The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Madhav V Marathe - One of the best experts on this subject based on the ideXlab platform.
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Formal Language constrained path problems
SIAM Journal on Computing, 2000Co-Authors: Christopher L Barrett, Riko Jacob, Madhav V MaratheAbstract:Given an alphabet $\Sigma$, a (directed) graph G whose edges are weighted and $\Sigma$-labeled, and a Formal Language $L\subseteq\Sigma^*$, the Formal-Language-constrained shortest/simple path problem consists of finding a shortest (simple) path p in G complying with the additional constraint that l(p) \in L$. Here l(p) denotes the unique word obtained by concatenating the $\Sigma$-labels of the edges along the path p. The main contributions of this paper include the following: We show that the Formal-Language-constrained shortest path problem is solvable efficiently in polynomial time when L is restricted to be a context-free Language (CFL). When L is specified as a regular Language we provide algorithms with improved space and time bounds. In contrast, we show that the problem of finding a simple path between a source and a given destination is NP-hard, even when L is restricted to fixed simple regular Languages and to very simple classes of graphs (e.g., complete grids). For the class of treewidth-bounded graphs, we show that (i) the problem of finding a regular-Language-constrained simple path between source and destination is solvable in polynomial time and (ii) the extension to finding CFL-constrained simple paths is NP-complete. Our results extend the previous results in [SIAM J. Comput., 24 (1995), pp. 1235--1258; Proceedings of the 76th Annual Meeting of the Transportation Research Board, 1997; and Proceedings of the 9th ACM SIGACT-SIGMOD-SIGART Symposium on Database Systems, 1990, pp. 230--242]. Several additional extensions and applications of our results in the context of transportation problems are presented. For instance, as a corollary of our results, we obtain a polynomial-time algorithm for the best k-similar path problem studied in Proceedings of the 76th Annual Meeting of the Transportation Reasearch Board, 1997]. The previous best algorithm was given by [ Proceedings of the 76th Annual Meeting of the Transportation Research Board, 1997] and takes exponential time in the worst case.
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Formal Language constrained path problems
Scandinavian Workshop on Algorithm Theory, 1998Co-Authors: Christopher L Barrett, Riko Jacob, Madhav V MaratheAbstract:Given an alphabet σ, a (directed) graph G whose edges are weighted and σ-labeled, and a Formal Language L \(\subseteq\) σ*, we consider the problem of finding a shortest (simple) path p in G complying with the additional constraint that l(p) ∃ L. Here l(p) denotes the unique word given by concatenating the σ-labels in G along the path p.
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Formal Language constrained path problems
Symposium on Discrete Algorithms, 1997Co-Authors: Christopher L Barrett, Riko Jacob, Madhav V MaratheAbstract:In many path finding problems arising in practice, certain patterns of edge/vertex labels in the labeled graph being traversed are allowed/preferred, while others are disallowed. Motivated by such applications as intermodal transportation planning, the authors investigate the complexity of finding feasible paths in a labeled network, where the mode choice for each traveler is specified by a Formal Language. The main contributions of this paper include the following: (1) the authors show that the problem of finding a shortest path between a source and destination for a traveler whose mode choice is specified as a context free Language is solvable efficiently in polynomial time, when the mode choice is specified as a regular Language they provide algorithms with improved space and time bounds; (2) in contrast, they show that the problem of finding simple paths between a source and a given destination is NP-hard, even when restricted to very simple regular expressions and/or very simple graphs; (3) for the class of treewidth bounded graphs, they show that (i) the problem of finding a regular Language constrained simple path between source and a destination is solvable in polynomial time and (ii) the extension to finding context free Language constrained simple paths is NP-complete. Several extensions of these results are presented in the context of finding shortest paths with additional constraints. These results significantly extend the results in [MW95]. As a corollary of the results, they obtain a polynomial time algorithm for the BEST k-SIMILAR PATH problem studied in [SJB97]. The previous best algorithm was given by [SJB97] and takes exponential time in the worst case.
Christopher L Barrett - One of the best experts on this subject based on the ideXlab platform.
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Formal Language constrained path problems
SIAM Journal on Computing, 2000Co-Authors: Christopher L Barrett, Riko Jacob, Madhav V MaratheAbstract:Given an alphabet $\Sigma$, a (directed) graph G whose edges are weighted and $\Sigma$-labeled, and a Formal Language $L\subseteq\Sigma^*$, the Formal-Language-constrained shortest/simple path problem consists of finding a shortest (simple) path p in G complying with the additional constraint that l(p) \in L$. Here l(p) denotes the unique word obtained by concatenating the $\Sigma$-labels of the edges along the path p. The main contributions of this paper include the following: We show that the Formal-Language-constrained shortest path problem is solvable efficiently in polynomial time when L is restricted to be a context-free Language (CFL). When L is specified as a regular Language we provide algorithms with improved space and time bounds. In contrast, we show that the problem of finding a simple path between a source and a given destination is NP-hard, even when L is restricted to fixed simple regular Languages and to very simple classes of graphs (e.g., complete grids). For the class of treewidth-bounded graphs, we show that (i) the problem of finding a regular-Language-constrained simple path between source and destination is solvable in polynomial time and (ii) the extension to finding CFL-constrained simple paths is NP-complete. Our results extend the previous results in [SIAM J. Comput., 24 (1995), pp. 1235--1258; Proceedings of the 76th Annual Meeting of the Transportation Research Board, 1997; and Proceedings of the 9th ACM SIGACT-SIGMOD-SIGART Symposium on Database Systems, 1990, pp. 230--242]. Several additional extensions and applications of our results in the context of transportation problems are presented. For instance, as a corollary of our results, we obtain a polynomial-time algorithm for the best k-similar path problem studied in Proceedings of the 76th Annual Meeting of the Transportation Reasearch Board, 1997]. The previous best algorithm was given by [ Proceedings of the 76th Annual Meeting of the Transportation Research Board, 1997] and takes exponential time in the worst case.
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Formal Language constrained path problems
Scandinavian Workshop on Algorithm Theory, 1998Co-Authors: Christopher L Barrett, Riko Jacob, Madhav V MaratheAbstract:Given an alphabet σ, a (directed) graph G whose edges are weighted and σ-labeled, and a Formal Language L \(\subseteq\) σ*, we consider the problem of finding a shortest (simple) path p in G complying with the additional constraint that l(p) ∃ L. Here l(p) denotes the unique word given by concatenating the σ-labels in G along the path p.
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Formal Language constrained path problems
Symposium on Discrete Algorithms, 1997Co-Authors: Christopher L Barrett, Riko Jacob, Madhav V MaratheAbstract:In many path finding problems arising in practice, certain patterns of edge/vertex labels in the labeled graph being traversed are allowed/preferred, while others are disallowed. Motivated by such applications as intermodal transportation planning, the authors investigate the complexity of finding feasible paths in a labeled network, where the mode choice for each traveler is specified by a Formal Language. The main contributions of this paper include the following: (1) the authors show that the problem of finding a shortest path between a source and destination for a traveler whose mode choice is specified as a context free Language is solvable efficiently in polynomial time, when the mode choice is specified as a regular Language they provide algorithms with improved space and time bounds; (2) in contrast, they show that the problem of finding simple paths between a source and a given destination is NP-hard, even when restricted to very simple regular expressions and/or very simple graphs; (3) for the class of treewidth bounded graphs, they show that (i) the problem of finding a regular Language constrained simple path between source and a destination is solvable in polynomial time and (ii) the extension to finding context free Language constrained simple paths is NP-complete. Several extensions of these results are presented in the context of finding shortest paths with additional constraints. These results significantly extend the results in [MW95]. As a corollary of the results, they obtain a polynomial time algorithm for the BEST k-SIMILAR PATH problem studied in [SJB97]. The previous best algorithm was given by [SJB97] and takes exponential time in the worst case.
Riko Jacob - One of the best experts on this subject based on the ideXlab platform.
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Formal Language constrained path problems
SIAM Journal on Computing, 2000Co-Authors: Christopher L Barrett, Riko Jacob, Madhav V MaratheAbstract:Given an alphabet $\Sigma$, a (directed) graph G whose edges are weighted and $\Sigma$-labeled, and a Formal Language $L\subseteq\Sigma^*$, the Formal-Language-constrained shortest/simple path problem consists of finding a shortest (simple) path p in G complying with the additional constraint that l(p) \in L$. Here l(p) denotes the unique word obtained by concatenating the $\Sigma$-labels of the edges along the path p. The main contributions of this paper include the following: We show that the Formal-Language-constrained shortest path problem is solvable efficiently in polynomial time when L is restricted to be a context-free Language (CFL). When L is specified as a regular Language we provide algorithms with improved space and time bounds. In contrast, we show that the problem of finding a simple path between a source and a given destination is NP-hard, even when L is restricted to fixed simple regular Languages and to very simple classes of graphs (e.g., complete grids). For the class of treewidth-bounded graphs, we show that (i) the problem of finding a regular-Language-constrained simple path between source and destination is solvable in polynomial time and (ii) the extension to finding CFL-constrained simple paths is NP-complete. Our results extend the previous results in [SIAM J. Comput., 24 (1995), pp. 1235--1258; Proceedings of the 76th Annual Meeting of the Transportation Research Board, 1997; and Proceedings of the 9th ACM SIGACT-SIGMOD-SIGART Symposium on Database Systems, 1990, pp. 230--242]. Several additional extensions and applications of our results in the context of transportation problems are presented. For instance, as a corollary of our results, we obtain a polynomial-time algorithm for the best k-similar path problem studied in Proceedings of the 76th Annual Meeting of the Transportation Reasearch Board, 1997]. The previous best algorithm was given by [ Proceedings of the 76th Annual Meeting of the Transportation Research Board, 1997] and takes exponential time in the worst case.
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Formal Language constrained path problems
Scandinavian Workshop on Algorithm Theory, 1998Co-Authors: Christopher L Barrett, Riko Jacob, Madhav V MaratheAbstract:Given an alphabet σ, a (directed) graph G whose edges are weighted and σ-labeled, and a Formal Language L \(\subseteq\) σ*, we consider the problem of finding a shortest (simple) path p in G complying with the additional constraint that l(p) ∃ L. Here l(p) denotes the unique word given by concatenating the σ-labels in G along the path p.
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Formal Language constrained path problems
Symposium on Discrete Algorithms, 1997Co-Authors: Christopher L Barrett, Riko Jacob, Madhav V MaratheAbstract:In many path finding problems arising in practice, certain patterns of edge/vertex labels in the labeled graph being traversed are allowed/preferred, while others are disallowed. Motivated by such applications as intermodal transportation planning, the authors investigate the complexity of finding feasible paths in a labeled network, where the mode choice for each traveler is specified by a Formal Language. The main contributions of this paper include the following: (1) the authors show that the problem of finding a shortest path between a source and destination for a traveler whose mode choice is specified as a context free Language is solvable efficiently in polynomial time, when the mode choice is specified as a regular Language they provide algorithms with improved space and time bounds; (2) in contrast, they show that the problem of finding simple paths between a source and a given destination is NP-hard, even when restricted to very simple regular expressions and/or very simple graphs; (3) for the class of treewidth bounded graphs, they show that (i) the problem of finding a regular Language constrained simple path between source and a destination is solvable in polynomial time and (ii) the extension to finding context free Language constrained simple paths is NP-complete. Several extensions of these results are presented in the context of finding shortest paths with additional constraints. These results significantly extend the results in [MW95]. As a corollary of the results, they obtain a polynomial time algorithm for the BEST k-SIMILAR PATH problem studied in [SJB97]. The previous best algorithm was given by [SJB97] and takes exponential time in the worst case.
Martin Von Löwis - One of the best experts on this subject based on the ideXlab platform.
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Engineering the SDL Formal Language definition
Lecture Notes in Computer Science, 2020Co-Authors: Andreas Prinz, Martin Von LöwisAbstract:With the latest revision of the ITU-T Specification and Description Language (SDL-2000), a Formal Language definition based on the concept of State Machines (ASMs) became integral part of the standard. Together with the Formal definition, we have developed software tools that allow executing the Formal Language definition on a computer. In doing so, we found that tools greatly help to eliminate numerous errors from the Formal definition, which likely would have not been found without tools.
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FMOODS - Engineering the SDL Formal Language Definition
Lecture Notes in Computer Science, 2003Co-Authors: Andreas Prinz, Martin Von LöwisAbstract:With the latest revision of the ITU-T Specification and Description Language (SDL-2000), a Formal Language definition based on the concept of Abstract State Machines (ASMs) became integral part of the standard. Together with the Formal definition, we have developed software tools that allow executing the Formal Language definition on a computer. In doing so, we found that tools greatly help to eliminate numerous errors from the Formal definition, which likely would have not been found without tools.
Qian Hu - One of the best experts on this subject based on the ideXlab platform.
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IRI - A Formal Language for Writing Contracts
Advances in Intelligent Systems and Computing, 2017Co-Authors: William M Farmer, Qian HuAbstract:A contract is an artifact that records an agreement made by the parties of the contract. Although contracts are considered to be legally binding and can be very complex, they are usually expressed in an inFormal Language that does not have a precise semantics. As a result, it is often not clear what a contract is intended to say. This is particularly true for contracts, like financial derivatives, that express agreements that depend on certain things that can be observed over time such as actions taken of the parties, events that happen, and values (like a stock price) that fluctuate with respect to time. As the complexity of the world and human interaction grows, contracts are naturally becoming more complex. Continuing to write complex contracts in natural Language is not sustainable if we want the contracts to be understandable and analyzable. A better approach is to write contracts in a Formal Language with a precise semantics. Contracts expressed in such a Language have a mathematically precise meaning and can be manipulated by software. The Formal Language thus provides a basis for integrating Formal methods into contracts. This paper outlines a Formal Language with a precise semantics for expressing general contracts that may depend on temporally based conditions. We argue that the Language is more effective for writing and analyzing contracts than previously proposed Formal contract Languages.
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a Formal Language for writing contracts
Information Reuse and Integration, 2016Co-Authors: William M Farmer, Qian HuAbstract:A contract is an artifact that records an agreement made by the parties of the contract. Although contracts are considered to be legally binding and can be very complex, they are usually expressed in an inFormal Language that does not have a precise semantics. As a result, it is often not clear what a contract is intended to say. This is particularly true for contracts, like financial derivatives, that express agreements that depend on certain things that can be observed over time such as actions taken of the parties, events that happen, and values (like a stock price) that fluctuate with respect to time. As the complexity of the world and human interaction grows, contracts are naturally becoming more complex. Continuing to write complex contracts in natural Language is not sustainable if we want the contracts to be understandable and analyzable. A better approach is to write contracts in a Formal Language with a precise semantics. Contracts expressed in such a Language have a mathematically precise meaning and can be manipulated by software. The Formal Language thus provides a basis for integrating Formal methods into contracts. This paper outlines a Formal Language with a precise semantics for expressing general contracts that may depend on temporally based conditions. We argue that the Language is more effective for writing and analyzing contracts than previously proposed Formal contract Languages.
