Information Technology Reference
In-Depth Information
By this definition, each sensor or effector action
x
either succeeds
orfails. Ifanactionstartsin
t
0
and if it finishes successfully, it
terminates at
t
1
=
t
0
+
t
succ
(
x
)with
t
succ
(
x
) denoting the duration
of the sensor or effector action
x
.If
x
fails, the action is aborted at
t
f
=
t
0
+
t
fail
(
x
)with
t
fail
(
x
) denoting how long
x
has been executed
before finally failing due to a constraint violation. It is important to
remember that an action can only fail by means of influences from
outside, i.e., by violation of some constraint (e.g., some conflict with
an action of another agent).
In general, each sensor or effector action
x
(either successful or
failed) implies state changes:
S
t
(
M
)
×
x
−→
S
t
+
t
(
x
)
(
M
)
(6.10)
The actual nature of this state change, especially in case of failed
actions is defined by the constraints of a model. A possible set of
constraints could define that actions are executed as a whole or not
at all. Another possibility would be to compute the result of a partial
execution of an action
x
if
x
failed.
6.7 Simulation of an agent-based model
The GRAMS reference model requires that a simulation engine adheres
to the given definitions and assures that all events are processed in
accordance with the following definition. No further requirements are
imposed on how to implement event handling.
Definition 23 (Processing an event)
For an agent-based model
M
,anevent
e
occurring at time
t ∈
T
is processed as follows:
If
e
is of category
endogenous, on macro-level
(1), the environment
is either directly altered or the appropriate update functions are
triggered.
If
e
is of category
exogenous, affecting agents
(2), the following
procedure applies:
