Similar concepts
<none>
Pages with this concept
| Similarity |
Page |
Snapshot |
| 9 |
Sparck Jones has carried on this work using measures of association between keywords based on their frequency of co occurrence that is,the frequency with which any two keywords occur together in the same document
...The term information structure for want of better words covers specifically a logical organisation of information,such as document representatives,for the purpose of information retrieval
...The organisation of these files is produced by an automatic classification method
...Evaluation of retrieval systems has proved extremely difficult
... |
| 31 |
In practice many of thesauri are constructed manually
...1 words which are deemed to be about the same topic are linked;2 words which are deemed to be about related things are linked
...The first kind of thesaurus connects words which are intersubstitutible,that is,it puts them into equivalence classes
...The second kind of thesaurus uses semantic links between words to,for example,relate them hierarchically
...However,methods have been proposed to construct thesauri automatically
...The basic relationship underlying the automatic construction of keyword classes is as follows:If keyword a and b are substitutible for one another in the sense that we are prepared to accept a document containing one in response to a request containing the other,this will be because they have the same meaning or refer to a common subject or topic
...It is not difficult to see that,based on this principle,a classification of keywords can be automatically constructed,of which the classes are used analogously to those of the manual thesaurus mentioned before
...1 replace each keyword in a document and query representative by the name of the class in which it occurs;2 replace each keyword by all the keywords occurring in theclass to which it belongs
... |
| 140 |
derives from the work of Yu and his collaborators [28,29]...According to Doyle [32]p
...The model in this chapter also connects with two other ideas in earlier research
...or in words,for any document the probability of relevance is inversely proportional the probability with which it will occur on a random basis
... |
| 131 |
When computing I xi,xj for the purpose of constructing an MST we need only to know the rank ordering of the I xi,xj s
...then I xi,xj will be strictly monotone with This is an extremely simple formulation of EMIM and easy to compute
...The problem of what to do with zero entries in one of the cells 1 to 4 is taken care of by letting 0 log 0 0
...Next we discuss the possibility of approximation
...d xi,xj P xi 1,xj 1 P xi 1 P xj 1 to measure the deviation from independence for any two index terms i and j
... |
| 125 |
document x for different settings of a pair of variables xi,xj i
...and similarly for the other three settings of xi and xj i
...This shows how simple the non linear weighting function really is
...Estimation of parameters The use of a weighting function of the kind derived above in actual retrieval requires the estimation of pertinent parameters
...Here I have adopted a labelling scheme for the cells in which [x]means the number of occurrences in the cell labelled x
... |
|
|
