details
Title
Galois theory and commutators
Abstract We explain how the relative commutator with respect to a
subvariety of a variety of omegagroups can be described in terms of
categorical Galois theory. This extends the known correspondence between
FrÃ¶hlich's and Janelidze and Kelly's notions of central extension.
Basing ourselves on the concept of double central extension, thus we
obtain a commutator which is defined relative to a Birkhoff subcategory
B of a semiabelian category A. In case the subcategory B is determined
by the abelian objects in A we regain Huq's commutator.
Speaker(s)
Tim Van der Linden (CMUC/FCT)
Date
December 02, 2008 Time 15.45 Room
Sala 5.5
