Traps and plugs in symplectic dynamics 

Hansj\"org Geiges  (K\"oln)


Abstract: The Seifert conjecture asserts that every non-singular
flow on the 3-sphere has at least one periodic orbit. This has
been disproved using so-called plugs that allow one to
break isolated periodic orbits. I shall review the construction
of plugs and traps (or half-plugs) in Hamiltonian and
Reeb dynamics. This is based on joint work with
Nena R\"ottgen and Kai Zehmisch.