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{{\large\bf In Memory of Svatopluk Poljak }}
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Svata Poljak was born in Prague on October 9, 1951. He did his training
at Charles University in Prague and received his PhD in 1980 under the
supervision of Jarik Nesetril.
His official position was with Charles University until 1994???? when he
moved to Passau. However, during that time he had extended
visits at many places: Kyoto University 1988; Simon Fraser University
1990; DIMACS 1990; University of Paris, 1990; Institute of Mathematics
at Bonn, 1991.
His main contributions are in combinatorics and combinatorial
optimization.
He has important contributions in many areas including:
theory of matroids, matching theory, the max-cut and stable set problem;
spectral approaches to graph problems;
convex and polyhedral relaxations; semidefinite programming;
and various other integer programming related problems.
His early important work was related to systems in neural networks.
Several of his publications and
a list of his publications (more than 100) can be found over WWW with URL:
http://orion.uwaterloo.ca/~hwolkowi/.preprints/authors.d/poljak.d
a picture can be found ????
family: wife Jana ??? two sons ???? ....
Svata was involved in a fatal car accident.
This occurred near Prague on Sunday April 2, 1995.
He died, while on a short trip from his summer house (he just bought
it and was really thrilled with it. In winter you can go skiing from
there
it is in the mountains, halfway between Passau and Prague. It was his
dream to have a place like that..) he was in the car with one of
his best friends from Prague, two children and two women, one of them
his friend's wife. They were hit by a car that came the other way, but
on their side. There was no way to escape.
(Notice: see Opt-Net Digest v95w15 )
Following are several anectodes contributed by collaborators and
friends.
\begin{enumerate}
\item
{\bf from Michele Conforti:}\\
I did not know Svata too well, but there is a story I would like to tell.
A few years ago, Svata applied for a position and he asked me
for a letter of
recommendation. He sent me his vitae together with some publications.
When I looked into his stuff, it became obvious that he was a much more
advanced and established researcher than I was. I felt quite embarassed
to write a letter for such a strong (and versatile!) person. I think that
he had a much larger mathematical culture than the average researcher in
our area, but his low profile played (although won him some admirers, like
me) a bit against him. When he proposed strikingly innovative
research, as the use of semidefinte programming to obtain bounds for
integer programs, he had trouble getting it accepted. It is very sad
that only now we are here to recognize the value of this very honest person.
\item
{\bf from Martin Loebl:}\\
My memory of Svata is closely associated with the Prague Combinatorial
Seminar which we both attended; Svata as one of its pillars and I as a
novice. I immediately liked Svata because of his singular friendliness, and
we became close friends and later collaborators.
The main topics of our joint work were
totally unimodular matrices and factors of graphs. Let me mention one
joint result I am particularly proud of: we classified the
algorithmic complexity of the $\{K_2,H\}$-factor problem, i.e.
\begin{quote}
let $H$
be a fixed graph; for a given graph $G$ decide if its vertices may be
covered by vertex-disjoint edges and copies of $H$.
\end{quote}
Svata made fundamental contributions in many areas of
combinatorial optimization, local optimization and
positive-semidefinite programming, his last subject which is covered
most
by this special issue.
Svata enjoyed life fully and doing mathematics played a major role in his
life. He will be
sorely missed.
\item
{\bf from Jarik Nesetril:}\\
Svata Poljak was my first diploma student which I suppervised at Charles
University. We had contacts ever since and Poljak , Turzik and my
families and all our then small kids took regular summer
canoing trips on various Bohemian
rivers. Some papers started there. And some 10 years later I was happy
to get Svata to Charles University back. I didn't expected this to
last so briefly.
\item
{\bf from Franz Rendl:}\\
My first personal meeting with Svata was at a conference
on partitioning in Grottaferrata (Italy) in 1991. We realized
very quickly that we had many common research interests.
This lead to a fruitful cooperation, but perhaps more important,
to a deep friendship.
Many of our joint results were obtained in a rather
relaxed environment, where we would combine family holidays
with mathematical discussions.
It is sad for me to see several of our papers appearing in print
only after his death.
\item
{\bf from Henry Wolkowicz:}\\
I met Svata while on sabbatical leave at DIMACS. Svata was visiting at
the same time and we were introduced by our mutual friend Franz Rendl.
Svata immediately showed me a conjecture he was working on:
\begin{quote}
four, seemingly unrelated, bounds for the max-cut problem are in fact
all equal.
\end{quote}
Though I knew little about max-cut problems, the bounds involved
continuous optimization techniques, which fell into
my area of expertise. Our joint effort resulted in a proof
of this conjecture. This work started our collaboration. Svata next met
me in Graz, Austria and ``took'' me by car to his new home in Passau.
Ironically, he disliked driving very much and I did all the driving from
Graz to Passau. At this time he was essentially commuting from his
family home in Prague to Passau. My lasting memory of Svata is spending
several extremely enjoyable days at Passau discussing Mathematics and
helping a very excited Svata explore his new home.
\end{enumerate}
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