16.3: Boolean search
- Page ID
- 12829
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Most search engines can perform “boolean searches”, which means you can combine the results from multiple search terms using boolean logic. For example:
- The search “java AND programming” might return only pages that contain both search terms: “java” and “programming”.
- “java OR programming” might return pages that contain either term but not necessarily both.
- “java -indonesia” might return pages that contain “java” and do not contain “indonesia”.
- Expressions like these that contain search terms and operators are called “queries”.
When applied to search results, the boolean operators AND, OR, and - correspond to the set operations intersection, union, and difference. For example, suppose
- s1 is the set of pages containing “java”,
- s2 is the set of pages containing “programming”, and
- s3 is the set of pages containing “indonesia”.
In that case:
- The intersection of s1 and s2 is the set of pages containing “java” AND “programming”.
- The union of s1 and s2 is the set of pages containing “java” OR “pro- gramming”.
- The difference of s1 and s2 is the set of pages containing “java” and not “indonesia”.
In the next section you will write a method to implement these operations.