We propose BERTSCORE, an automatic evaluation metric for text generation. Analogously to common metrics, BERTSCORE computes a similarity score for each token in the candidate sentence with each token in the reference sentence. However, instead of exact matches, we compute token similarity using contextual embeddings. We evaluate using the outputs of 363 machine translation and image captioning systems. BERTSCORE correlates better with human judgments and provides stronger model selection performance than existing metrics. Finally, we use an adversarial paraphrase detection task to show that BERTSCORE is more robust to challenging examples when compared to existing metrics.

Text generation has made significant advances in the last few years. Yet, evaluation metrics have lagged behind, as the most popular choices (e.g., BLEU and ROUGE) may correlate poorly with human judgments. We propose BLEURT, a learned evaluation metric based on BERT that can model human judgments with a few thousand possibly biased training examples. A key aspect of our approach is a novel pre-training scheme that uses millions of synthetic examples to help the model generalize. BLEURT provides state-ofthe-art results on the last three years of the WMT Metrics shared task and the WebNLG Competition dataset. In contrast to a vanilla BERT-based approach, it yields superior results even when the training data is scarce and out-of-distribution.

评估指标是文本生成系统的关键成分。近年来，已经提出了几十年前的文本生成质量的人类评估，提出了几个基于伯特的评估指标（包括Bertscore，Moverscore，BLEurt等），这些评估与文本生成质量的人类评估比Bleu或Rouge进行了更好。但是，很少是已知这些度量基于黑盒语言模型表示的指标实际捕获（通常假设它们模型语义相似性）。在这项工作中，我们使用基于简单的回归的全局解释技术来沿着语言因素解开度量标准分数，包括语义，语法，形态和词汇重叠。我们表明，不同的指标捕获了一定程度的各个方面，但它们对词汇重叠大大敏感，就像Bleu和Rouge一样。这暴露了这些新颖性拟议的指标的限制，我们还在对抗对抗测试场景中突出显示。

最近提出的基于BERT的评估指标在标准评估基准方面表现良好，但容易受到对抗性攻击的影响，例如与事实错误有关。我们认为这（部分原因）是因为它们是语义相似性的模型。相反，我们根据自然语言推断（NLI）制定评估指标，我们认为这是更合适的建模。我们设计了一个基于偏好的对抗攻击框架，并表明我们的基于NLI的指标比最近基于BERT的指标更强大。在标准基准上，我们的基于NLI的指标的表现优于现有的摘要指标，但在SOTA MT指标下执行。但是，当我们将现有指标与NLI指标相结合时，我们可以获得更高的对抗性鲁棒性（ +20％至 +30％）和较高质量的指标，如标准基准测量（ +5％至 +25％）。

As machine translation (MT) metrics improve their correlation with human judgement every year, it is crucial to understand the limitations of such metrics at the segment level. Specifically, it is important to investigate metric behaviour when facing accuracy errors in MT because these can have dangerous consequences in certain contexts (e.g., legal, medical). We curate ACES, a translation accuracy challenge set, consisting of 68 phenomena ranging from simple perturbations at the word/character level to more complex errors based on discourse and real-world knowledge. We use ACES to evaluate a wide range of MT metrics including the submissions to the WMT 2022 metrics shared task and perform several analyses leading to general recommendations for metric developers. We recommend: a) combining metrics with different strengths, b) developing metrics that give more weight to the source and less to surface-level overlap with the reference and c) explicitly modelling additional language-specific information beyond what is available via multilingual embeddings.

翻译质量估计（QE）是预测机器翻译（MT）输出质量的任务，而无需任何参考。作为MT实际应用中的重要组成部分，这项任务已越来越受到关注。在本文中，我们首先提出了XLMRScore，这是一种基于使用XLM-Roberta（XLMR）模型计算的BertScore的简单无监督的QE方法，同时讨论了使用此方法发生的问题。接下来，我们建议两种减轻问题的方法：用未知令牌和预训练模型的跨语性对准替换未翻译的单词，以表示彼此之间的一致性单词。我们在WMT21 QE共享任务的四个低资源语言对上评估了所提出的方法，以及本文介绍的新的英语FARSI测试数据集。实验表明，我们的方法可以在两个零射击方案的监督基线中获得可比的结果，即皮尔森相关性的差异少于0.01，同时在所有低资源语言对中的平均低资源语言对中的无人看管竞争对手的平均水平超过8％的平均水平超过8％。 。

这项工作适用于最低贝叶斯风险（MBR）解码，以优化翻译质量的各种自动化指标。机器翻译中的自动指标最近取得了巨大的进步。特别是，在人类评级（例如BLEurt，或Comet）上微调，在与人类判断的相关性方面是优于表面度量的微调。我们的实验表明，神经翻译模型与神经基于基于神经参考度量，BLEURT的组合导致自动和人类评估的显着改善。通过与经典光束搜索输出不同的翻译获得该改进：这些翻译的可能性较低，并且较少受到Bleu等表面度量的青睐。

自然语言处理研究人员已经确定了对生成任务的评估方法的局限性，具有新的问题，提出了自动指标和人群判断的有效性。同时，改善生成模型的努力倾向于专注于简单的n-gram重叠度量（例如，Bleu，Rouge）。我们认为，对模型和指标的新进展应该每个人都更直接受益并告知另一个。因此，我们提出了排行榜，竞争排行榜（广告牌）的概括，同时跟踪语言生成任务和指标的进展。与通过预定度量分类提交系统的传统的单向排行榜不同，广告牌可接受发电机和评估度量作为竞争条目。广告牌会自动创建一个基于跨发电机的全局分析选择和线性地组合一些指标的集合度量。此外，指标基于与人类判断的相关性进行排序。我们释放了用于机器翻译，摘要和图像标题的四个广告牌。我们展示了一些多样化度量的线性集合有时会在隔离中显着优于现有的度量。我们的混合效果模型分析表明，大多数自动度量，尤其是基于参考的机器，对人类发电的重估，展示了更新度量的重要性，将来变得更强大（也许与人类更相似）。

Semantic Textual Similarity (STS) measures the meaning similarity of sentences. Applications include machine translation (MT), summarization, generation, question answering (QA), short answer grading, semantic search, dialog and conversational systems. The STS shared task is a venue for assessing the current state-of-the-art. The 2017 task focuses on multilingual and cross-lingual pairs with one sub-track exploring MT quality estimation (MTQE) data. The task obtained strong participation from 31 teams, with 17 participating in all language tracks. We summarize performance and review a selection of well performing methods. Analysis highlights common errors, providing insight into the limitations of existing models. To support ongoing work on semantic representations, the STS Benchmark is introduced as a new shared training and evaluation set carefully selected from the corpus of English STS shared task data (2012-2017). 7 We use 50-dimensional GloVe word embeddings (Pennington et al., 2014) trained on a combination of Gigaword 5 (Parker et al., 2011) and English Wikipedia available at http://nlp.stanford.edu/projects/glove/.8 https://www.mturk.com/ 9 A designation that statistically identifies workers who perform high quality work across a diverse set of tasks.10 Spanish data from 2015 and 2014 uses a 5 point scale that collapses STS labels 4 and 3, removing the distinction between unimportant and important details.

我们假设现有的句子级机器翻译（MT）指标在人类参考包含歧义时会效率降低。为了验证这一假设，我们提出了一种非常简单的方法，用于扩展预审计的指标以在文档级别合并上下文。我们将我们的方法应用于三个流行的指标，即Bertscore，Prism和Comet，以及无参考的公制Comet-QE。我们使用提供的MQM注释评估WMT 2021指标共享任务的扩展指标。我们的结果表明，扩展指标的表现在约85％的测试条件下优于其句子级别的级别，而在排除低质量人类参考的结果时。此外，我们表明我们的文档级扩展大大提高了其对话语现象任务的准确性，从而优于专用基线高达6.1％。我们的实验结果支持我们的初始假设，并表明对指标的简单扩展使他们能够利用上下文来解决参考中的歧义。

Modern embedding-based metrics for evaluation of generated text generally fall into one of two paradigms: discriminative metrics that are trained to directly predict which outputs are of higher quality according to supervised human annotations, and generative metrics that are trained to evaluate text based on the probabilities of a generative model. Both have their advantages; discriminative metrics are able to directly optimize for the problem of distinguishing between good and bad outputs, while generative metrics can be trained using abundant raw text. In this paper, we present a framework that combines the best of both worlds, using both supervised and unsupervised signals from whatever data we have available. We operationalize this idea by training T5Score, a metric that uses these training signals with mT5 as the backbone. We perform an extensive empirical comparison with other existing metrics on 5 datasets, 19 languages and 280 systems, demonstrating the utility of our method. Experimental results show that: T5Score achieves the best performance on all datasets against existing top-scoring metrics at the segment level. We release our code and models at https://github.com/qinyiwei/T5Score.

在这项工作中，我们提出了一个系统的实证研究，专注于最先进的多语言编码器在跨越多种不同语言对的交叉语言文档和句子检索任务的适用性。我们首先将这些模型视为多语言文本编码器，并在无监督的ad-hoc句子和文档级CLIR中基准性能。与监督语言理解相比，我们的结果表明，对于无监督的文档级CLIR - 一个没有针对IR特定的微调 - 预训练的多语言编码器的相关性判断，平均未能基于CLWE显着优于早期模型。对于句子级检索，我们确实获得了最先进的性能：然而，通过多语言编码器来满足高峰分数，这些编码器已经进一步专注于监督的时尚，以便句子理解任务，而不是使用他们的香草'现货'变体。在这些结果之后，我们介绍了文档级CLIR的本地化相关性匹配，在那里我们独立地对文件部分进行了查询。在第二部分中，我们评估了在一系列零拍语言和域转移CLIR实验中的英语相关数据中进行微调的微调编码器精细调整的微调我们的结果表明，监督重新排名很少提高多语言变压器作为无监督的基数。最后，只有在域名对比度微调（即，同一域名，只有语言转移），我们设法提高排名质量。我们在目标语言中单次检索的交叉定向检索结果和结果（零拍摄）交叉传输之间的显着实证差异，这指出了在单机数据上训练的检索模型的“单声道过度装备”。

This paper demonstrates that multilingual denoising pre-training produces significant performance gains across a wide variety of machine translation (MT) tasks. We present mBART -a sequence-to-sequence denoising auto-encoder pre-trained on large-scale monolingual corpora in many languages using the BART objective . mBART is the first method for pre-training a complete sequence-to-sequence model by denoising full texts in multiple languages, while previous approaches have focused only on the encoder, decoder, or reconstructing parts of the text. Pre-training a complete model allows it to be directly fine tuned for supervised (both sentence-level and document-level) and unsupervised machine translation, with no task-specific modifications. We demonstrate that adding mBART initialization produces performance gains in all but the highest-resource settings, including up to 12 BLEU points for low resource MT and over 5 BLEU points for many document-level and unsupervised models. We also show it also enables new types of transfer to language pairs with no bi-text or that were not in the pre-training corpus, and present extensive analysis of which factors contribute the most to effective pre-training.

对文本生成的最新基于嵌入的评估指标的评估主要是基于衡量其与标准基准评估的相关性。但是，这些基准主要是从相似的域到用于浏览单词嵌入的域。这引起了人们对将基于嵌入的指标（缺乏）概括为新的和嘈杂的域的（缺乏）概括，这些指标包含与预处理数据不同的词汇。在本文中，我们研究了BertScore的鲁棒性，BertScore是文本生成最受欢迎的基于嵌入的指标之一。我们表明，（a）基于嵌入的度量与人类在标准基准上具有最高相关性的基于嵌入的度量，如果输入噪声或未知代币的量增加，则具有最低的相关性，（b）从预处理的第一层中嵌入的嵌入模型改善了所有指标的鲁棒性，并且（c）使用字符级嵌入式（而不是基于令牌的嵌入），从预科模型的第一层中实现了最高的鲁棒性。

文本生成的广泛使用的评估指标要么与更长的文本效果不错，要么无法评估文本质量的所有方面。在本文中，我们引入了一个名为SMART的新指标，以减轻此类限制。具体而言，我们将句子视为匹配的基本单位，而不是代币，并使用句子匹配函数来匹配匹配候选和参考句子。还将候选句子与源文件中的句子进行了比较，以允许接地（例如，事实）评估。我们的结果表明，我们提出的指标与基于模型的匹配函数的系统级相关性优于萨姆瓦尔摘要元评估数据集上的所有竞争指标指标。后者不使用任何神经模型，这在模型开发阶段很有用，在这些阶段，资源可以受到限制且需要快速评估。最后，我们还进行了广泛的分析，表明我们提出的指标与较长的摘要很好地运行，并且对特定模型的偏见较小。

现有的通用机器翻译或自然语言生成评估指标有几个问题，在这种情况下，提问（QA）系统无动于衷。为了构建强大的质量检查系统，我们需要具有等效鲁棒评估系统的能力，以验证对问题的模型预测是否类似于地面真相注释。比较基于语义而不是纯字符串重叠的相似性的能力对于公平比较模型并指出现实生活应用中更现实的接受标准很重要。我们首先建立在我们的知识论文的基础上，该论文使用基于变压器的模型指标来评估语义答案的相似性，并在没有词汇重叠的情况下实现与人类判断的更高相关性。我们提出了跨编码器增强双重编码器和Bertscore模型，以进行语义答案相似性，该模型在新的数据集中进行了培训，该数据集由美国公共人物的名称对组成。就我们而言，我们提供了第一个共同参考名称字符串对的数据集及其相似性，可用于培训。机器学习与应用第四届机器学习与应用国际会议（CMLA 2022）6月25日至2022年6月25日，哥本哈根，丹麦批量编辑：David C. Wyld，Dhinaharan Nagamalai（EDS）

Automatic machine translation (MT) metrics are widely used to distinguish the translation qualities of machine translation systems across relatively large test sets (system-level evaluation). However, it is unclear if automatic metrics are reliable at distinguishing good translations from bad translations at the sentence level (segment-level evaluation). In this paper, we investigate how useful MT metrics are at detecting the success of a machine translation component when placed in a larger platform with a downstream task. We evaluate the segment-level performance of the most widely used MT metrics (chrF, COMET, BERTScore, etc.) on three downstream cross-lingual tasks (dialogue state tracking, question answering, and semantic parsing). For each task, we only have access to a monolingual task-specific model. We calculate the correlation between the metric's ability to predict a good/bad translation with the success/failure on the final task for the Translate-Test setup. Our experiments demonstrate that all metrics exhibit negligible correlation with the extrinsic evaluation of the downstream outcomes. We also find that the scores provided by neural metrics are not interpretable mostly because of undefined ranges. Our analysis suggests that future MT metrics be designed to produce error labels rather than scores to facilitate extrinsic evaluation.

视频标题的当前度量主要基于参考和候选字幕之间的文本级别比较。然而，它们具有一些不可能的缺点，例如，它们不能在没有参考的情况下处理视频，并且由于视频到文本的一对多性质和忽视视觉相关性的一对多性质，它们可能导致偏见的评估。从人类评估者的观点来看，高质量的标题应与提供的视频一致，但不一定类似于文字或语义中的参考。灵感来自人类评估，我们提出了Emscore（基于匹配的分数），是视频字幕的一种新颖的无参考度量，其直接测量视频和候选字幕之间的相似性。受益于最近的大规模预训练模型的发展，我们利用了一个良好的预先训练的视觉语言模型来提取用于计算Emscore的视觉和语言嵌入。具体地，Emscore将粗粒（视频和标题）和细粒度（帧和单词）水平的匹配分数组合，这将考虑到视频的整体理解和详细特征。此外，考虑到潜在的信息增益，Emscore可以灵活地扩展到人类标记的参考可用的条件。最后但并非最不重要的是，我们收集Vatex-eval和ActivityNet-Foil数据集以系统地评估现有的度量标准。 Vatex-emp实验表明，Emscore具有更高的人类相关性和较低的参考依赖性。 ActivityNet-Foil实验验证Emscore可以有效地识别“幻觉”标题。将释放数据集以促进视频标题度量的开发。代码可在：https://github.com/shiyaya/emcore。

Grammatical Error Correction (GEC) is the task of automatically detecting and correcting errors in text. The task not only includes the correction of grammatical errors, such as missing prepositions and mismatched subject-verb agreement, but also orthographic and semantic errors, such as misspellings and word choice errors respectively. The field has seen significant progress in the last decade, motivated in part by a series of five shared tasks, which drove the development of rule-based methods, statistical classifiers, statistical machine translation, and finally neural machine translation systems which represent the current dominant state of the art. In this survey paper, we condense the field into a single article and first outline some of the linguistic challenges of the task, introduce the most popular datasets that are available to researchers (for both English and other languages), and summarise the various methods and techniques that have been developed with a particular focus on artificial error generation. We next describe the many different approaches to evaluation as well as concerns surrounding metric reliability, especially in relation to subjective human judgements, before concluding with an overview of recent progress and suggestions for future work and remaining challenges. We hope that this survey will serve as comprehensive resource for researchers who are new to the field or who want to be kept apprised of recent developments.

我们为机器翻译（MT）评估发布了70个小鉴别的测试集，称为方差感知测试集（VAT），从WMT16覆盖了35个翻译方向到WMT20竞争。VAT由一种新颖的方差感知过滤方法自动创建，该方法会在没有任何人工的情况下过滤当前MT测试集的不分度测试实例。实验结果表明，VAT在主流语言对和测试集中与人为判断的相关性方面优于原始的WMT测试集。进一步分析增值税的性质揭示了竞争MT系统的具有挑战性的语言特征（例如，低频词和专有名词），为构建未来MT测试集提供指导。测试集和准备方差感知MT测试集的代码可在https://github.com/nlp2ct/variance-aware-mt-test-sets自由使用。