Discrete Stochastic Processes and Optimal Filtering

If we remember that
the set of real n-tuples can be fitted to two laws:
making it a vector space of dimension n.
The basis implicitly considered on
will be the canonical base ? 1 = (1,0, ,0), , ? n = (0, ,0,1) and
expressed in this base will be denoted:
Beginning with a basic definition, without concerning ourselves at the moment with its rigor: we can say simply that a real vector
linked to a physical or biological phenomenon is random if the value taken by this vector is unknown and the phenomenon is not completed.
For typographical reasons, the vector will instead be written X T = ( X 1, , X n) or even X = ( X 1, , X n) when there is no risk of confusion.
In other words, given a random vector X and
we do not know if the assertion (also called the event) ( X ? B) is true or false:

However, we do usually know the "chance" that X ? B; this is denoted P( X ? B) and is called the probability of the event ( X ? B).
After completion of the phenomenon, the result (also called the realization) will be denoted
when there is no risk of confusion.
An...