Polylogarithmic

A polylogarithmic function in n is a polynomial in the logarithm of n,

a_k \log^k(n) %2B \cdots %2B a_1 \log(n) %2B a_0. \,

In computer science, polylogarithmic functions occur as the order of memory used by some algorithms (e.g., "it has polylogarithmic order").

All polylogarithmic functions are

 P_\ell(x) = o(x^\varepsilon)\,

for every exponent ε > 0 (for the meaning of this symbol, see small o notation), that is, a polylogarithmic function grows more slowly than any positive exponent. This observation is the basis for the soft O notation.

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