Linear pattern matching algorithms

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Compression of finite AbstractSeveral linear-time algorithms for automata-based pattern matching rely on failure transitions for efficient back-tracking. Like epsilon transitions, failure transition do not consume input symbols, but unlike them, they may only be taken when no other transition is applicable. At a semantic level, this conveniently models catch-all clauses and allows for compact language representation. This work investigates the transition-reduction problem for deterministic finite-state automata (DFA). The input is a DFA A and an integer k. The question is whether k or more transitions can be saved by replacing regular transitions with failure transitions. We show that while the problem is NP -complete, there are approximation techniques and heuristics that mitigate the computational complexity. We conclude by demonstrating the computational difficulty of two related minimisation problems, thereby cancelling the ongoing search for efficient algorithms.

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“…In this context, failure transitions are sometimes treated under the name suffix links (Weiner, 1973).…”

Section: Related Workmentioning

confidence: 99%

Compression of finite-state automata through failure transitions

Björklund

Zechner

2014

Theoretical Computer Science

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“…For efficiency, the graph is stored as a probabilistic suffix tree [11] enhanced to encapsulate different information and metrics regarding each interaction [10] . An example of this representation is displayed in Figure 1.…”

Section: Shared Memories Coordination Enginementioning

confidence: 99%

Shared Memories: A Trail-based Coordination Server for Robot Teams

Roussos¹,

Papadogkonas²,

Taylor³

et al. 2007

The Proceedings of First International Conference on Robot Communication and Coordination

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Abstract-Robust, dependable and concise coordination between members of a robot team is a critical ingredient of any such collective activity. Depending on the availability and the characteristics of the particular communication infrastructure, coordination mechanisms can take varied forms, leading to distinct system behaviors. In this paper, we consider the case of robot teams operating within relatively sparse wireless sensor network deployments. We introduce Shared Memories, a trailbased coordination engine, that analyzes interaction patterns between participating team members and sensor network nodes capable to discover significant aggregate patterns, which are made available to the team. To this end, we propose a model for the representation of captured interactions and their sensory context developed as a probabilistic grammar, as well as associated metrics used to rank trails and quantify their significance. Such trails are used as the basis for coordinated operation in team tasks and are made available by the engine to all team members. Our implementation deploys ad-hoc wireless local networking capability available through surrogate devices to commodity robots and RFID proximity sensors. We report on the performance of this system in experiments conducted in a laboratory environment, which highlight the advantages and limitations of our approach. I. INTRODUCTIONThe traditional robotics approach in capturing environmental information is one of self-sufficiency, that is each agent employs its own sensing capability to make sense of the environment around it and make task-related and navigation decisions. This mode of operation is challenged by two relatively recent developments: the wider availability of wireless adhoc networks which offer advanced networking opportunities; and the rapid proliferation of wireless sensor networks which establish a richer source of environmental information that can be employed to improve operational effectiveness. This recent shift in focus inevitably places greater importance in teams rather than individuals and the use of extended sensing capabilities as the enabler of new off-device functionalities. A critical challenge in capitalizing on these new developments is the management of the collective experience acquired in such a way, and the extraction of useful and usable knowledge.In this paper we propose a particular approach in organizing the collective information harvested by a robotic team and effective ways of providing cues for coordination employing a trail-based approach. We show within a simple feasibility study of this proposal how this approach can provide the foundation for effective coordinated operation. In addition to the use of trail records as the principle data primitive, our

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“…It is a generalization of the well-known suffix tree of a set of sequences [65,16], which is one of the most important data structures in the field of pattern recognition. Such a suffix tree has O(n 1 + · · · + n k ) nodes and can be constructed in O(n 1 + · · · + n k ) time by several algorithms [65,30,58,12,16].…”

Section: Suffix-set Treesmentioning

confidence: 99%

Multiple Sequence Alignment Based on Set Covers

Porto

Barbosa

2006

Lecture Notes in Computer Science

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We introduce a new heuristic for the multiple alignment of a set of sequences. The heuristic is based on a set cover of the residue alphabet of the sequences, and also on the determination of a significant set of blocks comprising subsequences of the sequences to be aligned. These blocks are obtained with the aid of a new data structure, called a suffix-set tree, which is constructed from the input sequences with the guidance of the residue-alphabet set cover and generalizes the well-known suffix tree of the sequence set. We provide performance results on selected BAliBASE amino-acid sequences and compare them with those yielded by some prominent approaches.

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Linear pattern matching algorithms

Cited by 1,338 publications

References 3 publications

Compression of finite-state automata through failure transitions

Compression of finite-state automata through failure transitions

Shared Memories: A Trail-based Coordination Server for Robot Teams

Multiple Sequence Alignment Based on Set Covers

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