Knowledge

Approximate identity

Source đź“ť

1637: 307: 182: 235: 110: 3019: 2802: 2892: 2929: 2968: 2736: 3095: 1024: 418:
if and only if every hereditary C*-subalgebra has an approximate identity consisting of projections. This was known as property (HP) in earlier literature.
1846: 3126: 2180: 1526: 1126: 2825: 248: 123: 759: 2302: 1362: 17: 1834: 3121: 1189: 781: 2235: 1352: 764: 537: 786: 2207: 1479: 1334: 1841: 1673: 1310: 1111: 774: 2554: 1004: 2496: 857: 655: 2312: 852: 195: 70: 2395: 1862: 1202: 414:
One sometimes considers approximate identities consisting of specific types of elements. For example, a C*-algebra has
2036: 1819: 1291: 1182: 1009: 2984: 2631: 1954: 1797: 1561: 827: 2484: 2420: 1971: 1206: 796: 2265: 415: 2758: 2676: 2479: 2158: 1937: 710: 594: 2855: 2517: 2295: 2250: 2240: 1357: 1019: 530: 2352: 2342: 2270: 2197: 2073: 1742: 1640: 1413: 1347: 1175: 645: 333:
of norm ≤ 1 with its natural order is an approximate identity for any C*-algebra. This is called the
2347: 2690: 2680: 2280: 1666: 1377: 1156: 1076: 630: 3049: 2851: 2513: 2327: 2220: 2215: 2110: 2083: 2048: 1900: 1793: 1622: 1576: 1500: 1382: 1131: 1029: 909: 450:
In ring theory, an approximate identity is defined in a similar way, except that the ring is given the
2907: 2807: 2501: 2474: 2457: 2275: 2120: 1789: 1617: 1433: 1136: 999: 832: 817: 625: 589: 3152: 3024: 2317: 2307: 2225: 2163: 2090: 2044: 1959: 1784: 1469: 1367: 1270: 728: 718: 599: 523: 400: 373: 2946: 2709: 2290: 2230: 1566: 1342: 1091: 1066: 884: 873: 584: 3058: 2332: 2245: 2026: 1942: 1778: 1772: 1659: 1597: 1541: 1505: 942: 932: 927: 635: 505: 349: 2572: 3116: 3111: 2586: 2534: 2491: 2415: 2368: 2105: 1767: 1734: 1707: 1304: 687: 2405: 1300: 3054: 2260: 2255: 1966: 1850: 1756: 1580: 1101: 1080: 994: 842: 469: 431: 1167: 8: 2897: 2698: 2655: 2469: 2192: 1922: 1729: 1546: 1484: 1198: 904: 640: 28: 2843: 3131: 3042: 2665: 2635: 2452: 2410: 2017: 1927: 1872: 1719: 1571: 1438: 1034: 963: 894: 738: 700: 510: 345:, the net consisting of finite rank projections would be another approximate identity. 44: 2973: 2943: 2904: 2812: 2285: 2066: 2009: 1989: 1551: 1141: 1116: 801: 723: 451: 329:
elements is the same as an approximate identity. The net of all positive elements in
313:
is a net which is both a right approximate identity and a left approximate identity.
36: 2442: 2437: 2425: 2337: 2322: 2185: 2125: 2100: 2031: 2021: 1884: 1556: 1474: 1443: 1423: 1408: 1403: 1398: 1146: 847: 695: 650: 574: 365: 338: 48: 1829: 1235: 2462: 2447: 2373: 2175: 2168: 2135: 2095: 2061: 2053: 1981: 1949: 1814: 1746: 1418: 1372: 1320: 1315: 1286: 1121: 1106: 1014: 977: 973: 937: 899: 837: 822: 791: 733: 692: 679: 604: 546: 515: 361: 1245: 435: 3032: 2980: 2640: 2506: 2153: 2143: 1762: 1714: 1607: 1459: 1260: 1071: 1050: 968: 958: 769: 676: 609: 569: 439: 369: 40: 3146: 3037: 2650: 2604: 2539: 2390: 2385: 2378: 1999: 1932: 1905: 1724: 1697: 1612: 1536: 1265: 1250: 1240: 342: 430:
algebra plays the same role as a sequence of function approximations to the
302:{\displaystyle \lim _{\lambda \in \Lambda }\lVert e_{\lambda }a-a\rVert =0.} 177:{\displaystyle \lim _{\lambda \in \Lambda }\lVert ae_{\lambda }-a\rVert =0.} 2549: 2544: 2004: 1994: 1867: 1857: 1702: 1682: 1602: 1255: 1225: 889: 743: 684: 326: 377: 2838: 2754: 2660: 2645: 2625: 2599: 2564: 2115: 2078: 1751: 1531: 1521: 1428: 1230: 1086: 671: 427: 337:
of a C*-algebra. Approximate identities are not unique. For example, for
32: 24: 2594: 2575: ((cs, lcs)-closed, (cs, bcs)-complete, (lower) ideally convex, (H 2559: 2400: 2148: 1910: 1464: 1296: 579: 322: 1651: 16:
This article is about the Banach algebra concept. For other uses, see
2670: 1915: 1879: 564: 550: 500: 2936: 2820: 2746: 2706: 2609: 2432: 1151: 1096: 434:(which is the identity element for convolution). For example, the 356:
and a C*-algebra with a sequential approximate identity is called
2741: 1824: 47:(generally without an identity) that acts as a substitute for an 1197: 388:
contains a strictly positive element, i.e. there exists
325:, a right (or left) approximate identity consisting of 3061: 2987: 2949: 2910: 2858: 2761: 2712: 251: 230:{\displaystyle \{e_{\lambda }:\lambda \in \Lambda \}} 198: 126: 105:{\displaystyle \{e_{\lambda }:\lambda \in \Lambda \}} 73: 368:
is false. A commutative C*-algebra is σ-unital
3089: 3013: 2962: 2923: 2886: 2796: 2730: 1527:Spectral theory of ordinary differential equations 1127:Spectral theory of ordinary differential equations 545: 301: 229: 176: 104: 1025:Schröder–Bernstein theorems for operator algebras 3144: 472:over a ring with approximate identity is called 253: 128: 3014:{\displaystyle S\left(\mathbb {R} ^{n}\right)} 3122:Mathematical formulation of quantum mechanics 1667: 1183: 531: 442:theory give rise to an approximate identity. 290: 268: 224: 199: 165: 143: 99: 74: 1674: 1660: 1190: 1176: 538: 524: 2997: 2797:{\displaystyle B_{p,q}^{s}(\mathbb {R} )} 2787: 1480:Group algebra of a locally compact group 364:C*-algebra is σ-unital, though the 2887:{\displaystyle L^{\lambda ,p}(\Omega )} 1681: 421: 3145: 3127:Ordinary Differential Equations (ODEs) 2241:Banach–Steinhaus (Uniform boundedness) 1655: 1171: 858:Spectral theory of normal C*-algebras 656:Spectral theory of normal C*-algebras 519: 853:Spectral theory of compact operators 480:in the module there is some λ with 13: 2955: 2916: 2878: 2722: 1005:Cohen–Hewitt factorization theorem 263: 221: 138: 96: 14: 3164: 2619:Subsets / set operations 2396:Differentiation in FrĂ©chet spaces 1010:Extensions of symmetric operators 1636: 1635: 1562:Topological quantum field theory 828:Positive operator-valued measure 384:is σ-unital if and only if 348:If an approximate identity is a 2924:{\displaystyle \ell ^{\infty }} 1112:Rayleigh–Faber–Krahn inequality 354:sequential approximate identity 35:, an approximate identity is a 3084: 3065: 2881: 2875: 2791: 2783: 2725: 2719: 2313:Lomonosov's invariant subspace 2236:Banach–Schauder (open mapping) 335:canonical approximate identity 316: 1: 1358:Uniform boundedness principle 1020:Limiting absorption principle 426:An approximate identity in a 54: 18:Approximation to the identity 2198:Singular value decomposition 646:Singular value decomposition 237:such that for every element 112:such that for every element 7: 2963:{\displaystyle L^{\infty }} 2731:{\displaystyle ba(\Sigma )} 2600:Radially convex/Star-shaped 1077:Hearing the shape of a drum 760:Decomposition of a spectrum 494: 380:. In general, a C*-algebra 10: 3169: 3090:{\displaystyle W(X,L^{p})} 1501:Invariant subspace problem 665:Special Elements/Operators 61:right approximate identity 15: 3104: 2689: 2636:Algebraic interior (core) 2618: 2527: 2361: 2251:Cauchy–Schwarz inequality 2206: 2134: 1980: 1894:Function space Topologies 1893: 1807: 1690: 1631: 1590: 1514: 1493: 1452: 1391: 1333: 1279: 1221: 1214: 1137:Superstrong approximation 1059: 1043: 1000:Banach algebra cohomology 987: 951: 920: 866: 833:Projection-valued measure 818:Borel functional calculus 810: 752: 709: 664: 618: 590:Projection-valued measure 557: 186:left approximate identity 1470:Spectrum of a C*-algebra 729:Spectrum of a C*-algebra 600:Spectrum of a C*-algebra 445: 401:hereditary C*-subalgebra 1567:Noncommutative geometry 1157:Wiener–Khinchin theorem 1092:Kuznetsov trace formula 1067:Almost Mathieu operator 885:Banach function algebra 874:Amenable Banach algebra 631:Gelfand–Naimark theorem 585:Noncommutative topology 3091: 3015: 2964: 2925: 2888: 2798: 2732: 1901:Banach–Mazur compactum 1691:Types of Banach spaces 1623:Tomita–Takesaki theory 1598:Approximation property 1542:Calculus of variations 1132:Sturm–Liouville theory 1030:Sherman–Takeda theorem 910:Tomita–Takesaki theory 685:Hermitian/Self-adjoint 636:Gelfand representation 506:Nascent delta function 303: 231: 178: 106: 3117:Finite element method 3112:Differential operator 3092: 3016: 2965: 2926: 2889: 2799: 2733: 2573:Convex series related 2369:Abstract Wiener space 2296:hyperplane separation 1851:Minkowski functionals 1735:Polarization identity 1618:Banach–Mazur distance 1581:Generalized functions 626:Gelfand–Mazur theorem 304: 232: 179: 107: 3059: 2985: 2947: 2908: 2856: 2759: 2710: 2699:Absolute continuity 2353:Schauder fixed-point 2343:Riesz representation 2303:Kakutani fixed-point 2271:Freudenthal spectral 1757:L-semi-inner product 1363:Kakutani fixed-point 1348:Riesz representation 1102:Proto-value function 1081:Dirichlet eigenvalue 995:Abstract index group 880:Approximate identity 843:Rigged Hilbert space 719:Krein–Rutman theorem 565:Involution/*-algebra 432:Dirac delta function 422:Convolution algebras 311:approximate identity 249: 196: 188:in a Banach algebra 124: 71: 63:in a Banach algebra 2782: 2520:measurable function 2470:Functional calculus 2333:Parseval's identity 2246:Bessel's inequality 2193:Polar decomposition 1972:Uniform convergence 1730:Inner product space 1547:Functional calculus 1506:Mahler's conjecture 1485:Von Neumann algebra 1199:Functional analysis 905:Von Neumann algebra 641:Polar decomposition 29:functional analysis 3132:Validated numerics 3087: 3043:Sobolev inequality 3011: 2960: 2921: 2884: 2813:Bounded variation 2794: 2762: 2747:Banach coordinate 2728: 2666:Minkowski addition 2328:M. Riesz extension 1808:Banach spaces are: 1572:Riemann hypothesis 1271:Topological vector 1035:Unbounded operator 964:Essential spectrum 943:Schur–Horn theorem 933:Bauer–Fike theorem 928:Alon–Boppana bound 921:Finite-Dimensional 895:Nuclear C*-algebra 739:Spectral asymmetry 511:Summability kernel 299: 267: 227: 174: 142: 102: 27:, particularly in 3140: 3139: 2852:Morrey–Campanato 2834:compact Hausdorff 2681:Relative interior 2535:Absolutely convex 2502:Projection-valued 2111:Strictly singular 2037:on Hilbert spaces 1798:of Hilbert spaces 1649: 1648: 1552:Integral operator 1329: 1328: 1165: 1164: 1142:Transfer operator 1117:Spectral geometry 802:Spectral abscissa 782:Approximate point 724:Normal eigenvalue 452:discrete topology 339:compact operators 252: 127: 3160: 3096: 3094: 3093: 3088: 3083: 3082: 3050:Triebel–Lizorkin 3020: 3018: 3017: 3012: 3010: 3006: 3005: 3000: 2969: 2967: 2966: 2961: 2959: 2958: 2930: 2928: 2927: 2922: 2920: 2919: 2893: 2891: 2890: 2885: 2874: 2873: 2803: 2801: 2800: 2795: 2790: 2781: 2776: 2737: 2735: 2734: 2729: 2590: 2568: 2550:Balanced/Circled 2348:Robinson-Ursescu 2266:Eberlein–Šmulian 2186:Spectral theorem 1982:Linear operators 1779:Uniformly smooth 1676: 1669: 1662: 1653: 1652: 1639: 1638: 1557:Jones polynomial 1475:Operator algebra 1219: 1218: 1192: 1185: 1178: 1169: 1168: 1147:Transform theory 867:Special algebras 848:Spectral theorem 811:Spectral Theorem 651:Spectral theorem 540: 533: 526: 517: 516: 308: 306: 305: 300: 280: 279: 266: 236: 234: 233: 228: 211: 210: 183: 181: 180: 175: 158: 157: 141: 111: 109: 108: 103: 86: 85: 49:identity element 3168: 3167: 3163: 3162: 3161: 3159: 3158: 3157: 3153:Banach algebras 3143: 3142: 3141: 3136: 3100: 3078: 3074: 3060: 3057: 3056: 3055:Wiener amalgam 3025:Segal–Bargmann 3001: 2996: 2995: 2991: 2986: 2983: 2982: 2954: 2950: 2948: 2945: 2944: 2915: 2911: 2909: 2906: 2905: 2863: 2859: 2857: 2854: 2853: 2808:Birnbaum–Orlicz 2786: 2777: 2766: 2760: 2757: 2756: 2711: 2708: 2707: 2685: 2641:Bounding points 2614: 2588: 2566: 2523: 2374:Banach manifold 2357: 2281:Gelfand–Naimark 2202: 2176:Spectral theory 2144:Banach algebras 2136:Operator theory 2130: 2091:Pseudo-monotone 2074:Hilbert–Schmidt 2054:Densely defined 1976: 1889: 1803: 1686: 1680: 1650: 1645: 1627: 1591:Advanced topics 1586: 1510: 1489: 1448: 1414:Hilbert–Schmidt 1387: 1378:Gelfand–Naimark 1325: 1275: 1210: 1196: 1166: 1161: 1122:Spectral method 1107:Ramanujan graph 1055: 1039: 1015:Fredholm theory 983: 978:Shilov boundary 974:Structure space 952:Generalizations 947: 938:Numerical range 916: 900:Uniform algebra 862: 838:Riesz projector 823:Min-max theorem 806: 792:Direct integral 748: 734:Spectral radius 705: 660: 614: 605:Spectral radius 553: 547:Spectral theory 544: 497: 490: 464: 448: 424: 398: 352:, we call it a 319: 275: 271: 256: 250: 247: 246: 206: 202: 197: 194: 193: 153: 149: 131: 125: 122: 121: 81: 77: 72: 69: 68: 57: 21: 12: 11: 5: 3166: 3156: 3155: 3138: 3137: 3135: 3134: 3129: 3124: 3119: 3114: 3108: 3106: 3102: 3101: 3099: 3098: 3086: 3081: 3077: 3073: 3070: 3067: 3064: 3052: 3047: 3046: 3045: 3035: 3033:Sequence space 3030: 3022: 3009: 3004: 2999: 2994: 2990: 2978: 2977: 2976: 2971: 2957: 2953: 2934: 2933: 2932: 2918: 2914: 2895: 2883: 2880: 2877: 2872: 2869: 2866: 2862: 2849: 2841: 2836: 2823: 2818: 2810: 2805: 2793: 2789: 2785: 2780: 2775: 2772: 2769: 2765: 2752: 2744: 2739: 2727: 2724: 2721: 2718: 2715: 2704: 2695: 2693: 2687: 2686: 2684: 2683: 2673: 2668: 2663: 2658: 2653: 2648: 2643: 2638: 2628: 2622: 2620: 2616: 2615: 2613: 2612: 2607: 2602: 2597: 2592: 2584: 2570: 2562: 2557: 2552: 2547: 2542: 2537: 2531: 2529: 2525: 2524: 2522: 2521: 2511: 2510: 2509: 2504: 2499: 2489: 2488: 2487: 2482: 2477: 2467: 2466: 2465: 2460: 2455: 2450: 2448:Gelfand–Pettis 2445: 2440: 2430: 2429: 2428: 2423: 2418: 2413: 2408: 2398: 2393: 2388: 2383: 2382: 2381: 2371: 2365: 2363: 2359: 2358: 2356: 2355: 2350: 2345: 2340: 2335: 2330: 2325: 2320: 2315: 2310: 2305: 2300: 2299: 2298: 2288: 2283: 2278: 2273: 2268: 2263: 2258: 2253: 2248: 2243: 2238: 2233: 2228: 2223: 2221:Banach–Alaoglu 2218: 2216:Anderson–Kadec 2212: 2210: 2204: 2203: 2201: 2200: 2195: 2190: 2189: 2188: 2183: 2173: 2172: 2171: 2166: 2156: 2154:Operator space 2151: 2146: 2140: 2138: 2132: 2131: 2129: 2128: 2123: 2118: 2113: 2108: 2103: 2098: 2093: 2088: 2087: 2086: 2076: 2071: 2070: 2069: 2064: 2056: 2051: 2041: 2040: 2039: 2029: 2024: 2014: 2013: 2012: 2007: 2002: 1992: 1986: 1984: 1978: 1977: 1975: 1974: 1969: 1964: 1963: 1962: 1957: 1947: 1946: 1945: 1940: 1930: 1925: 1920: 1919: 1918: 1908: 1903: 1897: 1895: 1891: 1890: 1888: 1887: 1882: 1877: 1876: 1875: 1865: 1860: 1855: 1854: 1853: 1842:Locally convex 1839: 1838: 1837: 1827: 1822: 1817: 1811: 1809: 1805: 1804: 1802: 1801: 1794:Tensor product 1787: 1781: 1776: 1770: 1765: 1759: 1754: 1749: 1739: 1738: 1737: 1732: 1722: 1717: 1715:Banach lattice 1712: 1711: 1710: 1700: 1694: 1692: 1688: 1687: 1679: 1678: 1671: 1664: 1656: 1647: 1646: 1644: 1643: 1632: 1629: 1628: 1626: 1625: 1620: 1615: 1610: 1608:Choquet theory 1605: 1600: 1594: 1592: 1588: 1587: 1585: 1584: 1574: 1569: 1564: 1559: 1554: 1549: 1544: 1539: 1534: 1529: 1524: 1518: 1516: 1512: 1511: 1509: 1508: 1503: 1497: 1495: 1491: 1490: 1488: 1487: 1482: 1477: 1472: 1467: 1462: 1460:Banach algebra 1456: 1454: 1450: 1449: 1447: 1446: 1441: 1436: 1431: 1426: 1421: 1416: 1411: 1406: 1401: 1395: 1393: 1389: 1388: 1386: 1385: 1383:Banach–Alaoglu 1380: 1375: 1370: 1365: 1360: 1355: 1350: 1345: 1339: 1337: 1331: 1330: 1327: 1326: 1324: 1323: 1318: 1313: 1311:Locally convex 1308: 1294: 1289: 1283: 1281: 1277: 1276: 1274: 1273: 1268: 1263: 1258: 1253: 1248: 1243: 1238: 1233: 1228: 1222: 1216: 1212: 1211: 1195: 1194: 1187: 1180: 1172: 1163: 1162: 1160: 1159: 1154: 1149: 1144: 1139: 1134: 1129: 1124: 1119: 1114: 1109: 1104: 1099: 1094: 1089: 1084: 1074: 1072:Corona theorem 1069: 1063: 1061: 1057: 1056: 1054: 1053: 1051:Wiener algebra 1047: 1045: 1041: 1040: 1038: 1037: 1032: 1027: 1022: 1017: 1012: 1007: 1002: 997: 991: 989: 985: 984: 982: 981: 971: 969:Pseudospectrum 966: 961: 959:Dirac spectrum 955: 953: 949: 948: 946: 945: 940: 935: 930: 924: 922: 918: 917: 915: 914: 913: 912: 902: 897: 892: 887: 882: 876: 870: 868: 864: 863: 861: 860: 855: 850: 845: 840: 835: 830: 825: 820: 814: 812: 808: 807: 805: 804: 799: 794: 789: 784: 779: 778: 777: 772: 767: 756: 754: 750: 749: 747: 746: 741: 736: 731: 726: 721: 715: 713: 707: 706: 704: 703: 698: 690: 682: 674: 668: 666: 662: 661: 659: 658: 653: 648: 643: 638: 633: 628: 622: 620: 616: 615: 613: 612: 610:Operator space 607: 602: 597: 592: 587: 582: 577: 572: 570:Banach algebra 567: 561: 559: 558:Basic concepts 555: 554: 543: 542: 535: 528: 520: 514: 513: 508: 503: 496: 493: 488: 474:non-degenerate 462: 447: 444: 440:Fourier series 423: 420: 416:real rank zero 399:such that the 396: 378:σ-compact 370:if and only if 318: 315: 298: 295: 292: 289: 286: 283: 278: 274: 270: 265: 262: 259: 255: 226: 223: 220: 217: 214: 209: 205: 201: 173: 170: 167: 164: 161: 156: 152: 148: 145: 140: 137: 134: 130: 101: 98: 95: 92: 89: 84: 80: 76: 56: 53: 41:Banach algebra 9: 6: 4: 3: 2: 3165: 3154: 3151: 3150: 3148: 3133: 3130: 3128: 3125: 3123: 3120: 3118: 3115: 3113: 3110: 3109: 3107: 3103: 3097: 3079: 3075: 3071: 3068: 3062: 3053: 3051: 3048: 3044: 3041: 3040: 3039: 3036: 3034: 3031: 3029: 3028: 3023: 3021: 3007: 3002: 2992: 2988: 2979: 2975: 2972: 2970: 2951: 2942: 2941: 2940: 2939: 2935: 2931: 2912: 2903: 2902: 2901: 2900: 2896: 2894: 2870: 2867: 2864: 2860: 2850: 2848: 2847: 2842: 2840: 2837: 2835: 2833: 2829: 2824: 2822: 2819: 2817: 2816: 2811: 2809: 2806: 2804: 2778: 2773: 2770: 2767: 2763: 2753: 2751: 2750: 2745: 2743: 2740: 2738: 2716: 2713: 2705: 2703: 2702: 2697: 2696: 2694: 2692: 2688: 2682: 2678: 2674: 2672: 2669: 2667: 2664: 2662: 2659: 2657: 2654: 2652: 2651:Extreme point 2649: 2647: 2644: 2642: 2639: 2637: 2633: 2629: 2627: 2624: 2623: 2621: 2617: 2611: 2608: 2606: 2603: 2601: 2598: 2596: 2593: 2591: 2585: 2582: 2578: 2574: 2571: 2569: 2563: 2561: 2558: 2556: 2553: 2551: 2548: 2546: 2543: 2541: 2538: 2536: 2533: 2532: 2530: 2528:Types of sets 2526: 2519: 2515: 2512: 2508: 2505: 2503: 2500: 2498: 2495: 2494: 2493: 2490: 2486: 2483: 2481: 2478: 2476: 2473: 2472: 2471: 2468: 2464: 2461: 2459: 2456: 2454: 2451: 2449: 2446: 2444: 2441: 2439: 2436: 2435: 2434: 2431: 2427: 2424: 2422: 2419: 2417: 2414: 2412: 2409: 2407: 2404: 2403: 2402: 2399: 2397: 2394: 2392: 2391:Convex series 2389: 2387: 2386:Bochner space 2384: 2380: 2377: 2376: 2375: 2372: 2370: 2367: 2366: 2364: 2360: 2354: 2351: 2349: 2346: 2344: 2341: 2339: 2338:Riesz's lemma 2336: 2334: 2331: 2329: 2326: 2324: 2323:Mazur's lemma 2321: 2319: 2316: 2314: 2311: 2309: 2306: 2304: 2301: 2297: 2294: 2293: 2292: 2289: 2287: 2284: 2282: 2279: 2277: 2276:Gelfand–Mazur 2274: 2272: 2269: 2267: 2264: 2262: 2259: 2257: 2254: 2252: 2249: 2247: 2244: 2242: 2239: 2237: 2234: 2232: 2229: 2227: 2224: 2222: 2219: 2217: 2214: 2213: 2211: 2209: 2205: 2199: 2196: 2194: 2191: 2187: 2184: 2182: 2179: 2178: 2177: 2174: 2170: 2167: 2165: 2162: 2161: 2160: 2157: 2155: 2152: 2150: 2147: 2145: 2142: 2141: 2139: 2137: 2133: 2127: 2124: 2122: 2119: 2117: 2114: 2112: 2109: 2107: 2104: 2102: 2099: 2097: 2094: 2092: 2089: 2085: 2082: 2081: 2080: 2077: 2075: 2072: 2068: 2065: 2063: 2060: 2059: 2057: 2055: 2052: 2050: 2046: 2042: 2038: 2035: 2034: 2033: 2030: 2028: 2025: 2023: 2019: 2015: 2011: 2008: 2006: 2003: 2001: 1998: 1997: 1996: 1993: 1991: 1988: 1987: 1985: 1983: 1979: 1973: 1970: 1968: 1965: 1961: 1958: 1956: 1953: 1952: 1951: 1948: 1944: 1941: 1939: 1936: 1935: 1934: 1931: 1929: 1926: 1924: 1921: 1917: 1914: 1913: 1912: 1909: 1907: 1904: 1902: 1899: 1898: 1896: 1892: 1886: 1883: 1881: 1878: 1874: 1871: 1870: 1869: 1866: 1864: 1861: 1859: 1856: 1852: 1848: 1845: 1844: 1843: 1840: 1836: 1833: 1832: 1831: 1828: 1826: 1823: 1821: 1818: 1816: 1813: 1812: 1810: 1806: 1799: 1795: 1791: 1788: 1786: 1782: 1780: 1777: 1775:) convex 1774: 1771: 1769: 1766: 1764: 1760: 1758: 1755: 1753: 1750: 1748: 1744: 1740: 1736: 1733: 1731: 1728: 1727: 1726: 1723: 1721: 1720:Grothendieck 1718: 1716: 1713: 1709: 1706: 1705: 1704: 1701: 1699: 1696: 1695: 1693: 1689: 1684: 1677: 1672: 1670: 1665: 1663: 1658: 1657: 1654: 1642: 1634: 1633: 1630: 1624: 1621: 1619: 1616: 1614: 1613:Weak topology 1611: 1609: 1606: 1604: 1601: 1599: 1596: 1595: 1593: 1589: 1582: 1578: 1575: 1573: 1570: 1568: 1565: 1563: 1560: 1558: 1555: 1553: 1550: 1548: 1545: 1543: 1540: 1538: 1537:Index theorem 1535: 1533: 1530: 1528: 1525: 1523: 1520: 1519: 1517: 1513: 1507: 1504: 1502: 1499: 1498: 1496: 1494:Open problems 1492: 1486: 1483: 1481: 1478: 1476: 1473: 1471: 1468: 1466: 1463: 1461: 1458: 1457: 1455: 1451: 1445: 1442: 1440: 1437: 1435: 1432: 1430: 1427: 1425: 1422: 1420: 1417: 1415: 1412: 1410: 1407: 1405: 1402: 1400: 1397: 1396: 1394: 1390: 1384: 1381: 1379: 1376: 1374: 1371: 1369: 1366: 1364: 1361: 1359: 1356: 1354: 1351: 1349: 1346: 1344: 1341: 1340: 1338: 1336: 1332: 1322: 1319: 1317: 1314: 1312: 1309: 1306: 1302: 1298: 1295: 1293: 1290: 1288: 1285: 1284: 1282: 1278: 1272: 1269: 1267: 1264: 1262: 1259: 1257: 1254: 1252: 1249: 1247: 1244: 1242: 1239: 1237: 1234: 1232: 1229: 1227: 1224: 1223: 1220: 1217: 1213: 1208: 1204: 1200: 1193: 1188: 1186: 1181: 1179: 1174: 1173: 1170: 1158: 1155: 1153: 1150: 1148: 1145: 1143: 1140: 1138: 1135: 1133: 1130: 1128: 1125: 1123: 1120: 1118: 1115: 1113: 1110: 1108: 1105: 1103: 1100: 1098: 1095: 1093: 1090: 1088: 1085: 1082: 1078: 1075: 1073: 1070: 1068: 1065: 1064: 1062: 1058: 1052: 1049: 1048: 1046: 1042: 1036: 1033: 1031: 1028: 1026: 1023: 1021: 1018: 1016: 1013: 1011: 1008: 1006: 1003: 1001: 998: 996: 993: 992: 990: 988:Miscellaneous 986: 979: 975: 972: 970: 967: 965: 962: 960: 957: 956: 954: 950: 944: 941: 939: 936: 934: 931: 929: 926: 925: 923: 919: 911: 908: 907: 906: 903: 901: 898: 896: 893: 891: 888: 886: 883: 881: 877: 875: 872: 871: 869: 865: 859: 856: 854: 851: 849: 846: 844: 841: 839: 836: 834: 831: 829: 826: 824: 821: 819: 816: 815: 813: 809: 803: 800: 798: 795: 793: 790: 788: 785: 783: 780: 776: 773: 771: 768: 766: 763: 762: 761: 758: 757: 755: 753:Decomposition 751: 745: 742: 740: 737: 735: 732: 730: 727: 725: 722: 720: 717: 716: 714: 712: 708: 702: 699: 697: 694: 691: 689: 686: 683: 681: 678: 675: 673: 670: 669: 667: 663: 657: 654: 652: 649: 647: 644: 642: 639: 637: 634: 632: 629: 627: 624: 623: 621: 617: 611: 608: 606: 603: 601: 598: 596: 593: 591: 588: 586: 583: 581: 578: 576: 573: 571: 568: 566: 563: 562: 560: 556: 552: 548: 541: 536: 534: 529: 527: 522: 521: 518: 512: 509: 507: 504: 502: 499: 498: 492: 487: 483: 479: 476:if for every 475: 471: 466: 461: 457: 453: 443: 441: 437: 436:FejĂ©r kernels 433: 429: 419: 417: 412: 410: 406: 403:generated by 402: 395: 391: 387: 383: 379: 375: 371: 367: 363: 359: 358:σ-unital 355: 351: 346: 344: 343:Hilbert space 340: 336: 332: 328: 324: 314: 312: 296: 293: 287: 284: 281: 276: 272: 260: 257: 244: 240: 218: 215: 212: 207: 203: 191: 187: 184:Similarly, a 171: 168: 162: 159: 154: 150: 146: 135: 132: 119: 115: 93: 90: 87: 82: 78: 66: 62: 52: 50: 46: 42: 38: 34: 30: 26: 19: 3105:Applications 3026: 2937: 2898: 2845: 2831: 2827: 2814: 2748: 2700: 2587:Linear cone 2580: 2576: 2565:Convex cone 2458:Paley–Wiener 2318:Mackey–Arens 2308:Krein–Milman 2261:Closed range 2256:Closed graph 2226:Banach–Mazur 2106:Self-adjoint 2010:sesquilinear 1743:Polynomially 1683:Banach space 1603:Balanced set 1577:Distribution 1515:Applications 1368:Krein–Milman 1353:Closed graph 1060:Applications 890:Disk algebra 879: 744:Spectral gap 619:Main results 485: 481: 477: 473: 467: 465:for some λ. 459: 455: 449: 425: 413: 408: 404: 393: 389: 385: 381: 357: 353: 347: 341:acting on a 334: 330: 327:self-adjoint 320: 310: 242: 238: 189: 185: 117: 113: 64: 60: 58: 22: 2826:Continuous 2661:Linear span 2646:Convex hull 2626:Affine hull 2485:holomorphic 2421:holomorphic 2401:Derivatives 2291:Hahn–Banach 2231:Banach–Saks 2149:C*-algebras 2116:Trace class 2079:Functionals 1967:Ultrastrong 1880:Quasinormed 1532:Heat kernel 1522:Hardy space 1429:Trace class 1343:Hahn–Banach 1305:Topological 1087:Heat kernel 787:Compression 672:Isospectral 428:convolution 323:C*-algebras 317:C*-algebras 33:ring theory 25:mathematics 2579:), and (Hw 2480:continuous 2416:functional 2164:C*-algebra 2049:Continuous 1911:Dual space 1885:Stereotype 1863:Metrizable 1790:Projective 1465:C*-algebra 1280:Properties 765:Continuous 580:C*-algebra 575:B*-algebra 55:Definition 3038:Sobolev W 2981:Schwartz 2956:∞ 2917:∞ 2913:ℓ 2879:Ω 2865:λ 2723:Σ 2605:Symmetric 2540:Absorbing 2453:regulated 2433:Integrals 2286:Goldstine 2121:Transpose 2058:Fredholm 1928:Ultraweak 1916:Dual norm 1847:Seminorms 1815:Barrelled 1785:Injective 1773:Uniformly 1747:Reflexive 1439:Unbounded 1434:Transpose 1392:Operators 1321:Separable 1316:Reflexive 1301:Algebraic 1287:Barrelled 551:-algebras 501:Mollifier 362:separable 291:‖ 285:− 277:λ 269:‖ 264:Λ 261:∈ 258:λ 222:Λ 219:∈ 216:λ 208:λ 192:is a net 166:‖ 160:− 155:λ 144:‖ 139:Λ 136:∈ 133:λ 97:Λ 94:∈ 91:λ 83:λ 67:is a net 3147:Category 2974:weighted 2844:Hilbert 2821:Bs space 2691:Examples 2656:Interior 2632:Relative 2610:Zonotope 2589:(subset) 2567:(subset) 2518:Strongly 2497:Lebesgue 2492:Measures 2362:Analysis 2208:Theorems 2159:Spectrum 2084:positive 2067:operator 2005:operator 1995:Bilinear 1960:operator 1943:operator 1923:Operator 1820:Complete 1768:Strictly 1641:Category 1453:Algebras 1335:Theorems 1292:Complete 1261:Schwartz 1207:glossary 1152:Weyl law 1097:Lax pair 1044:Examples 878:With an 797:Discrete 775:Residual 711:Spectrum 696:operator 688:operator 680:operator 595:Spectrum 495:See also 454:so that 374:spectrum 366:converse 360:. Every 350:sequence 2839:Hardy H 2742:c space 2679:)  2634:)  2555:Bounded 2443:Dunford 2438:Bochner 2411:Gateaux 2406:FrĂ©chet 2181:of ODEs 2126:Unitary 2101:Nuclear 2032:Compact 2022:Bounded 1990:Adjoint 1830:FrĂ©chet 1825:F-space 1796: ( 1792:)  1745:)  1725:Hilbert 1698:Asplund 1444:Unitary 1424:Nuclear 1409:Compact 1404:Bounded 1399:Adjoint 1373:Min–max 1266:Sobolev 1251:Nuclear 1241:Hilbert 1236:FrĂ©chet 1201: ( 693:Unitary 2755:Besov 2595:Radial 2560:Convex 2545:Affine 2514:Weakly 2507:Vector 2379:bundle 2169:radius 2096:Normal 2062:kernel 2027:Closed 1950:Strong 1868:Normed 1858:Mackey 1703:Banach 1685:topics 1419:Normal 1256:Orlicz 1246:Hölder 1226:Banach 1215:Spaces 1203:topics 677:Normal 470:module 2830:with 2677:Quasi 2671:Polar 2475:Borel 2426:quasi 1955:polar 1938:polar 1752:Riesz 1231:Besov 770:Point 446:Rings 39:in a 2828:C(K) 2463:weak 2000:form 1933:Weak 1906:Dual 1873:norm 1835:tame 1708:list 1579:(or 1297:Dual 701:Unit 549:and 372:its 321:For 45:ring 31:and 2045:Dis 438:of 407:is 392:in 376:is 309:An 254:lim 241:of 129:lim 116:of 43:or 37:net 23:In 3149:: 2815:BV 2749:BK 2701:AC 2583:)) 2516:/ 2018:Un 1205:– 491:. 486:me 484:= 468:A 460:ae 458:= 411:. 297:0. 245:, 172:0. 120:, 59:A 51:. 3085:) 3080:p 3076:L 3072:, 3069:X 3066:( 3063:W 3027:F 3008:) 3003:n 2998:R 2993:( 2989:S 2952:L 2938:L 2899:â„“ 2882:) 2876:( 2871:p 2868:, 2861:L 2846:H 2832:K 2792:) 2788:R 2784:( 2779:s 2774:q 2771:, 2768:p 2764:B 2726:) 2720:( 2717:a 2714:b 2675:( 2630:( 2581:x 2577:x 2047:) 2043:( 2020:) 2016:( 1849:/ 1800:) 1783:( 1763:B 1761:( 1741:( 1675:e 1668:t 1661:v 1583:) 1307:) 1303:/ 1299:( 1209:) 1191:e 1184:t 1177:v 1083:) 1079:( 980:) 976:( 539:e 532:t 525:v 489:λ 482:m 478:m 463:λ 456:a 409:A 405:h 397:+ 394:A 390:h 386:A 382:A 331:A 294:= 288:a 282:a 273:e 243:A 239:a 225:} 213:: 204:e 200:{ 190:A 169:= 163:a 151:e 147:a 118:A 114:a 100:} 88:: 79:e 75:{ 65:A 20:.

Index

Approximation to the identity
mathematics
functional analysis
ring theory
net
Banach algebra
ring
identity element
C*-algebras
self-adjoint
compact operators
Hilbert space
sequence
separable
converse
if and only if
spectrum
σ-compact
hereditary C*-subalgebra
real rank zero
convolution
Dirac delta function
Fejér kernels
Fourier series
discrete topology
module
Mollifier
Nascent delta function
Summability kernel
v

Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.

↑