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In-Depth Information
No matter which kind of specialization it is, a
duality
always covers two dis-
tinct
entity sets
; one describing the increments in the resource sets and the other
one the decrements in the resource sets. In the case of a
transfer
the decrement is
called
give
and the increment is called
take
. The decrement of a
non-consuming
transformation
is denoted as
use
and the one of a consuming transformation
is denoted as
consume
. In both kinds of
transformation
the increment is called
produce
.
Figure 3(b) shows an abstract example of a
duality
model to illustrate the
concepts and their stencils. An entity set is modeled as a partition. Accordingly,
a duality model includes two partitions. The
duality
shown in the example is a
transfer
. It follows that one
entity set
is a
give
and the other one is a
take
.The
kind of
entity set
is denoted in the upper left corner of the partition.
Accordingtothemetamodel,an
entity set
covers at least one but up to mul-
tiple
economic events
.An
economic event
is considered as a class of phenomena
reflecting changes in scare means [16]. An
economic event
is specific to the
entity
set
it belongs to. Following the principles of
duality
,all
economic events
in the
decrement
entity set
(
give
,
use
,
consume
) are counterbalanced by the
economic
events
in the corresponding increment
entity set
(
take
,
produce
)ofthesame
duality
model.
An
economic event
is usually executed at a certain point in time. However, in
certain cases the increment/decrement is realized by a series of economic events
each of the same nature. For example, consider that the payment for goods is
split into a number of partial payments. For this purpose we use the concept of an
economic event series
, which is defined as a specialization of the
economic event
in the meta model. Consequently, the concept of an
economic event series
may
substitute an
economic event
. This means, instead of modeling each
economic
event
of each partial payment, one may model a single
economic event series
of
partial payments.
An
economic event
in a
give
/
use
/
consume entity set
decrements resource(s).
Similarly, an
economic event
in a
take
/
produce entity set
increments resource(s).
This relationship between an
economic event
and an
economic resource
is de-
scribed by the concept of a
stock-flow
.A
stock-flow
models an association
between exactly one
economic event
and exactly one
economic resource
.An
economic event
will affect most of the time one
economic resource
only, but it
may affect multiple ones. Thus, an
economic event
may have one up to many
stock-flows
connected. An
economic resource
usually is affected by many differ-
ent
economic events
(in different
entity sets
of different
duality
models). At a
minimum an
economic resource
is affected by one
economic event
-otherwiseit
would not be worth considering the
economic resource
at all. Consequently, an
economic resource
is connected to one up to many
stock-flows
.
A similar concept to
economic event series
is defined for
economic resources
:
the
economic resource series
.An
economic resource series
is used if an
economic
event
affects a number of
economic resources
of the same kind. For example, on a
high level of abstraction one may define raw material as an
economic resource
and
an
economic event
mayaffectanumberof
economic resources
.Itisimportant