A classical result from graph theory is that every graph with chromatic number χ > t contains a subgraph with all degrees at least t, and therefore contains a copy of every t-edge tree. Bohman, Frieze, and Mubayi recently posed this problem for r-uniform hypergraphs. An r-tree is an runiform hypergraph with no pair of edges intersecting in more than one vertex, and no sequence of distinct verti...

Many spatio-temporal access methods, such as the HR-tree, the 3DR-tree, and the MV3R-tree, have been proposed for timestamp and interval queries. However, these access methods have the following problems: the poor performance of the 3DR-tree for timestamp queries, the huge size and the poor performance of the HR-tree for interval queries, and the large size and the high update cost of the MV3R-...

In this paper, we present a clustering-based color indexing scheme for effective amd efficient image retrieval, which is essentially an exploration on the application of clustering technique to image retrieval. In our approach, the color features are clustered automatically using a color clustering algorithm twice (called two-level clustering processing) and two color feature summarizations are...

We prove an acylindrical accessibility theorem for finitely generated groups acting on R-trees. Namely, we show that if G is a freely indecomposable non-cyclic k-generated group acting minimally and D-acylindrically on an R-tree X then there is a finite subtree Tε ⊆ X of measure at most 2D(k − 1) + ε such that GTε = X. This generalizes theorems of Z. Sela and T. Delzant about actions on simplic...

Article history: Received 12 March 2015 Accepted 28 June 2015 Available online 22 July 2015

In this paper we address the problem of indexing spatial data, in particular two dimensional rectangles. We propose an approach which uses two B +-trees, each of them indexing the projected sides of the given rectangles. The approach, which we name 2dMAP21, can also be easily parallelized. We focus on queries of the type \\nd all rectangles included within another (reference) rectangle". We com...

Deep convolutional neural networks (CNNs) have had a major impact in most areas of image understanding, including object category detection. In object detection, methods such as R-CNN have obtained excellent results by integrating CNNs with region proposal generation algorithms such as selective search. In this paper, we investigate the role of proposal generation in CNN-based detectors in orde...

The development of a spatiotemporal access method suitable for objects moving on fixed networks is a very attractive challenge due to the great number of real-world spatiotemporal database applications and fleet management systems dealing with this type of objects. In this work, a new indexing technique, named Fixed Network R-Tree (FNR-Tree), is proposed for objects constrained to move on fixed...

We prove an acylindrical accessibility theorem for finitely generated groups acting on R-trees. Namely, we show that if G is a freely indecomposable non-cyclic k-generated group acting minimally and M-acylindrically on an R-tree X then for any ǫ > 0 there is a finite subtree Yǫ ⊆ X of measure at most 2M (k − 1) + ǫ such that GYǫ = X. This generalizes theorems of Z.Sela and T.Delzant about actio...

Several applications require management of data which is spatially dynamic, e.g., tracking of battle ships or moving cells in a blood sample. The capability of handling the temporal aspect, i.e., the history of such type of data, is also important. This paper presents and evaluates three temporal extensions of the R-tree, the 3D R-tree, the 2+3 R-tree and the HR-tree, which are capable of index...