Series: Penn State Logic Seminar

Date: Tuesday, April 13, 2004

Time: 2:30 - 3:45 PM

Place: 307 Boucke Building

Speaker: Rebecca Weber, Mathematics, Notre Dame

Title: Orbits and Invariance in the Lattice of $\Pi^0_1$ Classes

  We present a definable quotient substructure of $\mathcal{E}_\Pi$,
  the lattice of $\Pi^0_1$ classes, and show that structure is
  isomorphic to $\mathcal{E}^*$, the lattice of c.e.\ sets modulo
  finite difference.  We then explore how to use that isomorphism to
  transfer information from $\mathcal{E}^*$ to $\mathcal{E}_\Pi$,
  especially about orbits and invariant classes.