Nevertheless, let us mention that some classes of black holes admit a vanishing horizon area
and zero temperature
limit such that the ratio
is finite. Such extremal vanishing horizon (EVH) black holes admit near-horizon limits,
which contain (singular) identifications of AdS3 that can be used for string model building [157
, 98
, 116
, 130
, 115
]. Most of
the ideas developed for the Kerr/CFT correspondence and its extensions can be developed similarly for EVH black
holes [243
].