G. Slutzki

Publications of G. Slutzki

• Federated ALCI: Preliminary Report

  Authors: G. Voutsadakis, G. Slutzki, V. Honavar, Jie Bao

  Web Intelligence and Intelligent Agent Technology, 2008. WI-IAT '08. IEEE/WIC/ACM International Conference on; 01/2009

  We introduce F-ALCI, a federated version of the description logic ALCI. An F-ALCI ontology, like its package-based counterpart ALCIP^-, consists of multiple ALCI ontologies that can importWe introduce F-ALCI, a federated version of the description logic ALCI. An F-ALCI ontology, like its package-based counterpart ALCIP^-, consists of multiple ALCI ontologies that can import concepts or roles defined in other modules. Unlike ALCIP^- which supports only contextualized negation, F-ALCI, supports contextualization of each of the logical connectives, a feature that allows more flexible reuse of knowledge from independently developed ontologies. We provide a new semantics for F-ALCI based on image domain relations and establish the conditions that need to be imposed on domain relations to ensure properties, such as preservation of unsatisfiability and monotonicity of inference, that are desirable in distributed web applications. We also establish the decidability of F-ALCI.

• Privacy-Preserving Reasoning on the SemanticWeb

  Authors: Jie Bao, G. Slutzki, V. Honavar

  Web Intelligence, IEEE/WIC/ACM International Conference on; 12/2007

  Many semantic web applications require selective sharing of ontologies between autonomous entities due to copyright, privacy or security concerns. In such cases, an agent might want to hide a part ofMany semantic web applications require selective sharing of ontologies between autonomous entities due to copyright, privacy or security concerns. In such cases, an agent might want to hide a part of its ontology while sharing the rest. However, prohibiting any use of the hidden part of the ontology in answering queries from other agents may be overly restrictive. We provide a framework for privacy- preserving reasoning in which an agent can safely answer queries against its knowledge base using inferences based on both the hidden and visible part of the knowledge base, without revealing the hidden knowledge. We show an application of this framework in the widely used special case of hierarchical ontologies.

• A complete pursuit-evasion algorithm for two pursuers using beam detection

  Authors: B.H. Simov, S.M. LaValle, G. Slutzki

  Robotics and Automation, 2002. Proceedings. ICRA '02. IEEE International Conference on; 02/2002

  We present an algorithm for a pair of pursuers, each with one rotating beam (flashlight, laser or a camera), searching for an unpredictable, moving target in a 2D environment (simple polygon). GivenWe present an algorithm for a pair of pursuers, each with one rotating beam (flashlight, laser or a camera), searching for an unpredictable, moving target in a 2D environment (simple polygon). Given a polygon with n edges, the algorithm decides in time O(n⁴) whether it can be cleared by the pursuers, and if so, constructs a search schedule. The pursuers are allowed to move on. the boundary and in the interior of the polygon. They are not required to maintain mutual visibility throughout the pursuit.

• Pursuit-evasion using beam detection

  Authors: B.H. Simov, G. Slutzki, S.M. LaValle

  Robotics and Automation, 2000. Proceedings. ICRA '00. IEEE International Conference on; 02/2000

  We present an algorithm for searching a 2D environment for unpredictable moving targets using only beam-based detection. One or more pursuers move along the environment boundary, and carry aWe present an algorithm for searching a 2D environment for unpredictable moving targets using only beam-based detection. One or more pursuers move along the environment boundary, and carry a rotating beam that detects evaders. The beam could correspond in practice to a laser or a camera. The task is to compute motions for pursuers and their beams that ensure that all evaders will be detected. For a 2D polygonal environment, we solve a long-standing open problem by presenting a complete O(n³)-time algorithm that is guaranteed to find a successful motion strategy for a single pursuer and its beam, if a solution exists. This algorithm is extended to the case of coordinating multiple pursuers, but the number of pursuers used in a solution is not necessarily optimal. An implementation is presented, and several computed examples are shown

• Computational complexity of some problems involving congruences on algebras

  Authors: C. Bergman, G. Slutzki

  Logic in Computer Science, 2000. Proceedings. 15th Annual IEEE Symposium on; 02/2000

  We prove that several problems concerning congruences on algebras are complete for nondeterministic log-space. These problems are: determining the congruence on a given algebra generated by a setWe prove that several problems concerning congruences on algebras are complete for nondeterministic log-space. These problems are: determining the congruence on a given algebra generated by a set of pairs, and determining whether a given algebra is simple or subdirectly irreducible. We also consider the problem of determining the smallest fully invariant congruence on a given algebra containing a given set of pairs. We prove that this problem is complete for nondeterministic polynomial time

• Bounds for parametric sequence comparison

  Authors: D. Fernandez-Baca, T. Seppalainen, G. Slutzki

  String Processing and Information Retrieval Symposium, 1999 and International Workshop on Groupware; 02/1999

  We consider the problem of computing a global alignment between two or more sequences subject to varying mismatch and indel penalties. We prove a tight 3(n/2π)^2/3+O(n^1/3logn)We consider the problem of computing a global alignment between two or more sequences subject to varying mismatch and indel penalties. We prove a tight 3(n/2π)^2/3+O(n^1/3logn) bound on the worst-case number of distinct optimum alignments for two sequences of length n as the parameters are varied. This refines a O(n ^2/3) upper bound by D. Gusfield et al. (1994). Our lower bound requires an unbounded alphabet. For strings over a binary alphabet, we prove a Ω(n^1/2) lower bound. For the parametric global alignment of k⩾2 sequences under sum-of-pairs scoring, we prove a 3((k/2)n/2π)^2/3+O(k^2/3n^1/3logn) upper bound on the number of distinct optimality regions and a Ω(n ^2/3) lower bound. Based on experimental evidence, we conjecture that for two random sequences, the number of optimality regions is approximately √n with high probability

• Distributing tokens on a hypercube without error accumulation

  Authors: B.S. Chlebus, J.D.P. Rolim, G. Slutzki

  Parallel Processing Symposium, 1996., Proceedings of IPPS '96, The 10th International; 05/1996

  The problem of load balancing on the hypercube is considered. A number of tokens are placed at the nodes and the goal is to redistribute them evenly throughout the network. Initially, each of the pThe problem of load balancing on the hypercube is considered. A number of tokens are placed at the nodes and the goal is to redistribute them evenly throughout the network. Initially, each of the p nodes stores up to m tokens. A simple algorithm is presented, operating in 𝒪(log p+m·log log p) time on average

• Fast algorithms for inferring evolutionary trees.

  Authors: R Agarwala, D Fernández-Baca, G Slutzki

  Journal of computational biology : a journal of computational molecular cell biology. 02/1995; 2(3):397-407.

  We present algorithms for the perfect phylogeny problem restricted to binary characters. The first algorithm is faster than a previous algorithm by Gusfield when the input matrix for the problem isWe present algorithms for the perfect phylogeny problem restricted to binary characters. The first algorithm is faster than a previous algorithm by Gusfield when the input matrix for the problem is sparse. Next, we present two online algorithms. For the first of these, the set of species is fixed and the characters are given as input one at a time, while, for the second, the set of characters is fixed and the species are given as input one at a time. These two online algorithms are then combined into an algorithm that can process any sequence of additions and deletions of species and characters.