## ::Riffle shuffle permutation

### ::concepts

''n''::riffle    Shuffle::''p''    ''q''::shuffles    First::cards    Which::number    Packets::title

In the mathematics of permutations and the study of shuffling playing cards, a riffle shuffle permutation is one of the permutations of a set of n items that can be obtained by a single riffle shuffle, in which a sorted deck of n cards is cut into two packets and then the two packets are interleaved (e.g. by moving cards one at a time from the bottom of one or the other of the packets to the top of the sorted deck).

As a special case of this, a (p,q)-shuffle, for numbers p and q with p + q = n, is a riffle in which the first packet has p cards and the second packet has q cards.<ref name=Weibel>Weibel, Charles (1994). An Introduction to Homological Algebra, p. 181. Cambridge University Press, Cambridge.</ref>

Riffle shuffle permutation sections
Intro  Combinatorial enumeration  Random distribution  Permutation patterns  Perfect shuffles  See also  References

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