  Boundary effects in the stepwise structure of the Lyapunov spectra and the
corresponding wavelike structure of the Lyapunov vectors are discussed
numerically in quasi-one-dimensional systems consisting of many hard-disks.
Four kinds of boundary conditions constructed by combinations of periodic
boundary conditions and hard-wall boundary conditions are considered, and lead
to different stepwise structures of the Lyapunov spectra in each case. We show
that a spatial wavelike structure with a time-oscillation appears in the
spatial part of the Lyapunov vectors divided by momenta in some steps of the
Lyapunov spectra, while a rather stationary wavelike structure appears in the
purely spatial part of the Lyapunov vectors corresponding to the other steps.
Using these two kinds of wavelike structure we categorize the sequence and the
kinds of steps of the Lyapunov spectra in the four different boundary condition
cases.
