Article history: Received 28 April 2011 Received in revised form 10 July 2012 Accepted 14 July 2012 Available online 11 September 2012 In this paper, we propose the Hybrid-Layer Index (simply, the HL-index) that is designed to answer top-k queries efficiently when the queries are expressed on any arbitrary subset of attributes in the database. Compared to existing approaches, the HL-index signi...

In this paper, we prove that there does not exist a set with more than 26 polynomials with integer coefficients, such that the product of any two of them plus a linear polynomial is a square of a polynomial with integer coefficients. 1991 Mathematics Subject Classification: 11D09.

How many prime numbers are there? How are they distributed among other numbers? These are questions that have intrigued mathematicians since ancient times. However, many questions in this area have remained unsolved, and seemingly unsolvable in the forseeable future. In this snapshot, we will discuss one such problem, the Twin Prime Conjecture, and a quantitative version of it known as the Hard...

Existing datacube precomputation schemes materialize selected datacube tuples on disk, choosing the most beneficial cuboids (i.e., combinations of dimensions) to materialize given a space limit. However, in the context of a data-warehouse receiving frequent “append” updates to the database, the cost of keeping these disk-resident cuboids up-to-date can be high. In this paper, we propose a main ...

The problem of performing database operations on parallel architectures has received much attention, both as applied and theoretical areas of research. Much of the attention has been focused on performing these operations on distributed-memory architectures, for example, a hyper-cube. Algorithms that perform, in particular, relational database operations on a hypercube typically exploit the hyp...

Among the many dimensionality reduction methods for timeseries data, Symbolic Aggregate approXimation (SAX) is perhaps the most popular due to its simplicity and uniqueness. With SAX, time-series data can be represented as string sequences which enables the utilization of methods found in text mining and bioinformatics to enhance data mining tasks. We propose an application of L-tuples to impro...