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If cooperating algorithms Al g 1 and Al g 2 are mutually autonomous, then solving
a problem x 0 with these algorithms does not cause any difficulties, as shown earlier.
However, a problem arises when the cooperating, component algorithms are not
autonomous. It results from the fact that the algorithm Al g 1 (properly Al g 2 ) needs
but has no access to the internal (local) data of the algorithm Al g 2 (properly Al g 1 ),
so it is unable to read the value of variables which are essential for the calculation
of its function f 1 (properly f 2 ) and for making the next step (Fig. 2.11 ).
However, there are possibilities of ensuring access of the algorithm Al g 1 (properly
Al g 2 ) to the internal (local) data of the algorithm Al g 2 (properly Al g 1 ). It comes
down to the replacement of algorithms which are mutually non-autonomous with the
algorithms that gain autonomy to some extent, which will be presented further.
Twomethods may be consideredwhich enable access of one algorithm to the inter-
nal (local) data of the other algorithm, that is to say that non-autonomous algorithms
are replaced with autonomous algorithms:
with the use of communication process between the algorithms,
with the use of observation operation of action of one algorithm (behaviour) by
the other algorithm.
These methods are presented in later parts of the monograph.
2.5.2.1 The Application of a Communication
Process Between the Algorithms
The application of a communication process enabling access to the internal data
of an algorithm was the underlying reason for introduction of the term of object
was introduced [180]. This term has been known and used for many years in the
algorithm formation and programming technique and especially in object-oriented
programming [67, 68].
The communication process between the algorithms that was used here enables
access to the internal data of an algorithm.
Let us consider the algorithms Al g 1 and Al g 2 which use the method of commu-
nication (Fig. 2.12 ). The algorithms communicating in this particular way will be
referred to as objects ( Obj 1 = (
).
The process of communication may proceed according to the following scenario:
X 1 ,
f 1 )
and Obj 2 = (
X 2 ,
f 2 )
Let us accept that the component algorithm (object) Obj 1 needs for the calcula-
tion of the function f 1 access to the parameters X 2 , being the internal data of the
algorithm (object) Obj 2 . It constitutes the fundamental difficulty in defining the
next steps changing the state of the object Obj 1 .
In order to receive the necessary data—the object Obj 2 may make its internal
parameters accessible for the calculation of the function f 1 of the object Obj 1
with the use of mechanism referred to as a method . The object Obj 1 starts up the
appropriate method (the method 1 2 ) of the object Obj 2 (Fig. 2.12 a, dashed arrow).
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