The apparently trifling unexpected hanging paradox has generated an enormous
philosophical literature. We introduce the mathematician to this literature,
paying special attention to aspects that involve nontrivial mathematics. This
xxx version of the paper contains an exhaustive bibliography that the editors
of the Monthly deemed too lengthy to publish. The bibliography will be
continually updated and readers are encouraged to inform the author of any
omissions that they discover.Comment: Exhaustive bibliography updated 6/25/11 with dozens of new reference