EN
Contents
Introduction............................................................................................................................................................................... 5
0. Explanatory notes, definitions and a lemma................................................................................................................. 5
1. Some fixed point theorems............................................................................................................................................... 7
2. Integrable solutions of a linear functional equation of order 1................................................................................... 15
3. Integrable solutions of a non-linear functional equation of order 1.......................................................................... 28
4. Integrable solutions of systems of functional equations............................................................................................ 40
5. Integrable solutions of equations of higher orders...................................................................................................... 46
6. The case of general measures........................................................................................................................................ 53
References............................................................................................................................................................................... 63