  Recently an interesting conjecture was put forward which states that any
asymptotically de Sitter space whose mass exceeds that of exact de Sitter space
contains a cosmological singularity. In order to test this mass bound
conjecture, we present two solutions. One is the topological de Sitter solution
and the other is its dilatonic deformation. Although the latter is not
asymptotically de Sitter space, the two solutions have a cosmological horizon
and a cosmological singularity. Using surface counterterm method we compute the
quasilocal stress-energy tensor of gravitational field and the mass of the two
solutions. It turns out that this conjecture holds within the two examples.
Also we show that the thermodynamic quantities associated with the cosmological
horizon of the two solutions obey the first law of thermodynamics. Furthermore,
the nonconformal extension of dS/CFT correspondence is discussed.
