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Claudia Schulz

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12 papers
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12

AAAI Conference 2020 Conference Paper

Can Embeddings Adequately Represent Medical Terminology? New Large-Scale Medical Term Similarity Datasets Have the Answer!

  • Claudia Schulz
  • Damir Juric

A large number of embeddings trained on medical data have emerged, but it remains unclear how well they represent medical terminology, in particular whether the close relationship of semantically similar medical terms is encoded in these embeddings. To date, only small datasets for testing medical term similarity are available, not allowing to draw conclusions about the generalisability of embeddings to the enormous amount of medical terms used by doctors. We present multiple automatically created large-scale medical term similarity datasets and confirm their high quality in an annotation study with doctors. We evaluate state-of-the-art word and contextual embeddings on our new datasets, comparing multiple vector similarity metrics and word vector aggregation techniques. Our results show that current embeddings are limited in their ability to adequately encode medical terms. The novel datasets thus form a challenging new benchmark for the development of medical embeddings able to accurately represent the whole medical terminology.

AAAI Conference 2019 Conference Paper

Challenges in the Automatic Analysis of Students’ Diagnostic Reasoning

  • Claudia Schulz
  • Christian M. Meyer
  • Iryna Gurevych

Diagnostic reasoning is a key component of many professions. To improve students’ diagnostic reasoning skills, educational psychologists analyse and give feedback on epistemic activities used by these students while diagnosing, in particular, hypothesis generation, evidence generation, evidence evaluation, and drawing conclusions. However, this manual analysis is highly time-consuming. We aim to enable the large-scale adoption of diagnostic reasoning analysis and feedback by automating the epistemic activity identification. We create the first corpus for this task, comprising diagnostic reasoning selfexplanations of students from two domains annotated with epistemic activities. Based on insights from the corpus creation and the task’s characteristics, we discuss three challenges for the automatic identification of epistemic activities using AI methods: the correct identification of epistemic activity spans, the reliable distinction of similar epistemic activities, and the detection of overlapping epistemic activities. We propose a separate performance metric for each challenge and thus provide an evaluation framework for future research. Indeed, our evaluation of various state-of-the-art recurrent neural network architectures reveals that current techniques fail to address some of these challenges.

IJCAI Conference 2019 Conference Paper

On the Responsibility for Undecisiveness in Preferred and Stable Labellings in Abstract Argumentation (Extended Abstract)

  • Claudia Schulz
  • Francesca Toni

Different semantics of abstract Argumentation Frameworks (AFs) provide different levels of decisiveness for reasoning about the acceptability of conflicting arguments. The stable semantics is useful for applications requiring a high level of decisiveness, as it assigns to each argument the label "accepted" or the label "rejected". Unfortunately, stable labellings are not guaranteed to exist, thus raising the question as to which parts of AFs are responsible for the non-existence. In this paper, we address this question by investigating a more general question concerning preferred labellings (which may be less decisive than stable labellings but are always guaranteed to exist), namely why a given preferred labelling may not be stable and thus undecided on some arguments. In particular, (1) we give various characterisations of parts of an AF, based on the given preferred labelling, and (2) we show that these parts are indeed responsible for the undecisiveness if the preferred labelling is not stable. We then use these characterisations to explain the non-existence of stable labellings.

IJCAI Conference 2018 Conference Paper

On the Equivalence between Assumption-Based Argumentation and Logic Programming (Extended Abstract)

  • Martin Caminada
  • Claudia Schulz

In this work, we explain how Assumption-Based Argumentation (ABA) is subsumed by Logic Programming (LP). The translation from ABA to LP (with a few restrictions on the ABA framework) results in a normal logic program whose semantics coincide with the semantics of the underlying ABA framework. Although the precise technicalities are beyond the current extended abstract (these can be found in the associated full paper) we provide a number of examples to illustrate the general idea.

FLAP Journal 2017 Journal Article

Assumption-based Argumentation: Disputes, Explanations, Preferences.

  • Kristijonas Cyras
  • Xiuyi Fan
  • Claudia Schulz
  • Francesca Toni

Assumption-Based Argumentation (ABA) is a form of structured argumentation with roots in non-monotonic reasoning. As in other forms of structured argumentation, notions of argument and attack are not primitive in ABA, but are instead defined in terms of other notions. In the case of ABA these other notions are those of rules in a deductive system, assumptions, and contraries. ABA is equipped with a range of computational tools, based on dispute trees and amounting to dispute derivations, and benefiting from equivalent views of the semantics of argumentation in ABA, in terms of sets of arguments and, equivalently, sets of assumptions. These computational tools can also provide the foundation for multi-agent argumentative dialogues and explanation of reasoning outputs, in various settings and senses. ABA is a flexible modelling formalism, despite its simplicity, allowing to support, in particular, various forms of non-monotonic reasoning, and reasoning with some forms of preferences and defeasible rules without requiring any additional machinery. ABA can also be naturally extended to accommodate further reasoning with preferences.

JAIR Journal 2017 Journal Article

On the Equivalence between Assumption-Based Argumentation and Logic Programming

  • Martin Caminada
  • Claudia Schulz

Assumption-Based Argumentation (ABA) has been shown to subsume various other non-monotonic reasoning formalisms, among them normal logic programming (LP). We re-examine the relationship between ABA and LP and show that normal LP also subsumes (flat) ABA. More precisely, we specify a procedure that given a (flat) ABA framework yields an associated logic program with almost the same syntax whose semantics coincide with those of the ABA framework. That is, the 3-valued stable (respectively well-founded, regular, 2-valued stable, and ideal) models of the associated logic program coincide with the complete (respectively grounded, preferred, stable, and ideal) assumption labellings and extensions of the ABA framework. Moreover, we show how our results on the translation from ABA to LP can be reapplied for a reverse translation from LP to ABA, and observe that some of the existing results in the literature are in fact special cases of our work. Overall, we show that (flat) ABA frameworks can be seen as normal logic programs with a slightly different syntax. This implies that methods developed for one of these formalisms can be equivalently applied to the other by simply modifying the syntax.

AAAI Conference 2015 Conference Paper

Graphical Representation of Assumption-Based Argumentation

  • Claudia Schulz

Since Assumption-Based Argumentation (ABA) was introduced in the nineties, the structure and semantics of an ABA framework have been studied exclusively in logical terms without any graphical representation. Here, we show how an ABA framework and its complete semantics can be displayed in a graph, clarifying the structure of the ABA framework as well as the resulting complete assumption labellings. Furthermore, we show that such an ABA graph can be used to represent the structure and semantics of a logic program (LP), based on the correspondence between the semantics of a LP and an ABA framework encoding this LP.

AAAI Conference 2015 Conference Paper

Logic Programming in Assumption-Based Argumentation Revisited – Semantics and Graphical Representation

  • Claudia Schulz
  • Francesca Toni

Logic Programming and Argumentation Theory have been existing side by side as two separate, yet related, techniques in the field of Knowledge Representation and Reasoning for many years. When Assumption-Based Argumentation (ABA) was first introduced in the nineties, the authors showed how a logic program can be encoded in an ABA framework and proved that the stable semantics of a logic program corresponds to the stable extension semantics of the ABA framework encoding this logic program. We revisit this initial work by proving that the 3-valued stable semantics of a logic program coincides with the complete semantics of the encoding ABA framework, and that the L-stable semantics of this logic program coincides with the semi-stable semantics of the encoding ABA framework. Furthermore, we show how to graphically represent the structure of a logic program encoded in an ABA framework and that not only logic programming and ABA semantics but also Abstract Argumentation semantics can be easily applied to a logic program using these graphical representations.