In §2 we tabulate for easy
reference probability distributions associated with some functions of random
mappings on large sets (e.g., number of points on cycles, size of the component
containing x) when the number of immediate predecessors of each point is required to
lie in some set 𝒟.
Our results allow the number of origins to be restricted, a useful constraint in
some shift register situations. Although limiting the number of immediate
predecessors to {0,1,2} and constraining the number of origins is in some ways a
poor model for random shift registers, we show in §§3 and 4 that most of the
tabulated results fit shift register data quite well.
Derivations of our results are given in §§5 through 9.
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