Counting Derangements, Non Bijective Functions and the Birthday Problem
Cezary Kaliszyk
Formalized Mathematics, Tome 18 (2010), p. 197-200 / Harvested from The Polish Digital Mathematics Library

The article provides counting derangements of finite sets and counting non bijective functions. We provide a recursive formula for the number of derangements of a finite set, together with an explicit formula involving the number e. We count the number of non-one-to-one functions between to finite sets and perform a computation to give explicitely a formalization of the birthday problem. The article is an extension of [10].

Publié le : 2010-01-01
EUDML-ID : urn:eudml:doc:266571
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     author = {Cezary Kaliszyk},
     title = {Counting Derangements, Non Bijective Functions and the Birthday Problem},
     journal = {Formalized Mathematics},
     volume = {18},
     year = {2010},
     pages = {197-200},
     language = {en},
     url = {http://dml.mathdoc.fr/item/bwmeta1.element.doi-10_2478_v10037-010-0023-9}
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Cezary Kaliszyk. Counting Derangements, Non Bijective Functions and the Birthday Problem. Formalized Mathematics, Tome 18 (2010) pp. 197-200. http://gdmltest.u-ga.fr/item/bwmeta1.element.doi-10_2478_v10037-010-0023-9/

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