Sharp local well-posedness for a fifth-order shallow water wave equation

In this paper we prove that the already-established local well-posedness in the range s>−5/4 of the Cauchy problem with an initial Hs(R) data for a fifth-order shallow water wave equation is extendable to s=−5/4 by using the space. This is sharp in the sense that the ill-posedness in the range s<−5/4 of this initial value problem is already known.