  The earliest attempts to construct general, rigorous proofs of Landauer's principle, from within statistical mechanics, were by Shizume (1995) and Piechocinska (2000). (Although Penrose (1970, Chapter VI) does, in effect, derive an entropic cost for the reset operation, it appears his work was motivated quite independently of Landauer's). Shizume's proof relies upon treating thermal contact as a Gaussian white noise field in a Langevin equation, while Piechocinska assumes Hamiltonian dynamics and a heat bath that is initially uncorrelated with the system and represented by a Gibbs canonical distribution.