@article{DimitrovaKoppitz2011,
  author    = {Dimitrova, Ilinka and Koppitz, J{\"o}rg},
  title     = {On the maximal regular subsemigroups of ideals of order-preserving or order-reversing transformations},
  series = {Semigroup forum},
  volume    = {82},
  journal   = {Semigroup forum},
  number    = {1},
  publisher = {Springer},
  address   = {New York},
  issn      = {0037-1912},
  doi       = {10.1007/s00233-010-9272-8},
  pages     = {172 -- 180},
  year      = {2011},
  abstract  = {We characterize the maximal regular subsemigroups of the ideals of the semigroup of all order-preserving transformations as well as of the semigroup of all order-preserving or order-reversing transformations on a finite ordered set.},
  language  = {en}
}
@article{DimitrovaKoppitz2012,
  author    = {Dimitrova, Ilinka and Koppitz, J{\"o}rg},
  title     = {On the monoid of all partial order-preserving extensive transformations},
  series = {Communications in algebra},
  volume    = {40},
  journal   = {Communications in algebra},
  number    = {5},
  publisher = {Taylor \& Francis Group},
  address   = {Philadelphia},
  issn      = {0092-7872},
  doi       = {10.1080/00927872.2011.557813},
  pages     = {1821 -- 1826},
  year      = {2012},
  abstract  = {A partial transformation alpha on an n-element chain X-n is called order-preserving if x <= y implies x alpha <= y alpha for all x, y in the domain of alpha and it is called extensive if x <= x alpha for all x in the domain of alpha. The set of all partial order-preserving extensive transformations on X-n forms a semiband POEn. We determine the maximal subsemigroups as well as the maximal subsemibands of POEn.},
  language  = {en}
}