Modal Logics for Qualitative Possibility and Beliefs
  Possibilistic logic has been proposed as a numerical formalism for reasoning
with uncertainty. There has been interest in developing qualitative accounts of
possibility, as well as an explanation of the relationship between possibility
and modal logics. We present two modal logics that can be used to represent and
reason with qualitative statements of possibility and necessity. Within this
modal framework, we are able to identify interesting relationships between
possibilistic logic, beliefs and conditionals. In particular, the most natural
conditional definable via possibilistic means for default reasoning is
identical to Pearl's conditional for e-semantics.
