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  2. Permutation - Wikipedia

    en.wikipedia.org/wiki/Permutation

    In elementary combinatorics, the k-permutations, or partial permutations, are the ordered arrangements of k distinct elements selected from a set. When k is equal to the size of the set, these are the permutations in the previous sense.

  3. Eulerian number - Wikipedia

    en.wikipedia.org/wiki/Eulerian_number

    The permutations of the multiset {,,,, …,,} which have the property that for each k, all the numbers appearing between the two occurrences of k in the permutation are greater than k are counted by the double factorial number ()!!.

  4. MinHash - Wikipedia

    en.wikipedia.org/wiki/MinHash

    The simplest version of the minhash scheme uses k different hash functions, where k is a fixed integer parameter, and represents each set S by the k values of h min (S) for these k functions. To estimate J(A,B) using this version of the scheme, let y be the number of hash functions for which h min (A) = h min (B), and use y/k as the estimate.

  5. Stirling numbers of the first kind - Wikipedia

    en.wikipedia.org/wiki/Stirling_numbers_of_the...

    These identities may be derived by enumerating permutations directly. For example, a permutation of n elements with n − 3 cycles must have one of the following forms: n − 6 fixed points and three two-cycles; n − 5 fixed points, a three-cycle and a two-cycle, or; n − 4 fixed points and a four-cycle.

  6. Fisher–Yates shuffle - Wikipedia

    en.wikipedia.org/wiki/Fisher–Yates_shuffle

    Suppose the initial iteration swapped the final element with the one at (non-final) position k, and that the subsequent permutation of first n − 1 elements then moved it to position l; we compare the permutation π of all n elements with that remaining permutation σ of the first n − 1 elements.

  7. Heap's algorithm - Wikipedia

    en.wikipedia.org/wiki/Heap's_algorithm

    A map of the 24 permutations and the 23 swaps used in Heap's algorithm permuting the four letters A (amber), B (blue), C (cyan) and D (dark red) Wheel diagram of all permutations of length = generated by Heap's algorithm, where each permutation is color-coded (1=blue, 2=green, 3=yellow, 4=red).

  8. Permutation pattern - Wikipedia

    en.wikipedia.org/wiki/Permutation_pattern

    A k-superpattern is a permutation that contains all permutations of length k. For example, 25314 is a 3-superpattern because it contains all 6 permutations of length 3. It is known that k-superpatterns must have length at least k 2 /e 2, where e ≈ 2.71828 is Euler's number, [33] and that there exist k-superpatterns of length ⌈(k 2 + 1)/2 ...

  9. Hash function - Wikipedia

    en.wikipedia.org/wiki/Hash_function

    4.6 Unique permutation ... The determinism is in the context of the reuse of the function. For example, Python adds the feature that hash ... Z is a function of k ...