  In this paper, we study the global existence of classical solutions to the
three dimensional incompressible viscous magneto-hydrodynamical system without
magnetic diffusion on periodic boxes, i.e., with periodic boundary conditions.
We work in Eulerian coordinate and employ a time-weighted energy estimate to
prove the global existence result, under the assumptions that the initial
magnetic field is close enough to an equilibrium state and the initial data
have some symmetries.
