Information Technology Reference
In-Depth Information
node is the
meet
of these two nodes. In the figure, capital letters denote top-level
budget figures and small letters denote budget figures on the level below that.
5 Operations, Resources, and Object Aspects
Operations, resources and object aspects are domain concepts concerning the
execution of projects. Models of these concepts are prerequisite for modelling
the concept of project plans and defining the
characteristics connection
between
budgets and project plans.
5.1 Intrinsics
The intrinsics of work is a pair of two values. The former value is the type of
operation to be performed (on:On). The latter value is the context in which it is
applied. When executing a construction work like painting a wall, the painting
is a type of operation and the wall is the context. Several works may concern
the same context and in various ways. Hence, it is tempting to model work as a
function from input resources (e.g. including the wall to paint) to output prod-
ucts (e.g. including the painted wall). However, this approach would obstruct
some basic metaphysical/mereological understandings that we shall assume.
One obstruction is as follows. The same wall may be the subject to different
works. Each of these works should then take the wall as an input resource and
produce a modified version of it. This approach indicates that we can make a
distinction between the products at each stage of development — in the extreme,
for every single brush stroke that is or may be performed. However, this requires
as many resource types as there may be stages for products. Ontologically we
then commit to as many concepts as there are objects of these concepts. This
is violates the metaphysical principle of
one-over-many
claiming that concepts
cover classes of objects. The problem in this ontological commitment is in [7]
called
the problem of flux
. This philosophical problem has obstructed many ap-
proaches to apply a part-whole theory explicitly in practice [8].
Another obstruction is as follows. The same object may be involved in different
works, but in different ways. In work descriptions we may have references to
different parts of the object like the
inner
and
outer
side of a wall. If we want
to model e.g. physical resources and their compositions into products explicitly,
we run into the problem of being able to distinguish which parts that physically
overlap and which that do not as this depends on the current context. E.g.,
the hinges of a door may be part of the door in one context, and of the frame
in another as we usually can take off the door. This will provide infinite many
part-whole combinations if explicitly expressed.
What prominent extensional mereological theories aim at covering is, however,
more far reaching than what is often needed in order for sentences indicating
part-whole information to make sense. For this reason, we introduced the notion
of
object aspects
in [7]. The definition is as follows
5
:
5
We only state this definition for completeness. Understanding the philosophical terms
used is not necessary for a comprehension of this paper.
Search WWH ::
Custom Search