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Rotation number

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420: 196: 243: 471: 706: 141: 302: 567: 614: 535: 637: 509: 927: 893: 340: 1002: 908: 958: 153: 212: 1007: 441: 903: 754:, and the order of the points on each such orbit coincides with the order of the points for a rotation by 843:
is a unique minimal set and the orbits of all points both in forward and backward direction converge to
652: 673: 727:
for topological classification of homeomorphisms of the circle. There are two distinct possibilities.
100: 46: 898: 810: 640: 251: 20: 944: 540: 203: 575: 1012: 780: 425: 327: 66: 925:[On the Differentiable Conjugation of Diffeomorphisms from the Circle to Rotations]. 936: 514: 476: 736: 86: 78: 772:, but the limiting periodic orbits in forward and backward directions may be different. 747: 622: 494: 82: 31: 27: 972: 436:
is unique modulo integers, therefore the rotation number is a well-defined element of
996: 986: 948: 724: 207: 144: 50: 428:
proved that the limit exists and is independent of the choice of the starting point
977: 148: 923:"Sur la conjugaison différentiable des difféomorphismes du cercle à des rotations" 922: 790:
has no periodic orbits (this follows immediately by considering a periodic point
38: 888: 829: 74: 70: 818: 940: 415:{\displaystyle \omega (f)=\lim _{n\to \infty }{\frac {F^{n}(x)-x}{n}}.} 54: 81:. Poincaré later proved a theorem characterizing the existence of 821:. Denjoy proved that this possibility is always realized when 715:
of the circle into itself (not necessarily homeomorphic) then
475:
Intuitively, it measures the average rotation angle along the
26:"Map winding number" redirects here. Not to be confused with 873:
when viewed as a map from the group of homeomorphisms (with
723:
have the same rotation numbers. It was used by Poincaré and
859:
of degree 1 is constant on components of the complement of
676: 625: 578: 543: 517: 497: 444: 343: 254: 215: 156: 103: 762:
converges to a periodic orbit. The same is true for
700: 631: 608: 561: 529: 503: 465: 414: 296: 237: 190: 135: 360: 191:{\displaystyle S^{1}=\mathbb {R} /\mathbb {Z} .} 851:is semiconjugate to the irrational rotation by 238:{\displaystyle F:\mathbb {R} \to \mathbb {R} } 8: 466:{\displaystyle \mathbb {R} /\mathbb {Z} .} 989:. From MathWorld--A Wolfram Web Resource. 879:topology) of the circle into the circle. 805:There exists a dense orbit. In this case 675: 667:are two homeomorphisms of the circle and 624: 577: 542: 516: 496: 456: 455: 450: 446: 445: 443: 382: 375: 363: 342: 253: 231: 230: 223: 222: 214: 181: 180: 175: 171: 170: 161: 155: 127: 114: 102: 16:Invariant of homeomorphisms of the circle 921:Herman, Michael Robert (December 1979). 766:orbits, corresponding to iterations of 651:The rotation number is invariant under 825:is twice continuously differentiable. 7: 928:Publications MathĂ©matiques de l'IHÉS 758:. Moreover, every forward orbit of 809:is topologically conjugate to the 750:, every periodic orbit has period 370: 14: 701:{\displaystyle h\circ f=g\circ h} 655:, and even monotone topological 136:{\displaystyle f:S^{1}\to S^{1}} 855:, and the semiconjugating map 711:for a monotone continuous map 588: 582: 394: 388: 367: 353: 347: 285: 279: 270: 258: 227: 120: 1: 297:{\displaystyle F(x+m)=F(x)+m} 245:of the real line, satisfying 143:is an orientation-preserving 742:(in the lowest terms). Then 69:in 1885, in relation to the 619:and its rotation number is 562:{\displaystyle 0<N<1} 326:is defined in terms of the 1029: 1003:Fixed points (mathematics) 971:MichaĹ‚ Misiurewicz (ed.). 909:Poincaré–Bendixson theorem 798:). There are two subcases. 25: 18: 957:for smaller file size in 609:{\displaystyle F(x)=x+N,} 89:of the rotation number. 65:It was first defined by 19:Not to be confused with 869:The rotation number is 775:The rotation number of 731:The rotation number of 702: 633: 610: 563: 531: 530:{\displaystyle 2\pi N} 505: 467: 416: 307:for every real number 298: 239: 192: 137: 894:Denjoy diffeomorphism 703: 653:topological conjugacy 634: 611: 564: 532: 506: 468: 417: 299: 240: 193: 138: 987:"Map Winding Number" 674: 623: 576: 541: 515: 495: 442: 341: 252: 213: 154: 101: 985:Weisstein, Eric W. 904:PoincarĂ© recurrence 817:and all orbits are 811:irrational rotation 641:irrational rotation 21:Rotation (quantity) 941:10.1007/BF02684798 698: 629: 606: 559: 527: 501: 463: 412: 374: 311:and every integer 294: 235: 188: 133: 1008:Dynamical systems 973:"Rotation theory" 781:irrational number 632:{\displaystyle N} 511:is a rotation by 504:{\displaystyle f} 407: 359: 1020: 982: 952: 899:PoincarĂ© section 878: 862: 858: 854: 850: 847:. In this case, 846: 842: 838: 835:invariant under 834: 824: 816: 808: 797: 793: 789: 785: 778: 771: 761: 757: 753: 745: 741: 734: 722: 718: 714: 707: 705: 704: 699: 666: 662: 638: 636: 635: 630: 615: 613: 612: 607: 568: 566: 565: 560: 536: 534: 533: 528: 510: 508: 507: 502: 482: 474: 472: 470: 469: 464: 459: 454: 449: 435: 431: 421: 419: 418: 413: 408: 403: 387: 386: 376: 373: 333: 325: 314: 310: 303: 301: 300: 295: 244: 242: 241: 236: 234: 226: 201: 197: 195: 194: 189: 184: 179: 174: 166: 165: 142: 140: 139: 134: 132: 131: 119: 118: 1028: 1027: 1023: 1022: 1021: 1019: 1018: 1017: 993: 992: 970: 967: 920: 917: 885: 874: 860: 856: 852: 848: 844: 840: 836: 832: 828:There exists a 822: 814: 806: 795: 791: 787: 783: 776: 767: 759: 755: 751: 743: 739: 737:rational number 732: 720: 716: 712: 672: 671: 664: 660: 649: 621: 620: 574: 573: 539: 538: 513: 512: 493: 492: 489: 480: 440: 439: 437: 433: 429: 378: 377: 339: 338: 331: 323: 320:rotation number 312: 308: 250: 249: 211: 210: 199: 157: 152: 151: 123: 110: 99: 98: 95: 83:periodic orbits 79:planetary orbit 63: 43:rotation number 35: 24: 17: 12: 11: 5: 1026: 1024: 1016: 1015: 1010: 1005: 995: 994: 991: 990: 983: 966: 965:External links 963: 962: 961: 916: 913: 912: 911: 906: 901: 896: 891: 884: 881: 867: 866: 865: 864: 826: 800: 799: 773: 748:periodic orbit 709: 708: 697: 694: 691: 688: 685: 682: 679: 648: 645: 628: 617: 616: 605: 602: 599: 596: 593: 590: 587: 584: 581: 558: 555: 552: 549: 546: 526: 523: 520: 500: 488: 485: 462: 458: 453: 448: 426:Henri PoincarĂ© 423: 422: 411: 406: 402: 399: 396: 393: 390: 385: 381: 372: 369: 366: 362: 358: 355: 352: 349: 346: 305: 304: 293: 290: 287: 284: 281: 278: 275: 272: 269: 266: 263: 260: 257: 233: 229: 225: 221: 218: 187: 183: 178: 173: 169: 164: 160: 130: 126: 122: 117: 113: 109: 106: 94: 91: 67:Henri PoincarĂ© 62: 59: 51:homeomorphisms 32:Turning number 28:Winding number 15: 13: 10: 9: 6: 4: 3: 2: 1025: 1014: 1011: 1009: 1006: 1004: 1001: 1000: 998: 988: 984: 980: 979: 974: 969: 968: 964: 960: 956: 950: 946: 942: 938: 934: 931:(in French). 930: 929: 924: 919: 918: 914: 910: 907: 905: 902: 900: 897: 895: 892: 890: 887: 886: 882: 880: 877: 872: 831: 827: 820: 813:by the angle 812: 804: 803: 802: 801: 782: 774: 770: 765: 749: 738: 730: 729: 728: 726: 725:Arnaud Denjoy 695: 692: 689: 686: 683: 680: 677: 670: 669: 668: 658: 657:semiconjugacy 654: 646: 644: 642: 626: 603: 600: 597: 594: 591: 585: 579: 572: 571: 570: 556: 553: 550: 547: 544: 524: 521: 518: 498: 486: 484: 478: 460: 451: 427: 409: 404: 400: 397: 391: 383: 379: 364: 356: 350: 344: 337: 336: 335: 329: 321: 316: 291: 288: 282: 276: 273: 267: 264: 261: 255: 248: 247: 246: 219: 216: 209: 208:homeomorphism 205: 185: 176: 167: 162: 158: 150: 146: 145:homeomorphism 128: 124: 115: 111: 107: 104: 97:Suppose that 92: 90: 88: 84: 80: 76: 72: 68: 60: 58: 56: 52: 48: 44: 40: 33: 29: 22: 978:Scholarpedia 976: 954: 932: 926: 875: 870: 868: 768: 763: 710: 656: 650: 618: 490: 424: 319: 317: 306: 96: 85:in terms of 64: 42: 36: 959:pdf ver 1.3 432:. The lift 87:rationality 39:mathematics 997:Categories 915:References 889:Circle map 871:continuous 830:Cantor set 647:Properties 93:Definition 75:perihelion 71:precession 949:118356096 935:: 5–233. 693:∘ 681:∘ 522:π 398:− 371:∞ 368:→ 345:ω 228:→ 121:→ 47:invariant 1013:Rotation 955:SciSpace 883:See also 764:backward 569:), then 328:iterates 953:, also 839:. Then 786:. Then 537:(where 487:Example 473:⁠ 438:⁠ 202:may be 147:of the 73:of the 61:History 53:of the 947:  779:is an 746:has a 477:orbits 204:lifted 149:circle 55:circle 45:is an 41:, the 945:S2CID 819:dense 735:is a 659:: if 639:(cf. 206:to a 198:Then 77:of a 719:and 663:and 554:< 548:< 318:The 937:doi 794:of 756:p/q 740:p/q 643:). 491:If 479:of 361:lim 330:of 322:of 49:of 37:In 30:or 999:: 975:. 943:. 933:49 483:. 334:: 315:. 57:. 981:. 951:. 939:: 876:C 863:. 861:C 857:h 853:θ 849:f 845:C 841:C 837:f 833:C 823:f 815:θ 807:f 796:f 792:x 788:f 784:θ 777:f 769:f 760:f 752:q 744:f 733:f 721:g 717:f 713:h 696:h 690:g 687:= 684:f 678:h 665:g 661:f 627:N 604:, 601:N 598:+ 595:x 592:= 589:) 586:x 583:( 580:F 557:1 551:N 545:0 525:N 519:2 499:f 481:f 461:. 457:Z 452:/ 447:R 434:F 430:x 410:. 405:n 401:x 395:) 392:x 389:( 384:n 380:F 365:n 357:= 354:) 351:f 348:( 332:F 324:f 313:m 309:x 292:m 289:+ 286:) 283:x 280:( 277:F 274:= 271:) 268:m 265:+ 262:x 259:( 256:F 232:R 224:R 220:: 217:F 200:f 186:. 182:Z 177:/ 172:R 168:= 163:1 159:S 129:1 125:S 116:1 112:S 108:: 105:f 34:. 23:.

Index

Rotation (quantity)
Winding number
Turning number
mathematics
invariant
homeomorphisms
circle
Henri Poincaré
precession
perihelion
planetary orbit
periodic orbits
rationality
homeomorphism
circle
lifted
homeomorphism
iterates
Henri Poincaré
orbits
irrational rotation
topological conjugacy
Arnaud Denjoy
rational number
periodic orbit
irrational number
irrational rotation
dense
Cantor set
Circle map

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