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...e number of times xi and yj share a constituent). To make the graph complete, we add zero weight edges between induced and target labels that do not share any constituent. The Kuhn-Munkres algorithm (=-=Kuhn, 1955-=-; Munkres, 1957) solves this problem, and we used it to perform the LL mapping (see also (Luo, 2005)). We assessed the overall quality of our algorithm, the quality of its labeling stage and the quali...

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...ally POS tagged corpus enables us to measure the performance of other induction stages in a controlled manner. Since supervised POS tagging is of very high quality and very efficient computationally (=-=Brants, 2000-=-), this requirement does not seriously limit the practical applicability of a grammar induction algorithm. Our labeled bracketings induction algorithm consists of three stages. We first induce unlabel...

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...times xi and yj share a constituent). To make the graph complete, we add zero weight edges between induced and target labels that do not share any constituent. The Kuhn-Munkres algorithm (Kuhn, 1955; =-=Munkres, 1957-=-) solves this problem, and we used it to perform the LL mapping (see also (Luo, 2005)). We assessed the overall quality of our algorithm, the quality of its labeling stage and the quality of the synta...

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...Licensed under the Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported license (http://creativecommons.org/licenses/by-nc-sa/3.0/). Some rights reserved. mar. Most recent work (e.g., (=-=Klein and Manning, 2004-=-; Dennis, 2005; Bod, 2006a; Smith and Eisner, 2006; Seginer, 2007)) annotates text sentences using a hierarchical bracketing (constituents) or a dependency structure, and thus represents the induced g...

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...ocus on the induction of labeled bracketing. Bayesian Model Merging 2 Using, as they did, a greedy mapping with an equal number of labels in the induced and target grammars. 722(BMM) (Stolcke, 1994; =-=Stolcke and Omohundro, 1994-=-) is a framework for inducing PCFG containing both a bracketing and a labeling. The characteristics of this framework (separating prior probability, data likelihood and heuristic search procedures) ca...

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...this paper we focus on the induction of labeled bracketing. Bayesian Model Merging 2 Using, as they did, a greedy mapping with an equal number of labels in the induced and target grammars. 722(BMM) (=-=Stolcke, 1994-=-; Stolcke and Omohundro, 1994) is a framework for inducing PCFG containing both a bracketing and a labeling. The characteristics of this framework (separating prior probability, data likelihood and he...

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...ch as the WSJ PennTreebank. Recently, works along this line have for the first time outperformed the right branching heuristic baseline for English. These include the constituent–context model (CCM) (=-=Klein and Manning, 2002-=-), its extension using a dependency model (Klein and Manning, 2004), (U)DOP based models (Bod, 2006a; Bod, 2006b; Bod, 2007), an exemplar– based approach (Dennis, 2005), guiding EM using contrastive e...

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...requires POS tags for its labeling stages. Parts-of-speech are widely considered to have a psychological reality (at least in English, including when they are viewed as low-level constructions as in (=-=Croft, 2001-=-)), so this kind of input is reasonable for theoretical research. Moreover, as POS induction is of medium quality (Clark, 2003), using a manually POS tagged corpus enables us to measure the performanc...

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...rk (separating prior probability, data likelihood and heuristic search procedures) can also be found in the grammar induction models of (Wolf, 1982; Langley and Stromsten, 2000; Petasis et al., 2004; =-=Solan et al., 2005-=-). The BMM model used here (Borensztajn and Zuidema, 2007) combines features of (Petasis et al., 2004) and Stolcke’s algorithm, applying the minimum description length (MDL) principle. We use it here ...

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...es between induced and target labels that do not share any constituent. The Kuhn-Munkres algorithm (Kuhn, 1955; Munkres, 1957) solves this problem, and we used it to perform the LL mapping (see also (=-=Luo, 2005-=-)). We assessed the overall quality of our algorithm, the quality of its labeling stage and the quality of the syntactic clustering (SC) stage. For the overall quality of the induced grammar (both bra...

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...human language acquisition (in particular, an empirical study of the poverty of stimulus hypothesis), preprocessing for constructing large treebanks (Van Zaanen, 2001), and improving language models (=-=Chen, 1995-=-). In recent years efforts have been made to evaluate the algorithms on manually annotated corpora such as the WSJ PennTreebank. Recently, works along this line have for the first time outperformed th...

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...nguistic and psycho-linguistic theories posit some kind of a hierarchical labeled constituent (or constructional) structure, arguing that it has a measurable psychological (cognitive) reality (e.g., (=-=Goldberg, 2006-=-)). The main practical arguments in favor of this approach are that it enables a detailed and large-scale evaluation using annotated corpora, as is done in this paper, and that the output format is su...

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...English, including when they are viewed as low-level constructions as in (Croft, 2001)), so this kind of input is reasonable for theoretical research. Moreover, as POS induction is of medium quality (=-=Clark, 2003-=-), using a manually POS tagged corpus enables us to measure the performance of other induction stages in a controlled manner. Since supervised POS tagging is of very high quality and very efficient co...

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...s, except of Seginer’s algorithm, which uses plain text. All of these papers induce unlabeled bracketing or dependencies. There are other algorithmic approaches to the problem (e.g., (Adriaans, 1992; =-=Daelemans, 1995-=-; Van Zaanen, 2001)). None of these had evaluated labeled bracketing on annotated corpora. In this paper we focus on the induction of labeled bracketing. Bayesian Model Merging 2 Using, as they did, a...

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....0 Unported license (http://creativecommons.org/licenses/by-nc-sa/3.0/). Some rights reserved. mar. Most recent work (e.g., (Klein and Manning, 2004; Dennis, 2005; Bod, 2006a; Smith and Eisner, 2006; =-=Seginer, 2007-=-)) annotates text sentences using a hierarchical bracketing (constituents) or a dependency structure, and thus represents the induced grammar through its behavior in a parsing task. Solan et al. (2005...

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... Section 3 we detail our algorithm. The experimental setup and results are presented in Sections 4 and 5. 2 Previous Work Unsupervised parsing has attracted researchers for decades (see (Clark, 2001; =-=Klein, 2005-=-) for recent reviews). Many types of input, syntax formalisms, search procedures, and success criteria were used. Among the theoretical and practical motivations to this problem are the study of human...

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...ious work. In Section 3 we detail our algorithm. The experimental setup and results are presented in Sections 4 and 5. 2 Previous Work Unsupervised parsing has attracted researchers for decades (see (=-=Clark, 2001-=-; Klein, 2005) for recent reviews). Many types of input, syntax formalisms, search procedures, and success criteria were used. Among the theoretical and practical motivations to this problem are the s...

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...and a labeling. The characteristics of this framework (separating prior probability, data likelihood and heuristic search procedures) can also be found in the grammar induction models of (Wolf, 1982; =-=Langley and Stromsten, 2000-=-; Petasis et al., 2004; Solan et al., 2005). The BMM model used here (Borensztajn and Zuidema, 2007) combines features of (Petasis et al., 2004) and Stolcke’s algorithm, applying the minimum descripti...

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...ribution-Noncommercial-Share Alike 3.0 Unported license (http://creativecommons.org/licenses/by-nc-sa/3.0/). Some rights reserved. mar. Most recent work (e.g., (Klein and Manning, 2004; Dennis, 2005; =-=Bod, 2006a-=-; Smith and Eisner, 2006; Seginer, 2007)) annotates text sentences using a hierarchical bracketing (constituents) or a dependency structure, and thus represents the induced grammar through its behavio...

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...s et al., 2004) and Stolcke’s algorithm, applying the minimum description length (MDL) principle. We use it here only for initial labeling of existing bracketings. The MDL principle was also used in (=-=Grunwald, 1994-=-; de Marcken, 1995; Clark, 2001). There are only two previous papers we are aware of that induce labeled bracketing and evaluate on corpora annotated with a similar representation (Haghighi and Klein,...

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...OS tagged) sentences. experimented with English (WSJ10, Brown10), German (NEGRA10) and Chinese (CTB10) corpora. When comparing to previous work that used manually annotated corpora in its evaluation (=-=Haghighi and Klein, 2006-=-) 2 , we obtained 59.5% labeled f-score on the WSJ10 setup vs. their 35.3% (Section 5). We also show substantial improvement over a random baseline, and that the clustering stage of our algorithm impr...

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...c baseline for English. These include the constituent–context model (CCM) (Klein and Manning, 2002), its extension using a dependency model (Klein and Manning, 2004), (U)DOP based models (Bod, 2006a; =-=Bod, 2006b-=-; Bod, 2007), an exemplar– based approach (Dennis, 2005), guiding EM using contrastive estimation (Smith and Eisner, 2006), and the incremental parser of (Seginer, 2007). All of these use as input POS...

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...ve Commons Attribution-Noncommercial-Share Alike 3.0 Unported license (http://creativecommons.org/licenses/by-nc-sa/3.0/). Some rights reserved. mar. Most recent work (e.g., (Klein and Manning, 2004; =-=Dennis, 2005-=-; Bod, 2006a; Smith and Eisner, 2006; Seginer, 2007)) annotates text sentences using a hierarchical bracketing (constituents) or a dependency structure, and thus represents the induced grammar through...

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...or English. These include the constituent–context model (CCM) (Klein and Manning, 2002), its extension using a dependency model (Klein and Manning, 2004), (U)DOP based models (Bod, 2006a; Bod, 2006b; =-=Bod, 2007-=-), an exemplar– based approach (Dennis, 2005), guiding EM using contrastive estimation (Smith and Eisner, 2006), and the incremental parser of (Seginer, 2007). All of these use as input POS tag sequen...

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...erarchical bracketing (constituents) or a dependency structure, and thus represents the induced grammar through its behavior in a parsing task. Solan et al. (2005) uses a graph representation, while (=-=Nakamura, 2006-=-) simply uses a grammar formalism such as PCFG. When the bracketing approach is taken, some algorithms label the resulting constituents, while most do not. Each of these approaches can be justified or...

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...POS tag sequences, except of Seginer’s algorithm, which uses plain text. All of these papers induce unlabeled bracketing or dependencies. There are other algorithmic approaches to the problem (e.g., (=-=Adriaans, 1992-=-; Daelemans, 1995; Van Zaanen, 2001)). None of these had evaluated labeled bracketing on annotated corpora. In this paper we focus on the induction of labeled bracketing. Bayesian Model Merging 2 Usin...

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...; X × Y ) where edge (Xi, Yj) has weight wij, 8 Excluding punctuation and null elements, according to the scheme of (Klein, 2005). 9 There are many possible methods for evaluating clustering quality (=-=Rosenberg and Hirschberg, 2007-=-). For our task, overall f-score is a very natural one. We will address other methods in future papers. (3) find a (one-to-one) matching M from X to Y having a maximal weight. In our case, X is the se...

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...commercial-Share Alike 3.0 Unported license (http://creativecommons.org/licenses/by-nc-sa/3.0/). Some rights reserved. mar. Most recent work (e.g., (Klein and Manning, 2004; Dennis, 2005; Bod, 2006a; =-=Smith and Eisner, 2006-=-; Seginer, 2007)) annotates text sentences using a hierarchical bracketing (constituents) or a dependency structure, and thus represents the induced grammar through its behavior in a parsing task. Sol...