  We study three different (co)homology theories for a family of pullbacks of
algebras that we call oriented. We obtain a Mayer Vietoris long exact sequence
of Hochschild and cyclic homology and cohomology groups for these algebras. We
give examples showing that our sequence for Hochschild cohomology groups is
different from the known ones. In case the algebras are given by quiver and
relations, and that the simplicial homology and cohomology groups are defined,
we obtain a similar result in a slightly wider context. Finally we also study
the fundamental groups of the bound quivers involved in the pullbacks.
