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2. Euler , p. 233.
3. For more details, see Hammer and Shin .
4. Such problems have been studied under the banner of “Topological Inference” and are nearly all NP hard [Grigni et al. 1995, Lemon & Pratt 1997b].
5. Now Ian Pratt-Hartmann.
6. As a practical instance of Helly's Theorem.
7. For example: Reasoning with Diagrammatic Representations: 1992 AAAI Spring Symposium; Cognitive and Computational Models of Spatial Representation: 1996 AAAI Spring Symposium; Reasoning with Diagrammatic Representations II: 1997 AAAI Fall Symposium; and Formalizing Reasoning with Visual and Diagrammatic Representations: 1998 AAAI Fall Symposium. See also Narajanan .
8. The following conferences are good evidence for this effort: VISUAL '98: Visualization Issues in Formal Methods (Lisbon); International Roundtable Conference on Visual and Spatial Reasoning in Design (MIT, 1999); and Theories of Visual Languages -- Track of VL '99 : 1999 IEEE Symposium on Visual Languages.
9. See Aristotle On the Soul and On the Memory and Recollection.
10. Block  is one
of the best collections of important papers on this debate, and Block
 presents a succinct summary of this controversy and raises
insightful philosophical questions about the debate. Chapters 1-4 of
Tye  are a good overview of both cognitive scientists' and
philosophers' various positions on this issue.