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Open mapping theorem (complex analysis)

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120: 111:
a portion of any line embedded in the complex plane. Images of holomorphic functions can be of real dimension zero (if constant) or two (if non-constant) but never of dimension 1.
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The open mapping theorem points to the sharp difference between holomorphy and real-differentiability. On the
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is given by the dashed line. Note that all poles are exterior to the open set. The smaller red disk is
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will have the same number of roots (counted with multiplicity) in
353:(although this single root may have multiplicity greater than 1). 423: 131:). Black annuli represent poles. The boundary of the open set 107: 101:
The theorem for example implies that a non-constant
337:, and by further decreasing the radius of the disk 202:) has a neighborhood (open disk) which is also in 170:of the complex plane. We have to show that every 749: 329:) is non-constant and holomorphic. The roots of 380:guarantees the existence of a positive minimum 162:is a non-constant holomorphic function and 98:(−1, 1) is the half-open interval [0, 1). 82:, for example, the differentiable function 715:Open mapping theorem (functional analysis) 118: 94:is not an open map, as the image of the 750: 726: 13: 14: 769: 265:> 0 such that the closed disk 686: 63:(i.e. it sends open subsets of 625:) is a subset of the image of 123:Black dots represent zeros of 1: 720: 228:). Then there exists a point 758:Theorems in complex analysis 679:was arbitrary, the function 569:, there exists at least one 349:) has only a single root in 194:), i.e. that every point in 7: 732:Real & Complex Analysis 708: 598:. This means that the disk 10: 774: 693:Maximum modulus principle 644:is an interior point of 360:is a circle and hence a 284:. Consider the function 114: 105:cannot map an open disk 613:The image of the ball 280:is fully contained in 213:Consider an arbitrary 147: 415:the open disk around 378:extreme value theorem 341:, we can assure that 261:is open, we can find 122: 558:|. Thus, for every 494:. This is because 333:are isolated by the 103:holomorphic function 73:invariance of domain 53:holomorphic function 22:open mapping theorem 528:on the boundary of 400:on the boundary of 388:is the minimum of | 374:continuous function 67:to open subsets of 318:of the function. 148: 51:is a non-constant 675:) is open. Since 659:was arbitrary in 372:)| is a positive 765: 744: 698:Rouché's theorem 602:is contained in 431:Rouché's theorem 356:The boundary of 335:identity theorem 18:complex analysis 773: 772: 768: 767: 766: 764: 763: 762: 748: 747: 742: 734:, McGraw-Hill, 723: 711: 689: 667:) we know that 658: 643: 597: 590: 575: 564: 557: 550: 523: 516: 489: 482: 455: 433:, the function 421: 313: 306: 275: 256: 245: 234: 219: 145: 117: 24:states that if 12: 11: 5: 771: 761: 760: 746: 745: 740: 722: 719: 718: 717: 710: 707: 706: 705: 700: 695: 688: 685: 656: 641: 595: 588: 573: 562: 555: 548: 521: 514: 487: 480: 453: 419: 311: 304: 273: 254: 243: 232: 217: 184:interior point 143: 139:, centered at 116: 113: 71:, and we have 9: 6: 4: 3: 2: 770: 759: 756: 755: 753: 743: 741:0-07-054234-1 737: 733: 729: 728:Rudin, Walter 725: 724: 716: 713: 712: 704: 703:Schwarz lemma 701: 699: 696: 694: 691: 690: 684: 682: 678: 674: 670: 666: 662: 655: 651: 647: 640: 636: 632: 628: 624: 620: 616: 611: 609: 605: 601: 594: 587: 583: 579: 572: 568: 561: 554: 547: 543: 539: 535: 531: 527: 520: 513: 509: 505: 501: 497: 493: 486: 479: 475: 471: 467: 463: 459: 452: 448: 444: 440: 436: 432: 428: 425: 418: 414: 409: 407: 403: 399: 395: 391: 387: 383: 379: 375: 371: 367: 363: 359: 354: 352: 348: 344: 340: 336: 332: 328: 324: 321:We know that 319: 317: 310: 303: 299: 295: 291: 287: 283: 279: 272: 268: 264: 260: 253: 249: 242: 238: 231: 227: 223: 216: 211: 209: 205: 201: 197: 193: 189: 185: 181: 177: 173: 169: 165: 161: 157: 153: 142: 138: 134: 130: 126: 121: 112: 110: 109: 104: 99: 97: 96:open interval 93: 89: 85: 81: 76: 74: 70: 66: 62: 58: 54: 50: 46: 42: 38: 35: 34:complex plane 31: 27: 23: 19: 731: 687:Applications 680: 676: 672: 668: 664: 660: 653: 649: 645: 638: 634: 630: 626: 622: 618: 614: 612: 607: 603: 599: 592: 585: 581: 577: 570: 566: 559: 552: 545: 541: 537: 533: 529: 525: 518: 511: 507: 503: 499: 495: 491: 484: 477: 473: 469: 465: 461: 457: 450: 446: 442: 438: 434: 426: 416: 412: 410: 405: 401: 397: 393: 389: 385: 381: 369: 365: 364:, on which | 357: 355: 350: 346: 342: 338: 330: 326: 322: 320: 308: 307:. Note that 301: 297: 293: 289: 285: 281: 277: 276:with radius 270: 266: 262: 258: 251: 247: 240: 236: 229: 225: 221: 214: 212: 207: 203: 199: 195: 191: 187: 179: 175: 163: 159: 155: 151: 149: 140: 136: 132: 128: 124: 106: 100: 91: 87: 83: 77: 68: 64: 56: 48: 44: 40: 36: 25: 21: 15: 524:), and for 384:, that is, 362:compact set 721:References 580:such that 411:Denote by 239:such that 683:is open. 652:). Since 408:> 0. 376:, so the 257:). Since 80:real line 752:Category 730:(1966), 709:See also 637:). Thus 483:for any 182:) is an 154: : 61:open map 43: : 396:)| for 269:around 150:Assume 55:, then 32:of the 738:  544:> | 424:radius 168:domain 59:is an 30:domain 20:, the 540:)| ≥ 510:) + ( 429:. By 422:with 314:is a 172:point 166:is a 115:Proof 28:is a 736:ISBN 610:). 591:) = 502:) = 441:) = 404:and 316:root 292:) = 108:onto 90:) = 75:.). 39:and 576:in 565:in 532:, | 490:in 468:):= 460:as 235:in 220:in 210:). 186:of 174:in 16:In 754:: 629:, 617:, 551:- 517:- 476:)− 449:)− 300:)− 246:= 158:→ 47:→ 681:f 677:U 673:U 671:( 669:f 665:U 663:( 661:f 657:0 654:w 650:U 648:( 646:f 642:0 639:w 635:U 633:( 631:f 627:U 623:B 621:( 619:f 615:B 608:B 606:( 604:f 600:D 596:1 593:w 589:1 586:z 584:( 582:f 578:B 574:1 571:z 567:D 563:1 560:w 556:1 553:w 549:0 546:w 542:e 538:z 536:( 534:g 530:B 526:z 522:1 519:w 515:0 512:w 508:z 506:( 504:g 500:z 498:( 496:h 492:D 488:1 485:w 481:1 478:w 474:z 472:( 470:f 466:z 464:( 462:h 458:B 454:0 451:w 447:z 445:( 443:f 439:z 437:( 435:g 427:e 420:0 417:w 413:D 406:e 402:B 398:z 394:z 392:( 390:g 386:e 382:e 370:z 368:( 366:g 358:B 351:B 347:z 345:( 343:g 339:B 331:g 327:z 325:( 323:g 312:0 309:z 305:0 302:w 298:z 296:( 294:f 290:z 288:( 286:g 282:U 278:d 274:0 271:z 267:B 263:d 259:U 255:0 252:z 250:( 248:f 244:0 241:w 237:U 233:0 230:z 226:U 224:( 222:f 218:0 215:w 208:U 206:( 204:f 200:U 198:( 196:f 192:U 190:( 188:f 180:U 178:( 176:f 164:U 160:C 156:U 152:f 146:. 144:0 141:z 137:B 133:U 129:z 127:( 125:g 92:x 88:x 86:( 84:f 69:C 65:U 57:f 49:C 45:U 41:f 37:C 26:U

Index

complex analysis
domain
complex plane
holomorphic function
open map
invariance of domain
real line
open interval
holomorphic function
onto

domain
point
interior point
root
identity theorem
compact set
continuous function
extreme value theorem
radius
Rouché's theorem
Maximum modulus principle
Rouché's theorem
Schwarz lemma
Open mapping theorem (functional analysis)
Rudin, Walter
ISBN
0-07-054234-1
Category
Theorems in complex analysis

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