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Commutator subspace

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there is a spectral characterisation for arbitrary (non-normal) operators. It is not valid for every two-sided ideal but necessary and sufficient conditions are known. Nigel Kalton and American mathematician Ken Dykema introduced the condition first for countably generated ideals. Uzbek and
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in 1954 showed that every bounded operator on a separable infinite dimensional Hilbert space is the sum of two commutators of bounded operators. In 1971 Carl Pearcy and David Topping revisited the topic and studied commutator subspaces for
1451: 630: 2211: 1840: 77:, noticing the spectral condition of Weiss, characterised all trace class commutators. Kalton's result forms the basis for the modern characterisation of the commutator subspace. In 2004 Ken Dykema, 1921: 682: 2702:
Function Spaces, Interpolation Theory, and Related Topics: Proceedings of the International Conference in Honour of Jaak Peetre on His 65th Birthday : Lund, Sweden, August 17–22, 2000
1530: 274: 1987: 1063: 1633: 1349: 503: 1136: 2700:
T. Figiel; N. Kalton (2002), "Symmetric linear functionals on function spaces", in M. Cwikel; M. Englis; A. Kufner; L.-E. Persson; G. Sparr (eds.),
2343: 60:, or Heisenberg, formulation of quantum mechanics. Commutator subspaces, though, received sparse attention until the 1970s. American mathematician 2114: 85:
published the spectral characterisation of normal operators in the commutator subspace for every two-sided ideal of compact operators.
1768: 2680:)-commutators: a historical survey", in Dumitru Gaşpar; Dan Timotin; László Zsidó; Israel Gohberg; Florian-Horia Vasilescu (eds.), 2739: 2709: 2689: 902:
In any two-sided ideal the difference between a positive operator and its diagonalisation is a sum of commutators. That is,
811:{\displaystyle \left\{{\frac {1}{1+n}}\sum _{k=0}^{n}\left(\lambda (k,A)-\lambda (k,B)\right)\right\}_{n=0}^{\infty }\in j} 1859: 1261: 36:
of operators in the ideal with bounded operators. Modern characterisation of the commutator subspace is through the
403:{\displaystyle \left\{{\frac {1}{1+n}}\sum _{k=0}^{n}\left(\mu (k,A)-\mu (k,B)\right)\right\}_{n=0}^{\infty }\in j} 1470: 862:
Most two-sided ideals satisfy the condition in the Theorem, included all Banach ideals and quasi-Banach ideals.
2763: 2248: 70: 69:. As a student American mathematician Gary Weiss began to investigate spectral conditions for commutators of 2090:{\displaystyle \left\{{\frac {a_{1}+a_{2}+\cdots +a_{n}}{n}}\right\}_{n=1}^{\infty }\in \ell _{1,\infty }} 56:
Commutators of linear operators on Hilbert spaces came to prominence in the 1930s as they featured in the
2684:, Operator Theory: Advances and Applications, vol. 153, Berlin: Birkhäuser Basel, pp. 307–320, 951:) the difference between an arbitrary operator and its diagonalisation is a sum of commutators. That is, 2262:
and it has a divergent series, and therefore the Cesàro means of the harmonic sequence do not belong to
467:
Australian mathematicians Fedor Sukochev and Dmitriy Zanin completed the eigenvalue characterisation.
1954: 2247:. The commutator subspace of the weak trace class operators contains the trace class operators. The 1730:{\displaystyle \left\{{\frac {a_{1}+a_{2}+\cdots +a_{n}}{n}}\right\}_{n=1}^{\infty }\in \ell _{1}} 1582:) and the commutator subspace of the finite rank operators are equal, ker Tr = Com( 1046: 2758: 2647: 2525: 2490: 66: 44:. This explicit spectral characterisation reduces problems and questions about commutators and 1446:{\displaystyle \left\{{\frac {a_{1}+a_{2}+\cdots +a_{n}}{n}}\right\}_{n=1}^{\infty }\in c_{00}} 625:{\displaystyle \prod _{k=0}^{n}\mu (k,A)\leq \prod _{k=0}^{n}\mu (k,B),\quad n=0,1,2,\ldots .} 165: 37: 2639: 2482: 1607: 1319: 40:
and it involves the invariance of the Calkin sequence space of an operator ideal to taking
234:. The following theorem is a slight extension to differences of normal operators (setting 8: 21: 2609:
K. Dykema; N. J. Kalton (1998). "Spectral characterization of sums of commutators, II".
2591: 2573: 2534: 2427: 2392: 2324: 1222: 1003: 858:, respectively, rearranged so that the absolute value of the eigenvalues is decreasing. 2661: 2504: 2735: 2705: 2685: 2595: 2463: 2446: 2431: 2396: 48:
on two-sided ideals to (more resolvable) problems and conditions on sequence spaces.
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which has sum zero but does not have a summable sequence of Cesàro means. Hence Com(
1571: 2727: 2656: 2583: 2544: 2499: 2458: 2419: 2384: 2355: 2316: 169: 82: 57: 33: 25: 200: 180: 2704:, De Gruyter: Proceedings in Mathematics, Berlin: De Gruyter, pp. 311–332, 2721: 1617: 1022: 875:
is a sum of commutators if and only if the corresponding Calkin sequence space
238: = 0 in the following gives the statement of the previous sentence). 78: 45: 2549: 2520: 1279: 880: 223: 41: 2752: 2682:
Recent Advances in Operator Theory, Operator Algebras, and their Applications
2360: 2206:{\displaystyle \left\{a_{1}+a_{2}+\cdots +a_{n}\right\}_{n=1}^{\infty }=O(1)} 29: 2564:
N. J. Kalton (1998). "Spectral characterization of sums of commutators, I".
74: 2731: 2587: 61: 2518: 2423: 2388: 2328: 455: 2637: 2578: 2480: 2320: 1964: 1329:) correspond to the space of sequences with finite non-zero terms, 2539: 2719: 2375:
G. Weiss (1980). "Commutators of Hilbert–Schmidt Operators, II".
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in an arbitrary orthonormal basis of the separable Hilbert space
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in an arbitrary orthonormal basis of the separable Hilbert space
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in an arbitrary orthonormal basis of the separable Hilbert space
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in an arbitrary orthonormal basis of the separable Hilbert space
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G. Weiss (1986). "Commutators of Hilbert–Schmidt Operators, I".
1835:{\displaystyle a_{n}={\frac {1}{n\log ^{2}(n)}},\quad n\geq 2.} 249:
are compact normal operators that belong to a two-sided ideal
2521:"Traces of compact operators and the noncommutative residue" 1271:) correspond to the space of converging to zero sequences, 2519:
N. J. Kalton; S. Lord; D. Potapov; F. Sukochev (2013).
865: 2608: 2117: 1990: 1862: 1771: 1636: 1473: 1352: 1049: 685: 506: 277: 2638:
K. Dykema; T. Figiel; G. Weiss; M. Wodzicki (2004).
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K. Dykema; T. Figiel; G. Weiss; M. Wodzicki (2004).
850:) are the sequence of eigenvalues of the operators 2341: 1253:is a separable infinite dimensional Hilbert space. 899:, where C denotes the Cesàro operator on sequences. 2699: 2307:P. Halmos (1954). "Commutators of operators. II". 2205: 2089: 1916:{\displaystyle a_{1}=-\sum _{n=2}^{\infty }a_{n}.} 1915: 1834: 1729: 1524: 1445: 1057: 810: 624: 478:is a two-sided ideal such that a bounded operator 402: 2750: 2344:"On commutators in ideals of compact operators" 830:is the Calkin sequence space corresponding to 422:is the Calkin sequence space corresponding to 93:The commutator subspace of a two-sided ideal 2563: 2444: 159: 1525:{\displaystyle a_{1}+a_{2}+\cdots +a_{N}=0} 203:that belong to the commutator subspace Com( 2720:S. Lord, F. A. Sukochev. D. Zanin (2012). 2660: 2640:"Commutator structure of operator ideals" 2577: 2548: 2538: 2503: 2483:"Commutator structure of operator ideals" 2462: 2359: 2306: 1759:... = 0. An example is the sequence with 1051: 2723:Singular traces: theory and applications 2671: 2409: 2374: 1278:. For a converging to zero sequence the 1016: 2447:"Trace-class operators and commutators" 669:belongs to the commutator subspace Com( 261:belongs to the commutator subspace Com( 2751: 2476: 2474: 2412:Integral Equations and Operator Theory 2377:Integral Equations and Operator Theory 1077:has a non-zero trace if and only if C( 486:whenever there is a bounded operator 191:belongs to the Calkin sequence space 1745:is stronger than the condition that 866:Consequences of the characterisation 497: 462:belong to the Calkin sequence space 2621: 2512: 2471: 1207:In any two-sided ideal satisfying ( 1146:In any two-sided ideal satisfying ( 945:In any two-sided ideal satisfying ( 109:is the linear span of operators in 13: 2438: 2403: 2368: 2300: 2183: 2082: 2063: 1895: 1709: 1425: 1135:are in direct correspondence with 797: 389: 32:is the linear subspace spanned by 14: 2775: 2602: 2557: 2335: 1939:) ⊊ ker Tr ⊊  1069:). The consequences above imply 1006:in a two-sided ideal satisfying ( 97:of the bounded linear operators 2309:American Journal of Mathematics 1822: 1282:converge to zero. Therefore, C( 1107:)) for every positive operator 1027:A trace φ on a two-sided ideal 591: 105:) on a separable Hilbert space 2451:Journal of Functional Analysis 2342:C. Pearcy; D. Topping (1971). 2200: 2194: 1813: 1807: 918:) for every positive operator 772: 760: 751: 739: 585: 573: 543: 531: 364: 352: 343: 331: 1: 2662:10.1016/s0001-8708(03)00141-5 2631: 2505:10.1016/s0001-8708(03)00141-5 2348:Michigan Mathematical Journal 1188:)) is the diagonalisation of 1123:)) is the diagonalisation of 983:)) is the diagonalisation of 934:)) is the diagonalisation of 442:) are the singular values of 207:) can characterised as those 175:belongs to a two-sided ideal 88: 2464:10.1016/0022-1236(89)90064-5 1204:) is an eigenvalue sequence. 1058:{\displaystyle \mathbb {C} } 999:) is an eigenvalue sequence. 7: 1244: 1209: 1148: 1008: 947: 638: 144:The commutator subspace of 10: 2780: 1955:weak trace class operators 1951:Weak trace class operators 1221:) = 0 for every 1020: 1012:) is a sum of commutators. 879:is invariant under taking 51: 2550:10.1016/j.aim.2012.11.007 2222:it is immediate that Com( 1039:is a linear functional φ: 160:Spectral characterisation 113:of the form  =  71:Hilbert–Schmidt operators 2293: 1262:compact linear operators 1223:quasi-nilpotent operator 1004:quasi-nilpotent operator 955: − diag( 906: − diag( 649:If the bounded operator 148:is a linear subspace of 73:. British mathematician 26:bounded linear operators 2648:Advances in Mathematics 2526:Advances in Mathematics 2491:Advances in Mathematics 2726:. Berlin: De Gruyter. 2361:10.1307/mmj/1029000686 2207: 2091: 1917: 1899: 1836: 1731: 1604:Trace class operators. 1526: 1461:occurs if and only if 1447: 1316:Finite rank operators. 1172:)) for every operator 1059: 812: 730: 626: 569: 527: 404: 322: 2732:10.1515/9783110262551 2588:10.1515/crll.1998.102 2445:N. J. Kalton (1989). 2208: 2092: 1918: 1879: 1837: 1732: 1608:trace class operators 1527: 1448: 1320:finite rank operators 1137:symmetric functionals 1131:. That is, traces on 1065:that vanishes on Com( 1060: 1017:Application to traces 967:) for every operator 813: 710: 627: 549: 507: 405: 302: 166:Calkin correspondence 38:Calkin correspondence 2764:Von Neumann algebras 2611:J. Reine Angew. Math 2566:J. Reine Angew. Math 2115: 1988: 1974:. From the condition 1860: 1769: 1634: 1570:. The kernel of the 1471: 1350: 1073:The two-sided ideal 1047: 683: 504: 458:of all operators in 456:eigenvalue sequences 275: 16:In mathematics, the 2187: 2067: 1713: 1429: 891:is equivalent to C( 801: 665: −  393: 257: −  179:if and only if the 117: −  18:commutator subspace 2672:G. Weiss (2005), " 2424:10.1007/bf01202521 2389:10.1007/BF01702316 2203: 2118: 2087: 1991: 1963:correspond to the 1913: 1832: 1727: 1637: 1618:summable sequences 1616:correspond to the 1540:for the sequence ( 1522: 1443: 1353: 1258:Compact operators. 1164: ∘ diag( 1099: ∘ diag( 1055: 963:)) belongs to Com( 914:)) belongs to Com( 883:. In symbols, Com( 871:Every operator in 808: 686: 622: 454:Provided that the 400: 278: 226:of the sequence μ( 121:for all operators 2741:978-3-11-026255-1 2711:978-3-11-019805-8 2691:978-3-7643-7127-2 2249:harmonic sequence 2045: 1817: 1691: 1563:, 0, 0 , ...) in 1407: 708: 673:) if and only if 646: 645: 300: 265:) if and only if 81:, Gary Weiss and 2771: 2745: 2714: 2694: 2666: 2664: 2644: 2625: 2619: 2618: 2606: 2600: 2599: 2581: 2572:(504): 115–125. 2561: 2555: 2554: 2552: 2542: 2516: 2510: 2509: 2507: 2487: 2478: 2469: 2468: 2466: 2442: 2436: 2435: 2407: 2401: 2400: 2372: 2366: 2365: 2363: 2339: 2333: 2332: 2304: 2255:,... belongs to 2251:1,1/2,1/3,...,1/ 2212: 2210: 2209: 2204: 2186: 2181: 2170: 2166: 2165: 2164: 2146: 2145: 2133: 2132: 2105:or equivalently 2096: 2094: 2093: 2088: 2086: 2085: 2066: 2061: 2050: 2046: 2041: 2040: 2039: 2021: 2020: 2008: 2007: 1997: 1922: 1920: 1919: 1914: 1909: 1908: 1898: 1893: 1872: 1871: 1841: 1839: 1838: 1833: 1818: 1816: 1803: 1802: 1786: 1781: 1780: 1736: 1734: 1733: 1728: 1726: 1725: 1712: 1707: 1696: 1692: 1687: 1686: 1685: 1667: 1666: 1654: 1653: 1643: 1531: 1529: 1528: 1523: 1515: 1514: 1496: 1495: 1483: 1482: 1452: 1450: 1449: 1444: 1442: 1441: 1428: 1423: 1412: 1408: 1403: 1402: 1401: 1383: 1382: 1370: 1369: 1359: 1232:and every trace 1064: 1062: 1061: 1056: 1054: 817: 815: 814: 809: 800: 795: 784: 780: 779: 775: 729: 724: 709: 707: 693: 640: 631: 629: 628: 623: 568: 563: 526: 521: 498: 409: 407: 406: 401: 392: 387: 376: 372: 371: 367: 321: 316: 301: 299: 285: 201:Normal operators 170:compact operator 83:Mariusz Wodzicki 58:matrix mechanics 2779: 2778: 2774: 2773: 2772: 2770: 2769: 2768: 2749: 2748: 2742: 2712: 2692: 2642: 2634: 2629: 2628: 2622: 2607: 2603: 2562: 2558: 2517: 2513: 2485: 2479: 2472: 2443: 2439: 2408: 2404: 2373: 2369: 2340: 2336: 2321:10.2307/2372409 2305: 2301: 2296: 2289: 2282: 2275: 2268: 2261: 2246: 2242: 2235: 2231: 2182: 2171: 2160: 2156: 2141: 2137: 2128: 2124: 2123: 2119: 2116: 2113: 2112: 2075: 2071: 2062: 2051: 2035: 2031: 2016: 2012: 2003: 1999: 1998: 1996: 1992: 1989: 1986: 1985: 1971: 1962: 1945: 1938: 1904: 1900: 1894: 1883: 1867: 1863: 1861: 1858: 1857: 1798: 1794: 1790: 1785: 1776: 1772: 1770: 1767: 1766: 1758: 1751: 1721: 1717: 1708: 1697: 1681: 1677: 1662: 1658: 1649: 1645: 1644: 1642: 1638: 1635: 1632: 1631: 1620:. The condition 1615: 1590:)) ⊊  1569: 1562: 1553: 1546: 1510: 1506: 1491: 1487: 1478: 1474: 1472: 1469: 1468: 1437: 1433: 1424: 1413: 1397: 1393: 1378: 1374: 1365: 1361: 1360: 1358: 1354: 1351: 1348: 1347: 1336:. The condition 1335: 1304:)) =  1295: 1288: 1277: 1247: 1050: 1048: 1045: 1044: 1025: 1019: 868: 796: 785: 735: 731: 725: 714: 697: 692: 691: 687: 684: 681: 680: 564: 553: 522: 511: 505: 502: 501: 450:, respectively. 388: 377: 327: 323: 317: 306: 289: 284: 283: 279: 276: 273: 272: 181:singular values 162: 152:denoted by Com( 91: 67:Schatten ideals 54: 28:on a separable 20:of a two-sided 12: 11: 5: 2777: 2767: 2766: 2761: 2759:Hilbert spaces 2747: 2746: 2740: 2716: 2715: 2710: 2696: 2695: 2690: 2668: 2667: 2633: 2630: 2627: 2626: 2620: 2601: 2556: 2511: 2470: 2437: 2418:(6): 877–892. 2402: 2383:(4): 574–600. 2367: 2354:(3): 247–252. 2334: 2315:(1): 191–198. 2298: 2297: 2295: 2292: 2287: 2280: 2273: 2269:. In summary, 2266: 2259: 2244: 2240: 2236: = ( 2233: 2226: 2220: 2219: 2218: 2217: 2216: 2215: 2214: 2213: 2202: 2199: 2196: 2193: 2190: 2185: 2180: 2177: 2174: 2169: 2163: 2159: 2155: 2152: 2149: 2144: 2140: 2136: 2131: 2127: 2122: 2103: 2102: 2101: 2100: 2099: 2098: 2097: 2084: 2081: 2078: 2074: 2070: 2065: 2060: 2057: 2054: 2049: 2044: 2038: 2034: 2030: 2027: 2024: 2019: 2015: 2011: 2006: 2002: 1995: 1976: 1975: 1972:sequence space 1969: 1960: 1943: 1936: 1930: 1929: 1928: 1927: 1926: 1925: 1924: 1923: 1912: 1907: 1903: 1897: 1892: 1889: 1886: 1882: 1878: 1875: 1870: 1866: 1848: 1847: 1846: 1845: 1844: 1843: 1842: 1831: 1828: 1825: 1821: 1815: 1812: 1809: 1806: 1801: 1797: 1793: 1789: 1784: 1779: 1775: 1756: 1749: 1743: 1742: 1741: 1740: 1739: 1738: 1737: 1724: 1720: 1716: 1711: 1706: 1703: 1700: 1695: 1690: 1684: 1680: 1676: 1673: 1670: 1665: 1661: 1657: 1652: 1648: 1641: 1622: 1621: 1613: 1600: 1599: 1572:operator trace 1567: 1558: 1551: 1544: 1538: 1537: 1536: 1535: 1534: 1533: 1532: 1521: 1518: 1513: 1509: 1505: 1502: 1499: 1494: 1490: 1486: 1481: 1477: 1459: 1458: 1457: 1456: 1455: 1454: 1453: 1440: 1436: 1432: 1427: 1422: 1419: 1416: 1411: 1406: 1400: 1396: 1392: 1389: 1386: 1381: 1377: 1373: 1368: 1364: 1357: 1338: 1337: 1333: 1313: 1293: 1286: 1275: 1246: 1243: 1242: 1241: 1205: 1160:) =  1144: 1086: 1081:) ≠  1053: 1023:Singular trace 1021:Main article: 1018: 1015: 1014: 1013: 1000: 943: 900: 895:) =  887:) =  867: 864: 860: 859: 824: 823: 822: 821: 820: 819: 818: 807: 804: 799: 794: 791: 788: 783: 778: 774: 771: 768: 765: 762: 759: 756: 753: 750: 747: 744: 741: 738: 734: 728: 723: 720: 717: 713: 706: 703: 700: 696: 690: 644: 643: 634: 632: 621: 618: 615: 612: 609: 606: 603: 600: 597: 594: 590: 587: 584: 581: 578: 575: 572: 567: 562: 559: 556: 552: 548: 545: 542: 539: 536: 533: 530: 525: 520: 517: 514: 510: 496: 495: 452: 451: 416: 415: 414: 413: 412: 411: 410: 399: 396: 391: 386: 383: 380: 375: 370: 366: 363: 360: 357: 354: 351: 348: 345: 342: 339: 336: 333: 330: 326: 320: 315: 312: 309: 305: 298: 295: 292: 288: 282: 195:associated to 168:states that a 161: 158: 90: 87: 79:Tadeusz Figiel 53: 50: 9: 6: 4: 3: 2: 2776: 2765: 2762: 2760: 2757: 2756: 2754: 2743: 2737: 2733: 2729: 2725: 2724: 2718: 2717: 2713: 2707: 2703: 2698: 2697: 2693: 2687: 2683: 2679: 2675: 2670: 2669: 2663: 2658: 2654: 2650: 2649: 2641: 2636: 2635: 2624: 2616: 2612: 2605: 2597: 2593: 2589: 2585: 2580: 2575: 2571: 2567: 2560: 2551: 2546: 2541: 2536: 2532: 2528: 2527: 2522: 2515: 2506: 2501: 2497: 2493: 2492: 2484: 2477: 2475: 2465: 2460: 2456: 2452: 2448: 2441: 2433: 2429: 2425: 2421: 2417: 2413: 2406: 2398: 2394: 2390: 2386: 2382: 2378: 2371: 2362: 2357: 2353: 2349: 2345: 2338: 2330: 2326: 2322: 2318: 2314: 2310: 2303: 2299: 2291: 2286: 2279: 2272: 2265: 2258: 2254: 2250: 2239: 2229: 2225: 2197: 2191: 2188: 2178: 2175: 2172: 2167: 2161: 2157: 2153: 2150: 2147: 2142: 2138: 2134: 2129: 2125: 2120: 2111: 2110: 2109: 2108: 2107: 2106: 2104: 2079: 2076: 2072: 2068: 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1332: 1328: 1324: 1321: 1317: 1314: 1311: 1307: 1303: 1299: 1292: 1285: 1281: 1274: 1270: 1266: 1263: 1259: 1256: 1255: 1254: 1252: 1239: 1235: 1231: 1227: 1224: 1220: 1216: 1212: 1211: 1206: 1203: 1199: 1195: 1191: 1187: 1183: 1179: 1175: 1171: 1167: 1163: 1159: 1155: 1151: 1150: 1145: 1142: 1138: 1134: 1130: 1126: 1122: 1118: 1114: 1110: 1106: 1102: 1098: 1094: 1090: 1087: 1084: 1080: 1076: 1072: 1071: 1070: 1068: 1042: 1038: 1034: 1030: 1024: 1011: 1010: 1005: 1001: 998: 994: 990: 986: 982: 978: 974: 970: 966: 962: 958: 954: 950: 949: 944: 941: 937: 933: 929: 925: 921: 917: 913: 909: 905: 901: 898: 894: 890: 886: 882: 878: 874: 870: 869: 863: 857: 853: 849: 845: 841: 837: 833: 829: 825: 805: 802: 792: 789: 786: 781: 776: 769: 766: 763: 757: 754: 748: 745: 742: 736: 732: 726: 721: 718: 715: 711: 704: 701: 698: 694: 688: 679: 678: 677: 676: 675: 674: 672: 668: 664: 660: 656: 652: 648: 647: 642: 635: 633: 619: 616: 613: 610: 607: 604: 601: 598: 595: 592: 588: 582: 579: 576: 570: 565: 560: 557: 554: 550: 546: 540: 537: 534: 528: 523: 518: 515: 512: 508: 500: 499: 493: 489: 485: 481: 477: 473: 470: 469: 468: 465: 461: 457: 449: 445: 441: 437: 433: 429: 425: 421: 417: 397: 394: 384: 381: 378: 373: 368: 361: 358: 355: 349: 346: 340: 337: 334: 328: 324: 318: 313: 310: 307: 303: 296: 293: 290: 286: 280: 271: 270: 269: 268: 267: 266: 264: 260: 256: 252: 248: 244: 241: 240: 239: 237: 233: 230:) belongs to 229: 225: 221: 218: 215:) belongs to 214: 210: 206: 202: 198: 194: 190: 186: 182: 178: 174: 171: 167: 157: 155: 151: 147: 142: 140: 136: 132: 128: 124: 120: 116: 112: 108: 104: 100: 96: 86: 84: 80: 76: 72: 68: 63: 59: 49: 47: 43: 39: 35: 31: 30:Hilbert space 27: 23: 19: 2722: 2701: 2681: 2677: 2673: 2652: 2646: 2623: 2614: 2610: 2604: 2579:math/9709209 2569: 2565: 2559: 2530: 2524: 2514: 2495: 2489: 2454: 2450: 2440: 2415: 2411: 2405: 2380: 2376: 2370: 2351: 2347: 2337: 2312: 2308: 2302: 2284: 2277: 2270: 2263: 2256: 2252: 2237: 2227: 2223: 2221: 1966: 1957: 1950: 1940: 1933: 1931: 1753: 1746: 1610: 1603: 1595: 1591: 1587: 1583: 1579: 1575: 1564: 1559: 1555: 1548: 1541: 1330: 1326: 1322: 1315: 1309: 1305: 1301: 1297: 1290: 1283: 1280:Cesàro means 1272: 1268: 1264: 1257: 1250: 1248: 1237: 1233: 1229: 1225: 1218: 1214: 1208: 1201: 1197: 1193: 1189: 1185: 1181: 1177: 1173: 1169: 1165: 1161: 1157: 1153: 1147: 1140: 1132: 1128: 1124: 1120: 1116: 1112: 1108: 1104: 1100: 1096: 1092: 1088: 1082: 1078: 1074: 1066: 1040: 1036: 1032: 1028: 1026: 1007: 996: 992: 988: 984: 980: 976: 972: 968: 964: 960: 956: 952: 946: 939: 935: 931: 927: 923: 919: 915: 911: 907: 903: 896: 892: 888: 884: 881:Cesàro means 876: 872: 861: 855: 851: 847: 843: 839: 835: 831: 827: 670: 666: 662: 658: 654: 650: 636: 491: 487: 483: 479: 475: 471: 463: 459: 453: 447: 443: 439: 435: 431: 427: 423: 419: 262: 258: 254: 250: 246: 242: 235: 231: 227: 219: 216: 212: 211:such that μ( 208: 204: 196: 192: 188: 184: 176: 172: 163: 153: 149: 145: 143: 138: 134: 130: 126: 122: 118: 114: 110: 106: 102: 98: 94: 92: 75:Nigel Kalton 55: 42:Cesàro means 17: 15: 2276:⊊ Com( 1180:where diag( 1115:where diag( 975:where diag( 926:where diag( 482:belongs to 224:Cesàro mean 62:Paul Halmos 34:commutators 2753:Categories 2632:References 2617:: 127–137. 657:belong to 89:Definition 2596:119124949 2540:1210.3423 2457:: 41–74. 2432:122936389 2397:189875793 2283:) ⊊  2184:∞ 2151:⋯ 2083:∞ 2073:ℓ 2069:∈ 2064:∞ 2026:⋯ 1896:∞ 1881:∑ 1877:− 1827:≥ 1805:⁡ 1719:ℓ 1715:∈ 1710:∞ 1672:⋯ 1501:⋯ 1431:∈ 1426:∞ 1388:⋯ 803:∈ 798:∞ 758:λ 755:− 737:λ 712:∑ 617:… 571:μ 551:∏ 547:≤ 529:μ 509:∏ 494:such that 395:∈ 390:∞ 350:μ 347:− 329:μ 304:∑ 2655:: 1–79. 2533:: 1–55. 2498:: 1–79. 1554:, ... , 1296:and Com( 1249:Suppose 1245:Examples 474:Suppose 472:Theorem. 253:. Then 245:Suppose 243:Theorem. 2329:2372409 156:) or . 52:History 2738:  2708:  2688:  2594:  2430:  2395:  2327:  1953:. The 1574:Tr on 1002:Every 826:where 418:where 46:traces 2643:(PDF) 2592:S2CID 2574:arXiv 2535:arXiv 2486:(PDF) 2428:S2CID 2393:S2CID 2325:JSTOR 2294:Notes 1965:weak- 1228:from 661:then 187:) of 133:from 125:from 22:ideal 2736:ISBN 2706:ISBN 2686:ISBN 2570:1998 1850:and 1606:The 1318:The 1289:) = 1260:The 1196:and 1095:) = 991:and 854:and 834:and 653:and 446:and 426:and 222:the 164:The 129:and 2728:doi 2657:doi 2653:185 2615:504 2584:doi 2545:doi 2531:235 2500:doi 2496:185 2459:doi 2420:doi 2385:doi 2356:doi 2317:doi 2288:1,∞ 2281:1,∞ 2267:1,∞ 2260:1,∞ 1961:1,∞ 1796:log 1236:on 1213:), 1176:in 1152:), 1139:on 1111:in 1031:of 971:in 922:in 842:), 490:in 434:), 247:A,B 220:and 199:. 141:). 24:of 2755:: 2734:. 2651:. 2645:. 2613:. 2590:. 2582:. 2568:. 2543:. 2529:. 2523:. 2494:. 2488:. 2473:^ 2455:86 2453:. 2449:. 2426:. 2414:. 2391:. 2379:. 2352:18 2350:. 2346:. 2323:. 2313:76 2311:. 2290:. 2230:,∞ 1946:. 1830:2. 1752:+ 1598:). 1568:00 1547:, 1439:00 1334:00 1312:). 1043:→ 1037:H) 183:μ( 119:BA 115:AB 2744:. 2730:: 2678:H 2676:( 2674:B 2665:. 2659:: 2598:. 2586:: 2576:: 2553:. 2547:: 2537:: 2508:. 2502:: 2467:. 2461:: 2434:. 2422:: 2416:9 2399:. 2387:: 2381:3 2364:. 2358:: 2331:. 2319:: 2285:L 2278:L 2274:1 2271:L 2264:l 2257:l 2253:n 2245:+ 2243:) 2241:1 2238:L 2234:+ 2232:) 2228:1 2224:L 2201:) 2198:1 2195:( 2192:O 2189:= 2179:1 2176:= 2173:n 2168:} 2162:n 2158:a 2154:+ 2148:+ 2143:2 2139:a 2135:+ 2130:1 2126:a 2121:{ 2080:, 2077:1 2059:1 2056:= 2053:n 2048:} 2043:n 2037:n 2033:a 2029:+ 2023:+ 2018:2 2014:a 2010:+ 2005:1 2001:a 1994:{ 1970:1 1967:l 1958:L 1944:1 1941:L 1937:1 1934:L 1911:. 1906:n 1902:a 1891:2 1888:= 1885:n 1874:= 1869:1 1865:a 1824:n 1820:, 1814:) 1811:n 1808:( 1800:2 1792:n 1788:1 1783:= 1778:n 1774:a 1757:2 1754:a 1750:1 1747:a 1723:1 1705:1 1702:= 1699:n 1694:} 1689:n 1683:n 1679:a 1675:+ 1669:+ 1664:2 1660:a 1656:+ 1651:1 1647:a 1640:{ 1614:1 1611:L 1596:H 1594:( 1592:F 1588:H 1586:( 1584:F 1580:H 1578:( 1576:F 1565:c 1560:N 1556:a 1552:2 1549:a 1545:1 1542:a 1520:0 1517:= 1512:N 1508:a 1504:+ 1498:+ 1493:2 1489:a 1485:+ 1480:1 1476:a 1435:c 1421:1 1418:= 1415:n 1410:} 1405:n 1399:n 1395:a 1391:+ 1385:+ 1380:2 1376:a 1372:+ 1367:1 1363:a 1356:{ 1331:c 1327:H 1325:( 1323:F 1310:H 1308:( 1306:K 1302:H 1300:( 1298:K 1294:0 1291:c 1287:0 1284:c 1276:0 1273:c 1269:H 1267:( 1265:K 1251:H 1240:. 1238:J 1234:φ 1230:J 1226:Q 1219:Q 1217:( 1215:φ 1210:1 1202:A 1200:( 1198:λ 1194:H 1190:A 1186:A 1184:( 1182:λ 1178:J 1174:A 1170:A 1168:( 1166:λ 1162:φ 1158:A 1156:( 1154:φ 1149:1 1143:. 1141:j 1133:J 1129:H 1125:A 1121:A 1119:( 1117:μ 1113:J 1109:A 1105:A 1103:( 1101:μ 1097:φ 1093:A 1091:( 1089:φ 1085:. 1083:j 1079:j 1075:J 1067:J 1052:C 1041:J 1035:( 1033:B 1029:J 1009:1 997:A 995:( 993:λ 989:H 985:A 981:A 979:( 977:λ 973:J 969:A 965:J 961:A 959:( 957:λ 953:A 948:1 942:. 940:H 936:A 932:A 930:( 928:μ 924:J 920:A 916:J 912:A 910:( 908:μ 904:A 897:j 893:j 889:J 885:J 877:j 873:J 856:B 852:A 848:B 846:( 844:λ 840:A 838:( 836:λ 832:J 828:j 806:j 793:0 790:= 787:n 782:} 777:) 773:) 770:B 767:, 764:k 761:( 752:) 749:A 746:, 743:k 740:( 733:( 727:n 722:0 719:= 716:k 705:n 702:+ 699:1 695:1 689:{ 671:J 667:B 663:A 659:J 655:B 651:A 641:) 639:1 637:( 620:. 614:, 611:2 608:, 605:1 602:, 599:0 596:= 593:n 589:, 586:) 583:B 580:, 577:k 574:( 566:n 561:0 558:= 555:k 544:) 541:A 538:, 535:k 532:( 524:n 519:0 516:= 513:k 492:J 488:B 484:J 480:A 476:J 464:j 460:J 448:B 444:A 440:B 438:( 436:μ 432:A 430:( 428:μ 424:J 420:j 398:j 385:0 382:= 379:n 374:} 369:) 365:) 362:B 359:, 356:k 353:( 344:) 341:A 338:, 335:k 332:( 325:( 319:n 314:0 311:= 308:k 297:n 294:+ 291:1 287:1 281:{ 263:J 259:B 255:A 251:J 236:B 232:j 228:A 217:j 213:A 209:A 205:J 197:J 193:j 189:A 185:A 177:J 173:A 154:J 150:J 146:J 139:H 137:( 135:B 131:B 127:J 123:A 111:J 107:H 103:H 101:( 99:B 95:J

Index

ideal
bounded linear operators
Hilbert space
commutators
Calkin correspondence
Cesàro means
traces
matrix mechanics
Paul Halmos
Schatten ideals
Hilbert–Schmidt operators
Nigel Kalton
Tadeusz Figiel
Mariusz Wodzicki
Calkin correspondence
compact operator
singular values
Normal operators
Cesàro mean
eigenvalue sequences
Cesàro means
1
quasi-nilpotent operator
1
Singular trace
symmetric functionals
1
1
quasi-nilpotent operator
compact linear operators

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