College of Education School of Information and Communication Studies Department of Information Studies 2018/2019 ACADEMIC YEAR Lecture 4: Information Retrieval Techniques/Model and Strategies LECTURER: DR. DE-GRAFT JOHNSON AMENUVEVE DEI [email protected]0243775571
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Lecture 4: Information Retrieval Techniques/Model and ... · –1) Basic Retrieval Techniques –Boolean Searching –Truncation Search –Proximity search/Operators –2) Advanced
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• A type of operator used by some search engines to improve search constraints by instructing the search to look for words that are within a short distance of each other in a document. – NEAR
– FBY (Followed BY)
– Within
– ADJACENT / ADJ
– Nesting
– NEXT
• Proximity search is as good as AND.
Dr. De-Graft Johnson Dei, Dept of Information Studies Slide 22
Proximity search: NEAR
• For example, using a search engine that supports proximity operators, querying the phrase "cable NEAR modem" will instruct the search engine to look in documents for instances of the words "cable" and "modem" that are near each other.
• NEAR retrieves documents with the search terms appearing within a specified number of words of each other. The exact number of words will vary from one database or search engine to another; in some, you can specify the proximity by a certain number of words.
Dr. De-Graft Johnson Dei, Dept of Information Studies Slide 23
Proximity search: NEAR
• Cancer NEAR horoscope would probably find information about the astrological sign Cancer, but likely not information about the disease. Fur NEAR coat would find fur coat, fur lined leather coat, or coat of mink fur
• Different search engines will specify different distances that the words must be within.
Dr. De-Graft Johnson Dei, Dept of Information Studies Slide 24
Proximity search: ADJACENT /ADJ
• ADJ
• ADJ retrieves documents in which one word directly follows another.
• However, this does not necessarily mean they will appear in the same order in which you typed them.
• Yellow ADJ Gold would find the precious metal, but also the phrase "gold, yellow or bronze highlights."
Dr. De-Graft Johnson Dei, Dept of Information Studies
Slide 25
Range Searching
• It is very useful in numerical searching.
• It is important in selecting records within certain data ranges.
• For example...
– Greater than (˃)
– Less than (˂)
– Equal to (=)
– Not equal to (1=0 or ˂˃)
– Greater than or equal to (˃ =)
– Less than or equal to (˂ =)
Dr. De-Graft Johnson Dei, Dept of Information Studies Slide 26