Reference: Pinheiro da Silva, P.; Hayes, P.; McGuinness, D. L.; & Fikes, R. PPDR: A Proof Protocol for Deductive Reasoning. Technical Report, Knowledge Systems Laboratory, Stanford University., 2004, 2004.
Abstract: The distributed and heterogeneous nature of the Web implies that a variety of agents may participate in helping to answer any question posed to a web application. Since multiple agents with various reasoning methods and representation languages may be used, inference rules used to derive any particular answer may be quite diverse. Since the evolving web is expected to continue to leverage diverse agents with diverse reasoning rules and since many users will need to have access to some explanation of how answers were obtained, this emerging web needs to have a way of leveraging and explaining hybrid reasoning. The emerging web needs an abstract, uniform way of specifying inference rules used in answer generation if tools are going to combine answers from hybrid systems, manipulate the justifications of those answers, and check to see if the justifications include correct applications of the inference rules. In this paper we introduce PPDR -- the Proof Protocol for Deductive Reasoning -- which is a language used to represent diverse inference rules. Also, in combination with the Proof Markup Language (PML), PPDR allows proofs produced by multiple agents to be combined, manipulated to present abstract explanations, and verified against the abstract rule specification.
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