Let R$R$ the polynomial ring in n$n$ variables with complex coefficients and I$I$ an ideal of R$R$. Is it true that if R/I$R/I$ is CM also R/J$R/J$ is CM (where J$J$ is the radical of I$I$)? Is there a relations between a resolution of R/J$R/J$ and one of R/I$R/I$? What if I suppose that proj.dim(R/I)=2$proj.dim(R/I)=2$?