Joshi, Aravind K

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2001 - 20107
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  • Publication
    The Penn Discourse Treebank 2.0 Annotation Manual
    (2007-12-17) Prasad, Rashmi; Miltsakaki, Eleni; Dinesh, Nikhil; Lee, Alan; Joshi, Aravind; Robaldo, Livio; Webber, Bonnie L
    This report contains the guidelines for the annotation of discourse relations in the Penn Discourse Treebank (http://www.seas.upenn.edu/~pdtb), PDTB. Discourse relations in the PDTB are annotated in a bottom up fashion, and capture both lexically realized relations as well as implicit relations. Guidelines in this report are provided for all aspects of the annotation, including annotation explicit discourse connectives, implicit relations, arguments of relations, senses of relations, and the attribution of relations and their arguments. The report also provides descriptions of the annotation format representation.
  • Publication
    Easily Identifiable Discourse Relations
    (2008-06-16) Pitler, Emily; Raghupathy, Mridhula; Mehta, Hena; Nenkova, Ani; Lee, Alan; Joshi, Aravind K
    We present a corpus study of local discourse relations based on the Penn Discourse Tree Bank, a large manually annotated corpus of explicitly or implicitly realized contingency, comparison, temporal and expansion relations. We show that while there is a large degree of ambiguity in temporal explicit discourse connectives, overall discourse connectives are mostly unambiguous and allow high accuracy classification of discourse relations. We achieve 93.09% accuracy in classifying the explicit relations and 74.74% accuracy overall. In addition, we show that some pairs of relations occur together in text more often than expected by chance. This finding suggest that global sequence classification of the relations in text can lead to better results, especially for implicit relations.
  • Publication
    Logic-based Regulatory Conformance Checking
    (2007-09-13) Dinesh, Nikhil; Joshi, Aravind K; Lee, Insup; Sokolsky, Oleg
    In this paper, we describe an approach to formally assess whether an organization conforms to a body of regulation. Conformance is cast as a model checking question where the regulation is represented in a logic that is evaluated against an abstract model representing the operations of an organization. Regulatory bases are large and complex, and the long term goal of our work is to be able to use natural language processing (NLP) to assist in the translation of regulation to logic. We argue that the translation of regulation to logic should proceed one sentence at a time. A challenge in taking this approach arises from the fact that sentences is regulation often refer to others. We motivate the need for a formal representation of regulation to accommodate references between statements. We briefly describe a logic in which statements can refer to and reason about others. We then discuss preliminary work on using NLP to assist in the translation of regulatory sentences into logic.
  • Publication
    Permission to Speak: A Logic for Access Control and Conformance
    (2010-01-01) Dinesh, Nikhil; Joshi, Aravind; Lee, Insup; Sokolsky, Oleg
    Formal languages for policy have been developed for access control and conformance checking. In this paper, we describe a formalism that combines features that have been developed for each application. From access control, we adopt the use of a saying operator. From conformance checking, we adopt the use of operators for obligation and permission. The operators are combined using an axiom that permits a principal to speak on behalf of another. The combination yields benefits to both applications. For access control, we overcome the problematic interaction between hand-off and classical reasoning. For conformance, we obtain a characterization of legal power by nesting saying with obligation and permission. The axioms result in a decidable logic. We integrate the axioms into a logic programming approach, which lets us use quantification in policies while preserving decidability of access control decisions. Conformance checking, in the presence of nested obligations and permissions, is shown to be decidable. Non-interference is characterized using reachability via permitted statements.
  • Publication
    Checking Traces for Regulatory Conformance
    (2008-03-30) Dinesh, Nikhil; Joshi, Aravind K; Lee, Insup; Sokolsky, Oleg
    We consider the problem of checking whether the operations of an organization conform to a body of regulation. The immediate motivation comes from the analysis of the U.S. Food and Drug Administration regulations that apply to bloodbanks - organizations that collect, process, store, and use donations of blood and blood components. Statements in such regulations convey constraints on operations or sequences of operations that are performed by an organization. It is natural to express these constraints in a temporal logic. There are two important features of regulatory texts that need to be accommodated by a representation in logic. First, the constraints conveyed by regulation can be obligatory (required) or permitted (optional). Second, statements in regulation refer to others for conditions or exceptions. An organization conforms to a body of regulation if and only if it satisfies all the obligations. However, permissions provide exceptions to obligations, indirectly affecting conformance. In this paper, we extend linear temporal logic to distinguish between obligations and permissions, and to allow statements to refer to others. While the resulting logic allows for a direct representation of regulation, evaluating references between statements has high complexity. We discuss an empirically motivated assumption that lets us replace references with tests of lower complexity, leading to efficient trace-checking algorithms in practice.
  • Publication
    Reasoning about Conditions and Exceptions to Laws in Regulatory Conformance Checking
    (2008-07-01) Dinesh, Nikhil; Joshi, Aravind K; Lee, Insup; Sokolsky, Oleg
    This paper considers the problem of checking whether an organization conforms to a body of regulation. Conformance is cast as a trace checking question – the regulation is represented in a logic that is evaluated against an abstract trace or run representing the operations of an organization. We focus on a problem in designing a logic to represent regulation. A common phenomenon in regulatory texts is for sentences to refer to others for conditions or exceptions. We motivate the need for a formal representation of regulation to accommodate such references between statements. We then extend linear temporal logic to allow statements to refer to others. The semantics of the resulting logic is defined via a combination of techniques from Reiter's default logic and Kripke's theory of truth.
  • Publication
    Anaphora and Discourse Semantics
    (2001-01-01) Webber, Bonnie L; Stone, Matthew; Joshi, Aravind; Knott, Alistair
    We argue in this paper that many common adverbial phrases generally taken to be discourse connectives signalling discourse relations between adjacent discourse units are instead anaphors. We do this by (i) demonstrating their behavioral similarity with more common anaphors (pronouns and definite NPs); (ii) presenting a general framework for understanding anaphora into which they nicely fit; (iii) showing the interpretational benefits of understanding discourse adverbials as anaphors; and (iv) sketching out a lexicalised grammar that facilitates discourse interpretation as a product of compositional rules, anaphor resolution and inference.