Conformally covariant bi-differential operators for differential forms

Salem Ben Saïd, Jean-Louis Clerc, Khalid Koufany

The classical Rankin-Cohen brackets are bi-differential operators from $C^{\infty }(\mathbb{R})\times C^{\infty }(\mathbb{R})$ into $C^{\infty }(\mathbb{R})$. They are covariant for the (diag…