q-DEFORMED W-ALGEBRA FROM q-FERMION OSCILLATORS AND THE ALGEBRAIC STRUCTURE OF VERTEX OPERATORS IN 2D STRING THEORY

q-deformed fermion oscillators are used to construct q-deformed higher order Virasaro algebra in the Fock space representation. These facilitate the realization of q-deformed W_∞-algebra. The vertex operators (positively dressed) in 2D string theory are interpreted in terms of q-fermionic states.