  We calculate the low-frequency magnetoplasmon excitation spectrum for a
square array of quantum dots on a two-dimensional (2D) graphene layer. The
confining potential is linear in the distance from the center of the quantum
dot. The electron eigenstates in a magnetic field and confining potential are
mapped onto a 2D plane of electron-hole pairs in an effective magnetic field
without any confinement. The tight-binding model for the array of quantum dots
leads to a wavefunction with inter-dot mixing of the quantum numbers associated
with an isolated quantum dot. For chosen confinement, magnetic field, wave
vector and frequency, we plot the dispersion equation as a function of the
period $d$ of the lattice. We obtain those values of $d$ which yield collective
plasma excitations. For the allowed transitions between the valence and
conduction bands in our calculations, we obtain plasmons when $d \lesssim 100
{\AA}$.
