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  • Conference paper
    Zhang D, Williams M, Toni F, 2023,

    Targeted activation penalties help CNNs ignore spurious signals

    , The 38th Annual AAAI Conference on Artificial Intelligence, Publisher: AAAI, ISSN: 2159-5399

    Neural networks (NNs) can learn to rely on spurious signals in the training data, leading to poor generalisation. Recent methods tackle this problem by training NNs with additional ground-truth annotations of such signals. These methods may, however, let spurious signals re-emerge in deep convolutional NNs (CNNs). We propose Targeted Activation Penalty (TAP), a new method tackling the same problem by penalising activations to control the re-emergence of spurious signals in deep CNNs, while also lowering training times and memory usage. In addition, ground-truth annotations can be expensive to obtain. We show that TAP still works well with annotations generated by pre-trained models as effective substitutes of ground-truth annotations. We demonstrate the power of TAP against two state-of-the-art baselines on the MNIST benchmark and on two clinical image datasets, using four different CNN architectures.

  • Conference paper
    Tirsi C-G, Proietti M, Toni F, 2023,

    ABALearn: an automated logic-based learning system for ABA frameworks

    , AIxIA 2023, Publisher: Springer Nature, ISSN: 1687-7470

    We introduce ABALearn, an automated algorithm that learns Assumption-Based Argumentation (ABA) frameworks from training data consisting of positive and negative examples, and a given background knowledge. ABALearn’s ability to generate comprehensible rules for decision-making promotes transparency and interpretability, addressing the challenges associated with the black-box nature of traditional machine learning models. This implementation is based on the strategy proposed in a previous work. The resulting ABA frameworks can be mapped onto logicprograms with negation as failure. The main advantage of this algorithm is that it requires minimal information about the learning problem and it is also capable of learning circular debates. Our results show that this approach is competitive with state-of-the-art alternatives, demonstrat-ing its potential to be used in real-world applications. Overall, this work contributes to the development of automated learning techniques for argumentation frameworks in the context of Explainable AI (XAI) andprovides insights into how such learners can be applied to make predictions.

  • Conference paper
    Paulino Passos G, Toni F, 2023,

    Learning Case Relevance in Case-Based Reasoning with Abstract Argumentation

    , The 36th International Conference on Legal Knowledge and Information Systems
  • Conference paper
    Russo F, Toni F, 2023,

    Causal discovery and knowledge injection for contestable neural networks

    , 26th European Conference on Artificial Intelligence ECAI 2023, Publisher: IOS Press, Pages: 2025-2032, ISSN: 0922-6389

    Neural networks have proven to be effective at solvingmachine learning tasks but it is unclear whether they learn any relevant causal relationships, while their black-box nature makes it difficult for modellers to understand and debug them. We propose a novelmethod overcoming these issues by allowing a two-way interactionwhereby neural-network-empowered machines can expose the underpinning learnt causal graphs and humans can contest the machinesby modifying the causal graphs before re-injecting them into the machines, so that the learnt models are guaranteed to conform to thegraphs and adhere to expert knowledge (some of which can also begiven up-front). By building a window into the model behaviour andenabling knowledge injection, our method allows practitioners to debug networks based on the causal structure discovered from the dataand underpinning the predictions. Experiments with real and synthetic tabular data show that our method improves predictive performance up to 2.4x while producing parsimonious networks, up to 7xsmaller in the input layer, compared to SOTA regularised networks.

  • Conference paper
    Jiang J, Lan J, Leofante F, Rago A, Toni Fet al., 2023,

    Provably Robust and Plausible Counterfactual Explanations for Neural Networks via Robust Optimisation

    , The 15th Asian Conference on Machine Learning
  • Conference paper
    Rago A, Li H, Toni F, 2023,

    Interactive explanations by conflict resolution via argumentative exchanges

    , 20th International Conference on Principles of Knowledge Representation and Reasoning (KR2023), Publisher: IJCAI Organization, Pages: 582-592, ISSN: 2334-1033

    As the field of explainable AI (XAI) is maturing, calls forinteractive explanations for (the outputs of) AI models aregrowing, but the state-of-the-art predominantly focuses onstatic explanations. In this paper, we focus instead on interactive explanations framed as conflict resolution between agents (i.e. AI models and/or humans) by leveraging on computational argumentation. Specifically, we define Argumentative eXchanges (AXs) for dynamically sharing, in multi-agent systems, information harboured in individual agents’ quantitative bipolar argumentation frameworks towards resolving conflicts amongst the agents. We then deploy AXs in the XAI setting in which a machine and a human interact about the machine’s predictions. We identify and assess several theoretical properties characterising AXs that are suitable for XAI. Finally, we instantiate AXs for XAI by defining various agent behaviours, e.g. capturing counterfactual patterns of reasoning in machines and highlighting the effects ofcognitive biases in humans. We show experimentally (in asimulated environment) the comparative advantages of these behaviours in terms of conflict resolution, and show that the strongest argument may not always be the most effective.

  • Conference paper
    Rago A, Gorur D, Toni F, 2023,

    ArguCast: a system for online multi-forecasting with gradual argumentation

    , Knowledge Representation 2023, Publisher:, Pages: 40-51

    Judgmental forecasting is a form of forecasting which employs (human) users to make predictions about specied future events. Judgmental forecasting has been shown to perform better than quantitative methods for forecasting, e.g. when historical data is unavailable or causal reasoning is needed. However, it has a number of limitations, arising from users’ irrationality and cognitive biases. To mitigate against these phenomena, we leverage on computational argumentation, a eld which excels in the representation and resolution of conicting knowledge and human-like reasoning, and propose novel ArguCast frameworks (ACFs) and the novel online system ArguCast, integrating ACFs. ACFs and ArguCast accommodate multi-forecasting, by allowing multiple users to debate on multiple forecasting predictions simultaneously, each potentially admitting multiple outcomes. Finally, we propose a novel notion of user rationality in ACFs based on votes on arguments in ACFs, allowing the ltering out of irrational opinions before obtaining group forecasting predictions by means commonly used in judgmental forecasting.

  • Conference paper
    Nguyen H-T, Satoh K, Goebel R, Stathis K, Toni Fet al., 2023,

    Black-box analysis: GPTs across time in legal textual entailment task

    , ISAILD symposium - International Symposium on Artificial Intelligence and Legal Documents, Publisher: IEEE
  • Journal article
    Toni F, Rago A, Cyras K, 2023,

    Forecasting with jury-based probabilistic argumentation

    , Journal of Applied Non Classical Logics, Vol: 33, Pages: 224-243, ISSN: 1166-3081

    Probabilistic Argumentation supports a form of hybrid reasoning by integratingquantitative (probabilistic) reasoning and qualitative argumentation in a naturalway. Jury-based Probabilistic Argumentation supports the combination of opinionsby different reasoners. In this paper we show how Jury-based Probabilistic Abstract Argumentation (JPAA) and a form of Jury-based Probabilistic Assumptionbased Argumentation (JPABA) can naturally support forecasting, whereby subjective probability estimates are combined to make predictions about future occurrences of events. The form of JPABA we consider is an instance of JPAA andresults from integrating Assumption-Based Argumentation (ABA) and probabilityspaces expressed by Bayesian networks, under the so-called constellation approach.It keeps the underlying structured argumentation and probabilistic reasoning modules separate while integrating them. We show how JPAA and (the considered formof) JPABA can be used to support forecasting by 1) supporting different forecasters (jurors) to determine the probability of arguments (and, in the JPABA case,sentences) with respect to their own probability spaces, while sharing arguments(and their components); and 2) supporting the aggregation of individual forecaststo produce group forecasts.

  • Conference paper
    Yin X, Potyka N, Toni F, 2023,

    Argument attribution explanations in quantitative bipolar argumentation frameworks

    , 26th European Conference on Artificial Intelligence ECAI 2023
  • Conference paper
    Ayoobi H, Potyka N, Toni F, 2023,

    SpArX: Sparse Argumentative Explanations for Neural Networks

    , European Conference on Artificial Intelligence 2023

    Neural networks (NNs) have various applications in AI, but explaining their decisions remains challenging. Existing approaches often focus on explaining how changing individual inputs affects NNs' outputs. However, an explanation that is consistent with the input-output behaviour of an NN is not necessarily faithful to the actual mechanics thereof. In this paper, we exploit relationships between multi-layer perceptrons (MLPs) and quantitative argumentation frameworks (QAFs) to create argumentative explanations for the mechanics of MLPs. Our SpArX method first sparsifies the MLP while maintaining as much of the original structure as possible. It then translates the sparse MLP into an equivalent QAF to shed light on the underlying decision process of the MLP, producing global and/or local explanations. We demonstrate experimentally that SpArX can give more faithful explanations than existing approaches, while simultaneously providing deeper insightsinto the actual reasoning process of MLPs.

  • Conference paper
    Mihailescu I, Weng A, Sharma S, Ghitu M, Grewal D, Chew K, Ayoobi H, Potyka N, Toni Fet al., 2023,

    PySpArX - A Python library for generating Sparse Argumentative eXplanations for neural networks

    , ICLP 2023, Publisher: Open Publishing Association, Pages: 336-336, ISSN: 2075-2180
  • Conference paper
    Toni F, Potyka N, Ulbricht M, Totis Pet al., 2023,

    Understanding ProbLog as probabilistic argumentation

    , ICLP 2023, Publisher: Open Publishing Association, Pages: 183-189, ISSN: 2075-2180

    ProbLog is a popular probabilistic logic programming language and tool, widely used for applications requiring to deal with inherent uncertainties in structured domains. In this paper we study someconnections between ProbLog and a variant of another well-known formalism combining symbolicreasoning and reasoning under uncertainty, namely probabilistic argumentation. Specifically, weshow that ProbLog is an instance of a form of Probabilistic Abstract Argumentation (PAA) underthe constellation approach, which builds upon Assumption-Based Argumentation (ABA). The connections pave the way towards equipping ProbLog with a variety of alternative semantics, inheritedfrom PAA/PABA, as well as obtaining novel argumentation semantics for PAA/PABA, leveraging onexisting connections between ProbLog and argumentation. Moreover, the connections pave the waytowards novel forms of argumentative explanations for ProbLog’s outputs.

  • Conference paper
    De Angelis E, Proietti M, Toni F, 2023,

    ABA learning via ASP

    , ICLP 2023, Publisher: Open Publishing Association, Pages: 1-8, ISSN: 2075-2180

    Recently, ABA Learning has been proposed as a form of symbolic machine learning for drawing Assumption-Based Argumentation frameworks from background knowledge and positive and negative examples. We propose a novel method for implementing ABA Learning using Answer SetProgramming as a way to help guide Rote Learning and generalisation in ABA Learning.

  • Conference paper
    Proietti M, Toni F, 2023,

    A roadmap for neuro-argumentative learning

    , 17th International Workshop on Neural-Symbolic Learning and Reasoning (NeSy 2023), Publisher: CEUR Workshop Proceedings, Pages: 1-8, ISSN: 1613-0073

    Computational argumentation (CA) has emerged, in recent decades, as a powerful formalism for knowl-edge representation and reasoning in the presence of conflicting information, notably when reasoningnon-monotonically with rules and exceptions. Much existing work in CA has focused, to date, on rea-soning with given argumentation frameworks (AFs) or, more recently, on using AFs, possibly automat-ically drawn from other systems, for supporting forms of XAI. In this short paper we focus insteadon the problem of learning AFs from data, with a focus on neuro-symbolic approaches. Specifically,we overview existing forms of neuro-argumentative (machine) learning, resulting from a combinationof neural machine learning mechanisms and argumentative (symbolic) reasoning. We include in ouroverview neuro-symbolic paradigms that integrate reasoners with a natural understanding in argumen-tative terms, notably those capturing forms of non-monotonic reasoning in logic programming. We alsooutline avenues and challenges for future work in this spectrum.

  • Conference paper
    Jiang J, Leofante F, Rago A, Toni Fet al., 2023,

    Formalising the robustness of counterfactual explanations for neural networks

    , 37th AAAI Conference on Artificial Intelligence (AAAI 2023), Publisher: Association for the Advancement of Artificial Intelligence, Pages: 14901-14909, ISSN: 2374-3468

    The use of counterfactual explanations (CFXs) is an increasingly popular explanation strategy for machine learning models. However, recent studies have shown that these explanations may not be robust to changes in the underlying model (e.g., following retraining), which raises questions about their reliability in real-world applications. Existing attempts towards solving this problem are heuristic, and the robustness to model changes of the resulting CFXs is evaluated with only a small number of retrained models, failing to provide exhaustive guarantees. To remedy this, we propose the first notion to formally and deterministically assess the robustness (to model changes) of CFXs for neural networks, that we call ∆-robustness. We introduce an abstraction framework based on interval neural networks to verify the ∆-robustness of CFXs against a possibly infinite set of changes to the model parameters, i.e., weights and biases. We then demonstrate the utility of this approach in two distinct ways. First, we analyse the ∆-robustness of a number of CFX generation methods from the literature and show that they unanimously host significant deficiencies in this regard. Second, we demonstrate how embedding ∆-robustness within existing methods can provide CFXs which are provably robust.

  • Conference paper
    Potyka N, Yin X, Toni F, 2023,

    Explaining random forests using bipolar argumentation and Markov networks

    , AAAI 23, Pages: 9458-9460, ISSN: 2159-5399

    Random forests are decision tree ensembles that can be used to solve a variety of machine learning problems. However, as the number of trees and their individual size can be large, their decision making process is often incomprehensible. We show that their decision process can be naturally represented as an argumentation problem, which allows creating global explanations via argumentative reasoning. We generalize sufficientand necessary argumentative explanations using a Markov network encoding, discuss the relevance of these explanations and establish relationships to families of abductive explanations from the literature. As the complexity of the explanation problems is high, we present an efficient approximation algorithm with probabilistic approximation guarantees.

  • Conference paper
    Nguyen H-T, Toni F, Stathis K, Satoh Ket al., 2023,

    Neurosymbolic approaches for legal reasoning

    , Logic Programming and Legal Reasoning Workshop@ICLP2023

    Logic programming has long being advocated for legal reasoning, and several approaches have been putforward relying upon explicit representation of the law in logic programming terms. In this positionpaper we focus on the PROLEG logic-programming-based framework for formalizing and reasoningwith Japanese presupposed ultimate fact theory. Specifically, we examine challenges and opportunitiesin leveraging deep learning techniques for improving legal reasoning using PROLEG, identifying fourdistinct options ranging from enhancing fact extraction using deep learning to end-to-end solutionsfor reasoning with textual legal descriptions. We assess advantages and limitations of each option,considering their technical feasibility, interpretability, and alignment with the needs of legal practitionersand decision-makers. We believe that our analysis can serve as a guideline for developers aiming tobuild effective decision-support systems for the legal domain, while fostering a deeper understanding ofchallenges and potential advancements by neuro-symbolic approaches in legal applications.

  • Conference paper
    Nguyen H-T, Goebel R, Toni F, Stathis K, Satoh Ket al., 2023,

    How well do SOTA legal reasoning models support abductive reasoning?

    , Logic Programming and Legal Reasoning Workshop@ICLP2023

    We examine how well the state-of-the-art (SOTA) models used in legal reasoning support abductivereasoning tasks. Abductive reasoning is a form of logical inference in which a hypothesis is formulatedfrom a set of observations, and that hypothesis is used to explain the observations. The ability toformulate such hypotheses is important for lawyers and legal scholars as it helps them articulate logicalarguments, interpret laws, and develop legal theories. Our motivation is to consider the belief thatdeep learning models, especially large language models (LLMs), will soon replace lawyers because theyperform well on tasks related to legal text processing. But to do so, we believe, requires some form ofabductive hypothesis formation. In other words, while LLMs become more popular and powerful, wewant to investigate their capacity for abductive reasoning. To pursue this goal, we start by building alogic-augmented dataset for abductive reasoning with 498,697 samples and then use it to evaluate theperformance of a SOTA model in the legal field. Our experimental results show that although thesemodels can perform well on tasks related to some aspects of legal text processing, they still fall short insupporting abductive reasoning tasks.

  • Conference paper
    Paulino Passos G, Satoh K, Toni F, 2023,

    A Dataset of Contractual Events in Court Decisions

    , Logic Programming and Legal Reasoning Workshop @ ICLP 2023

    The promise of automation of legal reasoning is developing technology that reduces human time required for legal tasks or that improves human performance on such tasks. In order to do so, different methods and systems based on logic programming were developed. However, in order to apply such methods on legal data, it is necessary to provide an interface between human users and the legal reasoning system, and the most natural interface in the legal domain is natural language, in particular, written text. In order to perform reasoning in written text using logic programming methods, it is then necessary to map expressions in text to atoms and predicates in the formal language, a task referred generally as information extraction. In this work, we propose a new dataset for the task of information extraction, in particular event extraction, in court decisions, focusing on contracts. Our dataset captures contractual relations and events that affect them in some way, such as negotiations preceding a (possible) contract, the execution of a contract, or its termination. We conducted text annotation with law students and graduates, resulting in a dataset with 207 documents, 3934 sentences, 4627 entities, and 1825 events. We describe here this resource, the annotation process, its evaluation with inter-annotator agreement metrics, and discuss challenges during the development of this resource and for the future.

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