Grammars & Parsing
Language Independent Neuro-Symbolic Semantic Parsing for Form Understanding
Voutharoja, Bhanu Prakash, Qu, Lizhen, Shiri, Fatemeh
Recent works on form understanding mostly employ multimodal transformers or large-scale pre-trained language models. These models need ample data for pre-training. In contrast, humans can usually identify key-value pairings from a form only by looking at layouts, even if they don't comprehend the language used. No prior research has been conducted to investigate how helpful layout information alone is for form understanding. Hence, we propose a unique entity-relation graph parsing method for scanned forms called LAGNN, a language-independent Graph Neural Network model. Our model parses a form into a word-relation graph in order to identify entities and relations jointly and reduce the time complexity of inference. This graph is then transformed by deterministic rules into a fully connected entity-relation graph. Our model simply takes into account relative spacing between bounding boxes from layout information to facilitate easy transfer across languages. To further improve the performance of LAGNN, and achieve isomorphism between entity-relation graphs and word-relation graphs, we use integer linear programming (ILP) based inference. Code is publicly available at https://github.com/Bhanu068/LAGNN
Laziness Is a Virtue When It Comes to Compositionality in Neural Semantic Parsing
Crouse, Maxwell, Kapanipathi, Pavan, Chaudhury, Subhajit, Naseem, Tahira, Astudillo, Ramon, Fokoue, Achille, Klinger, Tim
Nearly all general-purpose neural semantic parsers generate logical forms in a strictly top-down autoregressive fashion. Though such systems have achieved impressive results across a variety of datasets and domains, recent works have called into question whether they are ultimately limited in their ability to compositionally generalize. In this work, we approach semantic parsing from, quite literally, the opposite direction; that is, we introduce a neural semantic parsing generation method that constructs logical forms from the bottom up, beginning from the logical form's leaves. The system we introduce is lazy in that it incrementally builds up a set of potential semantic parses, but only expands and processes the most promising candidate parses at each generation step. Such a parsimonious expansion scheme allows the system to maintain an arbitrarily large set of parse hypotheses that are never realized and thus incur minimal computational overhead. We evaluate our approach on compositional generalization; specifically, on the challenging CFQ dataset and three Text-to-SQL datasets where we show that our novel, bottom-up semantic parsing technique outperforms general-purpose semantic parsers while also being competitive with comparable neural parsers that have been designed for each task.
LatinCy: Synthetic Trained Pipelines for Latin NLP
This paper introduces LatinCy, a set of trained general purpose Latin-language "core" pipelines for use with the spaCy natural language processing framework (Honnibal and Montani, 2023). These are end-to-end pipelines for taking plaintext Latin as input for basic NLP processing including sentence segmentation, word tokenization, lemmatization, part-of-speech and morphological tagging, dependency parsing, and named entity recognition (NER). Three models have so far been trained, named according to spaCy conventions: la_core_web_sm, la_core_web_md, and la_core_web_lg. To clarify, 'la' refers to the language code for Latin, 'core' refers to a pipeline that includes all of the components named above, including specifically NER; 'web' refers to the nature of the training data, specifically that the model is trained primarily on Universal Dependency treebanks; and'sm', 'md', and'lg' refer to the "size"--i.e., small, medium, or large--of the models, with'md' and'lg' models being larger because they include subword vectors that describe the vocabulary while'sm' models do not. The current default pipeline consists of the following spaCy components: 'tagger', 'morphologizer', 'trainable_lemmatizer' (i.e. the EditTreeLemmatizer based on Mรผller et al., 2015),
A Study on the Integration of Pipeline and E2E SLU systems for Spoken Semantic Parsing toward STOP Quality Challenge
Arora, Siddhant, Futami, Hayato, Wu, Shih-Lun, Huynh, Jessica, Peng, Yifan, Kashiwagi, Yosuke, Tsunoo, Emiru, Yan, Brian, Watanabe, Shinji
Recently there have been efforts to introduce new benchmark tasks for spoken language understanding (SLU), like semantic parsing. In this paper, we describe our proposed spoken semantic parsing system for the quality track (Track 1) in Spoken Language Understanding Grand Challenge which is part of ICASSP Signal Processing Grand Challenge 2023. We experiment with both end-to-end and pipeline systems for this task. Strong automatic speech recognition (ASR) models like Whisper and pretrained Language models (LM) like BART are utilized inside our SLU framework to boost performance. We also investigate the output level combination of various models to get an exact match accuracy of 80.8, which won the 1st place at the challenge.
Open Information Extraction via Chunks
Dong, Kuicai, Sun, Aixin, Kim, Jung-Jae, Li, Xiaoli
Open Information Extraction (OIE) aims to extract relational tuples from open-domain sentences. Existing OIE systems split a sentence into tokens and recognize token spans as tuple relations and arguments. We instead propose Sentence as Chunk sequence (SaC) and recognize chunk spans as tuple relations and arguments. We argue that SaC has better quantitative and qualitative properties for OIE than sentence as token sequence, and evaluate four choices of chunks (i.e., CoNLL chunks, simple phrases, NP chunks, and spans from SpanOIE) against gold OIE tuples. Accordingly, we propose a simple BERT-based model for sentence chunking, and propose Chunk-OIE for tuple extraction on top of SaC. Chunk-OIE achieves state-of-the-art results on multiple OIE datasets, showing that SaC benefits OIE task.
Towards Zero-Shot Frame Semantic Parsing with Task Agnostic Ontologies and Simple Labels
Ribeiro, Danilo, Abdar, Omid, Goetz, Jack, Ross, Mike, Dong, Annie, Forbus, Kenneth, Mohamed, Ahmed
Frame semantic parsing is an important component of task-oriented dialogue systems. Current models rely on a significant amount training data to successfully identify the intent and slots in the user's input utterance. This creates a significant barrier for adding new domains to virtual assistant capabilities, as creation of this data requires highly specialized NLP expertise. In this work we propose OpenFSP, a framework that allows for easy creation of new domains from a handful of simple labels that can be generated without specific NLP knowledge. Our approach relies on creating a small, but expressive, set of domain agnostic slot types that enables easy annotation of new domains. Given such annotation, a matching algorithm relying on sentence encoders predicts the intent and slots for domains defined by end-users. Extensive experiments on the TopV2 dataset shows that our model outperforms strong baselines in this simple labels setting.
From Parse-Execute to Parse-Execute-Refine: Improving Semantic Parser for Complex Question Answering over Knowledge Base
Guo, Wangzhen, Luo, Linyin, Lai, Hanjiang, Yin, Jian
Parsing questions into executable logical forms has showed impressive results for knowledge-base question answering (KBQA). However, complex KBQA is a more challenging task that requires to perform complex multi-step reasoning. Recently, a new semantic parser called KoPL has been proposed to explicitly model the reasoning processes, which achieved the state-of-the-art on complex KBQA. In this paper, we further explore how to unlock the reasoning ability of semantic parsers by a simple proposed parse-execute-refine paradigm. We refine and improve the KoPL parser by demonstrating the executed intermediate reasoning steps to the KBQA model. We show that such simple strategy can significantly improve the ability of complex reasoning. Specifically, we propose three components: a parsing stage, an execution stage and a refinement stage, to enhance the ability of complex reasoning. The parser uses the KoPL to generate the transparent logical forms. Then, the execution stage aligns and executes the logical forms over knowledge base to obtain intermediate reasoning processes. Finally, the intermediate step-by-step reasoning processes are demonstrated to the KBQA model in the refinement stage. With the explicit reasoning processes, it is much easier to answer the complex questions. Experiments on benchmark dataset shows that the proposed PER-KBQA performs significantly better than the stage-of-the-art baselines on the complex KBQA.
Benchmarking Long-tail Generalization with Likelihood Splits
In order to reliably process natural language, NLP systems must generalize to the long tail of rare utterances. We propose a method to create challenging benchmarks that require generalizing to the tail of the distribution by re-splitting existing datasets. We create 'Likelihood Splits' where examples that are assigned lower likelihood by a pre-trained language model (LM) are placed in the test set, and more likely examples are in the training set. This simple approach can be customized to construct meaningful train-test splits for a wide range of tasks. Likelihood Splits surface more challenges than random splits: relative error rates of state-of-the-art models increase by 59% for semantic parsing on Spider, 93% for natural language inference on SNLI, and 33% for yes/no question answering on BoolQ, on our splits compared with the corresponding random splits. Moreover, Likelihood Splits create fairer benchmarks than adversarial filtering; when the LM used to create the splits is also employed as the task model, our splits do not unfairly penalize the LM.
Evaluating statistical language models as pragmatic reasoners
Lipkin, Benjamin, Wong, Lionel, Grand, Gabriel, Tenenbaum, Joshua B
The relationship between communicated language and intended meaning is often probabilistic and sensitive to context. Numerous strategies attempt to estimate such a mapping, often leveraging recursive Bayesian models of communication. In parallel, large language models (LLMs) have been increasingly applied to semantic parsing applications, tasked with inferring logical representations from natural language. While existing LLM explorations have been largely restricted to literal language use, in this work, we evaluate the capacity of LLMs to infer the meanings of pragmatic utterances. Specifically, we explore the case of threshold estimation on the gradable adjective ``strong'', contextually conditioned on a strength prior, then extended to composition with qualification, negation, polarity inversion, and class comparison. We find that LLMs can derive context-grounded, human-like distributions over the interpretations of several complex pragmatic utterances, yet struggle composing with negation. These results inform the inferential capacity of statistical language models, and their use in pragmatic and semantic parsing applications. All corresponding code is made publicly available (https://github.com/benlipkin/probsem/tree/CogSci2023).
How to enumerate trees from a context-free grammar
While context-free grammars (CFGs) are important in computational linguistics and theoretical computer science, there is no simple, memoryless algorithm for enumerating the trees generated by an arbitrary CFG. One approach is to maintain a priority queue of partially expanded trees according to probability, and expand them through (e.g.) the leftmost unexpanded nonterminal in the tree. This, however, requires storing multiple trees in memory, which can become slow when enumerating many trees. Incremental polynomial time algorithms are also known [1] and related questions have been studied for lexicographic enumeration [2-4]. These algorithms are not particularly well-known, and the tools required to state and analyze them are complex. In contrast, simple techniques exist for enumerating binary trees with a fixed grammar (e.g. S SS | x). A variety of techniques and history is reviewed in Section 7.2.1.6 of [5], including permutation-based methods and gray codes [6-9]. These algorithms, however, do not obviously generalize to arbitrary CFGs. The goal of the present paper is to present an variant of integer-based enumeration schemes that works for arbitrary CFGs.