Math 2.0

Probability theory and stochastic processes Markov processes Theorem

Chapman–Kolmogorov equation

Builds on Markov chainTransition matrixLaw of total probabilityMarkov property

Statement

Let (Xn)n≥0(X_n)_{n \ge 0} be a time-homogeneous Markov chain on a countable state space SS. For n≥0n \ge 0, let pij(n)=P(Xm+n=j∣Xm=i)p^{(n)}_{ij} = P(X_{m+n} = j \mid X_m = i) be the nn-step transition probabilities. Then for all m,n≥0m, n \ge 0 and i,j∈Si, j \in S, pij(m+n)=∑k∈Spik(m) pkj(n).p^{(m+n)}_{ij} = \sum_{k \in S} p^{(m)}_{ik} \, p^{(n)}_{kj}. In matrix form, P(m+n)=P(m)P(n)P^{(m+n)} = P^{(m)} P^{(n)}, so P(n)=PnP^{(n)} = P^n for the transition matrix PP.

Remarks

Proof: condition on the state Xm=kX_m = k at the intermediate time, with the law of total probability, and use the Markov property. The equation says that to go from ii to jj in m+nm + n steps, the chain must be at some state kk after mm steps. For a Markov process with transition kernels ps,t(x,dy)p_{s,t}(x, dy), the equation reads ps,u(x,A)=∫ps,t(x,dy) pt,u(y,A)p_{s,u}(x, A) = \int p_{s,t}(x, dy) \, p_{t,u}(y, A) for s≤t≤us \le t \le u.

History

The equation is named after Sydney Chapman and Andrey Kolmogorov.

Reading path

To understand this page from the ground up, read these 60 pages in order. The foundations come first.

  1. Construction of the reals from Cauchy sequences concept
  2. Element definition
  3. Integers object
  4. Ordered field definition
  5. Proposition concept
  6. Random experiment concept
  7. Rational numbers object
  8. Real numbers object
  9. Set definition
  10. Ring of integers statement
  11. Conjunction definition
  12. Disjunction definition
  13. Implication definition
  14. Predicate definition
  15. Empty set object
  16. Family of sets definition
  17. Ordered pair definition
  18. Intersection definition
  19. Union definition
  20. Sample space definition
  21. The rationals form a field statement
  22. Existential quantifier definition
  23. Universal quantifier definition
  24. Disjoint sets definition
  25. Cartesian product definition
  26. Subset definition
  27. Union of a family of sets definition
  28. The rationals form an ordered field statement
  29. Uniqueness quantifier definition
  30. Universal set definition
  31. Binary relation definition
  32. Partition of a set definition
  33. Order on the reals definition
  34. Power set definition
  35. Complement definition
  36. Function definition
  37. Interval definition
  38. Injective function definition
  39. Preimage of a set definition
  40. Sigma-algebra definition
  41. Countable set definition
  42. Event definition
  43. Borel sigma-algebra definition
  44. Probability axioms concept
  45. Probability measure definition
  46. Probability space definition
  47. Conditional probability definition
  48. Random variable definition
  49. Independence of two events definition
  50. Discrete random variable definition
  51. Stochastic process concept
  52. Law of total probability statement
  53. Random variable with a density definition
  54. Conditional independence definition
  55. Expected value definition
  56. Conditional expectation definition
  57. Markov property definition
  58. Markov chain definition
  59. Transition matrix definition
  60. Chapman–Kolmogorov equation statement

Where this leads

2 pages build on this one.

Further reading

  1. Web https://en.wikipedia.org/wiki/Chapman–Kolmogorov_equation, Application to time-dilated Markov chains
About this page
Tag01APZ8GDQH
URIm2://01APZ8GDQH
Aliaseschapman-kolmogorov-equations
Kindstatement, theorem
WritingW1 stated
MSC60J10
StatusThis copy of the site has no build data. Run m2 status 01APZ8GDQH.
UsesMarkov chain, Transition matrix, Law of total probability, Markov property
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