Information Technology Reference
In-Depth Information
-
Σ
τ
defines the set of states that agents of type
τ
can assume;
-
Perception
τ
:
Σ
τ
→
[
N
× W
f
1
]
...
[
N
×
W
f
|
F
|
] is a function associating to
each agent state the vector of pairs
,
c
τ
(
s
)
,t
τ
(
s
)
c
τ
(
s
)
,t
τ
(
s
)
c
|F
τ
(
s
)
,t
|F
τ
(
s
)
,...,
where for each
i
(
i
=1
...|F|
),
c
τ
(
s
) and
t
τ
(
s
) express respectively a coe
2
-
cient to be applied to the field value
f
i
and the agent sensibility threshold to
f
i
in the given state
s
. This means that an agent of type
τ
in state
s ∈ Σ
τ
can perceive a field
f
i
only when it is verified
Compare
f
i
(
c
τ
(
s
)
· w
f
i
,t
τ
(
s
))
that is, when the first component of the
i
-th pair of the perception function
(i.e.
c
τ
(
s
)) multiplied for the received field value
w
f
i
is greater than the
second component of the pair (i.e.
t
τ
(
s
)).
-
Actions
τ
denotes the set of actions, described in the following subsection,
that agents of type
τ
can perform.
2.4 Actions
Actions
τ
specifies whether and how agents change their state and/or position,
how they interact with other agents, and how neighboring and at-a-distance
agents can influence them. In general, actions have two possible purposes: they
can be undertaken by an agent in order to modify its state or position (i.e.
intra-agent actions
), or to interact with other agents in both synchronous or
asynchronous ways (i.e.
inter-agent actions
). Specifically,
trigger
and
transport
are the intra-agent actions.
trigger
defines how the perception of a field causes a
change of state in the receiving agent, while
transport
defines how the perception
of a field causes a change of position in the receiving agent.
emit
and
react
are
the inter-agent actions that respectively are asynchronous and at-a-distance
and synchronous and local.
As previously introduced,
asynchronous interaction
among agents takes place
through a field emission-propagation-perception mechanism. An agent emits a
field, that is, it generates a field defining its parameters (i.e. intensity values, dif-
fusion function, and so on), when its state is such that it can be source for it. This
constitutes one side of the asynchronous interaction among agents: that is, the
sending of broadcast messages by an agent. Field values propagate throughout
the space according to the diffusion function of the field. Field diffusion along the
space allows the other agents to perceive it.
Perception
τ
function, characterizing
each agent type, defines the second side of an asynchronous interaction among
agents: that is, the possible reception of broadcast messages conveyed through
a field, if the sensitivity of the agent to the field is such that it can perceive it.
This means that a field can be neglected by an agent of type
τ
if its value at the
site where the agent is situated is less than the sensitivity threshold computed
by the second component of the
Perception
τ
function. This is the very essence
