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State sequence prediction in imprecise hidden Markov models Jasper - PowerPoint PPT Presentation

State sequence prediction in imprecise hidden Markov models Jasper De Bock & Gert de Cooman 27 July 2011 Jasper De Bock & Gert de Cooman Jasper De Bock & Gert de Cooman Research group SYSTeMS Jasper De Bock Gert de Cooman Research


  1. State sequence prediction in imprecise hidden Markov models Jasper De Bock & Gert de Cooman 27 July 2011

  2. Jasper De Bock & Gert de Cooman

  3. Jasper De Bock & Gert de Cooman

  4. Research group SYSTeMS Jasper De Bock Gert de Cooman

  5. Research group SYSTeMS Jasper De Bock Gert de Cooman Filip Hermans Erik Quaeghebeur Keivan Shariatmadar Arthur Van Camp

  6. State sequence prediction in imprecise hidden Markov models

  7. State sequence prediction in imprecise hidden Markov models The imprecise hidden Markov model

  8. Imprecise hidden Markov model A sequence of hidden state variables X 2 X 3 X 1 O 2 O 1 O 3 S 1 (O 1 |X 1 ) S 2 (O 2 |X 2 ) S 3 (O 3 |X 3 ) A sequence of observable variables Jasper De Bock 8

  9. Imprecise hidden Markov model Q 1 (X 1 ) Q 2 (X 2 |X 1 ) Q 2 (X 3 |X 2 ) A sequence of hidden state variables X 2 X 3 X 1 O 2 O 1 O 3 S 1 (O 1 |X 1 ) S 2 (O 2 |X 2 ) S 3 (O 3 |X 3 ) A sequence of observable variables Jasper De Bock 9

  10. Imprecise hidden Markov model Q 1 (X 1 ) Q 2 (X 2 |X 1 ) Q 2 (X 3 |X 2 ) X 2 X 3 X 1 All local models are coherent lower previsions O 2 O 1 O 3 S 1 (O 1 |X 1 ) S 2 (O 2 |X 2 ) S 3 (O 3 |X 3 ) Jasper De Bock 10

  11. Imprecise hidden Markov model Q 1 (X 1 ) Q 2 (X 2 |X 1 ) Q 2 (X 3 |X 2 ) X 2 X 3 X 1 O 2 O 1 O 3 S 1 (O 1 |X 1 ) S 2 (O 2 |X 2 ) S 3 (O 3 |X 3 ) Jasper De Bock 11

  12. State sequence prediction in imprecise hidden Markov models Epistemic Irrelevance

  13. Epistemic irrelevance X 2 X 3 X 1 O 1 O 2 O 3 Conditional on its mother variable , the non-parent non- descendants of any variable in the tree are epistemically irrelevant to this variable and its descendants Jasper De Bock 13

  14. State sequence prediction in imprecise hidden Markov models Recursive construction of a joint model for the imprecise hidden Markov model

  15. Recursive construction of a joint model

  16. Recursive construction of a joint model • Marginal extension • Independent natural extension

  17. Recursive construction of a joint model • Marginal extension • Independent natural extension

  18. State sequence prediction in imprecise hidden Markov models Conditioning the model on the observations

  19. State sequence prediction in imprecise hidden Markov models Conditioning the model on the observations Generalised Bayes rule: An extension of the Bayes rule to imprecise probabilities

  20. State sequence prediction in imprecise hidden Markov models Maximal state sequences

  21. State sequence prediction in We predict the state sequence by calculating a set of optimal sequences imprecise hidden Notion of optimality: maximality Markov models Strict partial ordening: Maximal state sequences: Maximal state sequences

  22. State sequence prediction in We predict the state sequence by calculating a set of optimal sequences imprecise hidden Notion of optimality: maximality Markov models Strict partial ordening: Maximal state sequences: Maximal state sequences

  23. State sequence prediction in imprecise hidden Markov models EstiHMM: an efficient algorithm to determine the maximal state sequences in an imprecise hidden Markov model

  24. State sequence prediction in imprecise hidden Markov models EstiHMM: an efficient algorithm to determine the maximal state sequences in an imprecise hidden Markov model

  25. EstiHMM: an efficient algorithm to determine the maximal sequences

  26. EstiHMM: an efficient algorithm to determine the maximal sequences • Principle of optimality

  27. EstiHMM: an efficient algorithm to determine the maximal sequences • Principle of optimality X 2 X 3 O 3 O 2

  28. EstiHMM: an efficient algorithm to determine the maximal sequences • Principle of optimality X 1 X 2 X 3 O 3 O 1 O 2

  29. EstiHMM: an efficient algorithm to determine the maximal sequences • Principle of optimality • Deriving an alternative Roptimality criterion

  30. EstiHMM: an efficient algorithm to determine the maximal sequences • Principle of optimality • Deriving an alternative Roptimality criterion

  31. EstiHMM: an efficient algorithm to determine the maximal sequences • Principle of optimality • Deriving an alternative Roptimality criterion • A recursive approach

  32. EstiHMM: an efficient algorithm to determine the maximal sequences • Principle of optimality • Deriving an alternative Roptimality criterion • A recursive approach Complexity

  33. EstiHMM: an efficient algorithm to determine the maximal sequences • Principle of optimality • Deriving an alternative Roptimality criterion • A recursive approach Complexity • Theoretical analysis

  34. EstiHMM: an efficient algorithm to determine the maximal sequences • Principle of optimality • Deriving an alternative Roptimality criterion • A recursive approach Complexity • Theoretical analysis • Linear in the number of Rmaximal sequences

  35. EstiHMM: an efficient algorithm to determine the maximal sequences • Principle of optimality • Deriving an alternative Roptimality criterion • A recursive approach Complexity • Theoretical analysis • Linear in the number of Rmaximal sequences • Empirical confirmation

  36. State sequence prediction in imprecise hidden Markov models A first experiment

  37. A first experiment

  38. A first experiment

  39. A first experiment See you at the poster session!

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