  Violation of equivalence principle predicts that neutrinos of different
flavor couple differently with gravity. Such a scenario can give rise to
gravity induced flavor oscillations in addition to the usual mass flavor
neutrino oscillations during the neutrino propagation. Even if the equivalence
principle is indeed violated, their measure will be extremely small. We explore
the possibility to probe the violation of equivalence principle (VEP) for the
case of long baseline (LBL) neutrinos in a 4-flavor neutrino framework (3
active + 1 sterile) where both mass and gravity induced oscillations are
considered. To this end, we have explicitly calculated the oscillation
probability in 4-flavor framework that includes in addition to the mass-flavor
mixing in matter, the gravity-flavor mixing also. The energy eigenvalues are
then obtained by diagonalizing such a 4-flavor mixing matrix. The formalism is
then employed to estimate the wrong and right sign muon yields at a far
detector for neutrinos produced in a neutrino factory and travel through the
Earth matter. These results are compared with the similar estimations when the
usual three active neutrinos are considered.
