mathlib

80a9e4f4 - refactor(data/mv_polynomial/pderivative): make pderivative a linear map (#4095)

refactor(data/mv_polynomial/pderivative): make pderivative a linear map (#4095) Make `pderivative i` a linear map as suggested at https://github.com/leanprover-community/mathlib/pull/4083#issuecomment-689712833