@phdthesis{Dimitrova2006,
  author    = {Dimitrova, Ilinka},
  title     = {Green{\"i}s equivalences on some classes of transformation semigroups},
  address   = {Potsdam},
  pages     = {ix, 91 Bl. : graph. Darst.},
  year      = {2006},
  language  = {en}
}
@article{DimitrovaFernandesKoppitz2017,
  author    = {Dimitrova, Ilinka and Fernandes, Vitor H. and Koppitz, J{\"o}rg},
  title     = {A note on generators of the endomorphism semigroup of an infinite countable chain},
  series = {Journal of Algebra and its Applications},
  volume    = {16},
  journal   = {Journal of Algebra and its Applications},
  number    = {2},
  publisher = {World Scientific},
  address   = {Singapore},
  issn      = {0219-4988},
  doi       = {10.1142/S0219498817500311},
  pages     = {9},
  year      = {2017},
  abstract  = {In this note, we consider the semigroup O(X) of all order endomorphisms of an infinite chain X and the subset J of O(X) of all transformations alpha such that vertical bar Im(alpha)vertical bar = vertical bar X vertical bar. For an infinite countable chain X, we give a necessary and sufficient condition on X for O(X) = < J > to hold. We also present a sufficient condition on X for O(X) = < J > to hold, for an arbitrary infinite chain X.},
  language  = {en}
}
@article{DimitrovaFernandesKoppitz2012,
  author    = {Dimitrova, Ilinka and Fernandes, Vitor H. and Koppitz, J{\"o}rg},
  title     = {The maximal subsemigroups of semigroups of transformations preserving or reversing the orientation on a finite chain},
  series = {Publicationes mathematicae},
  volume    = {81},
  journal   = {Publicationes mathematicae},
  number    = {1-2},
  publisher = {Institutum Mathematicum Universitatis Debreceniensis, Debreceni Tudom{\´a}nyegyetem Matematikai Int{\´e}zete},
  address   = {Debrecen},
  issn      = {0033-3883},
  doi       = {10.5486/PMD.2012.4897},
  pages     = {11 -- 29},
  year      = {2012},
  abstract  = {The study of the semigroups OPn, of all orientation-preserving transformations on an n-element chain, and ORn, of all orientation-preserving or orientation-reversing transformations on an n-element chain, has began in [17] and [5]. In order to bring more insight into the subsemigroup structure of OPn and ORn, we characterize their maximal subsemigroups.},
  language  = {en}
}
@article{DimitrovaKoppitz2017,
  author    = {Dimitrova, Ilinka and Koppitz, J{\"o}rg},
  title     = {On the semigroup of all partial fence-preserving injections on a finite set},
  series = {Journal of Algebra and Its Applications},
  volume    = {16},
  journal   = {Journal of Algebra and Its Applications},
  number    = {12},
  publisher = {World Scientific},
  address   = {Singapore},
  issn      = {0219-4988},
  doi       = {10.1142/S0219498817502231},
  pages     = {14},
  year      = {2017},
  abstract  = {For n∈N , let Xn={a1,a2,…,an} be an n-element set and let F=(Xn;<f) be a fence, also called a zigzag poset. As usual, we denote by In the symmetric inverse semigroup on Xn. We say that a transformation α∈In is fence-preserving if x<fy implies that xα<fyα, for all x,y in the domain of α. In this paper, we study the semigroup PFIn of all partial fence-preserving injections of Xn and its subsemigroup IFn={α∈PFIn:α-1∈PFIn}. Clearly, IFn is an inverse semigroup and contains all regular elements of PFIn. We characterize the Green's relations for the semigroup IFn. Further, we prove that the semigroup IFn is generated by its elements with rank ≥n-2. Moreover, for n∈2N, we find the least generating set and calculate the rank of IFn.},
  language  = {en}
}
@article{DimitrovaKoppitz2010,
  author    = {Dimitrova, Ilinka and Koppitz, J{\"o}rg},
  title     = {On some anti-inverse transformation semigroups},
  issn      = {1310-1331},
  year      = {2010},
  abstract  = {A semigroup S is called anti-inverse if for all a E S there is a b is an element of S such that aba = b and bab = a. Each anti-inverse semigroup is regular. In the present paper, we study anti-inverse subsemigroups within the semigroup T-n of all transformations on an n-element set (1 <= n is an element of N). In particular, we characterize all anti-inverse semigroups within the J-classes of T-n and illustrate our result by four examples.},
  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}
}
@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{DimitrovaKoppitz2022,
  author    = {Dimitrova, Ilinka and Koppitz, J{\"o}rg},
  title     = {On relative ranks of the semigroup of orientation-preserving transformations on infinite chain with restricted range},
  series = {Communications in algebra},
  volume    = {50},
  journal   = {Communications in algebra},
  number    = {5},
  publisher = {Taylor \& Francis Group},
  address   = {Philadelphia},
  issn      = {0092-7872},
  doi       = {10.1080/00927872.2021.2000998},
  pages     = {2157 -- 2168},
  year      = {2022},
  abstract  = {Let X be an infinite linearly ordered set and let Y be a nonempty subset of X. We calculate the relative rank of the semigroup OP(X,Y) of all orientation-preserving transformations on X with restricted range Y modulo the semigroup O(X,Y) of all order-preserving transformations on X with restricted range Y. For Y = X, we characterize the relative generating sets of minimal size.},
  language  = {en}
}
@article{DimitrovaKoppitz2020,
  author    = {Dimitrova, Ilinka and Koppitz, J{\"o}rg},
  title     = {On relative ranks of the semigroup of orientation-preserving transformations on infinite chains},
  series = {Asian-European journal of mathematics},
  volume    = {14},
  journal   = {Asian-European journal of mathematics},
  number    = {08},
  publisher = {World Scientific},
  address   = {Singapore},
  issn      = {1793-5571},
  doi       = {10.1142/S1793557121501461},
  pages     = {15},
  year      = {2020},
  abstract  = {In this paper, we determine the relative rank of the semigroup OP(X) of all orientation-preserving transformations on infinite chains modulo the semigroup O(X) of all order-preserving transformations.},
  language  = {en}
}