A stochastic process X is a random variable valued function of time (verifying some additional conditions depending on the precise situation). I.e. at every instant t, X(t) is a random variable having some probability distribution. (t can be real on integer, X(t) can be real or more complicated an object but the essential property is what I wrote above).
In general, the distribution of X(t) can depend on various things, eg can depend on the values the process took on instants st or many other complicated things.
A Markov stochastic process is a very particular stochastic process where the distribution of the random variable X(t) conditioned on the values it took at all times r
An important non-makovian quantity is persistence. Persistence is simply the probability that the fluctuating nonequilibrium field does not change sign upto time t [1]. The problem of persistence in spatially extended nonequilibrium systems has recently generated a lot of interest both theoretically [2, 3, 4, 5] and experimentally [6,7]. In Ising spin systems Single spin persistence provides a natural counterpart to the survival probability in the realm of many-particle systems. In the context of reaction processes, persistence is equivalent to the survival of immobile impurities and therefore does not provide information about collective properties of the bulk [8]. In Ising model, in a zero temperature quench, persistence is simply the probability that a spin has not flipped till time t .
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[8] P. L. Krapivsky and E. Ben-Naim, Phys Rev E, 56, 3788 (1997)