A Bayesian treatment of latent directed graph structure for non-iid data is provided where each child datum is sampled with a directed conditional dependence on a single unknown parent datum. The latent graph structure is assumed to lie in the family of directed out-tree graphs which leads to efficient Bayesian inference. The latent likelihood of the data and its gradients are computable in clo...

Abstract. Aggregate R-B-tree (aRB-tree) provides a framework for supporting OLAP operations over spatio-temporal data. Although existing aRB-tree implementations process sptio-temporal aggregate queries pretty efficiently, it is hardly applicable for online processing due to the excessive accesses to the aggregate B-trees of the entries in the R-tree and the overlap in the R-tree. This paper ad...

In this article we present a family of four tree-based access structures for indexing spatio-temporal objects. Our indexing methods support spatio-temporal, as well as purely spatial and purely temporal queries. 111 order to handle sets of extended spatio-teniporal objects we propose to specialize generalized search trees by combining the advantages of the well-known spatial structures R*-tree ...

We consider temporal graphs with discrete time labels and investigate the size and the approximability of minimum temporally connected spanning subgraphs. We present a family of minimally connected temporal graphs with n vertices and Ω(n2) edges, thus resolving an open question of (Kempe, Kleinberg, Kumar, JCSS 64, 2002) about the existence of sparse temporal connectivity certificates. Next, we...

Let V be a finite set of points in the plane. In this paper, we show that the ratio of the lengths of Steiner minimal tree for V and the minimal spanning tree for V can never be less than

We give a short and direct proof of a remarkable identity that arises in the enumeration of labeled trees with respect to their indegree sequence, where all edges are oriented from the vertex with lower label towards the vertex with higher label. This solves a problem posed by Shin and Zeng in a recent article. We also provide a generalization of this identity that translates to a formula for t...

Most Web pages contain temporal information. However, most of previous studies only consider the update time of Web pages rather than fully exploit different temporal features in Web. In this paper, we propose a novel approach to fusing different temporal features in Web pages to build an efficient index structure for temporal-textual Web search. Specially, we focus on update time and content t...