Classical hamiltonian reduction on D(2 vertical bar 1;alpha) Chern-Simons gauge theory and large N=4 superconformal symmetry

3d Chern-Simons gauge theory has a strong connection with 2d CFT and link i nvariants in knot theory. We impose some constraints on the D(2\1;a) CS the ory in the similar context of the hamiltonian reduction of 2d superconforma l algebras. There Hilbert states in D(2\1;alpha) CS theory are partly ident ified with characters of the large N=4 SCFT by their transformation propert ies. (C) 1999 Published by Elsevier Science B.V. All rights reserved.