%0 Journal Article %T Riesz bases generated by the spectra of Sturm-Liouville problems %A Tigran Harutyunyan %A Avetik Pahlevanyan %A Anna Srapionyan %J Electronic Journal of Differential Equations %D 2013 %I Texas State University %X Let ${lambda _n^2} _{n = 0}^infty$ be the spectra of a Sturm-Liouville problem on $[0,pi ]$. We investigate the question: Do the systems ${ cos(lambda_nx)} _{n = 0}^infty$ or ${ sin(lambda_n x)} _{n = 0}^infty$ form Riesz bases in ${L^2}[0,pi ]$? The answer is almost always positive. %K Sturm-Liouville problem %K eigenvalues %K Riesz bases %U http://ejde.math.txstate.edu/Volumes/2013/71/abstr.html