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Fourier algebra

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proved that, when G is compact and abelian, a function f defined on a closed convex subset of the plane operates in A(G) if and only if f is real analytic. In 1969
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of these groups. The Fourier–Stieltjes algebra and the Fourier–Stieltjes transform on the Fourier algebra of a locally compact group were introduced by
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of these functions is an algebra under pointwise multiplication is isomorphic to the measure algebra
1607: 1026: 939: 1697: 1673: 1579: 1193: 1086: 871: 100: 92: 81: 1318:{\displaystyle {\widehat {\mu }}(x)=\int _{\widehat {G}}{\overline {X(x)}}\,d\mu (X),\quad x\in G} 1829: 1751: 1747: 1896: 1601: 1489: 85: 1819: 1759: 435: 258: 1573: 1113: 768: 739: 525: 496: 467: 366: 290: 182: 117: 89: 1735: 1727: 172: 96: 46: 1885: 1833: 1762:
proved the result holds when G is compact and contains an infinite abelian subgroup.
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Let A(G) be the Fourier algebra of a compact group G. Building upon the work of
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The references used may be made clearer with a different or consistent style of
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is the space of all functions on Äś which are integrable with respect to the
1872:"Centralizers of the Fourier Algebra of an Amenable Group", P. F. Renaud, 1604:, to the Fourier–Stieltjes transform of a non-negative finite measure on 1877: 1868: 1859: 1850: 1824: 692:
function is just the Fourier transform of that function, we have that
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for the measure algebra on Äś, meaning the space of all finite regular
1876:, Vol. 32, No. 2. (Apr., 1972), pp. 539–542. Stable URL: 1867:, Vol. 77, No. 1. (Oct., 1979), pp. 99–102. Stable URL: 1863:"Uniform Closures of Fourier-Stieltjes Algebras", Ching Chou, 18: 1858:, Vol. 45, No. 3. (Sep., 1974), pp. 389–392. Stable URL: 1849:, Vol. 21, No. 3. (Jun., 1969), pp. 540–544. Stable URL: 392:
to be the set of Fourier-Stieltjes transforms of measures in
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H. Helson; J.-P. Kahane; Y. Katznelson; W. Rudin (1959).
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be a Fourier algebra such that the locally compact group
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of the set of continuous positive-definite functions on
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and its image is, by definition, the Fourier algebra
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The Fourier–Stieltjes transform of a finite measure
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to be the set of Fourier transforms of functions in
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Let G be a locally compact abelian group, and Äś the
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Thus, 936:be the measure algebra of finite measures on 522:can be defined as the linear span of the set 8: 1083:is the character group of the Abelian group 1481:{\displaystyle M({\widehat {\mathit {G}}})} 1394:{\displaystyle M({\widehat {\mathit {G}}})} 929:{\displaystyle M({\widehat {\mathit {G}}})} 685:{\displaystyle L_{1}({\hat {\mathit {G}}})} 598:{\displaystyle L_{1}({\hat {\mathit {G}}})} 248:{\displaystyle L_{1}({\hat {\mathit {G}}})} 160:{\displaystyle L_{1}({\hat {\mathit {G}}})} 1823: 1702: 1701: 1699: 1678: 1677: 1675: 1647: 1646: 1638: 1612: 1611: 1609: 1584: 1583: 1581: 1553: 1552: 1544: 1515: 1513: 1512: 1503: 1497: 1488:, the Fourier–Stieltjes transform is the 1464: 1462: 1461: 1453: 1424: 1422: 1421: 1412: 1406: 1377: 1375: 1374: 1366: 1342: 1341: 1333: 1286: 1265: 1253: 1252: 1225: 1224: 1222: 1198: 1197: 1195: 1169: 1168: 1166: 1140: 1138: 1137: 1135: 1115: 1091: 1090: 1088: 1062: 1060: 1059: 1057: 1031: 1030: 1028: 988: 986: 985: 976: 970: 944: 943: 941: 912: 910: 909: 901: 876: 875: 873: 849: 848: 840: 816: 815: 807: 770: 741: 697: 668: 666: 665: 656: 650: 621: 619: 618: 610: 581: 579: 578: 569: 563: 527: 498: 469: 437: 408: 406: 405: 397: 368: 335: 333: 332: 324: 292: 260: 231: 229: 228: 219: 213: 184: 143: 141: 140: 131: 125: 65:Learn how and when to remove this message 1154:{\displaystyle {\widehat {\mathit {G}}}} 1076:{\displaystyle {\widehat {\mathit {G}}}} 1771: 638:{\displaystyle M({\hat {\mathit {G}}})} 425:{\displaystyle M({\hat {\mathit {G}}})} 352:{\displaystyle M({\hat {\mathit {G}}})} 1722:Helson–Kahane–Katznelson–Rudin theorem 1694:. This definition is still valid when 1576:states that a measurable function on 95:. They play an important role in the 16:Algebras arising in harmonic analysis 7: 255:, and it is a closed sub-algebra of 835:be a Fourier–Stieltjes algebra and 14: 1183:{\displaystyle {\widehat {\mu }}} 1659:{\displaystyle B({\mathit {G}})} 1565:{\displaystyle A({\mathit {G}})} 1354:{\displaystyle B({\mathit {G}})} 861:{\displaystyle A({\mathit {G}})} 828:{\displaystyle B({\mathit {G}})} 729:{\displaystyle A(G)\subset B(G)} 432:. It is a closed sub-algebra of 23: 1305: 1653: 1643: 1626:{\displaystyle {\widehat {G}}} 1559: 1549: 1526: 1509: 1475: 1458: 1435: 1418: 1388: 1371: 1348: 1338: 1299: 1293: 1277: 1271: 1242: 1236: 1045:{\displaystyle {\widehat {G}}} 999: 982: 958:{\displaystyle {\widehat {G}}} 923: 906: 855: 845: 822: 812: 781: 775: 752: 746: 723: 717: 708: 702: 679: 673: 662: 632: 626: 615: 592: 586: 575: 538: 532: 509: 503: 480: 474: 451: 445: 419: 413: 402: 379: 373: 346: 340: 329: 303: 297: 274: 268: 242: 236: 225: 195: 189: 154: 148: 137: 1: 1711:{\displaystyle {\mathit {G}}} 1687:{\displaystyle {\mathit {G}}} 1593:{\displaystyle {\mathit {G}}} 1207:{\displaystyle {\mathit {G}}} 1100:{\displaystyle {\mathit {G}}} 885:{\displaystyle {\mathit {G}}} 1281: 1786:Encyclopedia of Mathematics 553:positive-definite functions 1913: 1448:, viewed as a subspace of 316:the Fourier algebra of G. 605:is naturally included in 1779:Renault, Jean (2001) , 84:occur naturally in the 1712: 1688: 1666:can be defined as the 1660: 1627: 1594: 1566: 1533: 1482: 1442: 1395: 1355: 1319: 1208: 1184: 1155: 1124: 1101: 1077: 1046: 1006: 959: 930: 886: 862: 829: 788: 759: 730: 686: 639: 599: 545: 516: 487: 458: 426: 386: 353: 310: 281: 249: 202: 161: 1713: 1689: 1661: 1628: 1595: 1567: 1534: 1483: 1443: 1396: 1356: 1320: 1209: 1185: 1156: 1125: 1102: 1078: 1047: 1007: 960: 931: 887: 863: 830: 789: 765:is a closed ideal in 760: 731: 687: 640: 600: 546: 517: 488: 459: 457:{\displaystyle CB(G)} 427: 387: 354: 311: 282: 280:{\displaystyle CB(G)} 250: 203: 162: 1781:"Fourier-algebra(2)" 1698: 1674: 1637: 1608: 1580: 1543: 1496: 1452: 1405: 1365: 1332: 1221: 1194: 1165: 1134: 1123:{\displaystyle \mu } 1114: 1087: 1056: 1027: 969: 940: 900: 872: 839: 806: 787:{\displaystyle B(G)} 769: 758:{\displaystyle A(G)} 740: 696: 649: 609: 562: 544:{\displaystyle P(G)} 526: 515:{\displaystyle B(G)} 497: 486:{\displaystyle B(G)} 468: 436: 396: 385:{\displaystyle B(G)} 367: 323: 319:Similarly, we write 309:{\displaystyle A(G)} 291: 259: 212: 201:{\displaystyle A(G)} 183: 124: 1014:convolution algebra 171:on Äś, and it has a 1825:10.1007/bf02559571 1708: 1684: 1656: 1623: 1590: 1572:. The generalized 1562: 1529: 1478: 1438: 1391: 1351: 1315: 1204: 1180: 1151: 1120: 1097: 1073: 1042: 1002: 955: 926: 882: 858: 825: 784: 755: 726: 682: 635: 595: 541: 512: 483: 454: 422: 382: 349: 306: 277: 245: 198: 157: 1892:Harmonic analysis 1620: 1602:almost everywhere 1523: 1490:Fourier transform 1472: 1432: 1385: 1284: 1261: 1233: 1177: 1148: 1070: 1039: 996: 952: 920: 676: 629: 589: 416: 363:on Äś. We define 343: 239: 151: 86:harmonic analysis 75: 74: 67: 1904: 1838: 1837: 1827: 1818:(1–2): 135–157. 1812:Acta Mathematica 1809: 1800: 1794: 1793: 1776: 1718:is not Abelian. 1717: 1715: 1714: 1709: 1707: 1706: 1693: 1691: 1690: 1685: 1683: 1682: 1665: 1663: 1662: 1657: 1652: 1651: 1632: 1630: 1629: 1624: 1622: 1621: 1613: 1599: 1597: 1596: 1591: 1589: 1588: 1571: 1569: 1568: 1563: 1558: 1557: 1538: 1536: 1535: 1530: 1525: 1524: 1519: 1514: 1508: 1507: 1487: 1485: 1484: 1479: 1474: 1473: 1468: 1463: 1447: 1445: 1444: 1439: 1434: 1433: 1428: 1423: 1417: 1416: 1401:. Restricted to 1400: 1398: 1397: 1392: 1387: 1386: 1381: 1376: 1360: 1358: 1357: 1352: 1347: 1346: 1324: 1322: 1321: 1316: 1285: 1280: 1266: 1264: 1263: 1262: 1254: 1235: 1234: 1226: 1213: 1211: 1210: 1205: 1203: 1202: 1189: 1187: 1186: 1181: 1179: 1178: 1170: 1161:is the function 1160: 1158: 1157: 1152: 1150: 1149: 1144: 1139: 1129: 1127: 1126: 1121: 1106: 1104: 1103: 1098: 1096: 1095: 1082: 1080: 1079: 1074: 1072: 1071: 1066: 1061: 1051: 1049: 1048: 1043: 1041: 1040: 1032: 1011: 1009: 1008: 1003: 998: 997: 992: 987: 981: 980: 964: 962: 961: 956: 954: 953: 945: 935: 933: 932: 927: 922: 921: 916: 911: 891: 889: 888: 883: 881: 880: 867: 865: 864: 859: 854: 853: 834: 832: 831: 826: 821: 820: 793: 791: 790: 785: 764: 762: 761: 756: 735: 733: 732: 727: 691: 689: 688: 683: 678: 677: 672: 667: 661: 660: 644: 642: 641: 636: 631: 630: 625: 620: 604: 602: 601: 596: 591: 590: 585: 580: 574: 573: 550: 548: 547: 542: 521: 519: 518: 513: 492: 490: 489: 484: 463: 461: 460: 455: 431: 429: 428: 423: 418: 417: 412: 407: 391: 389: 388: 383: 358: 356: 355: 350: 345: 344: 339: 334: 315: 313: 312: 307: 286: 284: 283: 278: 254: 252: 251: 246: 241: 240: 235: 230: 224: 223: 207: 205: 204: 199: 166: 164: 163: 158: 153: 152: 147: 142: 136: 135: 97:duality theories 70: 63: 59: 56: 50: 27: 26: 19: 1912: 1911: 1907: 1906: 1905: 1903: 1902: 1901: 1882: 1881: 1842: 1841: 1807: 1802: 1801: 1797: 1778: 1777: 1773: 1768: 1724: 1696: 1695: 1672: 1671: 1635: 1634: 1606: 1605: 1578: 1577: 1574:Bochner theorem 1541: 1540: 1499: 1494: 1493: 1450: 1449: 1408: 1403: 1402: 1363: 1362: 1330: 1329: 1267: 1248: 1219: 1218: 1192: 1191: 1163: 1162: 1132: 1131: 1112: 1111: 1085: 1084: 1054: 1053: 1025: 1024: 972: 967: 966: 938: 937: 898: 897: 870: 869: 837: 836: 804: 803: 800: 767: 766: 738: 737: 694: 693: 652: 647: 646: 607: 606: 565: 560: 559: 524: 523: 495: 494: 466: 465: 434: 433: 394: 393: 365: 364: 321: 320: 289: 288: 257: 256: 215: 210: 209: 181: 180: 127: 122: 121: 114: 109: 90:locally compact 71: 60: 54: 51: 40: 34:has an unclear 28: 24: 17: 12: 11: 5: 1910: 1908: 1900: 1899: 1894: 1884: 1883: 1880: 1879: 1870: 1861: 1852: 1840: 1839: 1795: 1770: 1769: 1767: 1764: 1723: 1720: 1705: 1681: 1655: 1650: 1645: 1642: 1619: 1616: 1587: 1561: 1556: 1551: 1548: 1528: 1522: 1518: 1511: 1506: 1502: 1477: 1471: 1467: 1460: 1457: 1437: 1431: 1427: 1420: 1415: 1411: 1390: 1384: 1380: 1373: 1370: 1350: 1345: 1340: 1337: 1326: 1325: 1314: 1311: 1308: 1304: 1301: 1298: 1295: 1292: 1289: 1283: 1279: 1276: 1273: 1270: 1260: 1257: 1251: 1247: 1244: 1241: 1238: 1232: 1229: 1201: 1176: 1173: 1147: 1143: 1119: 1094: 1069: 1065: 1038: 1035: 1001: 995: 991: 984: 979: 975: 951: 948: 925: 919: 915: 908: 905: 879: 857: 852: 847: 844: 824: 819: 814: 811: 799: 796: 783: 780: 777: 774: 754: 751: 748: 745: 725: 722: 719: 716: 713: 710: 707: 704: 701: 681: 675: 671: 664: 659: 655: 634: 628: 624: 617: 614: 594: 588: 584: 577: 572: 568: 551:of continuous 540: 537: 534: 531: 511: 508: 505: 502: 482: 479: 476: 473: 453: 450: 447: 444: 441: 421: 415: 411: 404: 401: 381: 378: 375: 372: 361:Borel measures 348: 342: 338: 331: 328: 305: 302: 299: 296: 276: 273: 270: 267: 264: 244: 238: 234: 227: 222: 218: 197: 194: 191: 188: 173:Banach algebra 156: 150: 146: 139: 134: 130: 113: 110: 108: 105: 73: 72: 36:citation style 31: 29: 22: 15: 13: 10: 9: 6: 4: 3: 2: 1909: 1898: 1895: 1893: 1890: 1889: 1887: 1878: 1875: 1871: 1869: 1866: 1862: 1860: 1857: 1853: 1851: 1848: 1844: 1843: 1835: 1831: 1826: 1821: 1817: 1813: 1806: 1799: 1796: 1792: 1788: 1787: 1782: 1775: 1772: 1765: 1763: 1761: 1757: 1753: 1749: 1745: 1741: 1737: 1733: 1729: 1721: 1719: 1669: 1640: 1617: 1614: 1603: 1575: 1546: 1520: 1504: 1500: 1491: 1469: 1455: 1429: 1413: 1409: 1382: 1368: 1335: 1312: 1309: 1306: 1302: 1296: 1290: 1287: 1274: 1268: 1258: 1255: 1249: 1245: 1239: 1230: 1227: 1217: 1216: 1215: 1174: 1171: 1145: 1117: 1108: 1067: 1036: 1033: 1022: 1019: 1015: 993: 977: 973: 949: 946: 917: 903: 895: 842: 809: 797: 795: 778: 772: 749: 743: 720: 714: 711: 705: 699: 657: 653: 612: 570: 566: 556: 554: 535: 529: 506: 500: 477: 471: 448: 442: 439: 399: 376: 370: 362: 326: 317: 300: 294: 271: 265: 262: 220: 216: 192: 186: 178: 174: 170: 132: 128: 119: 111: 106: 104: 102: 101:Pierre Eymard 98: 94: 91: 87: 83: 79: 69: 66: 58: 55:February 2012 48: 44: 38: 37: 32:This article 30: 21: 20: 1873: 1864: 1855: 1846: 1815: 1811: 1798: 1784: 1774: 1725: 1327: 1109: 801: 557: 318: 179:. We define 169:Haar measure 115: 80:and related 77: 76: 61: 52: 33: 1668:linear span 1214:defined by 736:. In fact, 177:convolution 120:of G. Then 1886:Categories 1766:References 1752:Katznelson 1742:, in 1959 1600:is equal, 1328:The space 1018:integrable 118:dual group 107:Definition 47:footnoting 1834:121739671 1791:EMS Press 1618:^ 1521:^ 1470:^ 1430:^ 1383:^ 1310:∈ 1291:μ 1282:¯ 1259:^ 1250:∫ 1231:^ 1228:μ 1175:^ 1172:μ 1146:^ 1118:μ 1068:^ 1037:^ 1021:functions 994:^ 950:^ 918:^ 712:⊂ 674:^ 627:^ 587:^ 414:^ 341:^ 237:^ 149:^ 103:in 1964. 1897:Algebras 1740:Beurling 1052:, where 965:and let 112:Informal 82:algebras 43:citation 1736:Gelfand 1012:be the 894:abelian 78:Fourier 1832:  1754:, and 1748:Kahane 1744:Helson 1738:, and 1728:Wiener 896:. Let 798:Formal 558:Since 555:on G. 93:groups 1830:S2CID 1808:(PDF) 1760:Dunkl 1756:Rudin 1732:LĂ©vy 802:Let 45:and 1820:doi 1816:102 1492:on 1190:on 1130:on 1023:on 1016:of 892:is 88:of 1888:: 1828:. 1814:. 1810:. 1789:, 1783:, 1750:, 1746:, 1734:, 1730:, 1107:. 794:. 1836:. 1822:: 1704:G 1680:G 1654:) 1649:G 1644:( 1641:B 1615:G 1586:G 1560:) 1555:G 1550:( 1547:A 1527:) 1517:G 1510:( 1505:1 1501:L 1476:) 1466:G 1459:( 1456:M 1436:) 1426:G 1419:( 1414:1 1410:L 1389:) 1379:G 1372:( 1369:M 1349:) 1344:G 1339:( 1336:B 1313:G 1307:x 1303:, 1300:) 1297:X 1294:( 1288:d 1278:) 1275:x 1272:( 1269:X 1256:G 1246:= 1243:) 1240:x 1237:( 1200:G 1142:G 1093:G 1064:G 1034:G 1000:) 990:G 983:( 978:1 974:L 947:G 924:) 914:G 907:( 904:M 878:G 856:) 851:G 846:( 843:A 823:) 818:G 813:( 810:B 782:) 779:G 776:( 773:B 753:) 750:G 747:( 744:A 724:) 721:G 718:( 715:B 709:) 706:G 703:( 700:A 680:) 670:G 663:( 658:1 654:L 633:) 623:G 616:( 613:M 593:) 583:G 576:( 571:1 567:L 539:) 536:G 533:( 530:P 510:) 507:G 504:( 501:B 481:) 478:G 475:( 472:B 452:) 449:G 446:( 443:B 440:C 420:) 410:G 403:( 400:M 380:) 377:G 374:( 371:B 347:) 337:G 330:( 327:M 304:) 301:G 298:( 295:A 275:) 272:G 269:( 266:B 263:C 243:) 233:G 226:( 221:1 217:L 196:) 193:G 190:( 187:A 155:) 145:G 138:( 133:1 129:L 68:) 62:( 57:) 53:( 49:. 39:.

Index

citation style
citation
footnoting
Learn how and when to remove this message
algebras
harmonic analysis
locally compact
groups
duality theories
Pierre Eymard
dual group
Haar measure
Banach algebra
convolution
Borel measures
positive-definite functions
abelian
convolution algebra
integrable
functions
Fourier transform
Bochner theorem
almost everywhere
linear span
Wiener
LĂ©vy
Gelfand
Beurling
Helson
Kahane

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