Papers with unsupervised parsing
Unsupervised Natural Language Parsing (Introductory Tutorial) (2021.eacl-tutorials)
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| Challenge: | Unsupervised parsing learns a syntactic parser from training sentences without parse tree annotations. |
| Approach: | This tutorial will introduce what unsupervised parsing does and how it can be useful for and beyond syntactic parse. |
| Outcome: | This paper will provide an overview of major approaches to unsupervised parsing and analyze their strengths and weaknesses. |
Neural Unsupervised Parsing Beyond English (D19-61)
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| Challenge: | Unsupervised parsing is a task that can be learned without substantial prior knowledge. |
| Approach: | They train an unsupervised model for Arabic, Chinese, English, and German to learn syntactic structure from unlabeled text. |
| Outcome: | The PRPN architecture outperforms trivial baselines and acquires at least some parsing ability for all languages. |
Grounded PCFG Induction with Images (2020.aacl-main)
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| Challenge: | Recent work in unsupervised parsing has tried to incorporate visual information into learning, but results suggest that these models need linguistic bias to compete against models that only rely on text. |
| Approach: | They propose to use visual information from images for labeled parsing and compare them to existing models which only use text. |
| Outcome: | The proposed models achieve state-of-the-art results on multilingual induction datasets even without help from linguistic knowledge or pretrained image encoders. |
Co-training an Unsupervised Constituency Parser with Weak Supervision (2022.findings-acl)
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| Challenge: | Existing methods for unsupervised parsing that use bootstrapping classifiers to identify if a node dominates a span are lacking. |
| Approach: | They propose a method for unsupervised parsing that relies on bootstrapping classifiers to identify if a node dominates a specific span. |
| Outcome: | The proposed method achieves 63.1 F1 on the English test set and new state-of-the-art on treebanks for Chinese and Japanese. |
Simple Hardware-Efficient PCFGs with Independent Left and Right Productions (2023.findings-emnlp)
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| Challenge: | Existing approaches to scaling dense PCFGs to thousands of nonterminals have shown to be beneficial for unsupervised parsing, but they still perform poorly as a language model and as an unsupervised model. |
| Approach: | They propose a simple PCFG formalism with independent left and right productions that scales more effectively as a language model and as an unsupervised parser. |
| Outcome: | The proposed formalism scales better as a language model and as an unsupervised parser despite imposing a stronger independence assumption compared to low-rank approaches. |
PCFGs Can Do Better: Inducing Probabilistic Context-Free Grammars with Many Symbols (2021.naacl-main)
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| Challenge: | Recent work shows that probabilistic context-free grammars with neural parameterization can be effective in unsupervised constituency parsing. |
| Approach: | They propose a parameterization form of PCFGs based on tensor decomposition which has at most quadratic computational complexity in the symbol number. |
| Outcome: | The proposed model improves unsupervised constituency parsing performance across ten languages. |
Neural Bi-Lexicalized PCFG Induction (2021.acl-long)
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| Challenge: | Neural lexicalized PCFGs make strong independence assumption on the generation of the child word and thus bilexical dependencies are ignored. |
| Approach: | They propose an approach to parameterize L-PCFGs without making implausible independence assumptions. |
| Outcome: | The proposed approach improves both running speed and unsupervised parsing performance on the English WSJ dataset. |
A Survey of Unsupervised Dependency Parsing (2020.coling-main)
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| Challenge: | Syntactic dependency parsing is an important task in natural language processing . unsupervised learning of dependency parses requires training sentences to be manually annotated with their correct parse trees. |
| Approach: | They propose to survey existing approaches to unsupervised dependency parsing . they identify two major classes of approaches and discuss recent trends . |
| Outcome: | The proposed methods can be used in semantic parsing, machine translation, relation extraction, and many other tasks. |
An Imitation Learning Approach to Unsupervised Parsing (P19-1)
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| Challenge: | Unsupervised parsing is a form of reinforcement learning that improves syntactic structures but lacks interpretability due to its lack of ad hoc heuristics. |
| Approach: | They propose an unsupervised approach that transfers syntactic knowledge to a Tree-LSTM model with discrete parsing actions. |
| Outcome: | The proposed model outperforms existing models on the All Natural Language Inference dataset and achieves a new state of the art in terms of parsing F-score. |
R2D2: Recursive Transformer based on Differentiable Tree for Interpretable Hierarchical Language Modeling (2021.acl-long)
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| Challenge: | Existing models with stacked layers do not explicitly model hierarchical structure of language understanding. |
| Approach: | They propose a recursive Transformer model based on differentiable CKY style binary trees to emulate hierarchical composition process. |
| Outcome: | The proposed model can predict words given their left and right abstraction nodes. |
Unsupervised Parsing via Constituency Tests (2020.emnlp-main)
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| Challenge: | Existing methods for unsupervised parsing rely on constituency tests . linguists can judge a sentence's grammatical validity by modifying it via some transformation . |
| Approach: | They propose a method for unsupervised parsing based on a constituency test . they specify a set of transformations and use an unsupervised neural acceptability model to make grammaticality decisions. |
| Outcome: | The proposed method achieves 62.8 F1 on the Penn Treebank test set, an improvement of 7.6 points over the previous best results. |
On the Inductive Bias of Masked Language Modeling: From Statistical to Syntactic Dependencies (2021.naacl-main)
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| Challenge: | Recent studies suggest that pretrained language models acquire useful inductive biases through masks that implicitly act as cloze reductions for downstream tasks. |
| Approach: | They construct cloze-like masks using task-specific lexicons to explain their results . they show that the majority of performance gains come from generic masks that are not associated with the lexical . |
| Outcome: | The proposed method outperforms a classic method for unsupervised parsing. |
Rule Augmented Unsupervised Constituency Parsing (2021.findings-acl)
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| Challenge: | Recent studies have shown that unsupervised parsing methods do not learn meaningful semantics (not even simple grammar) |
| Approach: | They propose an approach that utilizes very generic linguistic knowledge of the language present in the form of syntactic grammar rules and is independent of the base system. |
| Outcome: | The proposed model is independent of the base system and takes advantage of syntactic grammar rules. |
On the Role of Supervision in Unsupervised Constituency Parsing (2020.emnlp-main)
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| Challenge: | Recent work on unsupervised constituency parsing uses labeled examples for tuning . a few-shot parser with labeles can outperform other approaches by a significant margin . |
| Approach: | They propose to use as few labeled examples as possible for model development . they propose to train existing models on the same labeles they access . |
| Outcome: | The proposed model outperforms other models on the WSJ development set by a significant margin . the proposed model can be further improved by augmentation and self-training . |
Structural Optimization Ambiguity and Simplicity Bias in Unsupervised Neural Grammar Induction (2024.findings-acl)
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| Challenge: | Unsupervised grammar induction models lack analysis of traditional challenges, especially regarding the training loss. |
| Approach: | They propose a method to reduce the parse pool per sentence for loss evaluation using structural bias from pre-trained parsers. |
| Outcome: | The proposed method significantly improves performance while reducing variance and bias toward overly simplistic parses. |