Lectures and Colloquia during the semester
Monday, February 14, 2005
Freie Universität Berlin - Institut für
Informatik
Takustraße 9
14195 Berlin
Room 005
- map -
Lecture - 14:15
Uwe Schöning -Universität Ulm
A Survey on 3SAT algorithms
Abstract:
We discuss several 3SAT algorithms that achieve a time complexity bound of
cn where n is the number of Boolean variables, and c is larger than 1
but less than 2.
In some of these algorithms randomization plays a crucial role and
results in the best
known complexity bounds.
Colloquium - 16:00
Barbara Baumeister -Freie Universität Berlin
The third group of Janko
Abstract:
In an enormous proof all the finite simple groups have been
classified. (Recall that a group is simple if it has no normal
subgroup other than 1 and G.) There are some infinite families
and 26 sporadic exceptions. One of them is specially difficult to
handle, the third group of Janko, J3.
Janko gave evidence that there is a simple group G satisfying the
two conditions:
- If i and j are involutions in G (i.e. i2 = j2 =1), then there
is g in G such that g-1 i g = j.
- Let i be an involution in G and
CG(i) = {g ∈ G | ig = gi}, which is a subgroup of G. Then CG(i)
is a prescribed group with 27⋅ 3 ⋅ 5 elements.
Such a group is called "group of J3-type". He also showed that
a group of J3-type has 50.232.960 elements.
In my Phd thesis I proved the existence of a group of J3-type
by constructing a geometry with automorphism group isomorphic to
J3. Using this information I am now trying to show that there is
just one group of J3-type up to isomorphism.
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