  (To appear in Theory and Practice of Logic Programming (TPLP))
  ESmodels is designed and implemented as an experiment platform to investigate
the semantics, language, related reasoning algorithms, and possible
applications of epistemic specifications.We first give the epistemic
specification language of ESmodels and its semantics. The language employs only
one modal operator K but we prove that it is able to represent luxuriant modal
operators by presenting transformation rules. Then, we describe basic
algorithms and optimization approaches used in ESmodels. After that, we discuss
possible applications of ESmodels in conformant planning and constraint
satisfaction. Finally, we conclude with perspectives.
