Searching the World-Wide Web Using Signature Files

Parallel Computing, 1987

This paper considers the use of text signatures, fixed-length bit string representations of document content, in an experimental information retrieval system: such signatures may be generated from the list of keywords characterisin8 a document or a query. A file of docttments may be searched in a bit-serial parallel computer, such as the ICL Distributed Array Processor, usin8 a two-level retriev~ strategy in which a comparison of a query signature with the file of document sisnatures provides a simple and efficient means of identifyin 8 those few documents that need to undergo a computationally demandin8, character matching search. Text retrieval experiments using three larse collections of documents and queries demonstrate the efficiency" of the suggested approach.

Information Processing Letters, 2002

The signature file method is a popular indexing technique used in information retrieval and databases. It excels in efficient index maintenance and lower space overhead. However, it suffers from inefficiency in query processing due to the fact that for each query processed the entire signature file needs to be scanned. In this paper, we introduce a tree structure, called a signature tree, established over a signature file, which can be used to expedite the signature file scanning by one order of magnitude or more.

Proceedings, International Workshop on Advances in Databases and Information Systems (ADBIS), 1996

A new methodology is introduced, where blocks of text are replaced by a compressed, fully reversible, signature pattern. Full reversibility implies zero information loss, thus the new method is termed Perfect Encoding. The method's analytical model is produced and, where applicable, contrasted with the current practice in signature file organizations. Analysis results indicate that it comprises a potential candidacy for information retrieval implementations. In particular, perfect encoding has the potential to ...

1991

This paper discusses the implementation of nearest-neighbour document retrieval in serial files using transputer networks. The system uses a two-stage retrieval algorithm in which an initial text-signature search is used to exclude large numbers of documents from the detailed and time-consuming pattern-matching search. The latter is implemented using a processor farm, so that documents which match at the signature level can be examined in parallel to determine whether they are, in fact, a good match for the query. The results demonstrate that communication is the critical factor in all of the transputer networks that were investigated. A high degree of speed-up can be obtained when only the pattern-matching search is carried out. When text signatures are used, however, the speed-up is less, decreasing in line with an increase in the size of the text signatures that are used.

2003

This paper presents a new approach for document image decomposition and retrieval based on connected component analysis and geometric properties of the labelled regions. The database contains document images with Arabic/Persian text combined with English text, headlines, ruling lines, trade mark and signature. In particular, Arabic/Persian signature extraction is investigated using special characteristics of the signature that is fairly different from English signatures. A set of efficient, invariant and compact features is extracted for validation purposes using angularradial partitioning of the signature region. Experimental results show the robustness of the proposed method.

Lecture Notes in Computer Science, 1999

In this paper, a new indexing technique to support the query evaluation in document databases is proposed. The key idea of the method is the combination of the technique of pat-trees with signature files. While the signature files are built to expedite the traversal of object hierarchies, the pat-trees are constructed to speed up both the signature file searching and the text scanning. In this way, high performance can be achieved.

1997

With the explosive growth of the Web, one of the biggest challenges in exploiting the wealth of available information is to locate the relevant documents. Search engines play a crucial role in addressing this problem by precompiling a large index of available information to quickly produce a set of possibly relevant documents in response to a query. While most Web users make extensive use of the Internet search engines, few people have more than a vague idea of how these systems work.

Encyclopedia of Database Technologies and Applications, 2005

2005

Signature files and inverted files are well-known index structures. In this paper we undertake a direct comparison of the two for searching for partially-specified queries in a large lexicon stored in main memory. Using n-grams to index lexicon terms, a bit-sliced signature file can be compressed to a smaller size than an inverted file if each n-gram sets only one bit in the term signature.

1994

While the World−Wide Web (WWW, or Web for short) offers an incredibly rich base of information, organized as a hypertext, it does not provide a uniform and efficient way to retrieve specific information, based on user−defined search−criteria. Two types of search tools have been developed for the WWW: Gateways, offering (limited) search operations on small or large parts of the WWW, using a pre−compiled database. These databases are often built by an automated Web scanner (a "robot"). A client−based search tool that does automated navigation, thereby working more or less like a browsing user, but much faster and following an optimized strategy. This paper highlights the properties, implementation and possible future developments of a client−based search tool called the fish−search, and compares it to other approaches. The fish−search, implemented on top of Mosaic for X, offers an open−ended selection of search criteria. It allows the search to start from the "current" document or from the documents in the user's hotlist. The future of client−based searching will depend heavily on assistance from WWW servers. The fish−search algorithm is currently being used to search by navigating through individual WWW documents. Substantial speedup and reduction of network resource consumption will become possible when the same search algorithm is converted to navigate through a Web of servers instead of a Web of documents. In order to implement such a search algorithm, WWW servers need to offer a service similar to that provided by GlimpseHTTP.