Abstract
Let be a Leibniz algebra,
be a vector space and
be an epimorphism of vector spaces with
. The global extension problem asks for the classification of all Leibniz algebra structures that can be defined on
such that
is a morphism of Leibniz algebras: from a geometrical viewpoint this is to give the decomposition of the groupoid of all such structures in its connected components and to indicate a point in each component. All such Leibniz algebra structures on
are classified by a global cohomological object
which is explicitly constructed. It is shown that
is the coproduct of all local cohomological objects
which are classifying sets for all extensions of
by all Leibniz algebra structures
on
. The second cohomology group
of Loday and Pirashvili appears as the most elementary piece among all components of
. Several examples are worked out in details for co-flag Leibniz algebras over
, i.e. Leibniz algebras
that have a finite chain of epimorphisms of Leibniz algebras
such that
, for all
. Metabelian Leibniz algebras are introduced, described and classified using pure linear algebra tools.
Notes
1 The next proposition can be also proven directly by testing the Leibniz law for the bracket (Equation33 ) in all points of the form
and
, for all
,
.
This work was supported by a grant of the Romanian National Authority for Scientific Research, CNCS-UEFISCDI, [grant number 88/05.10.2011].