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  2. Inclusion–exclusion principle - Wikipedia

    en.wikipedia.org/wiki/Inclusion–exclusion...

    In the given example, there are 12 = 2(3!) permutations with property P 1, 6 = 3! permutations with property P 2 and no permutations have properties P 3 or P 4 as there are no restrictions for these two elements. The number of permutations satisfying the restrictions is thus: 4! − (12 + 6 + 0 + 0) + (4) = 24 − 18 + 4 = 10.

  3. Twelvefold way - Wikipedia

    en.wikipedia.org/wiki/Twelvefold_way

    In combinatorics, the twelvefold way is a systematic classification of 12 related enumerative problems concerning two finite sets, which include the classical problems of counting permutations, combinations, multisets, and partitions either of a set or of a number.

  4. Permutation pattern - Wikipedia

    en.wikipedia.org/wiki/Permutation_pattern

    There are several ways in which the notion of "pattern" has been generalized. For example, a vincular pattern is a permutation containing dashes indicating which adjacent pairs of entries need not occur consecutively. For example, the permutation 314265 has two copies of the dashed pattern 2−31−4, given by the entries 3426 and 3425.

  5. Permutation - Wikipedia

    en.wikipedia.org/wiki/Permutation

    Moreover, the positions of the zeroes in the inversion table give the values of left-to-right maxima of the permutation (in the example 6, 8, 9) while the positions of the zeroes in the Lehmer code are the positions of the right-to-left minima (in the example positions the 4, 8, 9 of the values 1, 2, 5); this allows computing the distribution ...

  6. Combinations and permutations - Wikipedia

    en.wikipedia.org/wiki/Combinations_and_permutations

    Combinations and permutations in the mathematical sense are described in several articles. Described together, in-depth: Twelvefold way; Explained separately in a more accessible way: Combination; Permutation; For meanings outside of mathematics, please see both words’ disambiguation pages: Combination (disambiguation) Permutation ...

  7. Lehmer code - Wikipedia

    en.wikipedia.org/wiki/Lehmer_code

    In mathematics and in particular in combinatorics, the Lehmer code is a particular way to encode each possible permutation of a sequence of n numbers. It is an instance of a scheme for numbering permutations and is an example of an inversion table. The Lehmer code is named in reference to D. H. Lehmer, [1] but the code had been known since 1888 ...

  8. Restriction (mathematics) - Wikipedia

    en.wikipedia.org/wiki/Restriction_(mathematics)

    The pasting lemma is a result in topology that relates the continuity of a function with the continuity of its restrictions to subsets. Let X , Y {\displaystyle X,Y} be two closed subsets (or two open subsets) of a topological space A {\displaystyle A} such that A = X ∪ Y , {\displaystyle A=X\cup Y,} and let B {\displaystyle B} also be a ...

  9. List of permutation topics - Wikipedia

    en.wikipedia.org/wiki/List_of_permutation_topics

    Enumerations of specific permutation classes; Factorial. Falling factorial; Permutation matrix. Generalized permutation matrix; Inversion (discrete mathematics) Major index; Ménage problem; Permutation graph; Permutation pattern; Permutation polynomial; Permutohedron; Rencontres numbers; Robinson–Schensted correspondence; Sum of permutations ...