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Kbenhavn, Danmark, 2013 Aggregation functions for social decision making Vicen c Torra torsdag den 17. oktober 2013 Institut dInvestigaci o en Intel lig` encia Artificial (IIIA-CSIC), Bellaterra Outline Outline 1. Introduction


  1. Introduction > Definition Outline Definitions Non-additive measures: ( X, A ) a measurable space, a non-additive (fuzzy) measure µ on ( X, A ) is a set function µ : A → [0 , 1] satisfying the following axioms: (i) µ ( ∅ ) = 0 , µ ( X ) = 1 (boundary conditions) (ii) A ⊆ B implies µ ( A ) ≤ µ ( B ) (monotonicity) Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 18 / 58

  2. Introduction > Differences Outline Differences Non-additive measures vs. additive measures: • In additive measures: µ ( A ) = � x ∈ A p x Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 19 / 58

  3. Introduction > Differences Outline Differences Non-additive measures vs. additive measures: • In additive measures: µ ( A ) = � x ∈ A p x • In non-additive measures: additivity no longer a constraint → three cases possible ◦ µ ( A ) = � x ∈ A p x Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 19 / 58

  4. Introduction > Differences Outline Differences Non-additive measures vs. additive measures: • In additive measures: µ ( A ) = � x ∈ A p x • In non-additive measures: additivity no longer a constraint → three cases possible ◦ µ ( A ) = � x ∈ A p x ◦ µ ( A ) < � x ∈ A p x Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 19 / 58

  5. Introduction > Differences Outline Differences Non-additive measures vs. additive measures: • In additive measures: µ ( A ) = � x ∈ A p x • In non-additive measures: additivity no longer a constraint → three cases possible ◦ µ ( A ) = � x ∈ A p x ◦ µ ( A ) < � x ∈ A p x ◦ µ ( A ) > � x ∈ A p x Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 19 / 58

  6. Introduction > Differences Outline Differences Non-additive measures vs. additive measures: • Is non-additivity useful ? Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 20 / 58

  7. Introduction > Differences Outline Differences Non-additive measures vs. additive measures: • Is non-additivity useful ? Yes Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 20 / 58

  8. Introduction > Differences Outline Differences Non-additive measures vs. additive measures: • Is non-additivity useful ? Yes • Why? Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 20 / 58

  9. Introduction > Differences Outline Differences Non-additive measures vs. additive measures: • Is non-additivity useful ? Yes • Why? some cases represent interactions ◦ µ ( A ) = � x ∈ A p x (no interaction) Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 20 / 58

  10. Introduction > Differences Outline Differences Non-additive measures vs. additive measures: • Is non-additivity useful ? Yes • Why? some cases represent interactions ◦ µ ( A ) = � x ∈ A p x (no interaction) ◦ µ ( A ) < � x ∈ A p x (negative interaction) Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 20 / 58

  11. Introduction > Differences Outline Differences Non-additive measures vs. additive measures: • Is non-additivity useful ? Yes • Why? some cases represent interactions ◦ µ ( A ) = � x ∈ A p x (no interaction) ◦ µ ( A ) < � x ∈ A p x (negative interaction) ◦ µ ( A ) > � x ∈ A p x (positive interaction) Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 20 / 58

  12. Introduction > Differences Outline Differences Non-additive measures vs. additive measures: • Is non-additivity useful ? Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 21 / 58

  13. Introduction > Differences Outline Differences Non-additive measures vs. additive measures: • Is non-additivity useful ? Yes Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 21 / 58

  14. Introduction > Differences Outline Differences Non-additive measures vs. additive measures: • Is non-additivity useful ? Yes • In our example: Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 21 / 58

  15. Introduction > Differences Outline Differences Non-additive measures vs. additive measures: • Is non-additivity useful ? Yes • In our example: ◦ µ ( { price } ) , µ ( { quality } ) , µ ( { confort } ) ◦ µ ( { price, quality } ) , µ ( { price, confort } ) , µ ( { quality, confort } ) ◦ µ ( { price, quality, confort } ) Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 21 / 58

  16. Introduction > Number of parameters Outline Number of parameters Non-additive measures vs. additive measures: • How to define an additive measure on X ? Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 22 / 58

  17. Introduction > Number of parameters Outline Number of parameters Non-additive measures vs. additive measures: • How to define an additive measure on X ? One probability value for each element → | X | values Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 22 / 58

  18. Introduction > Number of parameters Outline Number of parameters Non-additive measures vs. additive measures: • How to define an additive measure on X ? One probability value for each element → | X | values • How to define a non-additive measure? Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 22 / 58

  19. Introduction > Number of parameters Outline Number of parameters Non-additive measures vs. additive measures: • How to define an additive measure on X ? One probability value for each element → | X | values • How to define a non-additive measure? One value for each set → 2 | X | values Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 22 / 58

  20. Introduction > What to do? Outline What can we do with a measure? Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 23 / 58

  21. Introduction > What to do? Outline What can we do with a measure? Non-additive measures and additive measures: • Integrate a function f with respect to a measure: Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 23 / 58

  22. Introduction > What to do? Outline What can we do with a measure? Non-additive measures and additive measures: • Integrate a function f with respect to a measure: ◦ Integral w.r.t. additive measure p Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 23 / 58

  23. Introduction > What to do? Outline What can we do with a measure? Non-additive measures and additive measures: • Integrate a function f with respect to a measure: ◦ Integral w.r.t. additive measure p → expectation: � p x f ( x ) � − → Lebesgue integral (continuous case: fdp ) Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 23 / 58

  24. Introduction > What to do? Outline What can we do with a measure? Non-additive measures and additive measures: • Integrate a function f with respect to a measure: ◦ Integral w.r.t. additive measure p → expectation: � p x f ( x ) � − → Lebesgue integral (continuous case: fdp ) ◦ Integral w.r.t. non-additive measure µ → expectation like N � f ( x σ ( i ) )[ µ ( A σ ( i ) ) − µ ( A σ ( i − 1) )] i =1 � − → Choquet integral (continuous case: ( C ) fdµ ) Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 23 / 58

  25. Introduction > What to do? Outline What can we do with a measure? Non-additive measures and additive measures: • Integrate a function f with respect to a measure: ◦ Integral w.r.t. additive measure p → expectation: � p x f ( x ) � − → Lebesgue integral (continuous case: fdp ) ◦ Integral w.r.t. non-additive measure µ → expectation like N � f ( x σ ( i ) )[ µ ( A σ ( i ) ) − µ ( A σ ( i − 1) )] i =1 � − → Choquet integral (continuous case: ( C ) fdµ ) The Choquet integral is a Lebesgue integral when the measure is additive Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 23 / 58

  26. Introduction > What to do? Outline Choquet integrals � Integral: fdµ = (for additive measures) (6.5) � x ∈ X f ( x ) µ ( { x } ) (6.6) � R i =1 b i µ ( { x | f ( x ) = b i } ) (6.7) � N i =1 ( a i − a i − 1 ) µ ( { x | f ( x ) ≥ a i } ) (6.8) � N � � i =1 ( a i − a i − 1 ) 1 − µ ( { x | f ( x ) ≤ a i − 1 } ) (a) (b) (c) b i b i a i b i − 1 b i − 1 a i − 1 x 1 x N x 1 x N x 1 { x | f ( x ) = b i } { x | f ( x ) ≥ a i } x Among (6.5), (6.6) and (6.7), only (6.7) satisfies internality. Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 24 / 58

  27. Introduction > What to do? Outline Choquet integrals Aggregation functions: Choquet integral (CI) • Level curbes for Pareto Optimal solutions Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 25 / 58

  28. Outline Application (a paradox) København, Danmark, 2013 26 / 58

  29. Applications > Decision Making Outline Example Decision making: Ellsberg paradox (Ellsberg, 1961), an urn, 90 balls ... Color of balls Red Black Yellow Number of balls 30 60 f R $ 100 0 0 f B $ 0 $ 100 0 f RY $ 100 0 $ 100 f BY $ 0 $ 100 $ 100 • Usual (most people’s) preferences ◦ f B ≺ f R København, Danmark, 2013 27 / 58

  30. Applications > Decision Making Outline Example Decision making: Ellsberg paradox (Ellsberg, 1961), an urn, 90 balls ... Color of balls Red Black Yellow Number of balls 30 60 f R $ 100 0 0 f B $ 0 $ 100 0 f RY $ 100 0 $ 100 f BY $ 0 $ 100 $ 100 • Usual (most people’s) preferences ◦ f B ≺ f R ◦ f RY ≺ f BY København, Danmark, 2013 27 / 58

  31. Applications > Decision Making Outline Example Decision making: Ellsberg paradox (Ellsberg, 1961), an urn, 90 balls ... Color of balls Red Black Yellow Number of balls 30 60 f R $ 100 0 0 f B $ 0 $ 100 0 f RY $ 100 0 $ 100 f BY $ 0 $ 100 $ 100 • Usual (most people’s) preferences ◦ f B ≺ f R ◦ f RY ≺ f BY • No solution exist with additive measures, but can be solved with non-additive ones København, Danmark, 2013 27 / 58

  32. Outline Distorted Probabilities København, Danmark, 2013 28 / 58

  33. Distorted Probabilities > Introduction Outline Distorted Probabilities: introduction An open question: Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 29 / 58

  34. Distorted Probabilities > Introduction Outline Distorted Probabilities: introduction An open question: Non-additive measures vs. additive measures: How to define a non-additive measure? One value for each set → 2 | X | values Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 29 / 58

  35. Distorted Probabilities > Introduction Outline Distorted Probabilities: introduction An open question: Non-additive measures vs. additive measures: How to define a non-additive measure? One value for each set → 2 | X | values A possible solution: Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 29 / 58

  36. Distorted Probabilities > Introduction Outline Distorted Probabilities: introduction An open question: Non-additive measures vs. additive measures: How to define a non-additive measure? One value for each set → 2 | X | values A possible solution: Distorted Probabilities. • Compact representation of non-additive measures: Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 29 / 58

  37. Distorted Probabilities > Introduction Outline Distorted Probabilities: introduction An open question: Non-additive measures vs. additive measures: How to define a non-additive measure? One value for each set → 2 | X | values A possible solution: Distorted Probabilities. • Compact representation of non-additive measures: ◦ Only | X | values (a probability) and a function (distorting function) Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 29 / 58

  38. Distorted Probabilities > Definition Outline Distorted Probabilities: Definition • Representation of a fuzzy measure: ◦ f and P represent a fuzzy measure µ , iff µ ( A ) = f ( P ( A )) for all A ∈ 2 X f a real-valued function, P a probability measure on ( X, 2 X ) ◦ f is strictly increasing w.r.t. a probability measure P iff P ( A ) < P ( B ) implies f ( P ( A )) < f ( P ( B )) ◦ f is nondecreasing w.r.t. a probability measure P iff P ( A ) < P ( B ) implies f ( P ( A )) ≤ f ( P ( B )) Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 30 / 58

  39. Distorted Probabilities > Definition Outline Distorted Probabilities: Definition • Representation of a fuzzy measure: distorted probability ◦ f and P represent a fuzzy measure µ , iff µ ( A ) = f ( P ( A )) for all A ∈ 2 X f a real-valued function, P a probability measure on ( X, 2 X ) ◦ f is strictly increasing w.r.t. a probability measure P iff P ( A ) < P ( B ) implies f ( P ( A )) < f ( P ( B )) ◦ f is nondecreasing w.r.t. a probability measure P iff P ( A ) < P ( B ) implies f ( P ( A )) ≤ f ( P ( B )) ◦ µ is a distorted probability if µ is represented by a probability distribution P and a function f nondecreasing w.r.t. a probability P . Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 31 / 58

  40. Distorted Probabilities > Definition Outline Distorted Probabilities: Definition • Representation of a fuzzy measure: distorted probability ◦ µ is a distorted probability if µ is represented by a probability distribution P and a function f nondecreasing w.r.t. a probability P . • So, for a given reference set X we need: ◦ Probability distribution on X : p ( x ) for all x ∈ X ◦ Distortion function f on the probability measure: f ( P ( A )) Vicen¸ c Torra; Aggregation functions København, Danmark, 2013 32 / 58

  41. Outline The End København, Danmark, 2013 33 / 58

  42. Outline m-dimensional Distorted Probabilities København, Danmark, 2013 34 / 58

  43. m-Dimensional Distorted Probabilities > Definition Outline m-Dimensional Distorted Probabilities Justification: Why any extension of distorted probabilities? København, Danmark, 2013 35 / 58

  44. m-Dimensional Distorted Probabilities > Definition Outline m-Dimensional Distorted Probabilities Justification: Why any extension of distorted probabilities? • The number of distorted probabilities. København, Danmark, 2013 35 / 58

  45. m-Dimensional Distorted Probabilities > Definition Outline m-Dimensional Distorted Probabilities Justification: Why any extension of distorted probabilities? • The number of distorted probabilities. Observe the following ◦ For X = { 1 , 2 , 3 } , 2/8 of distorted probabilities. ◦ For larger sets X ... ... the proportion of distorted probabilities decreases rapidly ◦ For µ ( { 1 } ) ≤ µ ( { 2 } ) ≤ . . . | X | Number of possible orderings for Number of possible orderings for Distorted Probabilities Fuzzy Measures 1 1 1 2 1 1 3 2 8 4 14 70016 O ( 10 12 ) 5 546 6 215470 – København, Danmark, 2013 35 / 58

  46. m-Dimensional Distorted Probabilities > Definition Outline m-Dimensional Distorted Probabilities Justification: Why any extension of distorted probabilities? The number of distorted probabilities. Goal: • To cover a larger region of the space of fuzzy measures Unconstrained fuzzy measures DP → (similar to the property of k -additive fuzzy measures) DP 1 ,X ⊂ DP 2 ,X ⊂ DP 3 ,X · · · ⊂ DP | X | ,X København, Danmark, 2013 36 / 58

  47. m-Dimensional Distorted Probabilities > Definition Outline m-Dimensional Distorted Probabilities • In distorted probabilities: ◦ One probability distribution ◦ One function f to distort the probabilities • Extension to: ◦ m probability distributions ◦ One function f to distort/combine the probabilities København, Danmark, 2013 37 / 58

  48. m-Dimensional Distorted Probabilities > Definition Outline m-Dimensional Distorted Probabilities • In distorted probabilities: ◦ One probability distribution ◦ One function f to distort the probabilities • Extension to: ◦ m probability distributions P i ⋆ Each P i defined on X i ⋆ Each X i is a partition element of X (a dimension) ◦ One function f to distort/combine the probabilities København, Danmark, 2013 38 / 58

  49. m-Dimensional Distorted Probabilities > Definition Outline m-Dimensional Distorted Probabilities: Example • Running example: ◦ A fuzzy measure that is not a distorted probability: µ ( ∅ ) = 0 µ ( { M, L } ) = 0 . 9 µ ( { M } ) = 0 . 45 µ ( { P, L } ) = 0 . 9 µ ( { P } ) = 0 . 45 µ ( { M, P } ) = 0 . 5 µ ( { L } ) = 0 . 3 µ ( { M, P, L } ) = 1 ◦ Partition on X : ⋆ X 1 = { L } (Literary subjects) ⋆ X 2 = { M, P } (Scientific Subjects) København, Danmark, 2013 39 / 58

  50. m-Dimensional Distorted Probabilities > Definition Outline m-Dimensional Distorted Probabilities: Definition • m -dimensional distorted probabilities. ◦ µ is an at most m dimensional distorted probability if µ ( A ) = f ( P 1 ( A ∩ X 1 ) , P 2 ( A ∩ X 2 ) , · · · , P m ( A ∩ X m )) where, { X 1 , X 2 , · · · , X m } is a partition of X , P i are probabilities on ( X i , 2 X i ) , f is a function on R m strictly increasing with respect to the i -th axis for all i = 1 , 2 , . . . , m . • µ is an m -dimensional distorted probability if it is an at most m dimensional distorted probability but it is not an at most m − 1 dimensional. København, Danmark, 2013 40 / 58

  51. m-Dimensional Distorted Probabilities > Definition Outline m-Dimensional Distorted Probabilities: Example • Running example: a two dimensional distorted probability µ ( A ) = f ( P 1 ( A ∩ { L } ) , P 2 ( A ∩ { M, P } )) ◦ with partition on X = { M, L, P } 1. Literary subject { L } 2. Science subjects { M, P } , ◦ probabilities 1. P 1 ( { L } ) = 1 2. P 2 ( { M } ) = P 2 ( { P } ) = 0 . 5 , ◦ and distortion function f defined by { L } 1 0.3 0.9 1.0 0 ∅ 0 0.45 0.5 sets ∅ { M } , { P } { M,P } ∅ f 0.5 1 København, Danmark, 2013 41 / 58

  52. Outline Distorted Probabilities and Multisets an approach to define (simple) fuzzy measures on multisets København, Danmark, 2013 42 / 58

  53. DP and Multisets > Multisets Outline Distorted Probabilities and Multisets Multisets: elements can appear more than once • Defined in terms of count M : X → { 0 } ∪ N e.g. when X = { a, b, c, d } and M = { a, a, b, b, c, c, c } , count M ( a ) = 2 , count M ( b ) = 3 , count M ( c ) = 3 , count M ( d ) = 0 . • A and B multisets on X , then ◦ A ⊆ B if and only if count A ( x ) ≤ count B ( x ) for all x in X (used to define submultiset). ◦ A ∪ B : count A ∪ B ( x ) = max( count A ( x ) , count B ( x )) for all x in X . ◦ A ∩ B : count A ∩ B ( x ) = min( count A ( x ) , count B ( x )) for all x in X . København, Danmark, 2013 43 / 58

  54. DP and Multisets > Fuzzy Measure Outline Distorted Probabilities and Multisets Fuzzy measure on multiset: X a reference set, M a multiset on X s.t. M � = ∅ ; then, the function µ from ( M, P ( M )) to [0 , 1] is a fuzzy measure if the following holds: • µ ( ∅ ) = 0 and µ ( M ) = 1 • µ ( A ) ≤ µ ( B ) when A ⊆ B and B ⊆ M . København, Danmark, 2013 44 / 58

  55. DP and Multisets > Fuzzy Measure Outline Distorted Probabilities and Multisets Fuzzy measure on multiset: X a reference set, M a multiset on X s.t. M � = ∅ ; then, the function µ from ( M, P ( M )) to [0 , 1] is a fuzzy measure if the following holds: • µ ( ∅ ) = 0 and µ ( M ) = 1 • µ ( A ) ≤ µ ( B ) when A ⊆ B and B ⊆ M . How to define fuzzy measures?: København, Danmark, 2013 44 / 58

  56. DP and Multisets > Fuzzy Measure Outline Distorted Probabilities and Multisets Fuzzy measure on multiset: X a reference set, M a multiset on X s.t. M � = ∅ ; then, the function µ from ( M, P ( M )) to [0 , 1] is a fuzzy measure if the following holds: • µ ( ∅ ) = 0 and µ ( M ) = 1 • µ ( A ) ≤ µ ( B ) when A ⊆ B and B ⊆ M . How to define fuzzy measures?: • Even more parameters � x ∈ X count M ( x ) !! København, Danmark, 2013 44 / 58

  57. DP and Multisets > Fuzzy Measure Outline Distorted Probabilities and Multisets Fuzzy measure on multiset: X a reference set, M a multiset on X s.t. M � = ∅ ; then, the function µ from ( M, P ( M )) to [0 , 1] is a fuzzy measure if the following holds: • µ ( ∅ ) = 0 and µ ( M ) = 1 • µ ( A ) ≤ µ ( B ) when A ⊆ B and B ⊆ M . How to define fuzzy measures?: • Even more parameters � x ∈ X count M ( x ) !! We present two alternative (but related) approaches København, Danmark, 2013 44 / 58

  58. DP and Multisets > Fuzzy Measure Outline Distorted Probabilities and Multisets 1st approach: Definition based on a pseudoadditive integral: Nondecreasing function-based fuzzy measures • X a reference set, M a multiset on X and µ a ⊕ -decomposable fuzzy measure on X . Let f : [0 , ∞ ) → [0 , ∞ ) be a non-decreasing function with f (0) = 0 and f ( m ( M )) = 1 . Then, we define a fuzzy measure ν on P ( M ) by ν f ( A ) = f ( m ( A )) where m is the multiset function m : P ( M ) → [0 , ∞ ) defined by � m ( A ) = ( D ) count A dµ. København, Danmark, 2013 45 / 58

  59. DP and Multisets > Fuzzy Measure Outline Distorted Probabilities and Multisets 1st approach: Definition based on a pseudoadditive integral: Nondecreasing function-based fuzzy measures • X a reference set, M a multiset on X and µ a ⊕ -decomposable fuzzy measure on X . Let f : [0 , ∞ ) → [0 , ∞ ) be a non-decreasing function with f (0) = 0 and f ( m ( M )) = 1 . Then, we define a fuzzy measure ν on P ( M ) by ν f ( A ) = f ( m ( A )) where m is the multiset function m : P ( M ) → [0 , ∞ ) defined by � m ( A ) = ( D ) count A dµ. � • Rationale of the definition: ( C ) χ A dµ = µ ( A ) København, Danmark, 2013 45 / 58

  60. DP and Multisets > Fuzzy Measure Outline Distorted Probabilities and Multisets 1st approach: Definition based on a pseudoadditive integral: Nondecreasing function-based fuzzy measures • X a reference set, M a multiset on X and µ a ⊕ -decomposable fuzzy measure on X . Let f : [0 , ∞ ) → [0 , ∞ ) be a non-decreasing function with f (0) = 0 and f ( m ( M )) = 1 . Then, we define a fuzzy measure ν on P ( M ) by ν f ( A ) = f ( m ( A )) where m is the multiset function m : P ( M ) → [0 , ∞ ) defined by � m ( A ) = ( D ) count A dµ. � • Rationale of the definition: ( C ) χ A dµ = µ ( A ) • Properties: København, Danmark, 2013 45 / 58

  61. DP and Multisets > Fuzzy Measure Outline if A ⊆ B by the monotonicity of the integral m ( A ) ≤ m ( B ) → monotonicity condition of the fuzzy measure fulfilled København, Danmark, 2013 46 / 58

  62. DP and Multisets > Fuzzy Measure Outline Distorted Probabilities and Multisets 2nd approach: Definition based on prime numbers 1 : • Define � φ ( x ) count A ( x ) , n ( A ) := x ∈ X where φ is an injective function from X to the prime numbers, and let h be a non-decreasing function from N to [0 , 1] satisfying h (1) = 0 and h ( n ( M )) = 1 . We define the prime number-based fuzzy measure ν φ,h ( A ) = h ( n ( A )) . 1 and using the unique factorization of integers into prime numbers København, Danmark, 2013 47 / 58

  63. DP and Multisets > Fuzzy Measure Outline Distorted Probabilities and Multisets 2nd approach: Definition based on prime numbers 1 : • Define � φ ( x ) count A ( x ) , n ( A ) := x ∈ X where φ is an injective function from X to the prime numbers, and let h be a non-decreasing function from N to [0 , 1] satisfying h (1) = 0 and h ( n ( M )) = 1 . We define the prime number-based fuzzy measure ν φ,h ( A ) = h ( n ( A )) . Properties: if A � = B by the unique factorization n ( A ) � = n ( B ) if A ⊆ B by the factorization n ( A ) < n ( B ) → monotonicity condition of the fuzzy measure fulfilled 1 and using the unique factorization of integers into prime numbers København, Danmark, 2013 47 / 58

  64. DP and Multisets > Fuzzy Measure Outline Distorted Probabilities and Multisets Properties: • Fuzzy measures based on prime-number are a particular case of the 1st approach København, Danmark, 2013 48 / 58

  65. DP and Multisets > Fuzzy Measure Outline Distorted Probabilities and Multisets Properties: • Fuzzy measures based on prime-number are a particular case of the 1st approach • Neither the 1st nor the 2nd approach represent all possible fuzzy measures København, Danmark, 2013 48 / 58

  66. DP and Multisets > Fuzzy Measure Outline Distorted Probabilities and Multisets Properties: • Fuzzy measures based on prime-number are a particular case of the 1st approach • Neither the 1st nor the 2nd approach represent all possible fuzzy measures • It seems that there is some parallelism between prime-number based fuzzy measures and distorted probabilities ◦ f and the distortion ◦ φ and the probability distribution København, Danmark, 2013 48 / 58

  67. DP and Multisets > Fuzzy Measure Outline Distorted Probabilities and Multisets Properties: • Fuzzy measures based on prime-number are a particular case of the 1st approach • Neither the 1st nor the 2nd approach represent all possible fuzzy measures • It seems that there is some parallelism between prime-number based fuzzy measures and distorted probabilities ◦ f and the distortion ◦ φ and the probability distribution • Can we establish a relationship?? København, Danmark, 2013 48 / 58

  68. DP and Multisets > Fuzzy Measure Outline Results Properties: • ν a fuzzy measure according to Approach 1 on a proper finite set ( M, P ( M )) = ( X, 2 X ) . Then ν is a distorted probability on ( X, 2 X ) . København, Danmark, 2013 49 / 58

  69. DP and Multisets > Fuzzy Measure Outline Results Properties: • ν a fuzzy measure according to Approach 1 on a proper finite set ( M, P ( M )) = ( X, 2 X ) . Then ν is a distorted probability on ( X, 2 X ) . • Same for Approach 2 (primer-number definition) København, Danmark, 2013 49 / 58

  70. DP and Multisets > Fuzzy Measure Outline Results Properties: • ν a fuzzy measure according to Approach 1 on a proper finite set ( M, P ( M )) = ( X, 2 X ) . Then ν is a distorted probability on ( X, 2 X ) . • Same for Approach 2 (primer-number definition) • This is easy to prove (consists on defining the probability distribution) København, Danmark, 2013 49 / 58

  71. DP and Multisets > Fuzzy Measure Outline Results Properties: • ν a fuzzy measure according to Approach 1 on a proper finite set ( M, P ( M )) = ( X, 2 X ) . Then ν is a distorted probability on ( X, 2 X ) . • Same for Approach 2 (primer-number definition) • This is easy to prove (consists on defining the probability distribution) • So, Approach 1 and Approach 2 equal to or more general than distorted probabilities København, Danmark, 2013 49 / 58

  72. DP and Multisets > Fuzzy Measure Outline Results Properties: • Can we prove something else? much more general? almost the same? exactly the same? København, Danmark, 2013 50 / 58

  73. DP and Multisets > Fuzzy Measure Outline Results Properties: • Can we prove something else? much more general? almost the same? exactly the same? Not so surprising theorem: Fuzzy measures based on prime numbers on proper sets are equivalent to distorted probabilities København, Danmark, 2013 50 / 58

  74. DP and Multisets > Fuzzy Measure Outline Results Properties: • Can we prove something else? much more general? almost the same? exactly the same? Not so surprising theorem: Fuzzy measures based on prime numbers on proper sets are equivalent to distorted probabilities → probabilities and prime numbers play the same role → � x ∈ A p x and � x ∈ A φ ( x ) play the same role København, Danmark, 2013 50 / 58

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