The 34th International Symposium on Mathematical Foundations of Computer Science MFCS2009
washeld in Novy Smokovec High Tatras(Slovakia)during August 24 28 2009. This volume contains 7
invited and 56 contributed papers presented at the symposium. The contributed papers were
selected by the P- gram Committee out of a total of 148 submissions. MFCS 2009 was organized by
the Slovak Society for Computer Science and the Faculty of Mathematics Physics and Informatics
of the Comenius Univ- sity in Bratislava. It wassupported by the EuropeanAssociation for
Theoretical Computer Science. We acknowledge with gratitude the support of all these -
stitutions. The series of MFCS symposia has a well-established tradition dating back to 1972.
The aim is to encourage high-quality research in all branches of th- retical computer science
and to bring together researchers who do not usually meet at specialized conferences. The
symposium is organized on a rotating - sis in Poland Czech Republic and Slovakia.
