  Einstein-Hilbert action is supplemented by Gauss-Bonnet squared term, its
phase-space structure is constructed and canonical quantization is performed.
Resolution of a contradiction that emerges in the process, requires the
presence of other fields at least in the form of vacuum energy-density,
commonly known as the cosmological constant. This reveals the very importance
of the presence of other fields at least in the form of cosmological constant,
in the very early universe.
