Predavatelj: Wilfried Imrich (about joint work with Florian Lehner, Rafal Kalinowski, Monika Pilsniak and Marcin Stawiski)
Povzetek: The talk is a continuation of the seminar talk of November 12, 2018 about automorphism breaking of countable trees. One says a tree, or more generally a graph, is asymmetrizable if there exists a 2-coloring of its vertices that is only preserved by the identity automorphism. The talk outlines a proof that each infinite tree whose degrees are bounded by 2^m, where m is an arbitrary infinite cardinal, is asymmetrizable if all non-identity automorphisms move at least m vertices.
The talk begins with a few remarks about infinite cardinals, successor cardinals, regular and singular cardinals, the Generalized Continuum Hypothesis, results of Babai, Sabidussi and Polat and then presents the main result.