TY - JOUR ID - Yafaev2017 LB - Yafaev2017 AU - Yafaev, Dmitri R. TI - Hankel and Toeplitz operators: continuous and discrete representations ST - Hankel and Toeplitz operators: continuous and discrete representations JO - Opuscula Math. JA - Opuscula Math. JF - Opuscula Mathematica PY - 2017 VL - 37 IS - 1 SP - 189 EP - 218 DO - http://dx.doi.org/10.7494/OpMath.2017.37.1.189 UR - http://dx.doi.org/10.7494/OpMath.2017.37.1.189 AB - We find a relation guaranteeing that Hankel operators realized in the space of sequences \(\mathcal{l}^2 (\mathbb{Z}_{+})\) and in the space of functions \(L^2 (\mathbb{R}_{+})\) are unitarily equivalent. This allows us to obtain exhaustive spectral results for two classes of unbounded Hankel operators in the space \(\mathcal{l}^2 (\mathbb{Z}_{+})\) generalizing in different directions the classical Hilbert matrix. We also discuss a link between representations of Toeplitz operators in the spaces \(\mathcal{l}^2 (\mathbb{Z}_{+})\) and \(L^2 (\mathbb{R}_{+})\). KW - unbounded Hankel and Toeplitz operators KW - various representations KW - moment problems KW - generalized Hilbert matrices SN - 1232-9274 ER -