Doklady Mathematics.
Vol. 83.
2011.
P. 131-135
The auxiliary linear problems are presented for all discretization levels of the Hirota-Ohta system. The structure of these linear problems coincides essentially with the structure of Nonlinear Schrödinger hierarchy. The squared eigenfunction constraints are found which relate Hirota-Ohta and Kulish-Sklyanin vectorial NLS hierarchies. © 2010 Elsevier B.V. All rights reserved.