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This article explores the concepts of chain reachability and planar linkages, showcasing examples such as the Watt Linkage and Peaucellier Linkage. It also delves into the Kempe Universality Theorem and the Kapovich & Millson Proof. The Cinderella software and steam locomotive applications are discussed as well.
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Part I: Linkagesa: Universality Joseph O’Rourke Smith College
Outline • Chain Reachability • Ruler Folding • Pantograph • Watt Linkage; Peaucellier Linkage • Kempe Universality Theorem • Kapovich & Millson Proof
Chain Reachability • Connectivity of configuration space • Annulus • Two-kinks theorem
Cinderella(FU Berlin, J.-R. Gebert & U. Kortenkamp) • Example construction • Lamp example [lamp1.cdy] • Cinderella 1.4: • http://page.inf.fu-berlin.de/~kortenka/CinderellaJapan/install.htm • user: cindybeta, password: geo-i.pdf • Cinderella 2: • http://www.cinderella.de/beta/install.htm • user: cindybeta, password: geo-i.pdf
Watt Linkage • Circular to nearly linear • [Watt.cdy]
Peaucellier Linkage • Circular to linear • [Peaucellier.cdy]
Universality Theorems • Theorem 4.2.3 ([KM02]) Let C be a bounded portion of an algebraic curve in the plane. Then there exists a planar linkage such that the orbit of one joint is precisely C. • Theorem 4.2.4 ([JS99]) Let V ≤ Rd be a compact real algebraic variety (with topology induced by the Euclidean topology of Rd). Then V is homeomorphic to some components of a planar linkage.
Additor; Multiplicator • Additor • Multiplicator • [Contraparallelogram.cdy] • [Multiplicator.cdy]
Kapovich & Millson 2002 • [Kem76] Alfred Bray Kempe. On a general method of describing plane curves of the nth degree by linkwork. Proc. London Math. Soc., 7:213-216, 1876. • [KM02] Michael Kapovich and John J. Millson. Universality theorems for configuration spaces of planar linkages. Topology, 41(6):1051-1107, 2002.