Information Technology Reference
In-Depth Information
or from outside the MMASS in the case of open systems. Each field of a MASS is
characterized by the set of values that the field can assume during its propagation
throughout the
Space
. Propagation occurs according to the diffusion function
that characterizes the field and that specifies how its values propagate through-
out the space according to its spatial structure. Moreover, field comparison and
field composition functions are defined in order to allow field manipulation.
A field
f ∈ F
is defined by the 4-tuple
<W
f
,Diffusion
f
,Compare
f
,Compose
f
>
where:
-
W
f
denotes the set of values that the field can assume;
-
Diffusion
f
:
P × W
f
× P →
(
W
f
)
+
is the diffusion function of the field
computing the value of a field on a given site taking into account in which site
and with which value it has been generated. Since the structure of a
Space
is generally not regular and paths of different length can connect each pair
of sites,
Diffusion
f
returns a number of values depending on the number
of paths connecting the source site with each other site. Hence, each site can
receive different values of the same field along different paths.
-
Compose
f
:(
W
f
)
+
→ W
f
expresses how field values have to be combined
(for instance, in order to obtain the unique value of the field at a site).
-
Compare
f
:
W
f
× W
f
→{True,False}
is the function that compares field
values. For instance, in order to verify whether an agent can perceive a
field value the value of a field at a site and agent sensitivity threshold are
compared by this function (see the definition of agent perception in the
following subsection).
2.3 Agents
The
Space
of each MASS is populated by a set
A
of individuals called
agents
.
An agent
a ∈ A
is defined by the 3-tuple
<s,p,τ>
where:
-
s ∈ Σ
τ
denotes the
agent state
and can assume one of the values specified
by its type;
-
p ∈ P
is the site of the
Space
where the agent is situated;
-
τ
is the
agent type
describing the set of states the agent can assume, a
function to express agent sensitivity to fields, and the set of actions that the
agent can perform.
An agent type
τ
is defined by the 3-tuple
<Σ
τ
,Perception
τ
,Action
τ
>
where:
