Let A be a C∗-algebra
filtered by an increasing sequence of closed ideals {An} with ∪nAn= A. Then there
is a spectral sequence which converges to K∗(A) and has Ep,∗1= K∗(Ap∕Ap−1).
More generally, such spectral sequences obtain for the Brown-Douglas-Fillmore
functors ℰxt∗(A), the Pimsner-Popa-Voiculescu functors ℰxt∗(Y ;A), the Kasparov
functors ℰxt∗(A,B), or indeed for any sequence of covariant or contravariant functors
on C∗-algebras which satisfies an exactness axiom.