“…In vacuum, for instance, a reduced quantization is possible [1,2,3]. This reduction has thus often been used in diverse approaches to quantum gravity, and also loop quantum gravity [4,5,6] has provided its own formulation [7,8,9,10,11]. This allows one to use the loop representation constructed in the full theory in a simpler setting in which, as one hopes, one can find and analyze physical solutions.…”