  We define integrability preserving Yang-Baxter deformations of symmetric
space sigma models with non-semi-simple symmetry group, in particular the flat
space string, using only the essential structures of a symmetric space sigma
model. For homogeneous deformations, the Lax connection is of the same form as
the semi-simple case, although the R operator no longer satisfies a
freestanding operator equation. For inhomogeneous deformations, the form of the
Lax connection needs to be relaxed, by modifying the underlying algebra. We
illustrate the construction by discussing nonabelian deformations of three
dimensional Minkowski space.
