Semi-Infinite Cohomology and Potential Applications to Non-Lorentzian Physics

Semi-infinite cohomology, first introduced by Boris Feigin in 1984, was shown to be an invaluable tool in the computation of string theory spectra, since it provides the mathematical setting for BRST cohomology. In this talk, I will provide an elementary introduction to the semi-infinite cohomology of graded Lie algebras, with emphasis on the conditions required for Lie algebras to admit a semi-infinite structure. I will then comment on the possibility of defining a semi-infinite structure on the BMS3 algebra, which would have important implications on recent works in areas such as tensionless strings.