A BRST charge for non-critical W2,s strings

We present a general argument for the construction of BRST charges of the ‘non-critical’ W2,4, W2,5, W2,6 and W2,8 strings. This evidences the existence of BRST charges for a kind of soft-type algebras which can be constructed from two copies of quantum W2,s algebras, (s = 3,4,5,6,8).