Information Technology Reference
In-Depth Information
This definition associates each entity with a specific location within
the environment. Two important aspects should be noted:
1. The embedding imposes no restrictions whether a location may be
occupied by a limited number of entities only.
2. On the macro-level, inner structure and state of entities is not of
interest. The embedding defines the current position of any entity
at any specific point in time, i.e.,
emb
defines the
ground truth
(i.e., undistorted information) as opposed to
perceived truth
(i.e.,
the position assumed by an agent) which may differ [122].
6.5 Events
Events are an integral part of any agent-based model and are also an
essential part of the GRAMS reference model.
Definition 14 (Event)
An
event
e
is defined as an instantaneous
occurrence at a specific point in time
t
e
∈
T
that may change the
state of the model [16, p. 11].
Events are timeless which means that all events are
consumed
in the
same moment they occur. Multiple events may occur at the same
point in time, furthermore all events are distinguishable and can
be associated with specific properties (e.g., type of event, area of
influence).
The events defined by the GRAMS reference model may trigger
actions of agents, which in turn may change the model state. A
specific implementation of a simulation engine may represent such
actions by a start-event and an end-event. Therefore, it is important
to distinguish between the GRAMS reference model (defining events
and actions on the level of the conceptual model) and a technical
realization (executable model). With regard to technical realization,
a specific implementation of a simulation engine may be event-driven.
On the other hand, a simulation engine does not need to be event-
driven and can as well use a time-stepped execution, as long as all
specifications of the GRAMS reference model are fulfilled.
