Linearly degenerate hierarchies of quasiclassical SDYM type

We demonstrate that SDYM (self-dual Yang-Mills) equations for the Lie algebra of one-dimensional vector fields represent a natural reduction in the framework of a general linearly degenerate dispersionless hierarchy. We define the reduction in terms of wave functions and introduce a generating relation, Lax-Sato equations, and the dressing scheme for the reduced hierarchy. A multidimensional case is also discussed.