S.V.Duzhin Combinatorics Until recently, combinatorics was thought of as an irregular collection of beautiful isolated tricks. The first serious attempt to lay the foundation of combinatorics as a unified science was undertaken by Bergeron, Labelle and Leroux in their book "Combinatorial Species and Tree-like Structures". The book is dedicated to the exposition of combinatorics based on the notion of a combinatorial species introduced by A.Joyal. At first sight, the definition of a combinatorial species looks trivial; however, as the narration of the three authors goes on, you see that meaningful combinatorial constructions and facts appear naturally out of nothing. The present course covers the fundamentals of the theory of combinatorial species as well as a certain related set of beautiful isolated tricks of classical combinatorics. Draft course program 1. Sequences and generating functions o solution of linear recurrence relations o numbers of Fibonacci, Catalan, Bernoulli, Euler o algebra of formal power series o asymptotic of coefficients 2. Introduction to the theory of species o definition, examples o power series associated with a species o operations on species o molecular and atomic species o Lagrange inversion 3. Enumeration o Burnside's lemma o Polya's formula o tree enumeration o plethysm and Schur's functions 4. Partitions o Young diagrams o Euler's pentagonal theorem o Glasher's and Sylvester's correspondences o asymptotics of Hardy--Ramanujan o Robinson--Shensted--Knuth correspondence 5. Partially ordered sets o Moebius algebra o Moebius function o Moebius inversion Literature F.Bergeron, G.Labelle, P.Leroux "Th\'{e}orie des esp\`{e}ces et combinatoire des structures arborescentes", Montr\'{e}al, 1994 (English translation: "Combinatorial Species and Tree-like Structures", Cambridge University Press, 1998). P.Cameron. Combinatorics. Cambridge, 1994. R.Stanley. Enumerative combinatorics. éÚÄ. íÉÒ. S.K.Lando. Combinatorics. MCCME, 1994 (in Russian) (http://www.mccme.ru/ium/ancient/combs93.html).