dependencies.
algorithms
to
discuss
performance
on
joint
data,
and
in
speculative
discussions
of
data
fusion.
It
may
be
described
with
or
without
normalization,
and
with
different
aggregation
kernels.
explicit
domain,
data
structure,
and
aggregation
rules
are
necessary
for
meaningful
comparisons.
As
a
result,
sumjt
is
more
a
mnemonic
or
thought
experiment
than
a
practical
standard
operator
at
present.