%0 Journal Article %T Irrationality of the Roots of the Yablonskii-Vorob'ev Polynomials and Relations between Them %A Pieter Roffelsen %J Symmetry, Integrability and Geometry : Methods and Applications %D 2010 %I National Academy of Science of Ukraine %X We study the Yablonskii-Vorob'ev polynomials, which are special polynomials used to represent rational solutions of the second Painlev¨¦ equation. Divisibility properties of the coefficients of these polynomials, concerning powers of 4, are obtained and we prove that the nonzero roots of the Yablonskii-Vorob'ev polynomials are irrational. Furthermore, relations between the roots of these polynomials for consecutive degree are found by considering power series expansions of rational solutions of the second Painlev¨¦ equation. %K second Painlev¨¦ equation %K rational solutions %K power series expansion %K irrational roots %K Yablonskii-Vorob'ev polynomials %U http://dx.doi.org/10.3842/SIGMA.2010.095