Dialogue systems and large language models (LLMs) have gained considerable attention. However, the direct utilization of LLMs as task-oriented dialogue (TOD) models has been found to underperform compared to smaller task-specific models. Nonetheless, it is crucial to acknowledge the significant potential of LLMs and explore improved approaches for leveraging their impressive abilities. Motivated by the goal of leveraging LLMs, we propose an alternative approach called User-Guided Response Optimization (UGRO) to combine it with a smaller TOD model. This approach uses LLM as an annotation-free user simulator to assess dialogue responses, combining them with smaller fine-tuned end-to-end TOD models. By utilizing the satisfaction feedback generated by LLMs, UGRO further optimizes the supervised fine-tuned TOD model. Specifically, the TOD model takes the dialogue history as input and, with the assistance of the user simulator's feedback, generates high-satisfaction responses that meet the user's requirements. Through empirical experiments on two TOD benchmarks, we validate the effectiveness of our method. The results demonstrate that our approach outperforms previous state-of-the-art (SOTA) results.

In order to accurately simulate users in conversational systems, it is essential to comprehend the factors that influence their behaviour. This is a critical challenge for the Information Retrieval (IR) field, as conventional methods are not well-suited for the interactive and unique sequential structure of conversational contexts. In this study, we employed the concept of Priming effects from the Psychology literature to identify core stimuli for each abstracted effect. We then examined these stimuli on various datasets to investigate their correlations with users' actions. Finally, we trained Logistic Regression (LR) models based on these stimuli to anticipate users' actions. Our findings offer a basis for creating more realistic user models and simulators, as we identified the subset of stimuli with strong relationships with users' actions. Additionally, we built a model that can predict users' actions.

The objective of High-Recall Information Retrieval (HRIR) is to retrieve as many relevant documents as possible for a given search topic. One approach to HRIR is Technology-Assisted Review (TAR), which uses information retrieval and machine learning techniques to aid the review of large document collections. TAR systems are commonly used in legal eDiscovery and systematic literature reviews. Successful TAR systems are able to find the majority of relevant documents using the least number of assessments. Commonly used retrospective evaluation assumes that the system achieves a specific, fixed recall level first, and then measures the precision or work saved (e.g., precision at r% recall). This approach can cause problems related to understanding the behaviour of evaluation measures in a fixed recall setting. It is also problematic when estimating time and money savings during technology-assisted reviews.

In the midst of digital transformation, automatically understanding the structure and composition of scanned documents is important in order to allow correct indexing, archiving, and processing. In many organizations, different types of documents are usually scanned together in folders, so it is essential to automate the task of segmenting the folders into documents which then proceed to further analysis tailored to specific document types. This task is known as Page Stream Segmentation (PSS). In this paper, we propose a deep learning solution to solve the task of determining whether or not a page is a breaking-point given a sequence of scanned pages (a folder) as input. We also provide a dataset called TABME (TAB this folder of docuMEnts) generated specifically for this task. Our proposed architecture combines LayoutLM and ResNet to exploit both textual and visual features of the document pages and achieves an F1 score of 0.953. The dataset and code used to run the experiments in this paper are available at the following web link: https://github.com/aldolipani/TABME.

A human-like user simulator that anticipates users' satisfaction scores, actions, and utterances can help goal-oriented dialogue systems in evaluating the conversation and refining their dialogue strategies. However, little work has experimented with user simulators which can generate users' utterances. In this paper, we propose a deep learning-based user simulator that predicts users' satisfaction scores and actions while also jointly generating users' utterances in a multi-task manner. In particular, we show that 1) the proposed deep text-to-text multi-task neural model achieves state-of-the-art performance in the users' satisfaction scores and actions prediction tasks, and 2) in an ablation analysis, user satisfaction score prediction, action prediction, and utterance generation tasks can boost the performance with each other via positive transfers across the tasks. The source code and model checkpoints used for the experiments run in this paper are available at the following weblink: \urlhttps://github.com/kimdanny/user-simulation-t5.

Neural point processes (NPPs) employ neural networks to capture complicated dynamics of asynchronous event sequences. Existing NPPs feed all history events into neural networks, assuming that all event types contribute to the prediction of the target type. However, this assumption can be problematic because in reality some event types do not contribute to the predictions of another type. To correct this defect, we learn to omit those types of events that do not contribute to the prediction of one target type during the formulation of NPPs. Towards this end, we simultaneously consider the tasks of (1) finding event types that contribute to predictions of the target types and (2) learning a NPP model from event sequences. For the former, we formulate a latent graph, with event types being vertices and non-zero contributing relationships being directed edges; then we propose a probabilistic graph generator, from which we sample a latent graph. For the latter, the sampled graph can be readily used as a plug-in to modify an existing NPP model. Because these two tasks are nested, we propose to optimize the model parameters through bilevel programming, and develop an efficient solution based on truncated gradient back-propagation. Experimental results on both synthetic and real-world datasets show the improved performance against state-of-the-art baselines. This work removes disturbance of non-contributing event types with the aid of a validation procedure, similar to the practice to mitigate overfitting used when training machine learning models.

The empirical nature of Information Retrieval (IR) mandates strong experimental practices. A keystone of such experimental practices is the Cranfield evaluation paradigm. Within this paradigm, the collection of relevance judgments has been the subject of intense scientific investigation. This is because, on one hand, consistent, precise, and numerous judgements are keys to reducing evaluation uncertainty and test collection bias; on the other hand, however, relevance judgements are costly to collect. The selection of which documents to judge for relevance, known as pooling method, has therefore a great impact on IR evaluation. In this paper we focus on the bias introduced by the pooling method, known as pool bias, which affects the reusability of test collections, in particular when building test collections with a limited budget. In this paper we formalize and evaluate a set of 22 pooling strategies based on: traditional strategies, voting systems, retrieval fusion methods, evaluation measures, and multi-armed bandit models. To do this we run a large-scale evaluation by considering a set of 9 standard TREC test collections, in which we show that the choice of the pooling strategy has significant effects on the cost needed to obtain an unbiased test collection. We also identify the least biased pooling strategy in terms of pool bias according to three IR evaluation measures: AP, NDCG, and P@10.

As conversational agents like Siri and Alexa gain in popularity and use, conversation is becoming a more and more important mode of interaction for search. Conversational search shares some features with traditional search, but differs in some important respects: conversational search systems are less likely to return ranked lists of results (a SERP), more likely to involve iterated interactions, and more likely to feature longer, well-formed user queries in the form of natural language questions. Because of these differences, traditional methods for search evaluation (such as the Cranfield paradigm) do not translate easily to conversational search. In this work, we propose a framework for offline evaluation of conversational search, which includes a methodology for creating test collections with relevance judgments, an evaluation measure based on a user interaction model, and an approach to collecting user interaction data to train the model. The framework is based on the idea of “subtopics”, often used to model novelty and diversity in search and recommendation, and the user model is similar to the geometric browsing model introduced by RBP and used in ERR. As far as we know, this is the first work to combine these ideas into a comprehensive framework for offline evaluation of conversational search.

The use of stopwords has been thoroughly studied in traditional Information Retrieval systems, but remains unexplored in the context of neural models. Neural re-ranking models take the full text of both the query and document into account. Naturally, removing tokens that do not carry relevance information provides us with an opportunity to improve the effectiveness by reducing noise and lower document representation caching-storage requirements. In this work we propose a novel contextualized stopword detection mechanism for neural re-ranking models. This mechanism consists of training a sparse vector in order to filter out document tokens from the ranking decision. This vector is learned end-to-end based on the contextualized document representations, allowing the model to filter terms on a per occurrence basis. This leads to a more explainable model, as it reduces noise. We integrate our component into the state-of-the-art interaction-based TK neural re-ranking model. Our experiments on the MS MARCO passage collection and queries from the TREC 2019 Deep Learning Track show that filtering out traditional stopwords prior to the neural model reduces its effectiveness, while learning to filter out contextualized representations improves it.

Stance detection has gained increasing interest from the research community due to its importance for fake news detection. The goal of stance detection is to categorize an overall position of a subject towards an object into one of the four classes: agree, disagree, discuss, and unrelated. One of the major problems faced by current machine learning models used for stance detection is caused by a severe class imbalance among these classes. Hence, most models fail to correctly classify instances that fall into minority classes. In this paper, we address this problem by proposing a hierarchical representation of these classes, which combines the agree, disagree, and discuss classes under a new related class. Further, we propose a two-layer neural network that learns from this hierarchical representation and controls the error propagation between the two layers using the Maximum Mean Discrepancy regularizer. Compared with conventional four-way classifiers, this model has two advantages: (1) the hierarchical architecture mitigates the class imbalance problem; (2) the regularization makes the model to better discern between the related and unrelated stances. An extensive experimentation demonstrates state-of-the-art accuracy performance of the proposed model for stance detection.

Social media platforms are a plethora of misinformation and its potential negative influence on the public is a growing concern. This concern has drawn the attention of the research community on developing mechanisms to detect misinformation. The task of misinformation detection consists of classifying whether a claim is True or False. Most research concentrates on developing machine learning models, such as neural networks, that outputs a single value in order to predict the veracity of a claim. One of the major problem faced by these models is the inability of representing the uncertainty of the prediction, which is due incomplete or finite available information about the claim being examined. We address this problem by proposing a Bayesian deep learning model. The Bayesian model outputs a distribution used to represent both the prediction and its uncertainty. In addition to the claim content, we also encode auxiliary information given by people's replies to the claim. First, the model encodes a claim to be verified, and generate a prior belief distribution from which we sample a latent variable. Second, the model encodes all the people's replies to the claim in a temporal order through a Long Short Term Memory network in order to summarize their content. This summary is then used to update the prior belief generating the posterior belief. Moreover, in order to train this model, we develop a Stochastic Gradient Variational Bayes algorithm to approximate the analytically intractable posterior distribution. Experiments conducted on two public datasets demonstrate that our model outperforms the state-of-the-art detection models.

Every information retrieval (IR) model embeds in its scoring function a form of term frequency (TF) quantification. The contribution of the term frequency is determined by the properties of the function of the chosen TF quantification, and by its TF normalization. The first defines how independent the occurrences of multiple terms are, while the second acts on mitigating the a priori probability of having a high term frequency in a document (estimation usually based on the document length). New test collections, coming from different domains (e.g. medical, legal), give evidence that not only document length, but in addition, verboseness of documents should be explicitly considered. Therefore we propose and investigate a systematic combination of document verboseness and length. To theoretically justify the combination, we show the duality between document verboseness and length. In addition, we investigate the duality between verboseness and other components of IR models. We test these new TF normalizations on four suitable test collections. We do this on a well defined spectrum of TF quantifications. Finally, based on the theoretical and experimental observations, we show how the two components of this new normalization, document verboseness and length, interact with each other. Our experiments demonstrate that the new models never underperform existing models, while sometimes introducing statistically significantly better results, at no additional computational cost.

Every year more than 25 test collections are built among the main Information Retrieval (IR) evaluation campaigns. They are extremely important in IR because they become the evaluation praxis for the forthcoming years. Test collections are built mostly using the pooling method. The main advantage of this method is that it drastically reduces the number of documents to be judged. It does so at the cost of introducing biases, which are sometimes aggravated by non optimal configuration. In this paper we develop a novel visualization technique for the pooling method, and integrate it in a demo application named Visual Pool. This demo application enables the user to interact with the pooling method with ease, and develops visual hints in order to analyze existing test collections, and build better ones.

Pool bias is a well understood problem of test-collection based benchmarking in information retrieval. The pooling method itself is designed to identify all relevant documents. In practice, 'all' translates to `as many as possible given some budgetary constraints' and the problem persists, albeit mitigated. Recently, methods to address this pool bias for previously created test collections have been proposed, for the evaluation measure precision at cut-off ([email protected]). Analyzing previous methods, we make the empirical observation that the distribution of the probability of providing new relevant documents to the pool, over the runs, is log-normal (when the pooling strategy is fixed depth at cut-off). We use this observation to calculate a prior probability of providing new relevant documents, which we then use in a pool bias estimator that improves upon previous estimates of precision at cut-off. Through extensive experimental results, covering 15 test collections, we show that the proposed bias correction method is the new state of the art, providing the closest estimates yet when compared to the original pool.

The offline evaluation of Information Retrieval (IR) systems is performed through the use of test collections. A test collection, in its essence, is composed of: a collection of documents, a set of topics and, a set of relevance assessments for each topic, derived from the collection of documents. Ideally, for each topic, all the documents of the test collection should be judged, but due to the dimensions of the collections of documents, and their exponential growth over the years, this practice soon became impractical. Therefore, early in IR history, this problem has been addressed through the use of the pooling method. The pooling method consists of optimizing the relevance assessment process by pooling the documents retrieved by different search engines following a particular pooling strategy. The most common one consists on pooling the top d documents of each run. The pool is constructed from systems taking part in a challenge for which the collection was made, at a specific point in time, after which the collection is generally frozen in terms of relevance judgments. This method leads to a bias called pool bias, which is the effect that documents that were not selected in the pool created from the original runs will never be considered relevant. Thereby, this bias affects the evaluation of a system that has not been part of the pool, with any IR evaluation measures, making the comparison with pooled systems unfair.

Creating systematic reviews is a painstaking task undertaken especially in domains where experimental results are the primary method to knowledge creation. For the review authors, analysing documents to extract relevant data is a demanding activity. To support the creation of systematic reviews, we have created DASyR-a semi-automatic document analysis system. DASyR is our solution to annotating published papers for the purpose of ontology population. For domains where dictionaries are not existing or inadequate, DASyR relies on a semi-automatic annotation bootstrapping method based on positional Random Indexing, followed by traditional Machine Learning algorithms to extend the annotation set. We provide an example of the method application to a subdomain of Computer Science, the Information Retrieval evaluation domain. The reliance of this domain on large scale experimental studies makes it a perfect domain to test on. We show the utility of DASyR through experimental results for different parameter values for the bootstrap procedure, evaluated in terms of annotator agreement, error rate, precision and recall.

For many tasks in evaluation campaigns, especially those modeling narrow domain-specific challenges, lack of participation leads to a potential pooling bias due to the scarce number of pooled runs. It is well known that the reliability of a test collection is proportional to the number of topics and relevance assessments provided for each topic, but also to same extent to the diversity in participation in the challenges. Hence, in this paper we present a new perspective in reducing the pool bias by studying the effect of merging an unpooled run with the pooled runs. We also introduce an indicator used by the bias correction method to decide whether the correction needs to be applied or not. This indicator gives strong clues about the potential of a "good" run tested on an "unfriendly" test collection (i.e. a collection where the pool was contributed to by runs very different from the one at hand). We demonstrate the correctness of our method on a set of fifteen test collections from the Text REtrieval Conference (TREC). We observe a reduction in system ranking error and absolute score difference error.