Carnegie Mellon University
Riffled Independence for Ranked Data

Jonathan Huang and Carlos Ernesto Guestrin
Advances in Neural Information Processing Systems (NIPS 2009) , December, 2009.

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Representing distributions over permutations can be a daunting task due to the fact that the number of permutations of n objects scales factorially in n. One recent way that has been used to reduce storage complexity has been to exploit probabilistic independence, but as we argue, full independence assumptions impose strong sparsity constraints on distributions and are unsuitable for modeling rankings. We identify a novel class of independence structures, called riffled independence, encompassing a more expressive family of distributions while retaining many of the properties necessary for performing efficient inference and reducing sample complexity. In riffled independence, one draws two permutations independently, then performs the riffle shuffle, common in card games, to combine the two permutations to form a single permutation. In ranking, riffled independence corresponds to ranking disjoint sets of objects independently, then interleaving those rankings. We provide a formal introduction and present algorithms for using riffled independence within Fourier-theoretic frameworks which have been explored by a number of recent papers.


Text Reference
Jonathan Huang and Carlos Ernesto Guestrin, "Riffled Independence for Ranked Data," Advances in Neural Information Processing Systems (NIPS 2009) , December, 2009.

BibTeX Reference
   author = "Jonathan Huang and Carlos Ernesto Guestrin",
   title = "Riffled Independence for Ranked Data",
   booktitle = " Advances in Neural Information Processing Systems (NIPS 2009) ",
   month = "December",
   year = "2009",