CeVis
  1. Center of Complex Systems and Visualization
  2. Lehre
  3. Oberseminar

In dem regelmäßig stattfindenden Oberseminar tragen Gäste aus aller Welt über Forschungsarbeiten zu Themen vor, die mit der Arbeit von CeVis und MeVis in Verbindung stehen, und Mitarbeiter von CeVis und MeVis präsentieren ihre neusten Ergebnisse.


C(M)eVis-Oberseminar am 10.11.1999


Datum: Mittwoch, der 10.11.1999
Zeit: 11.00 Uhr s.t.
Ort: Seminarraum Mandelbrot
Referent: Prof. Dr. Jean-Paul Allouche (CNRS, LRI, Orsay)
ON A RESULT OF S. LEHR

S. Lehr proved that the set of real numbers whose expansion in a fixed base can be generated by a finite automaton is a vector space on the field of rational numbers. But (see also the work of Lehr, Shallit and Tromp), this is not an algebra: to compute the product of two real numbers is somehow ``more complicated'' than to compute their sum. Ketkar and Zamboni studied the case where finite automata (i.e., constant length morphisms) are replaced by non-constant length morphisms: only the stability by rational multiplication still holds.

After reviewing the previous results we show our (yet unsuccessful) attempts to use them for proving the transcendence of real numbers, and the curious questions in combinatorics of words that were thus raised.


A. Rodenhausen, 3.9.1999