- Seifert conjecture
In
mathematics , the Seifert conjecture states that every nonsingular, continuousvector field on the3-sphere has a closed orbit. It is named afterHerbert Seifert . In a 1950 paper, Seifert asked if such a vector field exists, but did not phrase non-existence as a conjecture. He also established the conjecture for perturbations of theHopf fibration .The conjecture was disproven in 1974 by
Paul Schweitzer , who exhibited a counterexample. Schweitzer's construction was then modified byJenny Harrison in 1988 to make a counterexample for some . The existence of smoother counterexamples remained an open question until 1993 whenKrystyna Kuperberg constructed a very different counterexample. Later this construction was shown to have real analytic and piecewise linear versions.References
*V. Ginzburg and B. Gürel, " [http://front.math.ucdavis.edu/math.DG/0110047 A -smooth counterexample to the Hamiltonian Seifert conjecture in ] ", Ann. of Math. (2) 158 (2003), no. 3, 953--976
*J. Harrison, " counterexamples to the Seifert conjecture", Topology 27 (1988), no. 3, 249--278.
*G. Kuperberg "A volume-preserving counterexample to the Seifert conjecture", Comment. Math. Helv. 71 (1996), no. 1, 70--97.
*K. Kuperberg "A smooth counterexample to the Seifert conjecture", Ann. of Math. (2) 140 (1994), no. 3, 723--732.
*G. Kuperberg and K. Kuperberg, " [http://front.math.ucdavis.edu/math.DS/9802040 Generalized counterexamples to the Seifert conjecture] ", Ann. of Math. (2) 143 (1996), no. 3, 547--576.
*H. Seifert, "Closed integral curves in 3-space and isotopic two-dimensional deformations", Proc. Amer. Math. Soc. 1, (1950). 287--302.
*P. A. Schweitzer, "Counterexamples to the Seifert conjecture and opening closed leaves of foliations", Ann. of Math. (2) 100 (1974), 386--400.Further reading
*K. Kuperberg, " [http://www.ams.org/notices/199909/fea-kuperberg.pdf Aperiodic dynamical systems] ". Notices Amer. Math. Soc. 46 (1999), no. 9, 1035--1040.
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