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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Learning without Expert Labels for Multimodal Data

Maruf, Md Abdullah Al 09 January 2025 (has links)
While advancements in deep learning have been largely possible due to the availability of large-scale labeled datasets, obtaining labeled datasets at the required granularity is challenging in many real-world applications, especially in scientific domains, due to the costly and labor-intensive nature of generating annotations. Hence, there is a need to develop new paradigms for learning that do not rely on expert-labeled data and can work even with indirect supervision. Approaches for learning with indirect supervision include unsupervised learning, self-supervised learning, weakly supervised learning, few-shot learning, and knowledge distillation. This thesis addresses these opportunities in the context of multi-modal data through three main contributions. First, this thesis proposes a novel Distance-aware Negative Sampling method for self-supervised Graph Representation Learning (GRL) that learns node representations directly from the graph structure by maximizing separation between distant nodes and maximizing cohesion among nearby nodes. Second, this thesis introduces effective modifications to weakly supervised semantic segmentation (WS3) models, such as stochastic aggregation to saliency maps that improve the learning of pseudo-ground truths from class-level coarse-grained labels and address the limitations of class activation maps. Finally, this thesis evaluates whether pre-trained Vision-Language Models (VLMs) contain the necessary scientific knowledge to identify and reason about biological traits from scientific images. The zero-shot performance of 12 large VLMs is evaluated on a novel VLM4Bio dataset, along with the effects of prompting and reasoning hallucinations are explored. / Doctor of Philosophy / While advancements in machine learning (ML), such as deep learning, have been largely possible due to the availability of large-scale labeled datasets, obtaining high-quality and high-resolution labels is challenging in many real-world applications due to the costly and labor-intensive nature of generating annotations. This thesis explores new ways of training ML models without relying heavily on expert-labeled data using indirect supervision. First, it introduces a novel way of using the structure of graphs for learning representations of graph-based data. Second, it analyzes the effect of weak supervision using coarse labels for image-based data. Third, it evaluates whether current ML models can recognize and reason about scientific images on their own, aiming to make learning more efficient and less dependent on exhaustive labeling.
52

Improving Rainfall Index Insurance: Evaluating Effects of Fine-Scale Data and Interactive Tools in the PRF-RI Program

Ramanujan, Ramaraja 04 June 2024 (has links)
Since its inception, the Pasture, Rangeland, and Forage Rainfall Index (PRF-RI) insurance program has issued a total of $8.8 billion in payouts. Given the program's significance, this thesis investigates methodologies to help improve it. For the first part, we evaluated the impact of finer-scale precipitation data on insurance payouts by comparing how the payout distribution differs between the program's current dataset and the finer-scale precipitation dataset by creating a simulated scenario where all parameters are constant except the rainfall index computed by the respective dataset. The analysis for Texas in 2021 revealed that using the finer-scale dataset to compute the rainfall index would result in payouts worth $27 million less than the current dataset. The second part of the research involved the development of two interactive decision-support tools: the "Next-Gen PRF" web tool and the "AgInsurance LLM" chatbot. These tools were designed to help users understand complex insurance parameters and make informed decisions regarding their insurance policies. User studies for the "Next-Gen PRF" tool measured usability, comprehension decision-making efficiency, and user experience, showing that it outperforms traditional methods by providing insightful visualizations and detailed descriptions. The findings suggest that using fine-scale precipitation data and advanced decision-support technologies can substantially benefit the PRF-RI program by reducing spatial basis risk and promoting user education, thus leading to higher user engagement and enrollment. / Master of Science / The Pasture, Rangeland, and Forage Rainfall Index (PRF-RI) program helps farmers manage drought risk. Since it started, it has paid farmers about $8.8 billion. This study looks into ways to improve the program. We first examined whether using rain data at a more finer spatial resolution could affect how much money is paid out. In Texas in 2021, we found that using this finer spatial resolution data could have reduced payouts by $27 million, underscoring the importance of evaluating our proposed change. Additionally, we created two new tools to help farmers understand and choose their insurance options more easily: the "Next-Gen PRF" web tool and the "AgInsurance LLM" chatbot. These tools seek to provide clear visuals and explanations. User studies with these tools show they help users learn more effectively and make more informed decisions compared to existing tools. Overall, our research suggests that using finer spatial resolution precipitation data as well as these interactive tools can enhance the insurance program, including by making it easier to engage with, and enabling farmers to evaluate if and how this program can help them resolve their weather risk management problems.
53

Designing AI Software for Large Classroom Engagement / INTERACTIVE LEARNING AT SCALE: LEVERAGING GENERATIVE AI TO IMPROVE ENGAGEMENT AND PARTICIPATION IN LARGE CLASSROOM SETTINGS

Koehl, Stephanie January 2025 (has links)
This thesis presents the design of an educational tool that enhances student engagement and interaction during group presentations in large classroom settings. Specifically, the study aimed to create a tool that streamlines the management of questions and participation, making the process more efficient and equitable for students and instructors. The research explored three primary questions: (1) How can educational software be designed to increase engagement and participation during student presentations? (2) How can AI be used to assist in tasks traditionally performed by professors, such as managing Q&A sessions? (3) How does the application of design thinking, particularly the empathy stage, influence the development of effective educational tools? Students provided ample feedback on improving the course and detailed explanations for their preferences. Qualitative methods including reflexive thematic analysis were used to process this volume of feedback. Descriptive statistics, confusion matrices, and Kappa scores were used to ensure the integrity of the analysis. An open-source large language model, Meta’s LLaMA, was implemented to automate the selection and clustering of questions during student-led Q&A sessions, with these results compared against instructor-selected questions. AI-driven question selection matched the effectiveness of instructor selections and enhanced efficiency, significantly reducing the logistical burden on educators while sustaining student engagement. Additionally, the research gathered extensive data on students’ experiences within the university classroom, with particular attention to issues such as anxiety, group dynamics, and disengagement. A paper prototype was developed to address these challenges, leveraging AI to foster interaction and improve peer-to-peer communication. These results have broader implications for educational technology, showing how AI could foster deeper student involvement and provide instructors with tools to manage participation effortlessly at scale, improving the overall learning experience. / Thesis / Master of Computer Science (MCS)
54

Large Language Models : Bedömning av ChatGPT:s potential som verktyg för kommentering av kod / Large Language Models : Assessment of ChatGPT's Potential as a Tool for Code Commenting

Svensson, Tom, Vuk, Dennis January 2023 (has links)
Användningen av Artificiell Intelligens (AI) är utbredd bland verksamma företag idag, likväl privatpersoner. Det har blivit en integrerad del av vårt samhälle som ofta går obemärkt förbi. Allt från face recognition, självkörande bilar och automatisering inom arbetsrelaterade områden, har AI onekligen påverkat omvärlden. I takt med att AI-modeller fortsätter att utvecklas tillkommer även farhågor om dess påverkan på jobb, tillhörande säkerhetsrisker och etiska dilemman. Uppsatsens litteratur hjälper till att skildra AI historiskt, i nutid, men även ge en uppfattning om vart den är på väg. Den AI-modell som i nuläget har väckt störst uppmärksamhet är ChatGPT. Dess potential tycks inte ha några gränser, därmed uppstod relevansen för att öka kunskapen kring AI-modellen. Vidare gjordes en avgränsning, där fokusområdet var att undersöka hur ChatGPT kan generera kodkommentarer och potentiellt agera som ett hjälpmedel vid kommentering av källkod. I samband med avgränsningen och fokusområdet bildades även forskningsfrågan: Large Language Models: Bedömning av ChatGPT:s potential som verktyg för kommentering av kod För att besvara forskningsfrågan har avhandlingen varit baserat på en kvalitativ ansats, där urvalet av respondenter har varit programmerare. Den primära datainsamlingen har genomförts via två semistrukturerade intervjuer, varav den inledande innefattade initiala känslor kring ChatGPT och övergripande fakta om respektive intervjuobjekt. Vidare gjordes det en observation för att få en inblick i hur AI-modellen används av programmerare, för att avslutningsvis göra en uppföljande intervju post-observation i syfte att samla tankarna från intervjuobjekten efter användning av ChatGPT för att generera kodkommentarer. Baserat på den insamlade empirin kunde studien konkludera vissa begränsningar i den nuvarande modellen, inte minst behovet av tydliga instruktioner. Trots brister visar ChatGPTs framställning potential att vara en betydande resurs för kommentering av kod i framtiden. Resultaten indikerar att modellen kan generera relativt passande kommentarer i de analyserade kodkodstycken. Emellertid uttryckte deltagarna under de avslutande intervjuerna generellt sett att kommentarerna var redundanta och saknade betydande värde för att öka förståelsen av källkoden. Respondenterna diskuterade dock möjligheterna att använda ChatGPT i framtiden, men underströk behovet av förbättringar för att göra det till en tillförlitlig metod inom arbetsrelaterade situationer. / The usage of Artificial Intelligence (AI) is widespread among both companies and individuals today. It has become an integrated part of our society, often going unnoticed. From face recognition and self-driving cars to automation in work-related areas, AI has undeniably impacted the world. As AI models continue to evolve, concerns about their impact on jobs, associated security risks, and ethical dilemmas arise. The literature in this essay helps portray AI historically, in the present, and provides an insight into its future direction. The AI model that has currently garnered the most attention is ChatGPT. Its potential seems limitless, which prompted the relevance of increasing knowledge about the AI model. Furthermore, a delimitation was made, where the focus area was to investigate how ChatGPT can generate code comments and potentially act as a tool for commenting source code. As part of the research focus and scope, the research question was formulated: "Large Language Models: Assessment of ChatGPT's Potential as a Tool for Code Commenting." To answer the research question, the thesis adopted a qualitative approach, with programmers as the selected respondents. The primary data collection was conducted through two semi-structured interviews, where the initial interview involved capturing initial impressions of ChatGPT and gathering general information about the interviewees. Additionally, an observation was carried out to gain insights into how programmers utilize the AI model, followed by a post-observation interview to gather the interviewees' thoughts after using ChatGPT to generate code comments. Based on the collected empirical data, the study was able to conclude certain limitations in the current model, particularly the need for clear instructions. Despite these limitations, ChatGPT's performance demonstrates the potential to be a significant resource for code commenting in the future. The results indicate that the model can generate relatively suitable comments in the analyzed code snippets. However, during the concluding interviews, participants generally expressed that the comments were redundant and lacked significant value in enhancing the understanding of the source code. Nevertheless, the respondents 2 discussed the possibilities of using ChatGPT in the future, while emphasizing the need for improvements to establish it as a reliable method in work-related situations.
55

AUTOMATED EVALUATION OF NEUROLOGICAL DISORDERS THROUGH ELECTRONIC HEALTH RECORD ANALYSIS

Md Rakibul Islam Prince (18771646) 03 September 2024 (has links)
<p dir="ltr">Neurological disorders present a considerable challenge due to their variety and diagnostic complexity especially for older adults. Early prediction of the onset and ongoing assessment of the severity of these disease conditions can allow timely interventions. Currently, most of the assessment tools are time-consuming, costly, and not suitable for use in primary care. To reduce this burden, the present thesis introduces passive digital markers for different disease conditions that can effectively automate the severity assessment and risk prediction from different modalities of electronic health records (EHR). The focus of the first phase of the present study in on developing passive digital markers for the functional assessment of patients suffering from Bipolar disorder and Schizophrenia. The second phase of the study explores different architectures for passive digital markers that can predict patients at risk for dementia. The functional severity PDM uses only a single EHR modality, namely medical notes in order to assess the severity of the functioning of schizophrenia, bipolar type I, or mixed bipolar patients. In this case, the input of is a single medical note from the electronic medical record of the patient. This note is submitted to a hierarchical BERT model which classifies at-risk patients. A hierarchical attention mechanism is adopted because medical notes can exceed the maximum allowed number of tokens by most language models including BERT. The functional severity PDM follows three steps. First, a sentence-level embedding is produced for each sentence in the note using a token-level attention mechanism. Second, an embedding for the entire note is constructed using a sentence-level attention mechanism. Third, the final embedding is classified using a feed-forward neural network which estimates the impairment level of the patient. When used prior to the onset of the disease, this PDM is able to differentiate between severe and moderate functioning levels with an AUC of 76%. Disease-specific severity assessment PDMs are only applicable after the onset of the disease and have AUCs of nearly 85% for schizophrenia and bipolar patients. The dementia risk prediction PDM considers multiple EHR modalities including socio-demographic data, diagnosis codes and medical notes. Moreover, the observation period and prediction horizon are varied for a better understanding of the practical limitations of the model. This PDM is able to identify patients at risk of dementia with AUCs ranging from 70% to 92% as the observation period approaches the index date. The present study introduces methodologies for the automation of important clinical outcomes such as the assessment of the general functioning of psychiatric patients and the prediction of risk for dementia using only routine care data.</p>
56

Frontiers of Large Language Models: Empowering Decision Optimization, Scene Understanding, and Summarization Through Advanced Computational Approaches

de Curtò i Díaz, Joaquim 23 January 2024 (has links)
Tesis por compendio / [ES] El advenimiento de los Large Language Models (LLMs) marca una fase transformadora en el campo de la Inteligencia Artificial (IA), significando el cambio hacia sistemas inteligentes y autónomos capaces de una comprensión y toma de decisiones complejas. Esta tesis profundiza en las capacidades multifacéticas de los LLMs, explorando sus posibles aplicaciones en la optimización de decisiones, la comprensión de escenas y tareas avanzadas de resumen de video en diversos contextos. En el primer segmento de la tesis, el foco está en la comprensión semántica de escenas de Vehículos Aéreos No Tripulados (UAVs). La capacidad de proporcionar instantáneamente datos de alto nivel y señales visuales sitúa a los UAVs como plataformas ideales para realizar tareas complejas. El trabajo combina el potencial de los LLMs, los Visual Language Models (VLMs), y los sistemas de detección objetos de última generación para ofrecer descripciones de escenas matizadas y contextualmente precisas. Se presenta una implementación práctica eficiente y bien controlada usando microdrones en entornos complejos, complementando el estudio con métricas de legibilidad estandarizadas propuestas para medir la calidad de las descripciones mejoradas por los LLMs. Estos avances podrían impactar significativamente en sectores como el cine, la publicidad y los parques temáticos, mejorando las experiencias de los usuarios de manera exponencial. El segundo segmento arroja luz sobre el problema cada vez más crucial de la toma de decisiones bajo incertidumbre. Utilizando el problema de Multi-Armed Bandits (MAB) como base, el estudio explora el uso de los LLMs para informar y guiar estrategias en entornos dinámicos. Se postula que el poder predictivo de los LLMs puede ayudar a elegir el equilibrio correcto entre exploración y explotación basado en el estado actual del sistema. A través de pruebas rigurosas, la estrategia informada por los LLMs propuesta demuestra su adaptabilidad y su rendimiento competitivo frente a las estrategias convencionales. A continuación, la investigación se centra en el estudio de las evaluaciones de bondad de ajuste de las Generative Adversarial Networks (GANs) utilizando la Signature Transform. Al proporcionar una medida eficiente de similitud entre las distribuciones de imágenes, el estudio arroja luz sobre la estructura intrínseca de las muestras generadas por los GANs. Un análisis exhaustivo utilizando medidas estadísticas como las pruebas de Kruskal-Wallis proporciona una comprensión más amplia de la convergencia de los GANs y la bondad de ajuste. En la sección final, la tesis introduce un nuevo benchmark para la síntesis automática de vídeos, enfatizando la integración armoniosa de los LLMs y la Signature Transform. Se propone un enfoque innovador basado en los componentes armónicos capturados por la Signature Transform. Las medidas son evaluadas extensivamente, demostrando ofrecer una precisión convincente que se correlaciona bien con el concepto humano de un buen resumen. Este trabajo de investigación establece a los LLMs como herramientas poderosas para abordar tareas complejas en diversos dominios, redefiniendo la optimización de decisiones, la comprensión de escenas y las tareas de resumen de video. No solo establece nuevos postulados en las aplicaciones de los LLMs, sino que también establece la dirección para futuros trabajos en este emocionante y rápidamente evolucionante campo. / [CA] L'adveniment dels Large Language Models (LLMs) marca una fase transformadora en el camp de la Intel·ligència Artificial (IA), significat el canvi cap a sistemes intel·ligents i autònoms capaços d'una comprensió i presa de decisions complexes. Aquesta tesi profunditza en les capacitats multifacètiques dels LLMs, explorant les seues possibles aplicacions en l'optimització de decisions, la comprensió d'escenes i tasques avançades de resum de vídeo en diversos contexts. En el primer segment de la tesi, el focus està en la comprensió semàntica d'escenes de Vehicles Aeris No Tripulats (UAVs). La capacitat de proporcionar instantàniament dades d'alt nivell i senyals visuals situa els UAVs com a plataformes ideals per a realitzar tasques complexes. El treball combina el potencial dels LLMs, els Visual Language Models (VLMs), i els sistemes de detecció d'objectes d'última generació per a oferir descripcions d'escenes matisades i contextualment precises. Es presenta una implementació pràctica eficient i ben controlada usant microdrons en entorns complexos, complementant l'estudi amb mètriques de llegibilitat estandarditzades proposades per a mesurar la qualitat de les descripcions millorades pels LLMs. Aquests avenços podrien impactar significativament en sectors com el cinema, la publicitat i els parcs temàtics, millorant les experiències dels usuaris de manera exponencial. El segon segment arroja llum sobre el problema cada vegada més crucial de la presa de decisions sota incertesa. Utilitzant el problema dels Multi-Armed Bandits (MAB) com a base, l'estudi explora l'ús dels LLMs per a informar i guiar estratègies en entorns dinàmics. Es postula que el poder predictiu dels LLMs pot ajudar a triar l'equilibri correcte entre exploració i explotació basat en l'estat actual del sistema. A través de proves rigoroses, l'estratègia informada pels LLMs proposada demostra la seua adaptabilitat i el seu rendiment competitiu front a les estratègies convencionals. A continuació, la recerca es centra en l'estudi de les avaluacions de bondat d'ajust de les Generative Adversarial Networks (GANs) utilitzant la Signature Transform. En proporcionar una mesura eficient de similitud entre les distribucions d'imatges, l'estudi arroja llum sobre l'estructura intrínseca de les mostres generades pels GANs. Una anàlisi exhaustiva utilitzant mesures estadístiques com les proves de Kruskal-Wallis proporciona una comprensió més àmplia de la convergència dels GANs i la bondat d'ajust. En la secció final, la tesi introdueix un nou benchmark per a la síntesi automàtica de vídeos, enfatitzant la integració harmònica dels LLMs i la Signature Transform. Es proposa un enfocament innovador basat en els components harmònics capturats per la Signature Transform. Les mesures són avaluades extensivament, demostrant oferir una precisió convincent que es correlaciona bé amb el concepte humà d'un bon resum. Aquest treball de recerca estableix els LLMs com a eines poderoses per a abordar tasques complexes en diversos dominis, redefinint l'optimització de decisions, la comprensió d'escenes i les tasques de resum de vídeo. No solament estableix nous postulats en les aplicacions dels LLMs, sinó que també estableix la direcció per a futurs treballs en aquest emocionant i ràpidament evolucionant camp. / [EN] The advent of Large Language Models (LLMs) marks a transformative phase in the field of Artificial Intelligence (AI), signifying the shift towards intelligent and autonomous systems capable of complex understanding and decision-making. This thesis delves deep into the multifaceted capabilities of LLMs, exploring their potential applications in decision optimization, scene understanding, and advanced summarization tasks in diverse contexts. In the first segment of the thesis, the focus is on Unmanned Aerial Vehicles' (UAVs) semantic scene understanding. The capability of instantaneously providing high-level data and visual cues positions UAVs as ideal platforms for performing complex tasks. The work combines the potential of LLMs, Visual Language Models (VLMs), and state-of-the-art detection pipelines to offer nuanced and contextually accurate scene descriptions. A well-controlled, efficient practical implementation of microdrones in challenging settings is presented, supplementing the study with proposed standardized readability metrics to gauge the quality of LLM-enhanced descriptions. This could significantly impact sectors such as film, advertising, and theme parks, enhancing user experiences manifold. The second segment brings to light the increasingly crucial problem of decision-making under uncertainty. Using the Multi-Armed Bandit (MAB) problem as a foundation, the study explores the use of LLMs to inform and guide strategies in dynamic environments. It is postulated that the predictive power of LLMs can aid in choosing the correct balance between exploration and exploitation based on the current state of the system. Through rigorous testing, the proposed LLM-informed strategy showcases its adaptability and its competitive performance against conventional strategies. Next, the research transitions into studying the goodness-of-fit assessments of Generative Adversarial Networks (GANs) utilizing the Signature Transform. By providing an efficient measure of similarity between image distributions, the study sheds light on the intrinsic structure of the samples generated by GANs. A comprehensive analysis using statistical measures, such as the test Kruskal-Wallis, provides a more extensive understanding of the GAN convergence and goodness of fit. In the final section, the thesis introduces a novel benchmark for automatic video summarization, emphasizing the harmonious integration of LLMs and Signature Transform. An innovative approach grounded in the harmonic components captured by the Signature Transform is put forth. The measures are extensively evaluated, proving to offer compelling accuracy that correlates well with the concept of a good summary. This research work establishes LLMs as powerful tools in addressing complex tasks across diverse domains, redefining decision optimization, scene understanding, and summarization tasks. It not only breaks new ground in the applications of LLMs but also sets the direction for future work in this exciting and rapidly evolving field. / De Curtò I Díaz, J. (2023). Frontiers of Large Language Models: Empowering Decision Optimization, Scene Understanding, and Summarization Through Advanced Computational Approaches [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/202200 / Compendio
57

Automatic recognition of multiparty human interactions using dynamic Bayesian networks

Dielmann, Alfred January 2009 (has links)
Relating statistical machine learning approaches to the automatic analysis of multiparty communicative events, such as meetings, is an ambitious research area. We have investigated automatic meeting segmentation both in terms of “Meeting Actions” and “Dialogue Acts”. Dialogue acts model the discourse structure at a fine grained level highlighting individual speaker intentions. Group meeting actions describe the same process at a coarse level, highlighting interactions between different meeting participants and showing overall group intentions. A framework based on probabilistic graphical models such as dynamic Bayesian networks (DBNs) has been investigated for both tasks. Our first set of experiments is concerned with the segmentation and structuring of meetings (recorded using multiple cameras and microphones) into sequences of group meeting actions such as monologue, discussion and presentation. We outline four families of multimodal features based on speaker turns, lexical transcription, prosody, and visual motion that are extracted from the raw audio and video recordings. We relate these lowlevel multimodal features to complex group behaviours proposing a multistreammodelling framework based on dynamic Bayesian networks. Later experiments are concerned with the automatic recognition of Dialogue Acts (DAs) in multiparty conversational speech. We present a joint generative approach based on a switching DBN for DA recognition in which segmentation and classification of DAs are carried out in parallel. This approach models a set of features, related to lexical content and prosody, and incorporates a weighted interpolated factored language model. In conjunction with this joint generative model, we have also investigated the use of a discriminative approach, based on conditional random fields, to perform a reclassification of the segmented DAs. The DBN based approach yielded significant improvements when applied both to the meeting action and the dialogue act recognition task. On both tasks, the DBN framework provided an effective factorisation of the state-space and a flexible infrastructure able to integrate a heterogeneous set of resources such as continuous and discrete multimodal features, and statistical language models. Although our experiments have been principally targeted on multiparty meetings; features, models, and methodologies developed in this thesis can be employed for a wide range of applications. Moreover both group meeting actions and DAs offer valuable insights about the current conversational context providing valuable cues and features for several related research areas such as speaker addressing and focus of attention modelling, automatic speech recognition and understanding, topic and decision detection.
58

Chyba: prokletí nebo požehnání? Perspektiva ELF / Mistakes: curse or blessing? The ELF perspective

Dunková, Jiřina January 2014 (has links)
The present research focuses on students' attitudes and preferences towards English language learning at Czech private language schools. The study approaches language learning from two perspectives, the English as a Foreign Language (EFL) paradigm and the English as a Lingua Franca (ELF) paradigm. The key concepts discussed are: mistakes, re-labelled modifications, learner goals, learner needs, language models, accuracy and language creativity (or 'languaging'). Key words: EFL, ELF, learner goals, language models, accuracy, language creativity, languaging
59

Neural Language Models with Explicit Coreference Decision

Kunz, Jenny January 2019 (has links)
Coreference is an important and frequent concept in any form of discourse, and Coreference Resolution (CR) a widely used task in Natural Language Understanding (NLU). In this thesis, we implement and explore two recent models that include the concept of coreference in Recurrent Neural Network (RNN)-based Language Models (LM). Entity and reference decisions are modeled explicitly in these models using attention mechanisms. Both models learn to save the previously observed entities in a set and to decide if the next token created by the LM is a mention of one of the entities in the set, an entity that has not been observed yet, or not an entity. After a theoretical analysis where we compare the two LMs to each other and to a state of the art Coreference Resolution system, we perform an extensive quantitative and qualitative analysis. For this purpose, we train the two models and a classical RNN-LM as the baseline model on the OntoNotes 5.0 corpus with coreference annotation. While we do not reach the baseline in the perplexity metric, we show that the models’ relative performance on entity tokens has the potential to improve when including the explicit entity modeling. We show that the most challenging point in the systems is the decision if the next token is an entity token, while the decision which entity the next token refers to performs comparatively well. Our analysis in the context of a text generation task shows that a wide-spread error source for the mention creation process is the confusion of tokens that refer to related but different entities in the real world, presumably a result of the context-based word representations in the models. Our re-implementation of the DeepMind model by Yang et al. 2016 performs notably better than the re-implementation of the EntityNLM model by Ji et al. 2017 with a perplexity of 107 compared to a perplexity of 131.
60

Parafrasidentifiering med maskinklassificerad data : utvärdering av olika metoder / Paraphrase identification with computer classified paraphrases : An evaluation of different methods

Johansson, Oskar January 2020 (has links)
Detta arbete undersöker hur språkmodellen BERT och en MaLSTM-arkitektur fungerar att för att identifiera parafraser ur 'Microsoft Paraphrase Research Corpus' (MPRC) om dessa tränats på automatiskt identifierade parafraser ur 'Paraphrase Database' (PPDB). Metoderna ställs mot varandra för att undersöka vilken som presterar bäst och metoden att träna på maskinklassificerad data för att användas på mänskligt klassificerad data utvärderas i förhållande till annan klassificering av samma dataset. Meningsparen som används för att träna modellerna hämtas från de högst rankade parafraserna ur PPDB och genom en genereringsmetod som skapar icke-parafraser ur samma dataset. I resultatet visar sig BERT vara kapabel till att identifiera en del parafraser ur MPRC, medan MaLSTM-arkitekturen inte klarade av detta trots förmåga att särskilja på parafraser och icke-parafraser under träning. Både BERT och MaLSTM presterade sämre på att identifiera parafraser ur MPRC än modeller som till exempel StructBERT, som tränat och utvärderats på samma dataset, presterar. Anledningar till att MaLSTM inte klarar av uppgiften diskuteras och främst lyfts att meningarna från icke-parafraserna ur träningsdatan är för olika varandra i förhållande till hur de ser ut i MPRC. Slutligen diskuteras vikten av att forska vidare på hur man kan använda sig av maskinframtagna parafraser inom parafraseringsrelaterad forskning.

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