The basic set of operations for the relational model is known as the relational algebra. These operations enable a user to specify basic retrieval requests.
The result of a retrieval is a new relation, which may have been formed from one or more relations. The algebra operations thus produce new relations, which can be further manipulated using operations of the same algebra.
Chapter 6 "The relational algebra and relational calculus" present contents: The relational algebra, unary relational operations, relational algebra operations from set theory, binary relational operations,...
This chapter introduce Relational algebra . After completing this chapter, students will be able to: relational operations unary , relational algebra operations from set theory, binary relational operations, additional relational operations , brief introduction to relational calculus.
File-System Structure File-System Implementation Directory Implementation Allocation Methods Free-Space Management Efficiency and Performance Recovery Log-Structured File Systems NFS Example: WAFL File System
To describe the details of implementing local file systems and directory structures To describe the implementation of remote file systems To discuss block allocation and free-block algorithms and trade-offs
File structure Logical storage unit Collection of related information File system resides on secondary storage (disks) File system organized into...
SQL is full of difficulties and traps for the unwary. You can avoid them if you understand relational theory, but only if you know how to put the theory into practice. In this insightful book, author C.J. Date explains relational theory in depth, and demonstrates through numerous examples and exercises how you can apply it directly to your use of SQL.
This second edition includes new material on recursive queries, “missing information” without nulls, new update operators, and topics such as aggregate operators, grouping and ungrouping, and view updating.
This operation manual and the labels on the products are indicated with the symbols below for proper use and to avoid injuries or property damage. Read this manual and the related documents thoroughly before installation, operation, maintenance and inspection.
The relational Model of Data is based on the concept of a Relation.
A Relation is a mathematical concept based on the ideas of sets.
The strength of the relational approach to data management comes from the formal foundation provided by the theory of relations.
We review the essentials of the relational approach in this chapter.
We propose an unsupervised, iterative method for detecting downward-entailing operators (DEOs), which are important for deducing entailment relations between sentences. Like the distillation algorithm of Danescu-Niculescu-Mizil et al. (2009), the initialization of our method depends on the correlation between DEOs and negative polarity items (NPIs). However, our method trusts the initialization more and aggressively separates likely DEOs from spurious distractors and other words, unlike distillation, which we show to be equivalent to one iteration of EM prior re-estimation.
Lean production is based on the logic that nothing will be produced until it is needed. Need is created by an actual demand for the product. When an item is sold, in theory, the market pulls a replacement from the last position in the system or final assembly. This triggers an order to the production line which generates orders at upstream work stations. Lean demands high levels o quality at each stage of the process, strong vendor relations, and a fairly predictable demand for the end product.
Tuyển tập các báo cáo nghiên cứu khoa học ngành toán học tạp chí Journal of Operator Theory đề tài: Trên một số vấn đề tiếp tục liên quan chặt chẽ với lý thuyết của các nhà khai thác trong không gian $ \ Pi_ \ chi $. IV...
Recently manuals of industrial products become large and often consist of separated volumes. In reading such individual but related manuals, we must consider the relation among segments, which contain explanations of sequences of operation. In this paper, we propose methods for linking relevant segments in hypertext authoring of a set of related manuals. Our method is based on the similarity calculation between two segments. Our experimental results show that the proposed method improves both recall and precision comparing with the conventional t f . idf based method. ...
This paper describes a heuristic-based approach t o word-sense disambiguation. The heuristics that are applied to disambiguate a word depend on its part of speech, and on its relationship to neighboring salient words in the text. Parts of speech are found through a tagger, and related neighboring words are identified by a phrase extractor operating on the tagged text. To suggest possible senses, each heuristic draws on semantic relations extracted from a Webster's dictionary and the semantic thesaurus WordNet.
A project of machine Czech computer manuals described, description of the presenting translation into Russian first overall and a of is a system mainly parsing parser in cooperation with Mathematical Mathematics University,
Department Physics, Charles structure and c o n c e n t r a t i n g then on input text preparation algorithm programmed based on bottom-up Input texts in olmerauer's Q-systems. The texts our system should translate are software manuals DOS-4 operating to V~MS-developed which is an DOS. on system the and advanced extension to common maintained. ...
In this chapter you will learn: To introduce the notion of a thread a fundamental unit of CPU utilization that forms the basis of multithreaded computer systems; to discuss the APIs for the Pthreads, Windows, and Java thread libraries; to explore several strategies that provide implicit threading; to examine issues related to multithreaded programming; to cover operating system support for threads in Windows and Linux.