Using Boolean logic operators to logically combine search words or codes is the most commonly used technology in modern information retrieval systems. There are three commonly used Boolean logic operators, namely logical OR, logical AND and logical NOT.
2. Intercept retrieval
Interception retrieval is a very common technology in computer retrieval system. Due to the word formation characteristics of western languages, the singular and plural forms of nouns are often inconsistent in retrieval; English and American spellings of words with the same meaning are inconsistent; Adding prefixes and suffixes with different properties to the stems can lead to many words with similar meanings, and so on. This is using cut-off retrieval.
3. Location retrieval
Location retrieval is also called full-text retrieval and proximity retrieval. The so-called full-text retrieval is to search by using the natural language in the record, and the logical relationship between words is combined with the position operator to limit the relative position between the search words. This is a technical method that does not depend on thesaurus and can directly use free words to search.
4. Limited field retrieval
Field-limited retrieval refers to a retrieval method that limits search terms to one or several fields in database records. In the retrieval system, there are usually two kinds of fields available for retrieval in the database: the basic fields that express the characteristics of literature subject content and the auxiliary fields that express the external characteristics of literature.
5. Weighted retrieval
Weighted retrieval is a quantitative retrieval technology provided by some retrieval systems. Weighted retrieval, like Boolean retrieval and truncated retrieval, is also a basic retrieval method of literature retrieval, but different from them, the focus of weighted retrieval is not to determine whether the retrieval word or string exists in the database and what is the relationship with other retrieval words or strings, but to determine the degree of influence of the retrieval word or string on whether the literature hits after satisfying the retrieval logic.
6. Clustering retrieval
Clustering is to classify unclassified things into the same category without knowing how many categories they should be classified into, and to classify information with similar attributes into the same category according to the different internal attributes of things.