Similar concepts
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| 77 |
is no K 3 list,the field reserved for its pointer could well have been omitted
...The multi list is designed to overcome the difficulties of updating an inverted file
...Cellular multi lists A further modification of the multi list is inspired by the fact that many storage media are divided into pages,which can be retrieved one at a time
...At this point the full power of the notation introduced before comes into play
...Ki,ni,hi,ai 1,...where the hi have beenpicked to ensure that a Ki list does not cross a page boundary
...Ring structures A ring is simply a linear list that closes upon itself
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| 91 |
A description of the use of a sequential file in an on line environment may be found in Negus and Hall [36]...Work on tree structures in IR goes back a long way as illustrated by the early papers by Salton [43]where not only methods of construction are discussed but also techniques of reorganisation
...More recently a special kind of tree,called a trie,has attracted attention
...The use of hashing in document retrieval is dealt with in Higgins and Smith [50]...It has become fashionable to refer to document collections which |
| 71 |
To unify the discussion of file structures we need some further concepts
...1 the K pointers are distinct;2 each non null K pointer in L gives the address of a record within L;3 there is a unique record in L not pointed to by any record containing K;it is called the beginning of the list;and 4 there is a unique record in L containing the null K pointer;it is the end of the list
...Hsiao and Harary state condition 2 slightly differently so that no two K lists have a record in common;this only appears to complicate things
...From our previous example:K 1 list:R 1,R 2,R 5 K 2 list:R 2,R 4 K 4 list:R 1,R 2,R 3 Finally,we need the definition of a directory of a file
...Ki,ni,hi,ai 1,ai 2,...We are now in a position to give a unified treatment of sequential files,inverted files,index sequential files and multi list files
...Sequential files A sequential file is the most primitive of all file structures
...The implementation of this file structure requires the use of asorting routine
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