The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform
Derick Wood - One of the best experts on this subject based on the ideXlab platform.
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Structural Equivalence of regularly extended e0l grammars an automata theoretic proof
Lecture Notes in Computer Science, 2004Co-Authors: Kai Salomaa, Derick WoodAbstract:Regularly extended E0L grammars allow an infinite number of rules for a given nonterminal provided that the set of right sides of the rules for each nonterminal is a regular language. We show that Structural Equivalence remains decidable for regularly extended E0L grammars.
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Theory Is Forever - Structural Equivalence of Regularly Extended E0L Grammars: An Automata Theoretic Proof
Theory Is Forever, 2004Co-Authors: Kai Salomaa, Derick WoodAbstract:Regularly extended E0L grammars allow an infinite number of rules for a given nonterminal provided that the set of right sides of the rules for each nonterminal is a regular language. We show that Structural Equivalence remains decidable for regularly extended E0L grammars.
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Structural Equivalence and ET0L grammars
Theoretical Computer Science, 1996Co-Authors: Kai Salomaa, Derick WoodAbstract:For a given context-sensitive grammar G we construct ET0L grammars G1 and G2 that are Structurally equivalent if and only if the language generated by G is empty, which implies that Structural Equivalence is undecidable for ET0L grammars. This is in contrast to the decidability result for the E0L case. In fact, we show that Structural Equivalence is undecidable for propagating ET0L grammars even when the number of tables is restricted to be at most two. A stronger notion of Equivalence that requires the sets of syntax trees to be isomorphic is shown to be decidable for ET0L grammars.
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Complexity of E0L Structural Equivalence
RAIRO - Theoretical Informatics and Applications, 1995Co-Authors: Kai Salomaa, Derick WoodAbstract:We show that the EOL Structural Equivalence problem is logspace hard for deterministic exponential time. Also, we show that this question can be solved in linear space by a synchronized alternating Turing machine, and thus establish an exponential space upper bound for its complexity. The Equivalence of finite tree automata is shown to be logspace reducible to context-free Structural Equivalence. The converse reduction is well known and thus context-free Structural Equivalence is complete for deterministic exponential time.
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MFCS - Complexity of E0L Structural Equivalence
Mathematical Foundations of Computer Science 1994, 1994Co-Authors: Kai Salomaa, Derick WoodAbstract:We show that the EOL Structural Equivalence problem is logspace hard for deterministic exponential time. Also, we show that this question can be solved in linear space by a synchronized alternating Turing machine, and thus establish an exponential space upper bound for its complexity. The Equivalence of finite tree automata is shown to be logspace reducible to context-free Structural Equivalence. The converse reduction is well known and thus context-free Structural Equivalence is complete for deterministic exponential time.
Kai Salomaa - One of the best experts on this subject based on the ideXlab platform.
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Theory Is Forever - Structural Equivalence of Regularly Extended E0L Grammars: An Automata Theoretic Proof
Theory Is Forever, 2004Co-Authors: Kai Salomaa, Derick WoodAbstract:Regularly extended E0L grammars allow an infinite number of rules for a given nonterminal provided that the set of right sides of the rules for each nonterminal is a regular language. We show that Structural Equivalence remains decidable for regularly extended E0L grammars.
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Structural Equivalence of regularly extended e0l grammars an automata theoretic proof
Lecture Notes in Computer Science, 2004Co-Authors: Kai Salomaa, Derick WoodAbstract:Regularly extended E0L grammars allow an infinite number of rules for a given nonterminal provided that the set of right sides of the rules for each nonterminal is a regular language. We show that Structural Equivalence remains decidable for regularly extended E0L grammars.
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Decidability of EDT0L Structural Equivalence
Theoretical Computer Science, 2002Co-Authors: Kai SalomaaAbstract:We show that a tree pushdown automaton can verify, for an arbitrary nondeterministically constructed structure tree t, that t does not correspond to any valid derivation of a given EDT0L grammar. In this way we reduce the Structural Equivalence problem for EDT0L grammars to deciding emptiness of the tree language recognized by a tree pushdown automaton, i.e., to the emptiness problem for context-free tree languages. Thus we establish that Structural Equivalence for EDT0L grammars can be decided effectively. The result contrasts the known undecidability result for ET0L Structural Equivalence.
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Structural Equivalence and ET0L grammars
Theoretical Computer Science, 1996Co-Authors: Kai Salomaa, Derick WoodAbstract:For a given context-sensitive grammar G we construct ET0L grammars G1 and G2 that are Structurally equivalent if and only if the language generated by G is empty, which implies that Structural Equivalence is undecidable for ET0L grammars. This is in contrast to the decidability result for the E0L case. In fact, we show that Structural Equivalence is undecidable for propagating ET0L grammars even when the number of tables is restricted to be at most two. A stronger notion of Equivalence that requires the sets of syntax trees to be isomorphic is shown to be decidable for ET0L grammars.
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Complexity of E0L Structural Equivalence
RAIRO - Theoretical Informatics and Applications, 1995Co-Authors: Kai Salomaa, Derick WoodAbstract:We show that the EOL Structural Equivalence problem is logspace hard for deterministic exponential time. Also, we show that this question can be solved in linear space by a synchronized alternating Turing machine, and thus establish an exponential space upper bound for its complexity. The Equivalence of finite tree automata is shown to be logspace reducible to context-free Structural Equivalence. The converse reduction is well known and thus context-free Structural Equivalence is complete for deterministic exponential time.
Steven J. Skinner - One of the best experts on this subject based on the ideXlab platform.
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The Ties that Buy: The Role of Interfirm Social Contagion Across Customer Accounts
Journal of Personal Selling & Sales Management, 2011Co-Authors: Matthew Bowler, Robert Dahlstrom, Matthew T. Seevers, Steven J. SkinnerAbstract:This study investigates how purchase decisions may be influenced by ties linking customer account personnel and sales personnel. Two distinct forms of social contagion—cohesion and Structural Equivalence—are posited as mechanisms for triggering purchase similarity among customer accounts. We empirically test our hypotheses using field-collected sociometric data that captures social ties among customer accounts and sales personnel within a retail sales territory. The results support Structural Equivalence rather than cohesion as a key driver of brand choice similarity among retail firms. The paper concludes with a discussion of implications for sales management practice and research.
Rian Viviers - One of the best experts on this subject based on the ideXlab platform.
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Construct Equivalence of the OPQ32n for Black and White people in South Africa
SA Journal of Industrial Psychology, 2010Co-Authors: Delene Visser, Rian ViviersAbstract:Orientation: The construct Equivalence of the Occupational Personality Questionnaire (OPQ32n) for black and white groups was investigated. Research purpose: The objective was to investigate the Structural invariance of the OPQ32n for two South African population groups. Motivation for the study: The OPQ32n is often used for making a variety of personnel decisions in South Africa. Evidence regarding the suitability of personality questionnaires for use across South Africa’s various population groups is required by practitioners for selecting appropriate psychometric instruments. Research design, approach and method: Data were collected by means of a questionnaire and the results were analysed using quantitative statistical methods. The sample consisted of 248 Black and 476 White people from the SHL (South Africa) database. Structural equation modelling was used to examine the Structural Equivalence of the OPQ32n scale scores for these two groups. Main findings: A good fit regarding factor correlations and covariances on the 32 scales was obtained, partially supporting the Structural Equivalence of the questionnaire for the two groups. The analyses furthermore indicated that there was Structural invariance, with the effect of the Social Desirability scale partialled out. Practical/managerial implications: The present study focused on aspects of Structural Equivalence only. The OPQ32n therefore passed the first hurdle in this particular context, but further investigation is necessary to provide evidence that the questionnaire is suitable for use in personnel decisions comparing the population groups. Contribution: Despite the positive findings with regard to Structural Equivalence and social desirability response style, it should be borne in mind that no assumptions regarding full scale Equivalence can be made on the basis of the present findings.
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Construct Equivalence of the OPQ32n for Black and White people in South Africa : original research
Sa Journal of Industrial Psychology, 2010Co-Authors: Dalene Visser, Rian ViviersAbstract:Orientation : The construct Equivalence of the Occupational Personality Questionnaire (OPQ32n) for black and white groups was investigated. Research purpose : The objective was to investigate the Structural invariance of the OPQ32n for two South African population groups. Motivation for the study : The OPQ32n is often used for making a variety of personnel decisions in South Africa. Evidence regarding the suitability of personality questionnaires for use across South Africa's various population groups is required by practitioners for selecting appropriate psychometric instruments. Research design, approach and method : Data were collected by means of a questionnaire and the results were analysed using quantitative statistical methods. The sample consisted of 248 Black and 476 White people from the SHL (South Africa) database. Structural equation modelling was used to examine the Structural Equivalence of the OPQ32n scale scores for these two groups. Main findings : A good fit regarding factor correlations and covariances on the 32 scales was obtained, partially supporting the Structural Equivalence of the questionnaire for the two groups. The analyses furthermore indicated that there was Structural invariance, with the effect of the Social Desirability scale partialled out. Practical/managerial implications : The present study focused on aspects of Structural Equivalence only. The OPQ32n therefore passed the first hurdle in this particular context, but further investigation is necessary to provide evidence that the questionnaire is suitable for use in personnel decisions comparing the population groups. Contribution : Despite the positive findings with regard to Structural Equivalence and social desirability response style, it should be borne in mind that no assumptions regarding full scale Equivalence can be made on the basis of the present findings.
Ype H. Poortinga - One of the best experts on this subject based on the ideXlab platform.
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Structural Equivalence in Multilevel Research
Journal of Cross-Cultural Psychology, 2002Co-Authors: Fons J. R. Van De Vijver, Ype H. PoortingaAbstract:In cross-cultural research, there is an increasing interest in the comparison of constructs at different levels of aggregation, such as the use of individualism—collectivism at the individual and country levels. A procedure is described for establishing Structural Equivalence (i.e., similarity of psychological meaning) at various levels of aggregation based on exploratory factor analysis. A construct shows Structural Equivalence across aggregation levels if its factor structure is invariant across levels. The procedure was applied to the Postmaterialism scale of the World Values Survey. The similarity of postmaterialism at the individual and country levels could not be unambiguously demonstrated; a likely reason is that the concept does not have an identical meaning in countries with low and high gross national products.
