Google Earth Engine: Planetary-scale geospatial analysis for everyone

We present YAGO, a light-weight and extensible ontology with high coverage and quality. YAGO builds on entities and relations and currently contains more than 1 million entities and 5 million facts. This includes the Is-A hierarchy as well as non-taxonomic relations between entities (such as HASONEPRIZE). The facts have been automatically extracted from Wikipedia and unified with WordNet, using a carefully designed combination of rule-based and heuristic methods described in this paper. The resulting knowledge base is a major step beyond WordNet: in quality by adding knowledge about individuals like persons, organizations, products, etc. with their semantic relationships - and in quantity by increasing the number of facts by more than an order of magnitude. Our empirical evaluation of fact correctness shows an accuracy of about 95%. YAGO is based on a logically clean model, which is decidable, extensible, and compatible with RDFS. Finally, we show how YAGO can be further extended by state-of-the-art information extraction techniques.

/pdf/yago-a-core-of-semantic-knowledge-13k3nmj6l2.pdf

Yago: a core of semantic knowledge

Social Network Analysis

The objective of this paper is to give a comprehensive introduction to applied cryptography with an engineer or computer scientist in mind. The emphasis is on the knowledge needed to create practical systems which supports integrity, confidentiality, or authenticity. Topics covered includes an introduction to the concepts in cryptography, attacks against cryptographic systems, key use and handling, random bit generation, encryption modes, and message authentication codes. Recommendations on algorithms and further reading is given in the end of the paper. This paper should make the reader able to build, understand and evaluate system descriptions and designs based on the cryptographic components described in the paper.

[서평]「Applied Cryptography」

The present report is submitted in response to General Assembly resolution 61/106, by which the Assembly adopted the Convention on the Rights of Persons with Disabilities and the Optional Protocol thereto. As requested by the Assembly, a brief overview of the status of the Convention as at 3 August 2007 is presented. The report also contains a brief description of technical arrangements on staff and facilities made necessary for the effective performance of the functions of the Conference of States Parties and the Committee under the Convention and the Optional Protocol, and a description on the progressive implementation of standards and guidelines for the accessibility of facilities and services of the United Nations system. Recent efforts of the United Nations and agencies to disseminate information on the Convention and the Optional Protocol are also described.

わかりやすい障害者の権利条約 : 知的障害のある人の権利のために = Convention on the rights of persons with disabilities

With the emergence of an infrastructure that enables the geo-positioning of on-line, mobile users, the management of so-called moving objects has emerged as an active area of research. Among the indexing techniques for efficiently answering predictive queries on moving-object positions, the recent Bx-tree is based on the B+-tree and is relatively easy to integrate into an existing DBMS. However, the Bx-tree is sensitive to data skew. This paper proposes a new query processing algorithm for the B^x-tree that fully exploits the available data statistics to reduce the query enlargement that is needed to guarantee perfect recall, thus significantly improving robustness. The new technique is empirically evaluated and compared with four other approaches and with the TPR-tree, a competitor that is based on the R*-tree. The results indicate that the new index is indeed more robust than its predecessor-it significantly reduces the number of I/O operations per query for the workloads considered. In many settings, the TPR-tree is outperformed as well.

/pdf/robust-b-tree-based-indexing-of-moving-objects-2pf7ljqet1.pdf

Robust B+-Tree-Based Indexing of Moving Objects

A conceptual temporal data model that captures the time-dependent semantics of data while permitting multiple data models at the representation level is described. A conceptual notion of a bitemporal relation in which tuples are stamped with sets of two-dimensional chronons in transaction-time/valid-time space is defined. A tuple-timestamped first normal form representation is introduced to show how the conceptual bitemporal data model is related, by means of snapshot equivalence, with representational models. Querying within the two-level framework is discussed. An algebra is defined at the conceptual level and mapped to the sample representational model in such a way that new operators compute equivalent results for different representations of the same conceptual bitemporal relation. >

/pdf/unification-of-temporal-data-models-4fdhy1q220.pdf

Unification of temporal data models

Specification-based data reduction in dimensional data warehouses

An infrastructure is emerging that enables the positioning of populations of on-line, mobile service users. In step with this, research in the management of moving objects has attracted substantial attention. In particular, quite a few proposals now exist for the indexing of moving objects, and more are underway. As a result, there is an increasing need for an independent benchmark for spatio-temporal indexes.

This paper characterizes the spatio-temporal indexing problem and proposes a benchmark for the performance evaluation and comparison of spatio-temporal indexes. Notably, the benchmark takes into account that the available positions of the moving objects are inaccurate, an aspect largely ignored in previous indexing research. The concepts of data and query enlargement are introduced for addressing inaccuracy. As proof of concepts of the benchmark, the paper covers the application of the benchmark to three spatio-temporal indexes—the TPR-, TPR*-, and Bx-trees. Representative experimental results and consequent guidelines for the usage of these indexes are reported.

/pdf/the-cost-benchmark-comparison-and-evaluation-of-spatio-44uz7da9hi.pdf

The COST benchmark—comparison and evaluation of spatio-temporal indexes

With the proliferation of mobile computing, the ability to index efficiently the movements of mobile objects becomes important. Objects are typically seen as moving in two-dimensional (x, y) space, which means that their movements across time may be embedded in the three-dimensional (x, y, t) space. Further, the movements are typically represented as trajectories, sequences of connected line segments. In certain cases, movement is restricted; specifically, in this paper, we aim at exploiting that movements occur in transportation networks to reduce the dimensionality of the data. Briefly, the idea is to reduce movements to occur in one spatial dimension. As a consequence, the movement occurs in two-dimensional (x, t) space. The advantages of considering such lower-dimensional trajectories are that the overall size of the data is reduced and that lower-dimensional data is to be indexed. Since off-the-shelf database management systems typically do not offer higher-dimensional indexing, this reduction in dimensionality allows us to use existing DBMSes to store and index trajectories. Moreover, we argue that, given the right circumstances, indexing these dimensionality-reduced trajectories can be more efficient than using a three-dimensional index. A decisive factor here is the fractal dimension of the network--the lower, the more efficient is the proposed approach. This hypothesis is verified by an experimental study that incorporates trajectories stemming from real and synthetic road networks.

Christian S. Jensen

Papers

Robust B+-Tree-Based Indexing of Moving Objects

Unification of temporal data models

Specification-based data reduction in dimensional data warehouses

The COST benchmark—comparison and evaluation of spatio-temporal indexes

Trajectory Indexing Using Movement Constraints