For more information about this meeting, contact Barbara Baum.

Title: | The Endomorphism Conjecture for Posets |

Seminar: | Combinatorics/Partitions Seminar |

Speaker: | Ryan Flynn, Department of Mathematics, The Pennsylvania State University |

Abstract: |

Let P be a finite partially ordered set. An automorphism of P is an order-preserving bijection from P to P, and an endomorphism of P is an order preserving map from P to P. The set of automorphisms of P forms a group under composition, and is denoted Aut(P). The set of endomorphisms of P forms a monoid under composition, and is denoted End(P).
The Endomorphism conjecture states, roughly, that as the cardinality of P becomes large, the ratio #Aut(P)/#End(P) tends to 0. This problem is surprisingly hard! We prove the conjecture for join-semilattices, and if time permits, for posets that are 'wide enough'. |

### Room Reservation Information

Room Number: | MB106 |

Date: | 04 / 28 / 2009 |

Time: | 11:15am - 12:05pm |