Generating Random Derangements
نویسندگان
چکیده
منابع مشابه
An Analysis of a Simple Algorithm for Random Derangements
We consider the uniform generation of random derangements, i.e., permutations without any fixed point. By using a rejection algorithm, we improve the straight-forward method of generating a random permutation until a derangement is obtained. This and our procedure are both linear with respect to the number of calls to the random generator, but we obtain an improvement of more than 36%. By using...
متن کاملA New Decomposition of Derangements
We give a new decomposition of derangements, which gives a direct interpretation of a formula for their generating function. This decomposition also works for counting derangements by number of excedances.
متن کاملDerangements with Ascending and Descending Blocks
We continue the work of Eriksen, Freij, and Wästlund [3], who study derangements that descend in blocks of prescribed lengths. We generalize their work to derangements that ascend in some blocks and descend in others. In particular, we obtain a generating function for the derangements that ascend in blocks of prescribed lengths, thus solving a problem posed in [3]. We also work towards a combin...
متن کاملSome Recursion Formulae for the Number of Derangements and Bell Numbers
In this paper, a further investigation for the number of Derangements and Bell numbers is performed, and some new recursion formulae for the number of Derangements and Bell numbers are established by applying the generating function methods and Padé approximation techniques. Illustrative special cases of the main results are also presented.
متن کاملAsymptotic probability distributions of some permutation statistics
We present in this work results on some distributions of permutation statistics of random elements of the wreath product Gr,n = Cr ! Sn. We consider the distribution of the descent number, the flag major index, the excedance, and the number of fixed points, over the whole group Gr,n or over the subclasses of derangements and involutions. We compute the mean, variance and moment generating funct...
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تاریخ انتشار 2008