  In many real-world situations, there are constraints on the ways in which a
physical system can be manipulated. We investigate the entropy production (EP)
and extractable work involved in bringing a system from some initial
distribution $p$ to some final distribution $p'$, given that the set of master
equations available to the driving protocol obeys some constraints. We first
derive general bounds on EP and extractable work, as well as a decomposition of
the nonequilibrium free energy into an "accessible free energy" (which can be
extracted as work, given a set of constraints) and an "inaccessible free
energy" (which must be dissipated as EP). In a similar vein, we consider the
thermodynamics of information in the presence of constraints, and decompose the
information acquired in a measurement into "accessible" and "inaccessible"
components. This decomposition allows us to consider the thermodynamic
efficiency of different measurements of the same system, given a set of
constraints. We use our framework to analyze protocols subject to symmetry,
modularity, and coarse-grained constraints, and consider various examples
including the Szilard box, the 2D Ising model, and a multi-particle flashing
ratchet.
