| Similarity |
Page |
Snapshot |
| 3 |
that in IR we are searching for relevant documents as opposed to exactly matching items
...Many automatic information retrieval systems are experimental
...Many of the techniques I shall discuss will not have proved themselves incontrovertibly superior to all other techniques,but they have promise and their promise will only be realised when they are understood
...My aim throughout has been to give a complete coverage of the more important ideas current in various special areas of information retrieval
... |
| 8 |
The process may involve structuring the information in some appropriate way,such as classifying it
...Finally,we come to the output,which is usually a set of citations or document numbers
...IR in perspective This section is not meant to constitute an attempt at an exhaustive and complete account of the historical development of IR
...Since the emphasis in this book is on a particular approach to document representation,I shall restrict myself here to a few remarks about its history
...At this point,it may be convenient to elaborate on the use of keyword
...The use of statistical information about distributions of words in documents was further exploited by Maron and Kuhns [11]who obtained statistical associations between keywords
... |
| 37 |
influence the choice of [classification]method and the results obtained
...There are two main areas of application of classification methods in IR:1 keyword clustering;2 document clustering
...The first area is very well dealt with in a recent book by Sparck Jones [5]...Good [6]:We define the organisation as the grouping together of items e
...The efficiency of document clustering has been emphasised by |
| 10 |
In the past there has been much debate about the validity of evaluations based on relevance judgments provided by erring human beings
...Effectiveness and efficiency Much of the research and development in information retrieval is aimed at improving the effectiveness and efficiency of retrieval
... |
| 15 |
linguistics in information science
...The chapter therefore starts with the original ideas of Luhn on which much of automatic text analysis has been built,and then goes on to describe a concrete way of generating document representatives
...Luhn s ideas In one of Luhn s [6]early papers he states:It is here proposed that the frequency of word occurrence in an article furnishes a useful measurement of word significance
...I think this quote fairly summaries Luhn s contribution to automatic text analysis
...Let f be the frequency of occurrence of various word types in a given position of text and r their rank order,that is,the order of their frequency of occurrence,then a plot relating f and r yields a curve similar to the hyperbolic curve in Figure 2
... |
| 188 |
In basing a theory of evaluation on the theory of measurement,is it possible to devise a measure of effectiveness not starting with precision and recall but simply with the set of relevant documents and the set of retrieved documents?If so,can we generalise such a measure to take account of degree of relevance?An alternative derivation of an E type measure could be done in terms of recall and fallout
...Up to now the measurement of effectiveness has proved fairly intractable to statistical analysis
...I think the Robertson model described in Chapter 7 goes some way to being considered as a reasonable statistical model
...There may be laws of retrieval such as the well known trade off between precision and recall that are worth establishing either empirically or by theoretical argument
...6
...There is a need for more intensive research into the problems of what to use to represent the content of documents in a computer
...Information retrieval systems,both operational and experimental,have been keyword based
...The major reason for this rather simple minded approach to document retrieval is a very good one
... |
| 186 |
behaviour of any one of the components depends in only an aggregate way on the behaviour of the other components
...2
...On the file structure chosen and the way it is used depends the efficiency of an information retrieval system
...Inverted files have been rather popular in IR systems
...There are many more problems in this area which are of interest to IR systems
...3
...So far fairly simple search strategies have been tried
... |
| 90 |
Finally,let me recommend two very readable discussions on hashing,one is in Page and Wilson [33]...Clustered files It is now common practice to refer to a file processed by a clustering algorithm as a clustered file,and to refer to the resulting structure as a file structure
...Bibliographic remarks There is now a vast literature on file structures although there are very few survey articles
...A general article on data structures of a more philosophical nature well worth reading is Mealey [32]... |
| 32 |
If we think of a simple retrieval strategy as operating by matching on the descriptors,whether they be keyword names or class names,then expanding representatives in either of these ways will have the effect of increasing the number of matches between document and query,and hence tends to improve recall
...Recall is defined in the introduction
...Jones [41]has reported a large number of experiments using automatic keyword classifications and found that in general one obtained a better retrieval performance with the aid of automatic keyword classification than with the unclassified keywords alone
...Unfortunately,even here the evidence has not been conclusive
...The discussion of keyword classifications has by necessity been rather sketchy
...Normalisation It is probably useful at this stage to recapitulate and show how a number of levels of normalisation of text is involved in generating document representatives
...Index term weighting can also be thought of as a process of normalisation,if the weighting scheme takes into account the number of different index terms per document
... |
