Inspired by Speicher's multidimensional free central limit theorem and semicircle families, we prove an in?nite dimensional compound Poisson limit theorem in free probability, and de?ne in?nite dimensional compound free Poisson distributions in a non-commutative probability space. In?nite dimensional free in?nitely divisible distributions are de?ned and characterized in terms of their free cumulants. It is proved that for a sequence of random variables, the following three statements are equivalent:(1) the distribution of the sequence is multidimensional free in?nitely divisible;(2) the sequence is the limit in distribution of a sequence of triangular trays of families of random variables;(3) the sequence has the same distribution as that of {a_1^((i)): i = 1, 2,...}of a multidimensional free L′evy process {{a_1^((i)): i = 1, 2,...} : t≥0}. Under certain technical assumptions, this is the case if and only if the sequence is the limit in distribution of a sequence of sequences of random variables having multidimensional compound free Poisson distributions.
Let BΩp , 1 ≤ p < ∞, be the space of all bounded functions from Lp(R) which can be extended to entire functions of exponential type Ω. The uniform error bounds for truncated Whittaker-Kotelnikov-Shannon series based on local sampling are derived for functions f ∈ BΩp without decay assumption at infinity. Then the optimal bounds of the aliasing error and truncation error of Whittaker-Kotelnikov-Shannon expansion for non-bandlimited functions from Sobolev classes U(Wpr(R)) are determined up to a logarithmic factor.
Let Bp, 1≤p≤∞, be the set of all bounded functions in Lp(R) which can be extended to entire functions of exponential type . The uniform bounds for truncation error of Shannon sampling expansion from local averages are obtained for functions f∈Bp with the decay condition A|f(t)| ≤, t = 0,|tδ|where A and δ are positive constants. Furthermore we also establish similar results for non-bandlimit functions in Besov classes with the same decay condition as above.
