Phase transitions for the topological de Sitter spaces and   Schwarzschild-de Sitter black hole
  We study whether the Hawking-Page phase transition may occur in topological de Sitter spaces (TdS) and Schwarzschild-de Sitter black hole (SdS).   We show that at the critical temperature $T=T_1$, TdS with hyperbolic cosmological horizon can make the   Hawking-Page transition from the zero mass de Sitter space to TdS. It is also shown that there is no Hawking-Page transition for TdS with Ricci-flat and spherical horizons, when the zero mass de Sitter space is taken as the thermal background. Also we find that the SdS undergoes a different phase transition at T=0 which the Nariai black hole is formed. Finally we connect our results to the dS/CFT correspondence. 
Yun Soo mYung