Markov kernel: Difference between revisions

Content deleted Content added
General Markov processes with countable state space: Add \forall i \in X in singleton to arbitrary
Line 19:
More generally take <math>X</math> and <math>Y</math> both countable and <math>\mathcal A = \mathcal P(X),\ \mathcal B = \mathcal P(Y)</math>.
Again a Markov kernel is defined by the probability it assigns to singleton sets for each <math>i \in X</math>
:<math>\kappa(B|i)=\sum_{j \in B}\kappa(\{j\}|i), \quadqquad \forall i \in X, \, \forall B \in \mathcal B</math>,
We define a Markov process by defining a transition probability <math>P(j|i) = K_{ji}</math> where the numbers <math>K_{ji}</math> define a (countable) [[stochastic matrix]] <math>(K_{ji})</math> i.e.
:<math>\begin{align}
:<math>\forall (i,j) \in X\times Y: K_{ji} \ge 0,</math>
:<math>\forall i K_{ji} &\inge X:0, \qquad &\sum_{forall (j,i) \in Y}K_{ji}=1.</math>\times X, \\
\sum_{j \in Y}K_{ji}&=1, \qquad &\forall i \in X.\\
\end{align}
</math>
We then define
:<math> \kappa(\{j\} | i) = K_{ji} = P(j|i), \qquad \forall i \in X, \quad \forall B \in \mathcal B</math>.