  In two recent papers, Maroney and Turgut separately and independently show
generalisations of Landauer's erasure principle to indeterministic logical
operations, as well as to logical states with variable energies and entropies.
Here we show that, although Turgut's generalisation seems more powerful, in
that it implies but is not implied by Maroney's and that it does not rely upon
initial probability distributions over logical states, it does not hold for
non-equilibrium states, while Maroney's generalisation holds even in
non-equilibrium. While a generalisation of Turgut's inequality to
non-equilibrium seems possible, it lacks the properties that makes the
equilibrium inequality appealing. The non-equilibrium generalisation also no
longer implies Maroney's inequality, which may still be derived independently.
Furthermore, we show that Turgut's inequality can only give a necessary, but
not sufficient, criteria for thermodynamic reversibility. Maroney's inequality
gives the necessary and sufficient conditions.
