PLIERS AT TREC8

The use of the PLIERS text retrieval system in TREC8 experiments is described. The tracks entered for are: Ad-Hoc, Filtering (Batch and Routing) and the Web Track (Large only). We describe both retrieval efficiency and effectiveness results for all these tracks. We also describe some preliminary experiments with BM_25 tuning constant variation

Pliers at TREC 2002

We describe our experiments with the .GOV collection in both the topic distillation and named page tasks at the 2002 TREC web track. We report on our indexing speed, retrieval efficiency results and effectiveness results for both tasks

Parallel computing for passage retrieval

In this paper we examine methods for both speeding up passage processing and examining more passages using parallel computers. We vary the number of passages processed in order to examine the effect on retrieval effectiveness and efficiency. The particular algorithm we apply has previously been used to good effect in Okapi experiments at TREC. We describe this algorithm and our mechanism for applying parallel computing to speed up the processing

Pliers and snowball at CLEF 2002

We test the utility of European language stemmers created using the Snowball language [1]. This allows us to experiment with PLIERS in languages other than English. We also report on some BM25 tuning constant experiments conducted in order to find the best settings for our searches

Parallel methods for the update of partitioned inverted files

Purpose – An issue which tends to be ignored in information retrieval is the issue of updating inverted files. This is largely because inverted files were devised to provide fast query service, and much work has been done with the emphasis strongly on queries. In this paper we study the effect of using parallel methods for the update of inverted files in order to reduce costs, by looking at two types of partitioning for inverted files: document identifier and term identifier. Design/methodology/approach – Raw update service and update with query service are studied with these partitioning schemes using an incremental update strategy. We use standard measures used in parallel computing such as speedup to examine the computing results and also the costs of reorganising indexes while servicing transactions. Findings – Empirical results show that for both transaction processing and index reorganisation the document identifier method is superior. However, there is evidence that the term identifier partitioning method could be useful in a concurrent transaction processing context. Practical implications – There is an increasing need to service updates which is now becoming a requirement of inverted files (for dynamic collections such as the Web), demonstrating that a shift in requirements of inverted file maintenance is needed from the past. Originality/value – The paper is of value to database administrators who manage large-scale and dynamic text collections, and who need to use parallel computing to implement their text retrieval services

Distributed Inverted Files and Performance: A Study of Parallelism and Data Distribution Methods in IR

The study investigates the performance of parallel information retrieval (IR) algorithms on different data distribution methods for Inverted files to identify which is the best for the requirements of specific IR tasks. We define a data distribution method as a way of distributing Inverted file data to local disks on a parallel machine. A data distribution method may be on-the-fly (with one copy of the index held), replication (all nodes have all of the index) or partitioning (data for index is split amongst nodes). Partitioning of inverted file data can be done in many ways but we consider only two: by term (Termld) and by document (Dodd). Termld partitioning is a type of partitioning which distributes unique word data to a single partition, while D odd partitioning distributes unique document data to a single partition. We consider the issue of improving the performance of standard IR algorithms on these data distribution methods by looking at sequential job service not concurrent job service, e.g. we consider the issue of sequential query service not concurrent query service. This methodology rules out some distribution methods for some tasks studied. We consider the following main tasks of IR: indexing, search, passage retrieval, inverted file update and query optimisation for routing /filtering. We produce a synthetic performance model for each of these tasks for the purposes of comparison. We have two subsidiary aims; one was to demonstrate portability of our implemented data structures and algorithms on different parallel machines. Secondly, we also study the possibility of increased retrieval effectiveness by examining a larger section of the search space for both passage retrieval and routing/filtering. We consider the implications of concurrency in updates on Inverted files. Our theoretical and empirical results show that in most cases the D odd partitioning method is the best data distribution method apart from routing/filtering where replication was found to be superior

Parallel methods for the generation of partitioned inverted files

Purpose – The generation of inverted indexes is one of the most computationally intensive activities for information retrieval systems: indexing large multi‐gigabyte text databases can take many hours or even days to complete. We examine the generation of partitioned inverted files in order to speed up the process of indexing. Two types of index partitions are investigated: TermId and DocId. Design/methodology/approach – We use standard measures used in parallel computing such as speedup and efficiency to examine the computing results and also the space costs of our trial indexing experiments. Findings – The results from runs on both partitioning methods are compared and contrasted, concluding that DocId is the more efficient method. Practical implications – The practical implications are that the DocId partitioning method would in most circumstances be used for distributing inverted file data in a parallel computer, particularly if indexing speed is the primary consideration. Originality/value – The paper is of value to database administrators who manage large‐scale text collections, and who need to use parallel computing to implement their text retrieval services

PLIERS AT TREC8

Abstract: The use of the PLIERS text retrieval system in TREC8 experiments is described. The tracks entered for are: Ad-Hoc, Filtering (Batch and Routing) and the Web Track (Large only). We describe both retrieval efficiency and effectiveness results for all these tracks. We also describe some preliminary experiments with BM_25 tuning constant variation. 1