Pushing the EL Envelope
- F. Baader, S. Brandt, C. Lutz
- Computer ScienceInternational Joint Conference on Artificial…
- 30 July 2005
This work will extend the positive result for EL by identifying a set of expressive means that can be added to EL without sacrificing tractability and show that basically all other additions of typical DL constructors to EL with GCIs make subsumption intractable, and in most cases even EXPTIME-complete.
Pushing the EL Envelope Further
This work extends the description logic EL with reflexive roles and range restrictions, and proves that tractability is lost when symmetric roles are added and subsumption becomes ExpTimehard.
Polynomial Time Reasoning in a Description Logic with Existential Restrictions, GCI Axioms, and - What Else?
- S. Brandt
- Computer ScienceEuropean Conference on Artificial Intelligence
- 22 August 2004
It is shown that even admitting general concept inclusion (GCI) axioms and role hierarchies in ℇL terminologies preserves the polynomial time upper bound for subsumption, and implication of the first result is that reasoning over the widely used medical terminology SNOMED is possible in polynometric time.
On consistent migration of flows in SDNs
- S. Brandt, Klaus-Tycho Förster, Roger Wattenhofer
- Computer ScienceIEEE INFOCOM - The 35th Annual IEEE…
- 10 April 2016
It is proved that deciding what flows need to be removed is an NP-hard optimization problem with no PTAS possible unless P = NP, and the maximum increase can be approximated arbitrarily well in polynomial time.
A lower bound for the distributed Lovász local lemma
- S. Brandt, O. Fischer, Jara Uitto
- Computer Science, MathematicsSymposium on the Theory of Computing
- 3 November 2015
We show that any randomised Monte Carlo distributed algorithm for the Lovász local lemma requires Omega(log log n) communication rounds, assuming that it finds a correct assignment with high…
Approximation and Difference in Description Logics
It is proved that approximations from the Description Logic ALC to ALE always exist and an algorithm computing them is proposed and a syntax-oriented difference operator is introduced, which yields a concept description that contains all aspects of the approximated concept that are not present in the approximation.
Collaboration Without Communication: Evacuating Two Robots from a Disk
A powerful new criterion is formulated that, for a given algorithm, reduces the number of possible worst-case exits radically radically and can be applied to any area shape.
An Automatic Speedup Theorem for Distributed Problems
- S. Brandt
- Computer Science, MathematicsACM SIGACT-SIGOPS Symposium on Principles of…
- 26 February 2019
A first application of the generalized speedup technique is solved, showing that weak 2-coloring in odd-degree graphs cannot be solved in o(łog^* Δ) rounds, thereby providing a matching lower bound to their upper bound.
Lower Bounds for Maximal Matchings and Maximal Independent Sets
- A. Balliu, S. Brandt, J. Hirvonen, D. Olivetti, M. Rabie, J. Suomela
- Computer Science, MathematicsIEEE Annual Symposium on Foundations of Computer…
- 8 January 2019
It follows that there is no deterministic algorithm for maximal matchings or maximal independent sets that runs in o(Δ + log n / log log n) rounds; this is an improvement over prior lower bounds also as a function of n.
Reasoning in ELH w.r.t. General Concept Inclusion Axioms
- S. Brandt
- Computer Science
This paper shows that even admitting general concept inclusion (GCI) axioms and role hierarchies in EL terminologies preserves the polynomial time upper bound for subsumption, and shows that subsumption becomes co-NP hard when adding one of the constructors number restriction, disjunction, and `allsome', an operator used in the DL k-rep.