Reconfiguration problems arise when we wish to find a step-by-step transformation between two feasible solutions of a problem such that all intermediate results are also feasible. We demonstrate that a host of reconfiguration problems derived from NP-complete problems are PSPACE-complete, while some are also NP-hard to approximate. In contrast, several reconfiguration versions of problems in P are solvable in polynomial time.
Based on a paper by Takehiro Itoa, Erik D. Demaine, Nicholas J.A. Harveyc, Christos H. Papadimitrioud, Martha Sideri, Ryuhei Uehara , Yushi Uno. ( https://core.ac.uk/download/pdf/78065210.pdf)