Let I be an ideal of a Noetherian ring R and let S be a multiplicative
ly closed subset of R. We define the n-th (S)-symbolic power of I as S
(I-n) = I-n R(S) boolean AND R. The purpose of this paper is to compar
e the topologies defined by the adic {I-n}(n greater than or equal to
0) and the (S)-symbolic filtration {S(I-n)}(n greater than or equal to
0) using the direct system {Exdt(R)(i)(R/I-n,R)}(n greater than or eq
ual to 0).