This book presents articles of L.V. Kantorovich on the descriptive theory of sets and function and on functional analysis in semi-ordered spaces, to demonstrate the unity of L.V. Kantorovich's creative research. It also includes two papers on the "extension of Hilbert space".
1. On sequences of functions contained in W.H. Young’s classification 2. On universal functions 3. On a problem of H. Steinhaus 4. On sequences of functions, continuous almost everywhere 5. An example of a semicontinuous function universal for continuous functions 6. On generalized derivatives of continuous functions 7. On two classes of operations on closed sets 8. Memoir on analytical operations and projective sets 9. On some theorems concerning the theory of projective sets 10. On certain general methods of the extension of Hilbert space 11. On certain particular methods of the extension of Hilbert space 12. Semi-ordered linear spaces and their application to the theory of linear operators 13. Linear semi-ordered spaces 14. Linear operators in semi-ordered spaces 15. The method of successive approximations for functional equations