  A new relation in Grassmann algebra is presented, corresponding naturally to
the four-dimensional Pachner move 3 -> 3. This relation is obtained by
deforming a known relation associated with an exotic chain complex built for a
triangulated four-manifold. The possible deformation terms turn out to
correspond to second (middle) homologies of one more exotic complex. Both sides
of the new relation are nonlinear in the deformation: they contain terms of
degrees 0, 1 and 2.
