  Considering the unphysical result obtained in the calculation of the
free-energy cost for twisting the boundary conditions in a spin glass, we trace
it to the negative multiplicities associated with the Parisi replica-symmetry
breaking (RSB). We point out that a distinct RSB, that keeps positive
multiplicities, was proposed long ago, in the spirit of an ultra-long time
dynamical approach due to Sompolinsky. For an homogeneous bulk system, both RSB
schemes are known to yield identical free energies and observables. However,
using the dynamical RSB, we have recalculated the twist free energy at the
mean-field level. The free-energy cost of this twist is, as expected, positive
in that scheme, as it should be.
