### 4.12 Renormalization group

There have been attempts to apply renormalization group techniques, assuming that the transition is
indeed continuous. Burda et al. [61] and later Bialas et al. [48] considered the “cutting of the last
generation of minimal-neck baby universes”. This step can only be performed once, which severely
limits the power of the procedure. Renken [178, 177] has applied a different blocking move,
involving node deletion, and studied the RG flow using the volume and the vertex order as
observables.