lower boundary theory, this symmetry is given by contraction of conformal symmetry. In this view, one can study flat-space holography by starting from AdS/CFT and takeing the appropriate limit. The flat-space limit of the bulk theory corresponds to the ultrarelativistic limit of the boundary CFT [@Bagchi:2012cy].

Since BMS symmetry is infinite dimensional, it is possible to find the universal aspects of BMSFTs that are independent of the action and details of the theory. In [@Bagchi:2012xr], a Cardy-like formula has been proposed for BMSFT$_2$. This formula gives an estimation for the degeneracy of the states of this field theory. The interesting point is that this formula yields the entropy of three-dimensional flat space cosmology (FSC), which is given by taking the flat space limit from the BTZ black holes. The universal structure of the correlation functions of BMSFT$_2$ and BMSFT$_3$ has been studied in [@Bagchi:2015wna]-[@Fareghbal:2018xii]. The entanglement entropy formula and also the holographic interpretation of this formula in the context of flat/BMSFT have been studied in [@Bagchi:2014iea]-[@Hijano:2018nhq] . In all of the above mentioned works, the calculations that are done in asymptotically flat spacetimes nicely fit to the results given by taking the ultrarelativistic limit of CFTs. For an almost complete 