In mathematics, an ancient solution to a differential equation is a solution that can be extrapolated backwards to all past times, without singularities. That is, it is a solution "that is defined on a time interval of the form (−∞, T ) ."[ 1]
The term was introduced by Richard Hamilton in his work on the Ricci flow .[ 2] It has since been applied to other geometric flows [ 3] [ 4] [ 5] [ 6] as well as to other systems such as the Navier–Stokes equations [ 7] [ 8] and heat equation .[ 9]
^ Perelman, Grigori (2002), The entropy formula for the Ricci flow and its geometric applications , arXiv :math/0211159 , Bibcode :2002math.....11159P .
^ Hamilton, Richard S. The formation of singularities in the Ricci flow. Surveys in differential geometry, Vol. II (Cambridge, MA, 1993), 7–136, Int. Press, Cambridge, MA, 1995
^ Loftin, John; Tsui, Mao-Pei (2008), "Ancient solutions of the affine normal flow", Journal of Differential Geometry , 78 (1): 113–162, arXiv :math/0602484 , doi :10.4310/jdg/1197320604 , MR 2406266 , S2CID 420652 .
^ Daskalopoulos, Panagiota ; Hamilton, Richard ; Sesum, Natasa (2010), "Classification of compact ancient solutions to the curve shortening flow", Journal of Differential Geometry , 84 (3): 455–464, arXiv :0806.1757 , Bibcode :2008arXiv0806.1757D , doi :10.4310/jdg/1279114297 , MR 2669361 , S2CID 18747005 .
^ You, Qian (2014), Some Ancient Solutions of Curve Shortening , Ph.D. thesis, University of Wisconsin–Madison , ProQuest 1641120538 .
^ Huisken, Gerhard ; Sinestrari, Carlo (2015), "Convex ancient solutions of the mean curvature flow", Journal of Differential Geometry , 101 (2): 267–287, arXiv :1405.7509 , doi :10.4310/jdg/1442364652 , MR 3399098 .
^ Seregin, Gregory A. (2010), "Weak solutions to the Navier-Stokes equations with bounded scale-invariant quantities", Proceedings of the International Congress of Mathematicians , vol. III, Hindustan Book Agency, New Delhi, pp. 2105–2127, MR 2827878 .
^ Barker, T.; Seregin, G. (2015), "Ancient solutions to Navier-Stokes equations in half space", Journal of Mathematical Fluid Mechanics , 17 (3): 551–575, arXiv :1503.07428 , Bibcode :2015JMFM...17..551B , doi :10.1007/s00021-015-0211-z , MR 3383928 , S2CID 119138067 .
^ Wang, Meng (2011), "Liouville theorems for the ancient solution of heat flows", Proceedings of the American Mathematical Society , 139 (10): 3491–3496, doi :10.1090/S0002-9939-2011-11170-5 , MR 2813381 .