Created by Knut M. Synstadfrom the Noun Project

Invariant Measure

Definition (Invariant measure)

Let PP be a transition matrix. A non-negative function λ:S[0,)\lambda:S\to[0,\infty) is said to be an invariant measure if λ=λP\lambda=\lambda P

Lemma (Positivity of Invariant Measure)

Let PP be an irreducible transition matrix, and λ\lambda be an invariant measure. If λ0\lambda\not=0 then λi>0, \mboxforiS\lambda_{i}>0, \ \mbox{for }i\in S

Theorem (Uniqueness of the Invariant Measure)

Let PP be an irreducible Markov chain, and λ\lambda be an invariant measure with λk=1\lambda_{k}=1 then

  • λγk\lambda\ge\gamma^{k}
  • If in addition PP is recurrent, then λ=γk\lambda=\gamma^{k}

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