Line transversals in families of connected sets in the plane

Line transversals in families of connected sets in the plane

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Shira Zerbib, Iowa State University
Fine Hall 224

In-Person Talk 

We prove that if a family of compact connected sets in the plane has the property that every three members of it are intersected by a line, then there are three lines intersecting all the sets in the family. This answers a question of Eckhoff from 1993, who proved that under the same condition there are four lines intersecting all the sets. We also prove a colorful version of this result under weakened conditions on the sets, improving results of Holmsen from 2013. Our proofs use the topological KKM theorem.

Joint with Daniel McGinnis.