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Kolmogorov–Arnold–Moser theorem

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The KAM theorem states that if the system is subjected to a weak nonlinear perturbation, some of the invariant tori are deformed and survive, i.e. there is a map from the original manifold to the deformed one that is continuous in the perturbation. Conversely, other invariant tori are destroyed: even
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arbitrarily small perturbations cause the manifold to no longer be invariant and there exists no such map to nearby manifolds. Surviving tori meet the non-resonance condition, i.e., they have “sufficiently irrational” frequencies. This implies that the motion on the deformed torus continues to be
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The non-resonance and non-degeneracy conditions of the KAM theorem become increasingly difficult to satisfy for systems with more degrees of freedom. As the number of dimensions of the system increases, the volume occupied by the tori decreases.
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The existence of a KAM theorem for perturbations of quantum many-body integrable systems is still an open question, although it is believed that arbitrarily small perturbations will destroy integrability in the infinite size limit.
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As the perturbation increases and the smooth curves disintegrate we move from KAM theory to Aubry–Mather theory which requires less stringent hypotheses and works with the Cantor-like sets.
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V. I. Arnold, "Proof of a theorem of A. N. Kolmogorov on the preservation of conditionally periodic motions under a small perturbation of the Hamiltonian ,"
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The methods introduced by Kolmogorov, Arnold, and Moser have developed into a large body of results related to quasiperiodic motions, now known as
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An important consequence of the KAM theorem is that for a large set of initial conditions the motion remains perpetually quasiperiodic.
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The KAM Story – A Friendly Introduction to the Content, History, and Significance of Classical Kolmogorov–Arnold–Moser Theory
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A. N. Kolmogorov, "On the Conservation of Conditionally Periodic Motions under Small Perturbation of the Hamiltonian ,"
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in phase space. Plotting the coordinates of an integrable system would show that they are quasiperiodic.
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showed how to eliminate this degeneracy by developing a rotation-invariant version of the theorem.
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case is normally excluded in classical KAM theory because it does not involve small divisors.
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Percival, I C (1979-03-01). "A variational principle for invariant tori of fixed frequency".
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Arnold originally thought that this theorem could apply to the motions of the
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J. Moser, "On invariant curves of area-preserving mappings of an annulus,"
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in his formulation of the problem for larger numbers of bodies. Later,
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of the integrable Hamiltonian system will trace different invariant
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Those KAM tori that are destroyed by perturbation become invariant
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The KAM theorem is usually stated in terms of trajectories in
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under small perturbations. The theorem partly resolves the
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The problem is whether or not a small perturbation of a
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and "badly" approximated by rationals, typically in a
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in 1954. This was rigorously proved and extended by
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Eugene (January 2008). 855: 707: 504:{\displaystyle \mathbb {T} ^{d}} 1174:"An Introduction to KAM Theory" 1291:Kolmogorov-Arnold-Moser theory 784: 766: 341: 131:Integrable Hamiltonian systems 1: 1337:Theorems in dynamical systems 1164:Arnold, Weinstein, Vogtmann. 1052:Göttingen Math.-Phys. Kl. II 994:Stability of the Solar System 155:-shaped surface). Different 27:Result in dynamical systems 1358: 1257:Rafael de la Llave (2001) 1148:10.1088/0305-4470/12/3/001 103:or other instances of the 1227:10.1090/pspum/069/1858551 1072:(1963) (English transl.: 636:incommensurable, that is 285:{\displaystyle \phi ^{t}} 46:about the persistence of 1342:Computer-assisted proofs 1260:A tutorial on KAM theory 632:rationally independent ( 606:If the frequency vector 1316:Chapter 1: Introduction 1196:Jürgen Pöschel (2001). 1102:James Colliander's Blog 947:{\displaystyle d\geq 2} 292:is called an invariant 32:Kolmogorov–Arnold–Moser 1009:Hofstadter's butterfly 978: 948: 922: 891: 867: 719: 666: 622: 593: 556: 505: 476: 380: 360: 306: 286: 259: 92:in 1963 (for analytic 1332:Hamiltonian mechanics 1014:Nekhoroshev estimates 979: 949: 923: 892: 868: 762: such that  720: 667: 623: 594: 557: 506: 477: 381: 361: 307: 287: 260: 52:small-divisor problem 48:quasiperiodic motions 1092:(October 24, 2011), 1034:Dokl. Akad. 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Percival 169: 149:invariant torus 133: 128: 105: 90:Vladimir Arnold 42:is a result in 28: 23: 22: 15: 12: 11: 5: 1355: 1353: 1345: 1344: 1339: 1334: 1324: 1323: 1320: 1319: 1297: 1288: 1283: 1264: 1255: 1235: 1193: 1169: 1160: 1157: 1154: 1153: 1134:(3): L57–L60. 1118: 1081: 1058: 1041: 1024: 1023: 1021: 1018: 1017: 1016: 1011: 1006: 1004:Ergodic theory 1001: 996: 989: 986: 973: 970: 967: 954:) is called a 943: 940: 937: 915: 909: 886: 875: 874: 861: 857: 853: 849: 844: 839: 834: 830: 823: 820: 812: 808: 803: 799: 795: 790: 786: 781: 777: 773: 768: 759: 756: 753: 750: 747: 741: 726: 713: 709: 705: 701: 696: 691: 686: 682: 661: 658: 654: 650: 646: 616: 586: 581: 576: 572: 550: 546: 543: 539: 534: 529: 524: 498: 493: 469: 463: 457: 452: 447: 444: 441: 436: 431: 426: 421: 416: 407: 402: 397: 375: 353: 348: 343: 338: 332: 326: 322: 301: 279: 275: 252: 246: 231: 228: 224:Michael Herman 215: 212: 207: 204: 168: 165: 132: 129: 127: 124: 26: 24: 14: 13: 10: 9: 6: 4: 3: 2: 1354: 1343: 1340: 1338: 1335: 1333: 1330: 1329: 1327: 1318: 1317: 1312: 1308: 1304: 1303: 1298: 1296: 1292: 1289: 1287: 1284: 1279: 1278: 1273: 1270: 1265: 1262: 1261: 1256: 1246:on 2016-03-03 1242: 1238: 1236:9780821826829 1232: 1228: 1224: 1219: 1214: 1210: 1206: 1199: 1194: 1182: 1175: 1170: 1167: 1163: 1162: 1158: 1149: 1145: 1141: 1137: 1133: 1129: 1122: 1119: 1107: 1103: 1099: 1095: 1091: 1090:Khesin, Boris 1085: 1082: 1078: 1075: 1071: 1068: 1062: 1059: 1056:(1962), 1–20. 1055: 1051: 1045: 1042: 1038: 1035: 1029: 1026: 1019: 1015: 1012: 1010: 1007: 1005: 1002: 1000: 997: 995: 992: 991: 987: 985: 971: 968: 965: 957: 941: 938: 935: 913: 884: 859: 851: 842: 832: 818: 810: 793: 788: 775: 757: 754: 751: 748: 745: 731: 727: 711: 703: 694: 684: 659: 656: 648: 635: 631: 630: 629: 604: 602: 584: 574: 544: 541: 532: 514: 496: 467: 461: 455: 445: 442: 439: 434: 424: 419: 405: 400: 373: 351: 336: 324: 299: 277: 273: 250: 229: 227: 225: 221: 213: 211: 205: 203: 199: 196: 192: 190: 186: 182: 177: 175: 174:quasiperiodic 167:Perturbations 166: 164: 162: 158: 154: 150: 146: 142: 138: 130: 125: 123: 121: 117: 114:because of a 113: 109: 108:-body problem 102: 97: 95: 91: 87: 83: 79: 75: 72: 71:quasiperiodic 68: 63: 61: 57: 53: 49: 45: 41: 37: 33: 19: 1314: 1300: 1295:Scholarpedia 1275: 1258: 1248:. 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Index

KAM theorem
dynamical systems
quasiperiodic motions
small-divisor problem
perturbation theory
classical mechanics
conservative
quasiperiodic
orbit
Andrey Kolmogorov
Jürgen Moser
twist maps
Vladimir Arnold
Hamiltonian systems
Solar System
n-body problem
three-body problem
degeneracy
Gabriella Pinzari
phase space
Hamiltonian system
integrable system
invariant torus
doughnut
initial conditions
tori
quasiperiodic
Cantor sets
Ian C. Percival
Michael Herman

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