Column-oriented indexes—such as projection or bitmap indexes—are compressed by run-length encoding to reduce storage and increase speed. Sorting the tables improves compression. On realistic data sets, permuting the columns in the right order before sorting can reduce the number of runs by a factor of two or more. For many cases, we prove that the number of runs in table columns is minimized if...

C-store environment uses a relational database for storing table tuples on the disk by columns. Can it be effectively used as XML database? This paper considers XML data without a schema. A two-level model of C-store based on XML-enabled relational databases is proposed. A measure of the model suitability is the possibility of evaluating effectively XPath queries. The XPath fragment considered ...

We obtain the singular value decomposition of multi-companion matrices. We completely characterise the columns of the matrix U and give a simple formula for obtaining the columns of the other unitary matrix, V , from the columns of U . We also obtain necessary and sufficient conditions for the related matrix polynomial to be hyperbolic.

The cortical column hypothesis is described along with backing evidence. Proposals for the functional properties of columns are reviewed, namely those based on construction of columnar models and networks of columns. An attempt is made to tie this knowledge into that of an existing model of planning, the TELOS model.

The aim of the talk is to introduce some notions about cortical modeling with a focus on cortical columns. In the first part, I introduce cortical columns from a biological point of view and point out why the notion of cortical column is complex. In the second part, I describe Jansen’s model of a single cortical column and discuss its adequacy to biological facts. The third and last part shows ...

Visual deprivation induced by monocular eyelid suture, a laboratory model for congenital cataract, results in shrinkage of ocular dominance columns serving the closed eye. We performed monocular suture in macaques at ages 1, 3, 5, 7, and 12 weeks to define the critical period for plasticity of ocular dominance columns. After a minimum survival of 8 months, complete montages of [3H]proline-label...