abstract representations of processes with memory (the state) that must
be modified or erased as time progresses. applying landauer’s principle assigns thermodynamic consequences
to the hmm time evolution. which hmm (and corresponding states) is appropriate, though? we now see
that prediction and generation, two very natural tasks
for a thermodynamic system to perform, actually deliver
two different answers. it is important to understand how
physical circumstances relate to this choice of task—it
will be expressed in terms of heat.