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A k-combination of a set S is a k-element subset of S: the elements of a combination are not ordered. Ordering the k-combinations of S in all possible ways produces the k-permutations of S. The number of k-combinations of an n-set, C(n,k), is therefore related to the number of k-permutations of n by: (,) = (,) (,) = _! =!
(3.a) If we want element k to be a fixed point we may choose one of the s(k − 1, j − 1) permutations with k − 1 elements and j − 1 cycles and add element k as a new cycle of length 1. (3.b) If we want element k not to be a fixed point we may choose one of the s(k − 1, j) permutations with k − 1 elements and j cycles and insert ...
In mathematics, and in particular in group theory, a cyclic permutation is a permutation consisting of a single cycle. [1] [2] In some cases, cyclic permutations are referred to as cycles; [3] if a cyclic permutation has k elements, it may be called a k-cycle. Some authors widen this definition to include permutations with fixed points in ...
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 ...
A cycle of length k is a permutation f for which there exists an element x in {1, ..., n} such that x, f(x), f 2 (x), ..., f k (x) = x are the only elements moved by f; it conventionally is required that k ≥ 2 since with k = 1 the element x itself would not be moved either. The permutation h defined by
Arratia (1999) observes that, because the longest increasing subsequence of a random permutation has length (with high probability) approximately 2√n, it follows that a random permutation must have length at least k 2 /4 to have high probability of being a k-superpattern: permutations shorter than this will likely not contain the identity ...
A permutation group is a subgroup of a symmetric group; that is, its elements are permutations of a given set. It is thus a subset of a symmetric group that is closed under composition of permutations, contains the identity permutation, and contains the inverse permutation of each of its elements. [2]
Some authors restrict partial permutations so that either the domain [4] or the range [3] of the bijection is forced to consist of the first k items in the set of n items being permuted, for some k. In the former case, a partial permutation of length k from an n-set is just a sequence of k terms from the n-set without repetition.