
This is a special issue of the
journal devoted to the jubilee of the outstanding Ukrainian and
Russian mathematician, one of the founder of our journal Professor
Rostislav Grigorchuk, who was 50 years of age on February 23,
2003. R. Grigorchuk was born in Ternopol oblast, Ukraine. He left
the Ukrainian school no.23 in Chernivtsi, Ukraine. In 1975, after
graduating Moscow Lomonosov State University (faculty of Mechanics
and Mathematics), he entered the postgraduate course in the same
university His scientific supervisor was the wellknown specialist
in ergodic theory and dynamic systems Professor A. M. Stepin.
In 1978, R. Grigorchuk defended his Ph.D. thesis: ``Banach
means on homogeneous spaces and random walks'' in Moscow Lomonosov
State University. The degree of Doctor of Sciences he received
in 1985 in Steklov Institute of Mathematics for his thesis ``Growth
functions of finitely generated groups and its applications''.
His teaching work R.I. Grigorchuk began in Department of
Mathematics of Moscow State University of Transportation; at first
as Assistant Professor, and then from 1992 till 1995 as Chair
of Department. Such known mathematicians as Yurii Kuzmin, Zoya
Lipkina, Leonid Sadovsky and Elena Ventzel worked at this department
worked at that time. In 1955 R.I.Grigorchuk passed to the Steklov
Institute of Mathematics where he is working till now as the leading
scientific researcher. He also is Professor of the Chair of Dynamical
Systems of Moscow State Lomonosov University. This chair was organized
with his active assistance.
Professor Grigorchuk is a mathematician of a wide range of
interests and the results he obtained belong to various areas
of Mathematics: group theory, as a whole, and such its directions
as asymptotic group theory and geometric group theory, branched
groups and groups generated by finite automata, problems of Burnside's
type, growth of groups (around Milnor's problem), dynamic systems.
In particular, ergodic theorems for noncommutative groups of
transformations. Theory of invariant means (amenable groups),
random walks on groups and graphs. Spectral theory of discrete
of Laplacian, bounded cohomologies and $L^{2}$invariants. Low
dimensional topology and discrete Mathematics.
In the paper ``On Burnside's problem on periodic groups''
(Functional Anal. Appl., v.14, no.1, 1980, 5354) R.I.Grigorchuk
constructed his first example of infinite finitely generated periodic
group. This group is known as the first Grigorchuk group and it
represents the simplest example of the socalled groups of Burnside
type. The first Grigorchuk group has had different applications
in various branches of mathematics and can be regarded as the
pearl in the collection of nice and useful algebraic objects.
R.I. Grigorchuk solved a series of important problems in asymptotic
and geometric group theory, in particular, he solved the famous
Milnor's problem about groups of intermediate growth. It is impossible
to imagine modern group theory without deep theorems and nice
constructions of R.I. Grigorchuk. Outstanding achievements in
science of R.I.Grigorchuk were highly rated by mathematical community,
he was repeatedly awarded to the prizes for the best scientific
results in Russia (1999, 2000 and 2001), and to the honorary title
``Outstanding scientist of Russia'' in 1996 and 1999. Many times
he has been invited by world mathematical centers for giving series
of lectures in rapidly developing areas of Mathematics.
Professor R.I. Grigorchuk is a wellknown organizer of mathematical
researches, in particular, in Russia and in Ukraine. With his
active assistance, International Algebraic conferences in Ukraine
in 1997, 1999, 2001 and 2003 were organized. He was a participant
of the Ukrainian Mathematical Congress 2001.
Practically every year R.I. Grigorchuk carries out winter
school on geometric group theory in Kiev Taras Shevchenko University.
In collaboration with V.I. Sushchansky he developed a new direction
of scientific investigations in Kiev University, namely, geometric
and asymptotic group theory.
We joint to all warm wishes and congratulations which were
given to Prof. Grigorchuk on the occasion of his 50th birthday
and also wish him good health and long years of further activity
as a scientists and teacher. As it is usually said in Ukraine
``Ç ðîñè ³ âîäè
Âàì, äîðîãèé
ïàíå Ðîñòèñëàâå!''


Yu.A. Drozd, V.V. Kirichenko, M.Ya. Komarnitsky,
L.A. Kurdachenko,
V.V. Lyubashenko, V.V. Nekrashevych, B.V. Novikov, A.S. Oliynyk,
A.P. Petravchuk, V.I. Sushchansky, V.M. Usenko.
