**Serge Lawrencenko** (Lao for short) is a mathematician, a member of the European Mathematical Society. Lawrencenko has published a hundred research papers in discrete mathematics, computer science, geometry and topology, delivered invited lectures at conferences and universities in three continents, in nine countries to date, although he is especially known for his work in mathematical outreach in USA and China. Lawrencenko known in the mathematical world as the author of the irreducible triangulations of the torus and (with co-authors) the Klein bottle as well as the author of the 4-genus of the complete graph (with triangular faces forbidden) and also the Even Map Color Theorem (with co-authors). A polyhedron, многогранник Лавренченко, is named in his honor. His biography has been included in 29th edition of Who is Who in the World 2012.

## Lectures of PDM:

**23.11, hours: 17-18 All combinatorics in one formula, Serge Lawrencenko**

It will be demonstrated that practically all combinatorics can be derived from Pólya’s enumeration theorem.