Parabolic smoothing effect and local well-posedness of fifth order semilinear dispersive equations on the torus

We consider the Cauchy problem of fifth order dispersive equations on the torus. We assume that the initial data is sufficiently smooth and the nonlinear term is a polynomial depending on $\partial_x^3 u, \partial_x^2 u, \partial_x u$and$u$\mathrm{.}Weprovethatthelocalwell-posednessholdson$[-T,T]$ when the nonlinear term satisfies a condition and otherwise, the local well-posedness holds with a smoothing effect only on either $[0,T]$ or $[-T,0]$ and nonexistence result holds on the other time interval, which means that the nonlinear term can not be treated as a perturbation of the linear part and the equation has a property of parabolic equations by an influence of the nonlinear term. As a corollary, we also have the same results for $(2j+1)$-st order dispersive equations.