  In this paper we propose a dynamic data structure that supports efficient
algorithms for updating and querying singly connected Bayesian networks (causal
trees and polytrees). In the conventional algorithms, new evidence in absorbed
in time O(1) and queries are processed in time O(N), where N is the size of the
network. We propose a practical algorithm which, after a preprocessing phase,
allows us to answer queries in time O(log N) at the expense of O(logn N) time
per evidence absorption. The usefulness of sub-linear processing time manifests
itself in applications requiring (near) real-time response over large
probabilistic databases.
