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| | Hi there. Let me start by introducing the author, her title is Sophia. What me and my family members love is performing ballet but I've been using on new issues recently. Invoicing is my profession. North Carolina is exactly where we've been residing for years and will by no means move.<br><br>Here is my blog clairvoyants ([http://si.dgmensa.org/xe/index.php?document_srl=48014&mid=c0102 click through the next website page]) |
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| In mathematics, in [[Riemannian geometry]], [[Mikhail Gromov (mathematician)|Mikhail Gromov]]'s '''filling area conjecture''' asserts that among all possible fillings of the [[Riemannian circle]] of length 2π by a surface with the strongly isometric property, the round hemisphere has the least area. Here the ''Riemannian circle'' refers to the unique closed 1-dimensional Riemannian manifold of total 1-volume 2π and Riemannian diameter π.
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| ==Explanation==
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| To explain the conjecture, we start with the observation that the equatorial circle of the unit 2-sphere
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| :<math>S^2 \subset \R^3 \,\!</math>
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| is a [[Riemannian circle]] ''S''<sup>1</sup> of length 2π and diameter π. More precisely, the Riemannian distance function of ''S''<sup>1</sup> is the restriction of the ambient Riemannian distance on the sphere. This property is ''not'' satisfied by the standard imbedding of the unit circle in the Euclidean plane, where a pair of opposite points are at distance 2, not π. | |
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| We consider all fillings of ''S''<sup>1</sup> by a surface, such that the restricted metric defined by the inclusion of the circle as the boundary of the surface is the Riemannian metric of a circle of length 2π. The inclusion of the circle as the boundary is then called a strongly isometric imbedding of the circle. In 1983 Gromov conjectured that the round hemisphere gives the "best" way of filling the circle among all filling surfaces.
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| ==Relation to Pu's inequality==
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| [[Image:Steiner's Roman Surface.gif|thumb|An animation of the [[Roman Surface]] representing RP<sup>2</sup> in R<sup>3</sup>]] | |
| The case of simply-connected fillings is equivalent to [[Pu's inequality|Pu's inequality for the real projective plane]] RP<sup>2</sup>. Recently the case of [[genus (mathematics)|genus]]-1 fillings was settled affirmatively, as well (see Bangert ''et al''). Namely, it turns out that one can exploit a half-century old formula by J. Hersch from integral geometry. Namely, consider the family of figure-8 loops on a football, with the self-intersection point at the equator (see figure at the beginning of the article). Hersch's formula expresses the area of a metric in the conformal class of the football, as an average of the energies of the figure-8 loops from the family. An application of Hersch's formula to the hyperelliptic quotient of the Riemann surface proves the filling area conjecture in this case.
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| ==See also==
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| *[[Filling radius]]
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| *[[Pu's inequality]]
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| *[[Systolic geometry]]
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| ==References==
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| * [[Victor Bangert|Bangert, V.]]; Croke, C.; Ivanov, S.; Katz, M.: Filling area conjecture and ovalless real hyperelliptic surfaces, Geometric and Functional Analysis (GAFA) 15 (2005), no. 3, 577-597. See {{arxiv|math.DG/0405583}}
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| *{{math-citation|authors=Gromov, M.|title=Filling Riemannian manifolds|journal=J. Diff. Geom.|volume=18|year=1983|pages=1–147}}
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| *{{Citation | last1=[[Mikhail Katz|Katz]] | first1=Mikhail G. | title=Systolic geometry and topology| publisher=[[American Mathematical Society]] | location=Providence, R.I. | series=Mathematical Surveys and Monographs | isbn=978-0-8218-4177-8 | year=2007 | volume=137}}
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| {{Systolic geometry navbox}}
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| [[Category:Conjectures]]
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| [[Category:Riemannian geometry]]
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| [[Category:Differential geometry]]
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| [[Category:Differential geometry of surfaces]]
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| [[Category:Surfaces]]
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| [[Category:Area]]
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