## Subjects

The main purpose of the classification of items in the mathematical literature using the Mathematics Subject Classification scheme is to help users find the items of present or potential interest to them as readily as possible. The MSC is a hierarchical scheme, with three levels of structure. A classification can be two, three or five digits long, depending on how many levels of the classification scheme are used. The first level representing the main mathematical disciplines is labeled by a two digit number, the second representing specific areas is labeled by a letter (or a hyphen), and the third level for specific kind of mathematical object or a well-known problem or research area is labeled by another two digit number.

1. 00-XX General
2. 01-XX History and biography
3. 03-XX Mathematical logic and foundations
4. 05-XX Combinatorics
5. 06-XX Order, lattices, ordered algebraic structures
6. 08-XX General algebraic systems
7. 11-XX Number theory
8. 12-XX Field theory and polynomials
9. 13-XX Commutative algebra
10. 14-XX Algebraic geometry
11. 15-XX Linear and multilinear algebra; matrix theory
12. 16-XX Associative rings and algebras
13. 17-XX Nonassociative rings and algebras
14. 18-XX Category theory; homological algebra
15. 19-XX $K$-theory
16. 20-XX Group theory and generalizations
17. 22-XX Topological groups, Lie groups
18. 26-XX Real functions
19. 28-XX Measure and integration
20. 30-XX Functions of a complex variable
21. 31-XX Potential theory
22. 32-XX Several complex variables and analytic spaces
23. 33-XX Special functions ( deals with the properties of functions as functions)
24. 34-XX Ordinary differential equations
25. 35-XX Partial differential equations
26. 37-XX Dynamical systems and ergodic theory
27. 39-XX Difference and functional equations
28. 40-XX Sequences, series, summability
29. 41-XX Approximations and expansions
30. 42-XX Harmonic analysis on Euclidean spaces
31. 43-XX Abstract harmonic analysis
32. 44-XX Integral transforms, operational calculus
1. 45-XX Integral equations
2. 46-XX Functional analysis
3. 47-XX Operator theory
4. 49-XX Calculus of variations and optimal control; optimization
5. 51-XX Geometry
6. 52-XX Convex and discrete geometry
7. 53-XX Differential geometry
8. 54-XX General topology
9. 55-XX Algebraic topology
10. 57-XX Manifolds and cell complexes
11. 58-XX Global analysis, analysis on manifolds
12. 60-XX Probability theory and stochastic processes
13. 62-XX Statistics
14. 65-XX Numerical analysis
15. 68-XX Computer science
16. 70-XX Mechanics of particles and systems
17. 74-XX Mechanics of deformable solids
18. 76-XX Fluid mechanics
19. 78-XX Optics, electromagnetic theory
20. 80-XX Classical thermodynamics, heat transfer
21. 81-XX Quantum theory
22. 82-XX Statistical mechanics, structure of matter
23. 83-XX Relativity and gravitational theory
24. 85-XX Astronomy and astrophysics
25. 86-XX Geophysics
26. 90-XX Operations research, mathematical programming
27. 91-XX Game theory, economics, social and behavioral sciences
28. 92-XX Biology and other natural sciences
29. 93-XX Systems theory; control
30. 94-XX Information and communication, circuits
31. 97-XX Mathematics education