Mathematics Subject Classification (MSC) and related Schemes in the Digital World

The present talk aims to point out problems, tools and techniques about converting discipline-specific classifications, in Mathematics and related sciences & technologies, into the Dewey Decimal Classification (DDC). DDC is widely used all over the world not only for book shelving in libraries, especially in public, school and general academic ones, but also for subject indexing in general online document retrieval tools, such as bibliographic databases, online library catalogs and OPACs, digital libraries, Web search engines. After recalling some general notions on structure, dynamics and interferences of Subject Classifications, we sketch a diachronical synopsis of classifications in Mathematics, Computing and Information Science and Technology, Control, Electronic and Electrical Engineering, and Physics. Then we review the development of DDC in these areas, till the recently proposed revision of section 510 (Mathematics, with the exclusion of Computing and Mathematical Physics) in view of the next (22nd) edition of DDC. In this context we present: 1. a methodology for interconnecting Subject Classifications via lexical correspondences in the textual descriptions of the classification numbers 2. some Web pages which demonstrate hypertextual combined modalities for displaying Subject Classifications 3. methods for developing hypertextual presentations of Subject Classifications from sequential source files. As a further step we propose a concept-oriented methodology for interconnecting Subject Classifications, with the concrete support of a relational analysis of the whole Mathematics Subject Classification, along its evolution since 1959, as available for online searches in the MathSci database. Such analysis provides for four phases: 1. defining the tree-based structure of the classification number space 2. defining the structure of a space of "abstract" (i.e., mobile across the classification numbers) nodes in time, which get identified via (permanence or limited variation of) textual descriptions 3. identifying concepts as sets of nodes 4. performing a full relational analysis of the concepts by means of knowledge representation techniques. We conclude with perspective considerations about how to define a procedure for the determination of DDC codes for documents in our areas of interest, through the conversion of the Subject Classification codes listed in discipline-specific bibliographic databases.