An original Markov process is described by a square matrix M (nxn) whose entries M i, j verify the following two conditions:
i- All inputs M i,j are real and belong to the closed interval [0,1]
ii-The sum of the entries for all columns (or all rows) is equal to 1.
However, since the Markov era, many attempts to improve M, and hence M-strings, have been suggested by adding one or two more conditions.
We guess the best improvement is to add one or two of the following physical conditions:
*iii- Constant remaining after each time jump dt, i.e.,
B i, i = RO , where RO is an element of [0,1] for all i = 1,2, ... n, which means that the main diagonal consists of constant entries.
For example if RO is equal to 0 , ie the matrix M is a null principal diagonal matrix which corresponds to the assumption of a null residue after each step or temporal jump dt for all the free nodes.
**iv- symmetry condition :
Mi,j=Mj,i for all i,j.
Condition-iv transforms the stochastic transition matrix M into a doubly stochastic transition matrix superior than the original Markov matrix which is just a single stochastic transition matrix.