 
Summary: Lehrstuhl Informatik 2
EINLADUNG
Zeit: Montag, 27. Juni 2011, 10.00 Uhr
Ort: AH 6, Ahornstr. 55
Referent: Prof. Dr. Javier Esparza,
TU München
Titel: Solving fixedpoint equations on semirings
Abstract:
Many problems in Computer Science, Physics, and Mathematics reduce to solving a
system of fixedpoint equations. Examples include the computation of thermal equilib
ria, shortest paths, dataflow invariants, critical radius of fisionable materials, multiset
languages, stationary distributions, population levels, termination probabilities, and
expected memory consumption. The equations are interpreted on a large variety of
domains, including integers, reals, intervals, languages, and multisets, but all of them
share a common algebraic structure: they are semirings with some continuity proper
ties.
Computer Science has not produced much theory on *generic* solution methods,
i.e., methods that work for *any* of these semirings. The ones around are based on
KnasterTarski's and Kleene's theorems, but, unfortunately, they rarely terminate for
infinite domains, and in metric interpretations their convergence order is very slow. In
