39Bxx
39A | 
39 | 
40 39Bxx | 39A | 39 | 40 |
| 39B05 | General |
| 39B12 | Iteration theory, iterative and composite equations [See also 26A18, 30D05, 37-XX] |
| 39B22 | Equations for real functions [See also 26A51, 26B25] |
| 39B32 | Equations for complex functions [See also 30D05] |
| 39B42 | Matrix and operator equations [See also 47Jxx] |
| 39B52 | Equations for functions with more general domains and/or ranges |
| 39B55 | Orthogonal additivity and other conditional equations |
| 39B62 | Functional inequalities, including subadditivity, convexity, etc. [See also 26A51, 26B25, 26Dxx] |
| 39B72 | Systems of functional equations and inequalities |
| 39B82 | Stability, separation, extension, and related topics [See also 46A22] |
| 39B99 | None of the above, but in this section |