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Hilbert's nineteenth problem

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597:, who reduced the differentiability requirements on the solution needed to prove that it is analytic. On the other hand, direct methods in the calculus of variations showed the existence of solutions with very weak differentiability properties. For many years there was a gap between these results. The solutions that could be constructed were known to have square integrable second derivatives, but this was not quite strong enough to feed into the machinery that could prove they were analytic, which needed continuity of first derivatives. This gap was filled independently by 2913: 437: 1961:
One of the most remarkable facts in the elements of the theory of analytic functions appears to me to be this: that there exist partial differential equations whose integrals are all of necessity analytic functions of the independent variables, that is, in short, equations susceptible of none but
84:
Eine der begrifflich merkwürdigsten Thatsachen in den Elementen der Theorie der analytischen Funktionen erblicke ich darin, daß es Partielle Differentialgleichungen giebt, deren Integrale sämtlich notwendig analytische Funktionen der unabhängigen Variabeln sind, die also, kurz gesagt, nur
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gave counterexamples showing that in the case when the solution is vector-valued rather than scalar-valued, it need not be analytic; the example of De Giorgi consists of an elliptic system with bounded coefficients, while the one of Giusti and Miranda has analytic coefficients. Later,
625:. By previous results this implied that the solutions are analytic whenever the differential equation has analytic coefficients, thus completing the solution of Hilbert's nineteenth problem. Subsequently, Jürgen Moser gave an alternate proof of the results obtained by 293: 110:, p. 288) he states that, in his opinion, one of the most remarkable facts of the theory of analytic functions is that there exist classes of partial differential equations which admit only analytic functions as solutions, listing 685:
gave several counterexamples involving a single elliptic equation of order greater than two with analytic coefficients. For experts, the fact that such equations could have nonanalytic and even nonsmooth solutions created a sensation.
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The Maz'ya anniversary collection. Vol. 1: On Maz'ya's work in functional analysis, partial differential equations and applications. Based on talks given at the conference, Rostock, Germany, August 31 – September 4,
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as examples. He then notes that most partial differential equations sharing this property are Euler–Lagrange equations of a well defined kind of variational problem, satisfying the following three properties:
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The affirmative answer to Hilbert's nineteenth problem given by Ennio De Giorgi and John Forbes Nash raised the question if the same conclusion holds also for Euler–Lagrange equations of more general
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for a class of elliptic partial differential equation with analytic coefficients. Therefore the first efforts of researchers who sought to solve it were aimed at studying the regularity of
918: 793: 1513: 2935: 1878: 1435: 3510:(1977), "Example of an irregular solution to a nonlinear elliptic system with analytic coefficients and conditions for regularity", in Kluge, Reinhard; Müller, Wolfdietrich (eds.), 525:" He asks further if this is the case even when the function is required to assume boundary values that are continuous, but not analytic, as happens for Dirichlet's problem for the 2783: 2618: 2556: 432:{\displaystyle {\frac {\partial ^{2}F}{\partial ^{2}p}}\cdot {\frac {\partial ^{2}F}{\partial ^{2}q}}-\left({\frac {\partial ^{2}F}{{\partial p}{\partial q}}}\right)^{2}>0} 3237: 1564: 1638: 1358: 2858:
Hedberg, Lars Inge (1999), "On Maz'ya's work in potential theory and the theory of function spaces", in Rossmann, Jürgen; Takáč, Peter; Wildenhain, Günther (eds.),
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Theory of nonlinear operators: constructive aspects. Proceedings of the fourth international summer school, held at Berlin, GDR, from September 22 to 26, 1975
3507: 2249: 2132:... d. h. ob jede Lagrangesche partielle Differentialgleichung eines reguläres Variationsproblem die Eigenschaft at, daß sie nur analytische Integrale zuläßt 593:
solutions of nonlinear elliptic analytic equations in 2 variables are analytic. Bernstein's result was improved over the years by several authors, such as
542: 1190: 523:... does every Lagrangian partial differential equation of a regular variation problem have the property of admitting analytic integrals exclusively? 3602: 3135: 3009: 2965: 139: 54:
with analytic coefficients, Hilbert's nineteenth problem, despite its seemingly technical statement, simply asks whether, in this class of
2387: 2786:(1968), "Un esempio di soluzioni discontinue per un problema di minimo relativo ad un integrale regolare del calcolo delle variazioni", 1946:, pp. 288–289), or the corresponding section on the nineteenth problem in any of its translations or reprints, or the subsection " 3066:
Compte Rendu du Deuxième Congrès International des Mathématiciens, tenu à Paris du 6 au 12 août 1900. Procès-Verbaux et Communications
1064: 2665:, Classics in Mathematics (Revised 3rd printing of 2nd ed.), Berlin – Heidelberg – New York: Springer Verlag, pp. xiv+517, 3309:, Die Grundlehren der mathematischen Wissenschaften, vol. 130, Berlin–Heidelberg–New York: Springer-Verlag, pp. xii+506, 103: 2820:(1999), "Vladimir Maz'ya: Friend and Mathematician. Recollections", in Rossman, Jürgen; Takáč, Peter; Wildenhain, Günther (eds.), 3765: 502: 51: 3314: 2908: 2879: 2832: 2753: 2670: 2626: 2582: 2399: 547: 3595: 3738: 3727: 3094:– There exists also an earlier (and shorter) resume of Hilbert's original talk, translated in French and published as 2473:
De Giorgi, Ennio (1957), "Sulla differenziabilità e l'analiticità delle estremali degli integrali multipli regolari",
3732: 3722: 2331: 1685: 3101: 3702: 3060: 2051:". Hilbert's definition of a regular variational problem is stronger than the one currently used, for example, in ( 872: 3770: 3707: 3687: 3682: 3438: 678:, showing that in general there is no hope of proving such regularity results without adding further hypotheses. 3760: 3514:, Abhandlungen der Akademie der Wissenschaften der DDR, vol. 1, Berlin: Akademie-Verlag, pp. 197–206, 2457:" (English translation of the title) is a short research announcement disclosing the results detailed later in ( 723: 3717: 3697: 3692: 3588: 3430: 2914:
Nachrichten von der Königlichen Gesellschaft der Wissenschaften zu Göttingen, Mathematisch-Physikalische Klasse
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De Giorgi, Ennio (1968), "Un esempio di estremali discontinue per un problema variazionale di tipo ellittico",
1446: 1809: 1366: 3672: 3186: 3154: 2391: 1803:≥ 0. From his estimate Nash was able to deduce a continuity estimate for solutions of the elliptic equation 55: 3677: 3652: 62:
from the equation it satisfies. Hilbert's nineteenth problem was solved independently in the late 1950s by
2357: 3657: 3637: 3627: 3189:(1968), "Examples of nonregular solutions of quasilinear elliptic equations with analytic coefficients", 2955: 2930: 2273: 1922: 1667:+2)nd derivatives are also Hölder continuous, so repeating this infinitely often shows that the solution 1055: 567: 47: 2430:
Atti della Accademia Nazionale dei Lincei. Rendiconti. Classe di Scienze Fisiche, Matematiche e Naturali
3667: 3662: 3647: 3642: 3632: 3622: 3535: 2708: 2560: 3078: 2277: 3142: 2827:, Operator Theory. Advances and Applications, vol. 109, Basel: Birkhäuser Verlag, pp. 1–5, 3251: 1525: 2475:
Memorie della Accademia delle Scienze di Torino. Classe di Scienze Fisiche, Matematicahe e Naturali
659: 506: 119: 3160:Примеры нерегулярных решений квазилинейных эллиптических уравнений с аналитическими коэффициентами 1566:
is bounded. When this is not the case, a further step is needed: one must prove that the solution
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Are the solutions of regular problems in the calculus of variations always necessarily analytic?
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David Hilbert presented what is now called his nineteenth problem in his speech at the second
3611: 3141:(Report). Oxford: Oxford Centre for Nonlinear PDE. pp. 1–30. OxPDE-11/17. Archived from 2282: 1974: 111: 43: 3565: 3519: 3491: 3447: 3392: 3354: 3324: 3276: 3178: 3032: 2996: 2889: 2842: 2801: 2763: 2716: 2680: 2636: 2592: 2523: 2486: 2441: 2409: 2345: 1587: 1160: 67: 3573: 3557: 3527: 3499: 3418: 3332: 3292: 3220: 3122: 3074: 3048: 2988: 2948: 2922: 2897: 2850: 2809: 2771: 2724: 2688: 2644: 2600: 2531: 2494: 2449: 2417: 2353: 2337:
Proceedings of the International Congress of Mathematicians, Vancouver, B.C., 1974, Vol. 1
2311: 622: 8: 2108: 3451: 3358: 1593: 970: 521:. Having identified the class of problems considered, he poses the following question: " 3479: 3380: 3280: 3208: 3036: 2500:
On the differentiability and the analyticity of extremals of regular multiple integrals
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that satisfies certain growth, smoothness, and convexity conditions. The smoothness of
1017: 997: 946: 926: 849: 821: 801: 538: 58:, any solution inherits the relatively simple and well understood property of being an 3401: 2621:, vol. 105, Princeton, New Jersey: Princeton University Press, pp. vii+297, 3471: 3406: 3372: 3310: 3233:"Regularity of minima: an invitation to the Dark Side of the Calculus of Variations." 3228: 3212: 3131: 2875: 2828: 2749: 2666: 2622: 2608: 2578: 2395: 2319: 2299: 2073: 710: 59: 35: 3284: 3040: 2979: 3569: 3553: 3523: 3495: 3463: 3455: 3426: 3414: 3396: 3362: 3340: 3328: 3288: 3264: 3256: 3216: 3200: 3118: 3110: 3070: 3044: 3018: 2984: 2974: 2944: 2918: 2893: 2867: 2846: 2805: 2767: 2741: 2720: 2684: 2640: 2596: 2570: 2527: 2490: 2445: 2413: 2349: 2307: 2291: 1987: 1310:{\displaystyle \sum \limits _{i=1}^{n}(L_{p_{i}p_{j}}(Dw)w_{x_{j}x_{k}})_{x_{i}}=0} 638: 610: 526: 23: 3136:
Sketches of Regularity Theory from The 20th Century and the Work of Jindřich Nečas
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is a solution of a suitable linear second order strictly elliptic PDE of the form
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An example of discontinuous extremals for a variational problem of elliptic type
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Proceedings of the National Academy of Sciences of the United States of America
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Multiple integrals in the calculus of variations and nonlinear elliptic systems
2548: 675: 3580: 3467: 3268: 3260: 3054:– Translated to French by M. L. Laugel (with additions of Hilbert himself) as 2574: 3754: 3475: 3376: 3096: 3056: 3004: 2960: 2904: 2779: 2696: 2652: 2377: 2340:, ICM Proceedings, Montreal: Canadian Mathematical Congress, pp. 53–63, 2303: 1679:
John Nash gave a continuity estimate for solutions of the parabolic equation
90: 27: 652: 3410: 3540:"Sur l'analyticité des solutions des systèmes d'équations différentielles" 3367: 3158: 2745: 2335: 1919:
Sind die Lösungen regulärer Variationsprobleme stets notwendig analytisch?
841: 2135: 3064: 3483: 3204: 3114: 2295: 2065: 621:), who were able to show the solutions had first derivatives that were 38:. Informally, and perhaps less directly, since Hilbert's concept of a " 2740:– London – Singapore: World Scientific Publishing, pp. viii+403, 701:
provided other, more refined, examples for the vector valued problem.
3384: 2428:(1956), "Sull'analiticità delle estremali degli integrali multipli", 275:{\displaystyle {\iint F(p,q,z;x,y)dxdy}={\text{Minimum}}\qquad \left} 3539: 3459: 2463:
Complete list of De Giorgi's scientific publication (De Giorgi 2006
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in 1900. It asks whether the solutions of regular problems in the
2704: 492: 1147:{\displaystyle \sum \limits _{i=1}^{n}(L_{p_{i}}(Dw))_{x_{i}}=0} 122:
and a class of linear partial differential equations studied by
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Unlike Liouville's work, Picard's work is explicitly cited by
3431:"Continuity of solutions of parabolic and elliptic equations" 3232: 3069:, ICM Proceedings, Paris: Gauthier-Villars, pp. 58–114, 2863: 2862:, Operator Theory: Advances and Applications, vol. 109, 1522:
has Hölder continuous first derivatives, provided the matrix
2565:, Springer Collected Works in Mathematics, Berlin–New York: 2465:, p. 6), an English translation should be included in ( 1973:
For a detailed historical analysis, see the relevant entry "
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th derivatives, so a theorem of Schauder implies that the (
2376:(1976), "Variational problems and elliptic equations", in 2076:, sense, even before the statement of its analyticity in 653:
Counterexamples to various generalizations of the problem
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When are solutions in the calculus of variations analytic
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for this variational problem is the non-linear equation
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solutions, Hilbert's problem was answered positively by
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on the Euler–Lagrange equations associated to the given
2662:
Elliptic partial differential equations of second order
2383:
Mathematical developments arising from Hilbert problems
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can be shown using De Giorgi's theorem as follows. The
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Application of De Giorgi's theorem to Hilbert's problem
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On the analyticity of extremals of multiple integrals
1959:
English translation by Mary Frances Winston Newson:-"
1812: 1688: 1619: 1596: 1572: 1528: 1449: 1369: 1326: 1193: 1163: 1067: 1040: 1020: 1000: 973: 949: 929: 875: 852: 824: 804: 726: 515:
is a simple regularity assumption about the function
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English translation by Mary Frances Winston Newson:
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is the Lagrangian, a function of the derivatives of
532: 1929:"), formulating the problem with the same words of 3129: 2253: 2202: 2164: 1872: 1764: 1632: 1605: 1578: 1558: 1507: 1429: 1352: 1309: 1176: 1146: 1046: 1026: 1006: 982: 955: 935: 912: 858: 830: 810: 787: 431: 274: 3752: 3306:Multiple integrals in the calculus of variations 2651: 2052: 3610: 1947: 1765:{\displaystyle D_{i}(a^{ij}(x)D_{j}u)=D_{t}(u)} 3545:Recueil Mathématique (Matematicheskii Sbornik) 2390:, vol. XXVIII, Providence, Rhode Island: 846:Hilbert's problem asks whether the minimizers 818:has square integrable first derivatives, then 3596: 3010:Bulletin of the American Mathematical Society 2966:Bulletin of the American Mathematical Society 2778: 2332:"Variational problems and elliptic equations" 2030: 2028: 2026: 913:{\displaystyle \int _{U}L(Dw)\,\mathrm {d} x} 693: 671: 453:is an analytic function of all its arguments 78: 3061:"Sur les problèmes futurs des Mathématiques" 2733:Direct Methods in the Calculus of Variations 1908:) or, equivalently, one of its translations. 2701:Metodi diretti nel calcolo delle variazioni 2388:Proceedings of Symposia in Pure Mathematics 545:for equations belonging to this class. For 537:Hilbert stated his nineteenth problem as a 3603: 3589: 3153: 2789:Bollettino dell'Unione Matematica Italiana 2512:Bollettino dell'Unione Matematica Italiana 2023: 2020:, p. 288 and footnote 1 in the same page). 1950:" in the historical section of this entry. 788:{\displaystyle D_{i}(a^{ij}(x)\,D_{j}u)=0} 709:The key theorem proved by De Giorgi is an 682: 663: 3534: 3400: 3366: 3250: 3166:Funktsional'nyĭ Analiz I Ego Prilozheniya 3022: 2978: 2607: 2546: 2540: 2509: 2503: 2472: 2466: 2462: 2458: 2424: 2272: 2232: 2181: 2148: 1508:{\displaystyle a^{ij}=L_{p_{i}p_{j}}(Dw)} 1157:and differentiating this with respect to 901: 762: 689: 667: 634: 630: 606: 602: 594: 571: 3227: 3192:Functional Analysis and Its Applications 2372: 2326: 2257: 2206: 2168: 1873:{\displaystyle D_{i}(a^{ij}(x)D_{j}u)=0} 1430:{\displaystyle D_{i}(a^{ij}(x)D_{j}u)=0} 104:International Congress of Mathematicians 2903: 2857: 2816: 2703:, Monografie Matematiche (in Italian), 2248:For more information about the work of 2219: 2198: 2160: 2156: 2127: 2035: 2017: 2004: 1943: 1930: 1905: 107: 94: 3753: 3299: 2729: 2695: 2236: 2185: 2152: 1518:so by De Giorgi's result the solution 704: 52:elliptic partial differential equation 3584: 3506: 2239:, p. 7, pp. 202–203 and pp. 317–318). 1880:by considering the special case when 698: 3425: 3339: 2866:: Birkhäuser Verlag, pp. 7–16, 2068:in the "classical", i.e. not in the 1647:is known to have Hölder continuous ( 646: 642: 618: 614: 3099:(1900), "Problèmes mathématiques", 2003:: compare the relevant entry with ( 1195: 1069: 13: 1625: 943:is a function on some compact set 903: 674:independently constructed several 403: 395: 380: 353: 338: 316: 301: 252: 244: 221: 213: 14: 3782: 3007:(2000), "Mathematical Problems", 2963:(1902), "Mathematical Problems", 2860:The Maz'ya Anniversary Collection 1986:Hilbert does not cite explicitly 1674: 533:The path to the complete solution 85:analytischer Lösungen fähig sind. 42:" identifies this precisely as a 2936:Archiv der Mathematik und Physik 2155:, p. 7 footnote 7 and p. 353), ( 866:of an energy functional such as 574:) in his thesis. He showed that 26:, set out in a list compiled by 3439:American Journal of Mathematics 3343:(1957), "Parabolic equations", 2980:10.1090/S0002-9904-1902-00923-3 2469:), it is unfortunately missing. 2254:Kristensen & Mingione (2011 2242: 2225: 2212: 2191: 2174: 2141: 2120: 2058: 240: 236: 204: 3766:Partial differential equations 2203:Kristensen & Mingione 2011 2165:Kristensen & Mingione 2011 2130:, p. 288) precise words are:-" 2041: 2010: 1980: 1967: 1953: 1936: 1911: 1898: 1861: 1845: 1839: 1823: 1759: 1753: 1737: 1721: 1715: 1699: 1559:{\displaystyle L_{p_{i}p_{j}}} 1502: 1493: 1418: 1402: 1396: 1380: 1360:satisfies the linear equation 1285: 1254: 1245: 1215: 1122: 1118: 1109: 1089: 898: 889: 776: 759: 753: 737: 445:      288:      180: 150: 134:      56:partial differential equations 1: 3024:10.1090/S0273-0979-00-00881-8 2619:Annals of Mathematics Studies 2392:American Mathematical Society 2266: 2113: 2078: 511: 497: 487: 2939:, dritte reihe (in German), 2535:. Translated in English as " 2498:. Translated in English as " 2064:Since Hilbert considers all 2053:Gilbarg & Trudinger 2001 20:Hilbert's nineteenth problem 7: 3238:Applications of Mathematics 3184:– Translated in English as 3102:L'Enseignement Mathématique 2956:Mary Frances Winston Newson 2954:– Translated to English by 2943:: 44–63 and 253–297, 1900, 2872:10.1007/978-3-0348-8675-8_2 2728:, translated in English as 2559:; Spagnolo, Sergio (eds.), 2461:). While, according to the 2432:, Serie VIII (in Italian), 2049:Reguläres Variationsproblem 1990:and considers the constant 1923:Mary Frances Winston Newson 1655:≥ 1, then the coefficients 1651:+1)st derivatives for some 1633:{\displaystyle L^{\infty }} 1353:{\displaystyle u=w_{x_{k}}} 694:Giusti & Miranda (1968) 672:Giusti & Miranda (1968) 662:. At the end of the 1960s, 483:regular variational problem 442: 285: 131: 40:regular variational problem 10: 3787: 2917:(in German) (3): 253–297, 2709:Unione Matematica Italiana 2477:, Serie III (in Italian), 2088:is assumed to be at least 1948:The origins of the problem 1921:" (English translation by 79:The origins of the problem 73: 3618: 3261:10.1007/s10778-006-0110-3 2792:, Serie IV (in Italian), 2575:10.1007/978-3-642-41496-1 2547:De Giorgi, Ennio (2006), 2514:, Serie IV (in Italian), 1779:is a bounded function of 3159: 3063:, in Duporcq, E. (ed.), 2931:"Mathematische Probleme" 2909:"Mathematische Probleme" 1892: 120:minimal surface equation 2730:Giusti, Enrico (2003), 2256:, §3.3, pp. 9–12) and ( 2235:, pp. 54–59) and ( 2167:, p. 5 and p. 8), and ( 1659:have Hölder continuous 1056:Euler–Lagrange equation 48:Euler–Lagrange equation 3771:Calculus of variations 2738:River Edge, New Jersey 2205:, p. 5 and p. 8) and ( 1874: 1766: 1634: 1607: 1580: 1560: 1509: 1431: 1354: 1311: 1214: 1178: 1148: 1088: 1048: 1028: 1008: 984: 957: 937: 914: 860: 838:is Hölder continuous. 832: 812: 789: 481:Hilbert calls this a " 433: 276: 100: 32:calculus of variations 3368:10.1073/pnas.43.8.754 2746:10.1142/9789812795557 2283:Mathematische Annalen 2260:, §3.3, pp. 369–370). 2047:In his exact words: " 1875: 1767: 1635: 1608: 1581: 1561: 1510: 1432: 1355: 1312: 1194: 1179: 1177:{\displaystyle x_{k}} 1149: 1068: 1049: 1029: 1009: 985: 958: 938: 915: 861: 833: 813: 790: 503:ellipticity condition 491:means that these are 434: 277: 82: 2543:, pp. 285–287). 2506:, pp. 149–166). 2394:, pp. 525–535, 2201:, pp. 10–11), ( 2188:, p. 7 and pp. 353). 2184:, pp. 54–59), ( 2163:, pp. 10–11), ( 2138:by Hilbert himself). 2107:, as the use of the 1810: 1686: 1617: 1594: 1590:, i.e. the gradient 1588:Lipschitz continuous 1570: 1526: 1447: 1367: 1324: 1191: 1161: 1065: 1038: 1018: 998: 971: 947: 927: 873: 850: 822: 802: 724: 639:John Forbes Nash 611:John Forbes Nash 568:Sergei Bernstein 294: 140: 116:Liouville's equation 68:John Forbes Nash, Jr 3452:1958AmJM...80..931N 3359:1957PNAS...43..754N 2711:, pp. VI+422, 2109:Hessian determinant 1884:does not depend on 923:are analytic. Here 705:De Giorgi's theorem 627:Ennio De Giorgi 599:Ennio De Giorgi 543:classical solutions 44:variational problem 3761:Hilbert's problems 3612:Hilbert's problems 3468:10338.dmlcz/101876 3301:Morrey, Charles B. 3269:10338.dmlcz/134645 3229:Mingione, Giuseppe 3205:10.1007/BF01076124 3132:Mingione, Giuseppe 3115:10.5169/seals-3575 2657:Trudinger, Neil S. 2609:Giaquinta, Mariano 2569:, pp. x+889, 2296:10.1007/BF01444746 1992:Gaussian curvature 1975:Hilbert's problems 1962:analytic solutions 1870: 1762: 1630: 1606:{\displaystyle Dw} 1603: 1576: 1556: 1505: 1427: 1350: 1307: 1174: 1144: 1044: 1024: 1004: 983:{\displaystyle Dw} 980: 953: 933: 910: 856: 828: 808: 785: 539:regularity problem 527:potential function 429: 272: 112:Laplace's equation 3748: 3747: 3316:978-3-540-69915-6 3130:Kristensen, Jan; 2881:978-3-0348-9726-6 2834:978-3-7643-6201-0 2755:978-981-238-043-2 2672:978-3-540-41160-4 2628:978-0-691-08330-8 2584:978-3-540-26169-8 2401:978-0-8218-1428-4 2378:Browder, Felix E. 1579:{\displaystyle w} 1047:{\displaystyle w} 1027:{\displaystyle w} 1007:{\displaystyle L} 956:{\displaystyle U} 936:{\displaystyle w} 859:{\displaystyle w} 831:{\displaystyle u} 811:{\displaystyle u} 711:a priori estimate 623:Hölder continuous 509:, while property 411: 366: 329: 259: 228: 202: 60:analytic function 22:is one of the 23 3778: 3605: 3598: 3591: 3582: 3581: 3576: 3536:Petrowsky, I. G. 3530: 3502: 3435: 3421: 3404: 3370: 3335: 3295: 3254: 3223: 3181: 3149: 3147: 3140: 3134:(October 2011). 3125: 3091: 3090: 3089: 3083: 3077:, archived from 3051: 3026: 2999: 2982: 2951: 2925: 2900: 2853: 2812: 2774: 2727: 2691: 2647: 2603: 2555:; Forti, Marco; 2553:Dal Maso, Gianni 2534: 2497: 2452: 2426:De Giorgi, Ennio 2420: 2374:Bombieri, Enrico 2370: 2369: 2368: 2362: 2356:, archived from 2328:Bombieri, Enrico 2322: 2261: 2252:see the work of 2246: 2240: 2229: 2223: 2216: 2210: 2195: 2189: 2178: 2172: 2151:, p. 59), ( 2145: 2139: 2136:Italics emphasis 2124: 2118: 2106: 2105: 2104: 2103: 2100: 2096: 2093: 2087: 2062: 2056: 2045: 2039: 2032: 2021: 2014: 2008: 2002: 1998: 1988:Joseph Liouville 1984: 1978: 1971: 1965: 1957: 1951: 1940: 1934: 1915: 1909: 1902: 1879: 1877: 1876: 1871: 1857: 1856: 1838: 1837: 1822: 1821: 1771: 1769: 1768: 1763: 1752: 1751: 1733: 1732: 1714: 1713: 1698: 1697: 1639: 1637: 1636: 1631: 1629: 1628: 1612: 1610: 1609: 1604: 1585: 1583: 1582: 1577: 1565: 1563: 1562: 1557: 1555: 1554: 1553: 1552: 1543: 1542: 1514: 1512: 1511: 1506: 1492: 1491: 1490: 1489: 1480: 1479: 1462: 1461: 1436: 1434: 1433: 1428: 1414: 1413: 1395: 1394: 1379: 1378: 1359: 1357: 1356: 1351: 1349: 1348: 1347: 1346: 1320:This means that 1316: 1314: 1313: 1308: 1300: 1299: 1298: 1297: 1283: 1282: 1281: 1280: 1271: 1270: 1244: 1243: 1242: 1241: 1232: 1231: 1213: 1208: 1183: 1181: 1180: 1175: 1173: 1172: 1153: 1151: 1150: 1145: 1137: 1136: 1135: 1134: 1108: 1107: 1106: 1105: 1087: 1082: 1053: 1051: 1050: 1045: 1033: 1031: 1030: 1025: 1013: 1011: 1010: 1005: 989: 987: 986: 981: 962: 960: 959: 954: 942: 940: 939: 934: 919: 917: 916: 911: 906: 885: 884: 865: 863: 862: 857: 837: 835: 834: 829: 817: 815: 814: 809: 794: 792: 791: 786: 772: 771: 752: 751: 736: 735: 713:stating that if 690:De Giorgi (1968) 668:De Giorgi (1968) 595:Petrowsky (1939) 592: 591: 590: 589: 586: 582: 579: 565: 563: 562: 561: 558: 554: 551: 520: 493:minimum problems 476: 470: 452: 447: 446: 438: 436: 435: 430: 422: 421: 416: 412: 410: 409: 401: 392: 388: 387: 377: 367: 365: 361: 360: 350: 346: 345: 335: 330: 328: 324: 323: 313: 309: 308: 298: 290: 289: 281: 279: 278: 273: 271: 267: 260: 258: 250: 242: 229: 227: 219: 211: 203: 200: 195: 136: 135: 98: 24:Hilbert problems 3786: 3785: 3781: 3780: 3779: 3777: 3776: 3775: 3751: 3750: 3749: 3744: 3614: 3609: 3508:Nečas, Jindřich 3460:10.2307/2372841 3433: 3317: 3252:10.1.1.214.9183 3185: 3183: 3161: 3145: 3138: 3095: 3093: 3087: 3085: 3081: 3055: 3053: 3003: 3002:– Reprinted as 3001: 2973:(10): 437–479, 2959: 2953: 2929: 2928:– Reprinted as 2927: 2882: 2835: 2818:Gohberg, Israel 2756: 2673: 2629: 2585: 2567:Springer-Verlag 2562:Selected papers 2549:Ambrosio, Luigi 2402: 2371:. Reprinted in 2366: 2364: 2360: 2269: 2264: 2247: 2243: 2230: 2226: 2217: 2213: 2209:, p. 368). 2196: 2192: 2179: 2175: 2171:, p. 368). 2159:, p. 1), ( 2146: 2142: 2128:Hilbert's (1900 2125: 2121: 2101: 2098: 2097: 2094: 2091: 2090: 2089: 2083: 2082:, the function 2063: 2059: 2055:, p. 289). 2046: 2042: 2038:, p. 288). 2033: 2024: 2015: 2011: 2007:, p. 288). 2000: 1994: 1985: 1981: 1972: 1968: 1958: 1954: 1941: 1937: 1933:, p. 288). 1916: 1912: 1903: 1899: 1895: 1852: 1848: 1830: 1826: 1817: 1813: 1811: 1808: 1807: 1794: 1785: 1747: 1743: 1728: 1724: 1706: 1702: 1693: 1689: 1687: 1684: 1683: 1677: 1624: 1620: 1618: 1615: 1614: 1595: 1592: 1591: 1571: 1568: 1567: 1548: 1544: 1538: 1534: 1533: 1529: 1527: 1524: 1523: 1485: 1481: 1475: 1471: 1470: 1466: 1454: 1450: 1448: 1445: 1444: 1409: 1405: 1387: 1383: 1374: 1370: 1368: 1365: 1364: 1342: 1338: 1337: 1333: 1325: 1322: 1321: 1293: 1289: 1288: 1284: 1276: 1272: 1266: 1262: 1261: 1257: 1237: 1233: 1227: 1223: 1222: 1218: 1209: 1198: 1192: 1189: 1188: 1168: 1164: 1162: 1159: 1158: 1130: 1126: 1125: 1121: 1101: 1097: 1096: 1092: 1083: 1072: 1066: 1063: 1062: 1039: 1036: 1035: 1019: 1016: 1015: 999: 996: 995: 972: 969: 968: 948: 945: 944: 928: 925: 924: 902: 880: 876: 874: 871: 870: 851: 848: 847: 844: 823: 820: 819: 803: 800: 799: 767: 763: 744: 740: 731: 727: 725: 722: 721: 707: 676:counterexamples 655: 587: 584: 583: 580: 577: 576: 575: 559: 556: 555: 552: 549: 548: 546: 535: 516: 472: 454: 448: 444: 417: 402: 394: 393: 383: 379: 378: 376: 372: 371: 356: 352: 351: 341: 337: 336: 334: 319: 315: 314: 304: 300: 299: 297: 295: 292: 291: 287: 251: 243: 241: 220: 212: 210: 209: 205: 199: 143: 141: 138: 137: 133: 99: 97:, p. 288). 89: 81: 76: 64:Ennio De Giorgi 17: 12: 11: 5: 3784: 3774: 3773: 3768: 3763: 3746: 3745: 3743: 3742: 3735: 3730: 3725: 3720: 3715: 3710: 3705: 3700: 3695: 3690: 3685: 3680: 3675: 3670: 3665: 3660: 3655: 3650: 3645: 3640: 3635: 3630: 3625: 3619: 3616: 3615: 3608: 3607: 3600: 3593: 3585: 3579: 3578: 3532: 3504: 3446:(4): 931–954, 3423: 3353:(8): 754–758, 3337: 3315: 3297: 3245:(4): 355–426, 3225: 3199:(3): 230–234, 3169:(in Russian), 3151: 3148:on 2014-01-07. 3127: 3057:Hilbert, David 3017:(4): 407–436, 3013:, New Series, 3005:Hilbert, David 2961:Hilbert, David 2905:Hilbert, David 2901: 2880: 2855: 2833: 2814: 2784:Miranda, Mario 2780:Giusti, Enrico 2776: 2754: 2697:Giusti, Enrico 2693: 2671: 2653:Gilbarg, David 2649: 2627: 2605: 2583: 2557:Miranda, Mario 2544: 2541:De Giorgi 2006 2507: 2504:De Giorgi 2006 2470: 2467:De Giorgi 2006 2459:De Giorgi 1957 2422: 2400: 2324: 2290:(1–2): 20–76, 2268: 2265: 2263: 2262: 2250:Jindřich Nečas 2241: 2233:Giaquinta 1983 2224: 2218:According to ( 2211: 2190: 2182:Giaquinta 1983 2173: 2149:Giaquinta 1983 2140: 2119: 2057: 2040: 2022: 2009: 1979: 1966: 1952: 1935: 1910: 1896: 1894: 1891: 1890: 1889: 1869: 1866: 1863: 1860: 1855: 1851: 1847: 1844: 1841: 1836: 1833: 1829: 1825: 1820: 1816: 1790: 1783: 1773: 1772: 1761: 1758: 1755: 1750: 1746: 1742: 1739: 1736: 1731: 1727: 1723: 1720: 1717: 1712: 1709: 1705: 1701: 1696: 1692: 1676: 1675:Nash's theorem 1673: 1627: 1623: 1602: 1599: 1575: 1551: 1547: 1541: 1537: 1532: 1516: 1515: 1504: 1501: 1498: 1495: 1488: 1484: 1478: 1474: 1469: 1465: 1460: 1457: 1453: 1438: 1437: 1426: 1423: 1420: 1417: 1412: 1408: 1404: 1401: 1398: 1393: 1390: 1386: 1382: 1377: 1373: 1345: 1341: 1336: 1332: 1329: 1318: 1317: 1306: 1303: 1296: 1292: 1287: 1279: 1275: 1269: 1265: 1260: 1256: 1253: 1250: 1247: 1240: 1236: 1230: 1226: 1221: 1217: 1212: 1207: 1204: 1201: 1197: 1171: 1167: 1155: 1154: 1143: 1140: 1133: 1129: 1124: 1120: 1117: 1114: 1111: 1104: 1100: 1095: 1091: 1086: 1081: 1078: 1075: 1071: 1043: 1023: 1003: 979: 976: 952: 932: 921: 920: 909: 905: 900: 897: 894: 891: 888: 883: 879: 855: 843: 840: 827: 807: 796: 795: 784: 781: 778: 775: 770: 766: 761: 758: 755: 750: 747: 743: 739: 734: 730: 706: 703: 654: 651: 534: 531: 479: 478: 440: 428: 425: 420: 415: 408: 405: 400: 397: 391: 386: 382: 375: 370: 364: 359: 355: 349: 344: 340: 333: 327: 322: 318: 312: 307: 303: 283: 270: 266: 263: 257: 254: 249: 246: 239: 235: 232: 226: 223: 218: 215: 208: 198: 194: 191: 188: 185: 182: 179: 176: 173: 170: 167: 164: 161: 158: 155: 152: 149: 146: 87: 80: 77: 75: 72: 15: 9: 6: 4: 3: 2: 3783: 3772: 3769: 3767: 3764: 3762: 3759: 3758: 3756: 3740: 3736: 3734: 3731: 3729: 3726: 3724: 3721: 3719: 3716: 3714: 3711: 3709: 3706: 3704: 3701: 3699: 3696: 3694: 3691: 3689: 3686: 3684: 3681: 3679: 3676: 3674: 3671: 3669: 3666: 3664: 3661: 3659: 3656: 3654: 3651: 3649: 3646: 3644: 3641: 3639: 3636: 3634: 3631: 3629: 3626: 3624: 3621: 3620: 3617: 3613: 3606: 3601: 3599: 3594: 3592: 3587: 3586: 3583: 3575: 3571: 3567: 3563: 3559: 3555: 3551: 3548:(in French), 3547: 3546: 3541: 3537: 3533: 3529: 3525: 3521: 3517: 3513: 3509: 3505: 3501: 3497: 3493: 3489: 3485: 3481: 3477: 3473: 3469: 3465: 3461: 3457: 3453: 3449: 3445: 3441: 3440: 3432: 3428: 3424: 3420: 3416: 3412: 3408: 3403: 3398: 3394: 3390: 3386: 3382: 3378: 3374: 3369: 3364: 3360: 3356: 3352: 3348: 3347: 3342: 3338: 3334: 3330: 3326: 3322: 3318: 3312: 3308: 3307: 3302: 3298: 3294: 3290: 3286: 3282: 3278: 3274: 3270: 3266: 3262: 3258: 3253: 3248: 3244: 3240: 3239: 3234: 3230: 3226: 3222: 3218: 3214: 3210: 3206: 3202: 3198: 3194: 3193: 3188: 3187:Maz'ya, V. G. 3180: 3176: 3172: 3168: 3167: 3162: 3156: 3155:Maz'ya, V. G. 3152: 3144: 3137: 3133: 3128: 3124: 3120: 3116: 3112: 3108: 3105:(in French), 3104: 3103: 3098: 3084:on 2013-12-31 3080: 3076: 3072: 3068: 3067: 3062: 3058: 3050: 3046: 3042: 3038: 3034: 3030: 3025: 3020: 3016: 3012: 3011: 3006: 2998: 2994: 2990: 2986: 2981: 2976: 2972: 2968: 2967: 2962: 2957: 2950: 2946: 2942: 2938: 2937: 2932: 2924: 2920: 2916: 2915: 2910: 2906: 2902: 2899: 2895: 2891: 2887: 2883: 2877: 2873: 2869: 2865: 2861: 2856: 2852: 2848: 2844: 2840: 2836: 2830: 2826: 2825: 2819: 2815: 2811: 2807: 2803: 2799: 2795: 2791: 2790: 2785: 2781: 2777: 2773: 2769: 2765: 2761: 2757: 2751: 2747: 2743: 2739: 2735: 2734: 2726: 2722: 2718: 2714: 2710: 2706: 2702: 2698: 2694: 2690: 2686: 2682: 2678: 2674: 2668: 2664: 2663: 2658: 2654: 2650: 2646: 2642: 2638: 2634: 2630: 2624: 2620: 2616: 2615: 2610: 2606: 2602: 2598: 2594: 2590: 2586: 2580: 2576: 2572: 2568: 2564: 2563: 2558: 2554: 2550: 2545: 2542: 2538: 2533: 2529: 2525: 2521: 2517: 2513: 2508: 2505: 2501: 2496: 2492: 2488: 2484: 2480: 2476: 2471: 2468: 2464: 2460: 2456: 2451: 2447: 2443: 2439: 2435: 2431: 2427: 2423: 2419: 2415: 2411: 2407: 2403: 2397: 2393: 2389: 2385: 2384: 2379: 2375: 2363:on 2013-12-31 2359: 2355: 2351: 2347: 2343: 2339: 2338: 2333: 2329: 2325: 2321: 2317: 2313: 2309: 2305: 2301: 2297: 2293: 2289: 2286:(in French), 2285: 2284: 2279: 2275: 2274:Bernstein, S. 2271: 2270: 2259: 2258:Mingione 2006 2255: 2251: 2245: 2238: 2234: 2228: 2222:, p. 1). 2221: 2215: 2208: 2207:Mingione 2006 2204: 2200: 2194: 2187: 2183: 2177: 2170: 2169:Mingione 2006 2166: 2162: 2158: 2154: 2150: 2144: 2137: 2133: 2129: 2123: 2116: 2115: 2110: 2086: 2081: 2080: 2075: 2071: 2067: 2061: 2054: 2050: 2044: 2037: 2031: 2029: 2027: 2019: 2018:Hilbert (1900 2013: 2006: 1997: 1993: 1989: 1983: 1976: 1970: 1963: 1956: 1949: 1945: 1939: 1932: 1931:Hilbert (1900 1928: 1924: 1920: 1914: 1907: 1901: 1897: 1887: 1883: 1867: 1864: 1858: 1853: 1849: 1842: 1834: 1831: 1827: 1818: 1814: 1806: 1805: 1804: 1802: 1798: 1793: 1789: 1782: 1778: 1756: 1748: 1744: 1740: 1734: 1729: 1725: 1718: 1710: 1707: 1703: 1694: 1690: 1682: 1681: 1680: 1672: 1670: 1666: 1662: 1658: 1654: 1650: 1646: 1641: 1621: 1600: 1597: 1589: 1573: 1549: 1545: 1539: 1535: 1530: 1521: 1499: 1496: 1486: 1482: 1476: 1472: 1467: 1463: 1458: 1455: 1451: 1443: 1442: 1441: 1424: 1421: 1415: 1410: 1406: 1399: 1391: 1388: 1384: 1375: 1371: 1363: 1362: 1361: 1343: 1339: 1334: 1330: 1327: 1304: 1301: 1294: 1290: 1277: 1273: 1267: 1263: 1258: 1251: 1248: 1238: 1234: 1228: 1224: 1219: 1210: 1205: 1202: 1199: 1187: 1186: 1185: 1169: 1165: 1141: 1138: 1131: 1127: 1115: 1112: 1102: 1098: 1093: 1084: 1079: 1076: 1073: 1061: 1060: 1059: 1057: 1041: 1021: 1001: 993: 977: 974: 966: 950: 930: 907: 895: 892: 886: 881: 877: 869: 868: 867: 853: 839: 825: 805: 782: 779: 773: 768: 764: 756: 748: 745: 741: 732: 728: 720: 719: 718: 716: 712: 702: 700: 695: 691: 687: 684: 683:Maz'ya (1968) 679: 677: 673: 669: 665: 664:Maz'ya (1968) 661: 650: 648: 644: 640: 636: 632: 628: 624: 620: 616: 612: 608: 604: 600: 596: 573: 569: 564: 544: 540: 530: 528: 524: 519: 514: 513: 508: 504: 500: 499: 494: 490: 489: 484: 475: 469: 465: 461: 457: 451: 441: 426: 423: 418: 413: 406: 398: 389: 384: 373: 368: 362: 357: 347: 342: 331: 325: 320: 310: 305: 284: 268: 264: 261: 255: 247: 237: 233: 230: 224: 216: 206: 196: 192: 189: 186: 183: 177: 174: 171: 168: 165: 162: 159: 156: 153: 147: 144: 130: 129: 128: 125: 121: 117: 113: 109: 105: 96: 92: 91:David Hilbert 86: 71: 69: 65: 61: 57: 53: 49: 45: 41: 37: 33: 29: 28:David Hilbert 25: 21: 3712: 3552:(47): 3–70, 3549: 3543: 3511: 3443: 3437: 3350: 3344: 3305: 3242: 3236: 3196: 3190: 3173:(3): 53–57, 3170: 3164: 3143:the original 3106: 3100: 3086:, retrieved 3079:the original 3065: 3014: 3008: 2970: 2964: 2940: 2934: 2912: 2859: 2822: 2793: 2787: 2732: 2700: 2661: 2613: 2561: 2536: 2515: 2511: 2499: 2478: 2474: 2454: 2433: 2429: 2382: 2365:, retrieved 2358:the original 2336: 2287: 2281: 2244: 2227: 2220:Gohberg 1999 2214: 2199:Hedberg 1999 2193: 2176: 2161:Hedberg 1999 2157:Gohberg 1999 2143: 2131: 2122: 2112: 2084: 2077: 2060: 2048: 2043: 2036:Hilbert 1900 2012: 2005:Hilbert 1900 1999:as equal to 1995: 1982: 1969: 1960: 1955: 1944:Hilbert 1900 1938: 1926: 1918: 1913: 1906:Hilbert 1900 1900: 1885: 1881: 1800: 1799:defined for 1796: 1791: 1787: 1780: 1776: 1774: 1678: 1668: 1664: 1660: 1656: 1652: 1648: 1644: 1642: 1519: 1517: 1439: 1319: 1156: 994:vector, and 964: 922: 845: 797: 714: 708: 699:Nečas (1977) 688: 680: 656: 536: 522: 517: 510: 496: 486: 485:". Property 482: 480: 473: 467: 463: 459: 455: 449: 124:Émile Picard 108:Hilbert 1900 101: 95:Hilbert 1900 83: 39: 19: 18: 3109:: 349–355, 3097:Hilbert, D. 2518:: 135–137, 2436:: 438–441, 2237:Giusti 1994 2186:Giusti 1994 2153:Giusti 1994 2072:but in the 2066:derivatives 1671:is smooth. 681:Precisely, 660:functionals 495:. Property 34:are always 3755:Categories 3574:0022.22601 3558:65.0405.02 3528:0372.35031 3500:0096.06902 3427:Nash, John 3419:0078.08704 3341:Nash, John 3333:0142.38701 3293:1164.49324 3221:0179.43601 3123:31.0905.03 3088:2013-12-28 3075:32.0084.06 3049:0979.01028 2989:33.0976.07 2949:32.0084.05 2923:31.0068.03 2898:0939.31001 2851:0939.01018 2810:0155.44501 2772:1028.49001 2725:0942.49002 2689:1042.35002 2645:0516.49003 2601:1096.01015 2532:0084.31901 2495:0084.31901 2450:0074.31503 2418:0347.35032 2367:2011-01-29 2354:0344.49002 2312:35.0354.01 2267:References 1640:function. 507:functional 3476:0002-9327 3377:0027-8424 3247:CiteSeerX 3213:121038871 2659:(2001) , 2481:: 25–43, 2320:121487650 2304:0025-5831 1626:∞ 1196:∑ 1070:∑ 878:∫ 404:∂ 396:∂ 381:∂ 369:− 354:∂ 339:∂ 332:⋅ 317:∂ 302:∂ 253:∂ 245:∂ 222:∂ 214:∂ 145:∬ 3538:(1939), 3429:(1958), 3411:16590082 3303:(1966), 3285:16385131 3231:(2006), 3157:(1968), 3059:(1902), 3041:12695502 2907:(1900), 2699:(1994), 2611:(1983), 2330:(1975), 2276:(1904), 2117:implies. 992:gradient 88:—  36:analytic 3566:0001425 3520:0509483 3492:0100158 3484:2372841 3448:Bibcode 3393:0089986 3355:Bibcode 3325:0202511 3277:2291779 3179:0237946 3033:1779412 2997:1557926 2890:1747862 2843:1747861 2802:0232265 2796:: 1–8, 2764:1962933 2717:1707291 2705:Bologna 2681:1814364 2637:0717034 2593:2229237 2524:0227827 2487:0093649 2442:0082045 2410:0425740 2380:(ed.), 2346:0509259 990:is its 641: ( 637:), and 629: ( 613: ( 609:), and 601: ( 570: ( 501:is the 201:Minimum 74:History 3572:  3564:  3556:  3526:  3518:  3498:  3490:  3482:  3474:  3417:  3409:  3402:528534 3399:  3391:  3383:  3375:  3331:  3323:  3313:  3291:  3283:  3275:  3249:  3219:  3211:  3177:  3121:  3073:  3047:  3039:  3031:  2995:  2987:  2947:  2921:  2896:  2888:  2878:  2849:  2841:  2831:  2808:  2800:  2770:  2762:  2752:  2723:  2715:  2687:  2679:  2669:  2643:  2635:  2625:  2599:  2591:  2581:  2539:" in ( 2530:  2522:  2502:" in ( 2493:  2485:  2448:  2440:  2416:  2408:  2398:  2352:  2344:  2318:  2310:  2302:  2102:  2095:  2074:strong 1775:where 1613:is an 1440:with 1184:gives 588:  581:  560:  553:  118:, the 106:. 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" 2446:Zbl 2414:Zbl 2350:Zbl 2308:JFM 2292:doi 2134:" ( 2114:(2) 2111:in 2079:(3) 1925::-" 1586:is 963:of 649:). 512:(3) 498:(2) 488:(1) 443:(3) 286:(2) 132:(1) 93:, ( 3757:: 3739:24 3733:23 3728:22 3723:21 3718:20 3713:19 3708:18 3703:17 3698:16 3693:15 3688:14 3683:13 3678:12 3673:11 3668:10 3568:, 3562:MR 3560:, 3542:, 3522:, 3516:MR 3494:, 3488:MR 3486:, 3478:, 3470:, 3462:, 3454:, 3444:80 3442:, 3436:, 3413:, 3405:, 3395:, 3389:MR 3387:, 3379:, 3371:, 3361:, 3351:43 3349:, 3327:, 3321:MR 3319:, 3287:, 3279:, 3273:MR 3271:, 3263:, 3255:, 3243:51 3241:, 3235:, 3215:, 3207:, 3195:, 3175:MR 3163:, 3117:, 3043:, 3035:, 3029:MR 3027:, 3015:37 2993:MR 2991:, 2983:, 2969:, 2933:, 2911:, 2892:, 2886:MR 2884:, 2874:, 2845:, 2839:MR 2837:, 2804:, 2798:MR 2782:; 2766:, 2760:MR 2758:, 2748:, 2736:, 2719:, 2713:MR 2707:: 2683:, 2677:MR 2675:, 2655:; 2639:, 2633:MR 2631:, 2617:, 2595:, 2589:MR 2587:, 2577:, 2551:; 2526:, 2520:MR 2489:, 2483:MR 2444:, 2438:MR 2434:20 2412:, 2406:MR 2404:, 2386:, 2348:, 2342:MR 2334:, 2314:, 2306:, 2298:, 2288:59 2280:, 2025:^ 1977:". 1964:". 1795:, 967:, 666:, 645:, 633:, 617:, 605:, 529:. 466:, 462:, 458:, 114:, 70:. 3741:) 3737:( 3663:9 3658:8 3653:7 3648:6 3643:5 3638:4 3633:3 3628:2 3623:1 3604:e 3597:t 3590:v 3577:. 3550:5 3531:. 3503:. 3466:: 3458:: 3450:: 3422:. 3365:: 3357:: 3336:. 3296:. 3267:: 3259:: 3224:. 3203:: 3197:2 3182:. 3171:2 3150:. 3126:. 3113:: 3107:2 3092:. 3052:. 3021:: 3000:. 2977:: 2971:8 2952:. 2941:1 2926:. 2870:: 2854:. 2813:. 2794:2 2775:. 2744:: 2692:. 2648:. 2604:. 2573:: 2516:1 2479:3 2421:. 2323:. 2294:: 2099:2 2092:C 2085:F 1996:K 1917:" 1888:. 1886:t 1882:u 1868:0 1865:= 1862:) 1859:u 1854:j 1850:D 1846:) 1843:x 1840:( 1835:j 1832:i 1828:a 1824:( 1819:i 1815:D 1801:t 1797:t 1792:n 1788:x 1784:1 1781:x 1777:u 1760:) 1757:u 1754:( 1749:t 1745:D 1741:= 1738:) 1735:u 1730:j 1726:D 1722:) 1719:x 1716:( 1711:j 1708:i 1704:a 1700:( 1695:i 1691:D 1669:w 1665:n 1661:n 1657:a 1653:n 1649:n 1645:w 1622:L 1601:w 1598:D 1574:w 1550:j 1546:p 1540:i 1536:p 1531:L 1520:w 1503:) 1500:w 1497:D 1494:( 1487:j 1483:p 1477:i 1473:p 1468:L 1464:= 1459:j 1456:i 1452:a 1425:0 1422:= 1419:) 1416:u 1411:j 1407:D 1403:) 1400:x 1397:( 1392:j 1389:i 1385:a 1381:( 1376:i 1372:D 1344:k 1340:x 1335:w 1331:= 1328:u 1305:0 1302:= 1295:i 1291:x 1286:) 1278:k 1274:x 1268:j 1264:x 1259:w 1255:) 1252:w 1249:D 1246:( 1239:j 1235:p 1229:i 1225:p 1220:L 1216:( 1211:n 1206:1 1203:= 1200:i 1170:k 1166:x 1142:0 1139:= 1132:i 1128:x 1123:) 1119:) 1116:w 1113:D 1110:( 1103:i 1099:p 1094:L 1090:( 1085:n 1080:1 1077:= 1074:i 1042:w 1022:w 1002:L 978:w 975:D 965:R 951:U 931:w 908:x 904:d 899:) 896:w 893:D 890:( 887:L 882:U 854:w 826:u 806:u 783:0 780:= 777:) 774:u 769:j 765:D 760:) 757:x 754:( 749:j 746:i 742:a 738:( 733:i 729:D 715:u 585:3 578:C 557:3 550:C 518:F 477:. 474:y 468:x 464:z 460:q 456:p 450:F 439:, 427:0 419:2 414:) 407:q 399:p 390:F 385:2 374:( 363:q 358:2 348:F 343:2 326:p 321:2 311:F 306:2 282:, 269:] 265:q 262:= 256:y 248:z 238:; 234:p 231:= 225:x 217:z 207:[ 197:= 193:y 190:d 187:x 184:d 181:) 178:y 175:, 172:x 169:; 166:z 163:, 160:q 157:, 154:p 151:( 148:F

Index

Hilbert problems
David Hilbert
calculus of variations
analytic
variational problem
Euler–Lagrange equation
elliptic partial differential equation
partial differential equations
analytic function
Ennio De Giorgi
John Forbes Nash, Jr
David Hilbert
Hilbert 1900
International Congress of Mathematicians
Hilbert 1900
Laplace's equation
Liouville's equation
minimal surface equation
Émile Picard
(1)
minimum problems
(2)
ellipticity condition
functional
(3)
potential function
regularity problem
classical solutions
C 3 
Sergei Bernstein

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