@article{GebserJanhunenRintanen2020,
  author    = {Gebser, Martin and Janhunen, Tomi and Rintanen, Jussi},
  title     = {Declarative encodings of acyclicity properties},
  series = {Journal of logic and computation},
  volume    = {30},
  journal   = {Journal of logic and computation},
  number    = {4},
  publisher = {Oxford Univ. Press},
  address   = {Eynsham, Oxford},
  issn      = {0955-792X},
  doi       = {10.1093/logcom/exv063},
  pages     = {923 -- 952},
  year      = {2020},
  abstract  = {Many knowledge representation tasks involve trees or similar structures as abstract datatypes. However, devising compact and efficient declarative representations of such structural properties is non-obvious and can be challenging indeed. In this article, we take a number of acyclicity properties into consideration and investigate various logic-based approaches to encode them. We use answer set programming as the primary representation language but also consider mappings to related formalisms, such as propositional logic, difference logic and linear programming. We study the compactness of encodings and the resulting computational performance on benchmarks involving acyclic or tree structures.},
  language  = {en}
}
@article{JanhunenKaminskiOstrowskietal.2017,
  author    = {Janhunen, Tomi and Kaminski, Roland and Ostrowski, Max and Schellhorn, Sebastian and Wanko, Philipp and Schaub, Torsten H.},
  title     = {Clingo goes linear constraints over reals and integers},
  series = {Theory and practice of logic programming},
  volume    = {17},
  journal   = {Theory and practice of logic programming},
  publisher = {Cambridge Univ. Press},
  address   = {New York},
  issn      = {1471-0684},
  doi       = {10.1017/S1471068417000242},
  pages     = {872 -- 888},
  year      = {2017},
  abstract  = {The recent series 5 of the Answer Set Programming (ASP) system clingo provides generic means to enhance basic ASP with theory reasoning capabilities. We instantiate this framework with different forms of linear constraints and elaborate upon its formal properties. Given this, we discuss the respective implementations, and present techniques for using these constraints in a reactive context. More precisely, we introduce extensions to clingo with difference and linear constraints over integers and reals, respectively, and realize them in complementary ways. Finally, we empirically evaluate the resulting clingo derivatives clingo[dl] and clingo[lp] on common language fragments and contrast them to related ASP systems.},
  language  = {en}
}
@article{BomansonJanhunenSchaubetal.2016,
  author    = {Bomanson, Jori and Janhunen, Tomi and Schaub, Torsten H. and Gebser, Martin and Kaufmann, Benjamin},
  title     = {Answer Set Programming Modulo Acyclicity},
  series = {Fundamenta informaticae},
  volume    = {147},
  journal   = {Fundamenta informaticae},
  publisher = {IOS Press},
  address   = {Amsterdam},
  issn      = {0169-2968},
  doi       = {10.3233/FI-2016-1398},
  pages     = {63 -- 91},
  year      = {2016},
  abstract  = {Acyclicity constraints are prevalent in knowledge representation and applications where acyclic data structures such as DAGs and trees play a role. Recently, such constraints have been considered in the satisfiability modulo theories (SMT) framework, and in this paper we carry out an analogous extension to the answer set programming (ASP) paradigm. The resulting formalism, ASP modulo acyclicity, offers a rich set of primitives to express constraints related to recursive structures. In the technical results of the paper, we relate the new generalization with standard ASP by showing (i) how acyclicity extensions translate into normal rules, (ii) how weight constraint programs can be instrumented by acyclicity extensions to capture stability in analogy to unfounded set checking, and (iii) how the gap between supported and stable models is effectively closed in the presence of such an extension. Moreover, we present an efficient implementation of acyclicity constraints by incorporating a respective propagator into the state-of-the-art ASP solver CLASP. The implementation provides a unique combination of traditional unfounded set checking with acyclicity propagation. In the experimental part, we evaluate the interplay of these orthogonal checks by equipping logic programs with supplementary acyclicity constraints. The performance results show that native support for acyclicity constraints is a worthwhile addition, furnishing a complementary modeling construct in ASP itself as well as effective means for translation-based ASP solving.},
  language  = {en}
}
@article{GressmannJanhunenMerceretal.2005,
  author    = {Gressmann, Jean and Janhunen, Tomi and Mercer, Robert E. and Schaub, Torsten H. and Thiele, Sven and Tichy, Richard},
  title     = {Platypus : a platform for distributed answer set solving},
  year      = {2005},
  language  = {en}
}
@article{AngerGebserJanhunenetal.2006,
  author    = {Anger, Christian and Gebser, Martin and Janhunen, Tomi and Schaub, Torsten H.},
  title     = {What's a head without a body?},
  year      = {2006},
  language  = {en}
}
@article{GressmannJanhunenMerceretal.2006,
  author    = {Gressmann, Jean and Janhunen, Tomi and Mercer, Robert E. and Schaub, Torsten H. and Thiele, Sven and Tichy, Richard},
  title     = {On probing and multi-threading in platypus},
  year      = {2006},
  language  = {en}
}
@article{GressmannJanhunenMerceretal.2006,
  author    = {Gressmann, Jean and Janhunen, Tomi and Mercer, Robert E. and Schaub, Torsten H. and Thiele, Sven and Tichy, Richard},
  title     = {On probing and multi-threading in platypus},
  year      = {2006},
  language  = {en}
}