A Note On the Hadamard Kth Root of a Rational Function
Robert S. Rumely, A. J. van der Poorten · Journal of the Australian Mathematical Society Series A Pure Mathematics and Statistics · 1987
Abstract Suppose the sequence of Taylor coefficients of a rational function f consists of kth powers of elements all belonging to some finitely generated extension field F of Q. Then it is a generalisation of a conjecture of Pisot that there is a rational function with Taylor coefficients term-by-term kth roots of those of f. The authors show that it suffices to prove the conjecture in the case that the field of definition is a number field and prove the conjecture in that case subject to the constraint that f has a dominant pole, that is, that there is a valuation with respect to which f has a unique pole either of maximal or of minimal absolute value.