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forcing (by calling the method) the action of another object, providing it with data
indispensable for this action.
However, the above schemas of cooperation between the objects limit to a large
extent the independence of a given object from other objects. The action of an object
taking the initiative to start communication may be completely blocked when the
object which is to respond positively to the proposal of communication does not
agree to the cooperation and will make access to its data impossible, which means
blocking the realization of the communication process.
Despite these inconveniences, by using the concept of an object and in particular
the ways of access of one object to the data (resources) of the other, it is possible to
realize (in some sense) decomposition of a system into subsystems of cooperating
objects and ensure the operation of the whole system (see [67]) realized with the use
of so-called object-oriented approach.
Further enhancement of independence of partial algorithms is possible due to the
application of the mechanism of observation of the action (behaviour) of one object
by another object. It leads to the introduction of the
agent notion
as well as the local
data considered as the state of an agent, whereas, the global data as the environment of
interaction of agents. The agent observing its surrounding environment must notice
other agents in it. We may, therefore, define the notion of an environment, specifying
it as the global data of other agents and relationships taking place between the agents
under observation and changes appearing in the environment. This image of the envi-
ronment will be referred to as the notion of
surrounding environment
of a given agent.
Consequently, the action of a given agent involves the agent's observation of
its surrounding environment and changes taking place in this environment, caused
by other agents' actions, and building a certain model
m
which represents the sur-
roundings. Using the concept of the agent's action concerning the
m
model of the
surrounding environment we may consider the following scenario of the agent's be-
haviour in a given environment in which other agents and resources exist (Fig.
3.1
):
•
The agent with the use of the observation operation receives the information from
the environment and creates the model (
m
) of this environment. To create this
model we have to take into account a certain level of abstraction, i.e., only certain
features of the surrounding environment, in particular those which are useful for
realising a given of the concrete action of a given agent.
•
On the basis of the analysis of this model, the agent plans actions it is to realize in
its surrounding environment.
•
Through the influence on its surrounding environment the agent realizes these
events, and at the same time changes the state of the environment.
The notion of an autonomous agent (later also referred to as an agent) is the
development of the notion of an object. In this case, an agent keeps a property of
encapsulation, characteristic of objects, however, the mechanism of the activation of
an agent has been extended and the manner of contact with the surrounding environ-
ment has been ordered. Like an object the autonomous agent contains information
about its state which is indispensable for an action, however, it undertakes the initia-
tive to act independently on the basis of observation of the (external) environment.
