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Combining Cardinal Direction Relations and Other Orientation Relations In QSR
 IN PROC. OF 8TH INTERNATIONAL SYMPOSIUM ON ARTIFICIAL INTELLIGENCE AND MATHEMATICS (AI&M’04
, 2004
"... We propose a calculus, cCOA, combining, thus more expressive than each of, two orientation calculi wellknown in QSR: Frank's projectionbased cardinal direction calculus, CDA, and a coarser version, ROA, of Freksa's relative orientation calculus. An original constraint propagation procedu ..."
Abstract

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We propose a calculus, cCOA, combining, thus more expressive than each of, two orientation calculi wellknown in QSR: Frank's projectionbased cardinal direction calculus, CDA, and a coarser version, ROA, of Freksa's relative orientation calculus. An original constraint propagation procedure, PcS4c+(), for cCOACSPs is presented, which aims at (1) achieving path consistency (Pc) for the CDA projection; (2) achieving strong 4consistency (S4c) for the ROA projection; and (3) more (+) the "+" consists of the implementation of the interaction between the two combined calculi. Dealing with the first two points is not new, and involves mainly the CDA composition table and the ROA composition table, which can be found in, or derived from, the literature. The originality of the propagation algorithm comes from the last point. Two tables, one for each of the two directions CDAtoROA and ROAtoCDA, capturing the interaction between the two kinds of knowledge, are defined, and used by the algorithm. The importance of taking into account the interaction is shown with a real example providing an inconsistent knowledge base, whose inconsistency (a) cannot be detected by reasoning separately about each of the two components of the knowledge, just because, taken separately, each is consistent, but (b) is detected by the proposed algorithm, thanks to the interaction knowledge propagated from each of the two compnents to the other.
unknown title
, 2003
"... Integrating existing coneshaped and projectionbased cardinal direction relations and a TCSP ⋆like decidable generalisation ⋆⋆ ..."
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Integrating existing coneshaped and projectionbased cardinal direction relations and a TCSP ⋆like decidable generalisation ⋆⋆