loose_plastik Loose Legendrians and the plastikstufe Emmy Murphy Klaus Niederkrüger Olga Plamenevskaya András Stipsicz http://dx.doi.org/10.2140/gt.2013.17.1791 Geom. & Topo. 17 (2013) 1791-1814 2013 gt.jpg
We show that the presence of a plastikstufe induces a certain degree of flexibility in contact manifolds of dimension 2n+1>3. More precisely, we prove that every Legendrian knot whose complement contains a "nice" plastikstufe can be destabilized (and, as a consequence, is loose). As an application, it follows in certain situations that two non-isomorphic contact structures become isomorphic after connect-summing with a manifold containing a plastikstufe.