In order to make full use of the books in the library, it is necessary for the library to reveal the contents of each book in its collection to readers.
Although there are various retrieval methods in the world at present, there are only two in the final analysis: book classification and subject method.
1. Book Classification and Subject Method
Book classification is a method to systematically reveal and organize books and materials according to the subject (knowledge) attribute of book content. Through the relationship between categories, it makes categories expand step by step according to the logical relationship of subject content, from general to concrete, from low to advanced, from simple to complex, which is a hierarchical classification. It uses numbers, letters or a mixture of numbers and letters as identification symbols, which represent all levels of categories and fix the order of all levels of categories. Take the basic category as the basic vocabulary. A retrieval language that expresses complex concepts through the relationship between categories. Chinese Library Book Classification is an embodiment of classification language. Subject method is a method to reveal and sort out books and materials according to their subject names. Through the basic relationship between words, the independent and scattered subject words are organically linked, which indirectly reflects the logical relationship of the subject system. It adopts noun terms in natural language. As a character recognition system to describe and express the content theme of books and materials. This method, in form, takes standard words as the basis of topic identification and search, and arranges them in the order of title words. In essence, it focuses on specific things, and by quoting the title "network" in the system form, some or all problems related to specific things are gathered.
2. Comparison between book classification and subject method
Classification and subject method are two retrieval methods widely used in library and information units, and their starting points are the same, both of which are based on the theme of documents. The category of classification and the title of topic method can be said to be a topic in a sense. Classification and thematic methods have both the same * * * and different characteristics. From the same nature, firstly, they are all used to reveal and retrieve all kinds of books and materials, and secondly, they are all a means used by library and information units to organize and sort out books and materials retrieval tools to reveal, publicize and circulate books and materials to readers. Judging from the distinguishing features of classification and topic method, it is mainly manifested in:
2. The architecture of1is different.
Logical sequential classification system is the main body of classification system. This architecture is to fully reveal the relationship between things, and facilitate readers to carry out systematic (ethnic) retrieval from disciplines. Word order system is the main body of topic method architecture, which is to meet the needs of specific (characteristic) retrieval of things.
2.2 reveal things from different angles
The subject law focuses on specific things, specific problems and objects. It does not care about the division of disciplines or the logical relationship between disciplines, but only discusses and studies specific things and other aspects. The classification law focuses on the subject nature of things and reveals what subject category things belong to, which is convenient for research and exploration in reading. For example, the classification method of "fertilizer" is to concentrate the information about fertilizer in the category of "fertilizer", and then divide it layer by layer according to the composition, nature and function of fertilizer. However, in the subject method, the information about various fertilizers is scattered under the names of various fertilizers, and there are only general works about fertilizers under the title of fertilizers. Therefore, it can be said that the classification reveals the extension of things, and the subject method reveals the connotation of things.
2.3 The concentration and dispersion of books and materials are different.
Due to the limitation of subject system, classification will inevitably disperse the books and materials of the same thing or subject under different subject categories, and the books and materials of the same subject will be dispersed, but the books and materials of the same subject will be concentrated, while the theme rule is to concentrate the books and materials of the same subject and disperse the books and materials of the same subject.
For example, in classification, books and materials of the same subject nature, such as plankton, plankton, swimming creatures, underwater creatures, etc., are all concentrated under the general category of "Q 179 aquatic creatures", while the theme rule is dispersion. For another example, the subject method concentrates books and materials under the same theme, such as "Chinese herbal medicine pharmacology, Chinese herbal medicine pharmacy and Chinese herbal medicine chemistry", while the classification method disperses them under the categories of medicine and agriculture.
2.4 Different identification symbols
The theme method adopts a direct character recognition system, that is, natural language is used as the recognition symbol of the theme of books and materials. Such as "qinq Baoxue" information science, this identification symbol gives people a clear effect. The classification adopts indirect number recognition system, and artificial language is used as the recognition symbol of books and materials. That is, letters, numbers or mixed numbers are used as the identification symbols of large categories and small categories.
2.5 Different ways to display semantic relations
The semantic relations between categories in taxonomy include subordination, juxtaposition, alternation and correlation. Use the hierarchy between categories to show the subordinate relationship between superiors and subordinates. The coordinate relationship is indicated by the note "should enter X X X" or "X X enter X X X". The Library Classification of China uses "reference" to express relevant relations. The semantic relationship between subject words is expressed by reference system, which mainly includes synonymous relationship, subordinate relationship and association relationship. The semantic relationship of the title method is that "Kan" and "Cong Kan" reflect synonymous relations, while "Kan, Cong Kan" reflects related relations and subordinate relations (the subordinate relations in the title method and the titles of relevant departments are treated in a unified way, and at the same time treated as related references). When it comes to dictionary compilation, its semantic relationship is mainly manifested in the following aspects. There are more detailed reference systems in the alphabetical list, such as (Y), (D), (F), (S), (Z) and (C). "Y" and "D" reflect synonymous relations, "Genus (S), Family (F) and Family (Z)" reflect the relations between genera and families, and "Zhi (C)" reflects the related relations. The semantic relationship of classification is obvious. The main grammar is influenced by the separation of word order, and its semantic relationship is an indirect and implicit semantic system.
2.6 Number matching methods are different.
Subject-based assembly is a combination of words because natural language terms are directly used as the logo of assembly, which is more intuitive and flexible to use, such as "International Internal Combustion Engine Conference", which can be used as an internal combustion engine-international conference.
The simple linear logical order of classification is difficult to reflect the books and materials of marginal disciplines, interdisciplinary disciplines and comprehensive disciplines. In order to meet this need, many modern classification rules have taken powerful measures such as general complex grouping, special complex grouping and main category number grouping to make up for this shortcoming. The combination of classification is limited by the form of numbers and its depth is also limited. The combination level is multi-level, the quantity is extremely long, and it is very complicated, so it is difficult to retrieve books and materials. The international decimal classification number of the International Internal Combustion Engine Conference is:
621.43: 061.3 (100) (main class number of internal combustion engine) (compound semicolon adopted at the meeting) (international compound semicolon)