Information Technology Reference
In-Depth Information
p
=
< ⊥,F
p
,P
p
>
p
=
<a,F
p
,P
p
>
3.
action:
emit
(
s,f,p
)
condit:
state
(
s
)
,position
(
p
)
effect:
added
(
f,p
)
where
state
(
s
) and
position
(
p
) are verified when the agent state and position
are
s
and
p
. The effect of a emit action (i.e.
added
(
f,p
)) is a change at each
site of the space according to
Diffusion
f
. In particular the set of fields in
p
where the emitting agent is situated changes to
p
=
<a,F
p
f,P
p
>
where the operator
F f
simply adds a field
f
to a field set
F
if the field does
not already belong to the set. Otherwise it composes the already present field
value(s) and the new one. Let
w
ol
f
and
w
new
f
be their names,
F f
=
F ∪f
and
w
f
=
w
ne
f
when
f ∈ F
(before the execution of the emit action) and
w
f
=
Compose
(
w
ol
f
,w
ne
f
)if
f ∈ F
.
4.
action:
reaction
(
s,a
p
1
,a
p
2
,...,a
p
n
,s
)
condit:
state
(
s
)
,agreed
(
a
p
1
,a
p
2
,...,a
p
n
)
effect:
state
(
s
)
where
state
(
s
) and
agreed
(
a
p
1
,a
p
2
,...,a
p
n
) are verified when the agent state
is
s
and agents situated in sites
{p
1
,p
2
,...,p
n
}⊂P
p
have previously agreed
to undertake a synchronous reaction. The effect of a reaction is the syn-
chronous change in state of the involved agents; in particular, agent
a
changes
its state to
s
.
3 Adding Features to the Basic MMASS Model
The basic MMASS model presented above has been extended to incorporate
relevant features of the target systems. Typically, the application of the MMASS
model to specific problems and domains required introducing the possibility to
dynamically modify both the spatial structure of environment and the number
of agents constituting each MASS. To this aim agent types can be characterized
by the following additional actions:
-
AddSite(p)
: the agent adds a site p to its neighborhood, i.e., the set of sites
adjacent to the site in which it is situated. Since agents have only a local
visibility of their environment (i.e. they ignore the existence of sites not
adjacent to the one hosting them) this action can be performed only after
that the agent has received from other agents the needed information about
a spatially not adjacent site (typically through a reaction or the perception
of a field).
-
DeleteSite(p)
: the agent deletes a site p from its neighborhood (obviously,
this action can be performed only if the site is not occupied by any agent).
-
Clone(a)
: the agent creates an agent, specifying all its parameters: its type
(only agents of the same type can be created), its initial state (one of the
