  Their intention seems to have been to have a general proof that can be shown to hold independently of any particular model of physical process of resetting. To achieve this without presuming something about the physics which governs a device that performs the resetting, they explicitly accepted the sound approach to Earman and Norton's Sound vs. Profound dilemma. This means they assumed that a particular modified form of the second law of thermodynamics must hold true. The modified version that they adopted is that there are no cyclic processes, whose sole result is to restore a system to its initial state and having a strictly positive expectation value for the conversion of heat into work.