  The antisymmetrization of the composite particles in cluster model
calculations manifests itself in Pauli forbidden states (ghost states), if one
restricts oneself on undeformed cluster in the low energy region. The
resonating group method and the generating coordinate method rely on a property
of the norm kernel, which introduces some of the ghost states. The norm kernel
has been usually calculated under the assumption that the inner wavefunctions
have a simple Gaussian form. It is the first time that this assumption is
tested by the rigorous way. In the 4He+N system, we demonstrate a ghost state,
which is calculated from a rigorous solution of Yakubovsky equations for the
alpha particle. The ghost states calculated by rigorous and approximate methods
turn out to have a very similar form. It is analytically proved that the trace
of the norm kernel does not depend on the inner wavefunction we choose.
