Hi letLet $I$ be an ideal in $S=K[x_1,...,x_n]$$S=K[x_1,\dots,x_n]$. Can we compute depth $( I \cap K[x_1,...,x_r])$$\operatorname{depth}(I\cap K[x_1,\dots,x_r])$ with $r \leq n$ ?? Is there any relation between depth $I$ and depth $( I \cap K[x_1,...,x_r])$ ?$\operatorname{depth}(I\cap K[x_1,\dots,x_r])$?
And what cacan we tell about depth $(M \cap N)$$\operatorname{depth}(M \cap N)$ when M,N$M,N$ are S $S$- modules modules? Does it have any bounds?