Daeyeoul Kim and Yan Li National Institute for Mathematical Sciences, China Agriculture University
Abstract : In this note, we show that ${\mathcal M}(\Gamma_0(N))$ is a weighted polynomial ring if and only if $N=1, 2, 4$, where ${\mathcal M}(\Gamma_0(N))$ is the graded ring of integral-weighted modular forms for the congruence subgroup $\Gamma_0(N)$.
Keywords : modular forms, congruence subgroup, weighted polynomial ring
