  Improperly efficient solutions in the sense of Geoffrion in linear fractional
vector optimization problems with unbounded constraint sets are studied in this
paper. We give two sets of conditions which assure that all the efficient
solutions of a given problem are improperly efficient. We also obtain necessary
conditions for an efficient solution to be improperly efficient. As a result,
we have new sufficient conditions for Geoffrion's proper efficiency. The
obtained results enrich our knowledge on properly efficient solutions in linear
fractional vector optimization.
