## Regular maps – combinatorial objects relating different fields of mathematics.

### Roman Nedela, Slovak Academy of Sciences

Regular maps and hypermaps are cellular decompositions of closed surfaces exhibiting the highest possible number of symmetries. The five Platonic solids present the most familiar examples of regular maps. The great dodecahedron, a 5-valent pentagonal regular map on the surface of genus 5 discovered by Kepler, is probably the first known non-spherical regular map. Modern history of regular maps goes back at least to Klein (1878) who described a regular map of type $(3,7)$ on the orientable surface of genus $3$. In its early times, the study of regular maps was closely connected with group theory as one can see in Burnside's famous monograph , and more recently in Coxeter's and Moser's book (Chapter~8). The present-time interest in regular maps extends to their connection to Dyck's triangle groups, Riemann surfaces, algebraic curves, Galois groups and other areas. Many of these links are nicely surveyed in the recent papers of Jones, and Jones and Singerman.

The presented survey talk is an upgrade version of the talk given at the conference "Mathematics in the New Millenium" held in Seoul, October 2000. The idea is, on one hand side, to show the relationship of (regular) maps and hypermaps to the above mentioned fields of mathematics. On the other hand, we want to stress some ideas and results that are important for understanding of the nature of these interesting mathematical objects.