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Strictly positive measure

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is a strictly positive measure — Wiener measure is an example of a Gaussian measure on an infinite-dimensional space.
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is strictly positive. This example illustrates the importance of the topology in determining strict positivity.
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is one that is "nowhere zero", or that is zero "only on points".
1229: â€“ Concept in mathematics − a measure is strictly positive 1245: 15: 573:
is particularly "coarse" (contains "few" sets). For example,
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is strictly positive as well. The proof is simple: let
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is usually not strictly positive unless the topology
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is never strictly positive, regardless of the space
2109: 2057: 2010: 1910: 1803: 1696: 1465: 1338: 1279: 984:are two measures on a measurable topological space 1197: 1162: 1124: 1104: 1078: 1058: 1031: 1011: 976: 956: 926: 906: 879: 859: 822: 787: 767: 729: 702: 659: 637: 617: 592: 565: 539: 508: 461: 431: 408: 384: 352: 332: 310: 288: 260: 240: 218: 197: 170: 703:{\displaystyle T=\{\varnothing ,\mathbb {R} \},} 509:{\displaystyle U\neq \varnothing ,\mu (U)>0.} 645:-algebra is not strictly positive; however, if 1257: 8: 2002:Riesz–Markov–Kakutani representation theorem 694: 680: 50:. Unsourced material may be challenged and 2097:Vitale's random Brunn–Minkowski inequality 2014: 1264: 1250: 1242: 1175: 1137: 1117: 1091: 1071: 1048: 1024: 989: 969: 949: 919: 899: 872: 851: 847: 846: 843: 814: 810: 809: 806: 780: 759: 755: 754: 751: 721: 715: 690: 689: 672: 653: 652: 650: 630: 611: 610: 608: 584: 578: 558: 547:(with any topology) is strictly positive. 532: 474: 448: 424: 401: 365: 345: 325: 303: 281: 253: 233: 211: 190: 151: 114:Learn how and when to remove this message 683: 482: 667:is equipped with the trivial topology 7: 2110:Applications & related 801:on the space of continuous paths in 130:, strict positivity is a concept in 48:adding citations to reliable sources 1000: 914:or the topology used, except when 625:with its usual Borel topology and 396:if every non-empty open subset of 376: 283: 192: 14: 2039:Lebesgue differentiation theorem 1920:CarathĂ©odory's extension theorem 1112:be an arbitrary open set; since 860:{\displaystyle \mathbb {R} ^{n}} 823:{\displaystyle \mathbb {R} ^{n}} 795:-algebra) is strictly positive. 768:{\displaystyle \mathbb {R} ^{n}} 20: 1233:its support is the whole space. 1208:Hence, strict positivity is an 887:-algebra) is strictly positive. 416:has strictly positive measure. 1186: 1180: 1148: 1142: 1003: 991: 497: 491: 379: 367: 165: 153: 1: 1163:{\displaystyle \mu (U)>0;} 867:(with its Borel topology and 775:(with its Borel topology and 1198:{\displaystyle \nu (U)>0} 1105:{\displaystyle U\subseteq X} 1012:{\displaystyle (X,\Sigma ),} 660:{\displaystyle \mathbb {R} } 618:{\displaystyle \mathbb {R} } 2092:PrĂ©kopa–Leindler inequality 1039:strictly positive and also 730:{\displaystyle \delta _{0}} 593:{\displaystyle \delta _{0}} 385:{\displaystyle (X,\Sigma )} 296:is at least as fine as the 248:that contains the topology 63:"Strictly positive measure" 2174: 2034:Lebesgue's density theorem 2158:Measures (measure theory) 2087:Minkowski–Steiner formula 2017: 1902:Projection-valued measure 136:strictly positive measure 2070:Isoperimetric inequality 2049:Vitali–Hahn–Saks theorem 1378:CarathĂ©odory's criterion 1227:Support (measure theory) 1170:by absolute continuity, 2075:Brunn–Minkowski theorem 1944:Decomposition theorems 1214:equivalence of measures 880:{\displaystyle \sigma } 788:{\displaystyle \sigma } 638:{\displaystyle \sigma } 311:{\displaystyle \sigma } 289:{\displaystyle \Sigma } 219:{\displaystyle \sigma } 198:{\displaystyle \Sigma } 2122:Descriptive set theory 2022:Disintegration theorem 1457:Universally measurable 1199: 1164: 1132:is strictly positive, 1126: 1106: 1080: 1060: 1033: 1013: 978: 958: 928: 908: 881: 861: 824: 789: 769: 731: 704: 661: 639: 619: 594: 567: 541: 510: 463: 462:{\displaystyle U\in T} 433: 410: 386: 354: 334: 312: 290: 262: 242: 220: 199: 172: 1924:Convergence theorems 1383:Cylindrical σ-algebra 1200: 1165: 1127: 1107: 1081: 1061: 1059:{\displaystyle \nu ,} 1041:absolutely continuous 1034: 1014: 979: 959: 929: 909: 882: 862: 825: 790: 770: 732: 705: 662: 640: 620: 595: 568: 542: 511: 464: 439:is strictly positive 434: 411: 387: 355: 335: 313: 291: 263: 243: 221: 200: 173: 171:{\displaystyle (X,T)} 1992:Minkowski inequality 1866:Cylinder set measure 1751:Infinite-dimensional 1366:equivalence relation 1296:Lebesgue integration 1174: 1136: 1125:{\displaystyle \mu } 1116: 1090: 1079:{\displaystyle \nu } 1070: 1047: 1032:{\displaystyle \mu } 1023: 988: 977:{\displaystyle \nu } 968: 957:{\displaystyle \mu } 948: 918: 898: 871: 842: 805: 779: 750: 714: 671: 649: 629: 607: 577: 557: 531: 473: 447: 432:{\displaystyle \mu } 423: 400: 364: 353:{\displaystyle \mu } 344: 324: 302: 280: 252: 232: 210: 189: 150: 44:improve this article 1987:Hölder's inequality 1849:of random variables 1811:Measurable function 1698:Particular measures 1287:Absolute continuity 2127:Probability theory 1452:Transverse measure 1430:Non-measurable set 1412:Locally measurable 1195: 1160: 1122: 1102: 1076: 1056: 1029: 1009: 974: 954: 924: 904: 877: 857: 820: 785: 765: 727: 700: 657: 635: 615: 590: 563: 537: 506: 459: 429: 406: 382: 350: 340:). Then a measure 330: 308: 286: 258: 238: 216: 195: 168: 2145: 2144: 2105: 2104: 1834:almost everywhere 1780:Spherical measure 1678:Strictly positive 1606:Projection-valued 1346:Almost everywhere 1319:Probability space 927:{\displaystyle X} 907:{\displaystyle X} 566:{\displaystyle T} 540:{\displaystyle X} 409:{\displaystyle X} 394:strictly positive 333:{\displaystyle X} 261:{\displaystyle T} 241:{\displaystyle X} 183:topological space 134:. Intuitively, a 124: 123: 116: 98: 2165: 2080:Milman's reverse 2063: 2061:Lebesgue measure 2015: 1419: 1405:infimum/supremum 1326:Measurable space 1266: 1259: 1252: 1243: 1212:with respect to 1204: 1202: 1201: 1196: 1169: 1167: 1166: 1161: 1131: 1129: 1128: 1123: 1111: 1109: 1108: 1103: 1085: 1083: 1082: 1077: 1065: 1063: 1062: 1057: 1043:with respect to 1038: 1036: 1035: 1030: 1018: 1016: 1015: 1010: 983: 981: 980: 975: 963: 961: 960: 955: 933: 931: 930: 925: 913: 911: 910: 905: 886: 884: 883: 878: 866: 864: 863: 858: 856: 855: 850: 836:Lebesgue measure 829: 827: 826: 821: 819: 818: 813: 794: 792: 791: 786: 774: 772: 771: 766: 764: 763: 758: 741:Gaussian measure 736: 734: 733: 728: 726: 725: 709: 707: 706: 701: 693: 666: 664: 663: 658: 656: 644: 642: 641: 636: 624: 622: 621: 616: 614: 599: 597: 596: 591: 589: 588: 572: 570: 569: 564: 546: 544: 543: 538: 525:Counting measure 515: 513: 512: 507: 468: 466: 465: 460: 438: 436: 435: 430: 419:More concisely, 415: 413: 412: 407: 391: 389: 388: 383: 359: 357: 356: 351: 339: 337: 336: 331: 317: 315: 314: 309: 295: 293: 292: 287: 267: 265: 264: 259: 247: 245: 244: 239: 225: 223: 222: 217: 204: 202: 201: 196: 177: 175: 174: 169: 119: 112: 108: 105: 99: 97: 56: 24: 16: 2173: 2172: 2168: 2167: 2166: 2164: 2163: 2162: 2148: 2147: 2146: 2141: 2137:Spectral theory 2117:Convex analysis 2101: 2058: 2053: 2006: 1906: 1854:in distribution 1799: 1692: 1522:Logarithmically 1461: 1417: 1400:Essential range 1334: 1275: 1270: 1240: 1223: 1172: 1171: 1134: 1133: 1114: 1113: 1088: 1087: 1068: 1067: 1045: 1044: 1021: 1020: 986: 985: 966: 965: 946: 945: 941: 916: 915: 896: 895: 892:trivial measure 869: 868: 845: 840: 839: 808: 803: 802: 777: 776: 753: 748: 747: 745:Euclidean space 717: 712: 711: 669: 668: 647: 646: 627: 626: 605: 604: 580: 575: 574: 555: 554: 529: 528: 521: 471: 470: 445: 444: 421: 420: 398: 397: 362: 361: 342: 341: 322: 321: 300: 299: 278: 277: 268:(so that every 250: 249: 230: 229: 208: 207: 187: 186: 148: 147: 144: 120: 109: 103: 100: 57: 55: 41: 25: 12: 11: 5: 2171: 2169: 2161: 2160: 2150: 2149: 2143: 2142: 2140: 2139: 2134: 2129: 2124: 2119: 2113: 2111: 2107: 2106: 2103: 2102: 2100: 2099: 2094: 2089: 2084: 2083: 2082: 2072: 2066: 2064: 2055: 2054: 2052: 2051: 2046: 2044:Sard's theorem 2041: 2036: 2031: 2030: 2029: 2027:Lifting theory 2018: 2012: 2008: 2007: 2005: 2004: 1999: 1994: 1989: 1984: 1983: 1982: 1980:Fubini–Tonelli 1972: 1967: 1962: 1961: 1960: 1955: 1950: 1942: 1941: 1940: 1935: 1930: 1922: 1916: 1914: 1908: 1907: 1905: 1904: 1899: 1894: 1889: 1884: 1879: 1874: 1868: 1863: 1862: 1861: 1859:in probability 1856: 1846: 1841: 1836: 1830: 1829: 1828: 1823: 1818: 1807: 1805: 1801: 1800: 1798: 1797: 1792: 1787: 1782: 1777: 1772: 1771: 1770: 1760: 1755: 1754: 1753: 1743: 1738: 1733: 1728: 1723: 1718: 1713: 1708: 1702: 1700: 1694: 1693: 1691: 1690: 1685: 1680: 1675: 1670: 1665: 1660: 1655: 1650: 1645: 1640: 1639: 1638: 1633: 1628: 1618: 1613: 1608: 1603: 1593: 1588: 1583: 1578: 1573: 1568: 1566:Locally finite 1563: 1553: 1548: 1543: 1538: 1533: 1528: 1518: 1513: 1508: 1503: 1498: 1493: 1488: 1483: 1478: 1472: 1470: 1463: 1462: 1460: 1459: 1454: 1449: 1444: 1439: 1438: 1437: 1427: 1422: 1414: 1409: 1408: 1407: 1397: 1392: 1391: 1390: 1380: 1375: 1370: 1369: 1368: 1358: 1353: 1348: 1342: 1340: 1336: 1335: 1333: 1332: 1323: 1322: 1321: 1311: 1306: 1298: 1293: 1283: 1281: 1280:Basic concepts 1277: 1276: 1273:Measure theory 1271: 1269: 1268: 1261: 1254: 1246: 1239: 1236: 1235: 1234: 1231:if and only if 1222: 1219: 1218: 1217: 1206: 1194: 1191: 1188: 1185: 1182: 1179: 1159: 1156: 1153: 1150: 1147: 1144: 1141: 1121: 1101: 1098: 1095: 1075: 1055: 1052: 1028: 1008: 1005: 1002: 999: 996: 993: 973: 953: 940: 937: 936: 935: 923: 903: 888: 876: 854: 849: 833: 832: 831: 817: 812: 799:Wiener measure 784: 762: 757: 738: 724: 720: 699: 696: 692: 688: 685: 682: 679: 676: 655: 634: 613: 587: 583: 562: 548: 536: 520: 517: 505: 502: 499: 496: 493: 490: 487: 484: 481: 478: 458: 455: 452: 441:if and only if 428: 405: 381: 378: 375: 372: 369: 349: 329: 307: 285: 274:measurable set 257: 237: 215: 194: 167: 164: 161: 158: 155: 143: 140: 132:measure theory 122: 121: 28: 26: 19: 13: 10: 9: 6: 4: 3: 2: 2170: 2159: 2156: 2155: 2153: 2138: 2135: 2133: 2132:Real analysis 2130: 2128: 2125: 2123: 2120: 2118: 2115: 2114: 2112: 2108: 2098: 2095: 2093: 2090: 2088: 2085: 2081: 2078: 2077: 2076: 2073: 2071: 2068: 2067: 2065: 2062: 2056: 2050: 2047: 2045: 2042: 2040: 2037: 2035: 2032: 2028: 2025: 2024: 2023: 2020: 2019: 2016: 2013: 2011:Other results 2009: 2003: 2000: 1998: 1997:Radon–Nikodym 1995: 1993: 1990: 1988: 1985: 1981: 1978: 1977: 1976: 1973: 1971: 1970:Fatou's lemma 1968: 1966: 1963: 1959: 1956: 1954: 1951: 1949: 1946: 1945: 1943: 1939: 1936: 1934: 1931: 1929: 1926: 1925: 1923: 1921: 1918: 1917: 1915: 1913: 1909: 1903: 1900: 1898: 1895: 1893: 1890: 1888: 1885: 1883: 1880: 1878: 1875: 1873: 1869: 1867: 1864: 1860: 1857: 1855: 1852: 1851: 1850: 1847: 1845: 1842: 1840: 1837: 1835: 1832:Convergence: 1831: 1827: 1824: 1822: 1819: 1817: 1814: 1813: 1812: 1809: 1808: 1806: 1802: 1796: 1793: 1791: 1788: 1786: 1783: 1781: 1778: 1776: 1773: 1769: 1766: 1765: 1764: 1761: 1759: 1756: 1752: 1749: 1748: 1747: 1744: 1742: 1739: 1737: 1734: 1732: 1729: 1727: 1724: 1722: 1719: 1717: 1714: 1712: 1709: 1707: 1704: 1703: 1701: 1699: 1695: 1689: 1686: 1684: 1681: 1679: 1676: 1674: 1671: 1669: 1666: 1664: 1661: 1659: 1656: 1654: 1651: 1649: 1646: 1644: 1641: 1637: 1636:Outer regular 1634: 1632: 1631:Inner regular 1629: 1627: 1626:Borel regular 1624: 1623: 1622: 1619: 1617: 1614: 1612: 1609: 1607: 1604: 1602: 1598: 1594: 1592: 1589: 1587: 1584: 1582: 1579: 1577: 1574: 1572: 1569: 1567: 1564: 1562: 1558: 1554: 1552: 1549: 1547: 1544: 1542: 1539: 1537: 1534: 1532: 1529: 1527: 1523: 1519: 1517: 1514: 1512: 1509: 1507: 1504: 1502: 1499: 1497: 1494: 1492: 1489: 1487: 1484: 1482: 1479: 1477: 1474: 1473: 1471: 1469: 1464: 1458: 1455: 1453: 1450: 1448: 1445: 1443: 1440: 1436: 1433: 1432: 1431: 1428: 1426: 1423: 1421: 1415: 1413: 1410: 1406: 1403: 1402: 1401: 1398: 1396: 1393: 1389: 1386: 1385: 1384: 1381: 1379: 1376: 1374: 1371: 1367: 1364: 1363: 1362: 1359: 1357: 1354: 1352: 1349: 1347: 1344: 1343: 1341: 1337: 1331: 1327: 1324: 1320: 1317: 1316: 1315: 1314:Measure space 1312: 1310: 1307: 1305: 1303: 1299: 1297: 1294: 1292: 1288: 1285: 1284: 1282: 1278: 1274: 1267: 1262: 1260: 1255: 1253: 1248: 1247: 1244: 1237: 1232: 1228: 1225: 1224: 1220: 1215: 1211: 1207: 1192: 1189: 1183: 1177: 1157: 1154: 1151: 1145: 1139: 1119: 1099: 1096: 1093: 1073: 1053: 1050: 1042: 1026: 1006: 997: 994: 971: 951: 943: 942: 938: 921: 901: 893: 889: 874: 852: 837: 834: 815: 800: 797: 796: 782: 760: 746: 742: 739: 722: 718: 697: 686: 677: 674: 632: 603: 585: 581: 560: 552: 551:Dirac measure 549: 534: 526: 523: 522: 518: 516: 503: 500: 494: 488: 485: 479: 476: 456: 453: 450: 442: 426: 417: 403: 395: 373: 370: 347: 327: 319: 305: 275: 271: 255: 235: 227: 213: 184: 181: 162: 159: 156: 141: 139: 137: 133: 129: 118: 115: 107: 104:December 2009 96: 93: 89: 86: 82: 79: 75: 72: 68: 65: â€“  64: 60: 59:Find sources: 53: 49: 45: 39: 38: 34: 29:This article 27: 23: 18: 17: 1912:Main results 1677: 1648:Set function 1576:Metric outer 1531:Decomposable 1388:Cylinder set 1301: 418: 393: 145: 135: 125: 110: 101: 91: 84: 77: 70: 58: 42:Please help 30: 1872:compact set 1839:of measures 1775:Pushforward 1768:Projections 1758:Logarithmic 1601:Probability 1591:Pre-measure 1373:Borel space 1291:of measures 527:on any set 128:mathematics 1844:in measure 1571:Maximising 1541:Equivalent 1435:Vitali set 1238:References 939:Properties 469:such that 392:is called 142:Definition 74:newspapers 1958:Maharam's 1928:Dominated 1741:Intensity 1736:Hausdorff 1643:Saturated 1561:Invariant 1466:Types of 1425:σ-algebra 1395:𝜆-system 1361:Borel set 1356:Baire set 1210:invariant 1178:ν 1140:μ 1120:μ 1097:⊆ 1074:ν 1051:ν 1027:μ 1001:Σ 972:ν 952:μ 934:is empty. 875:σ 783:σ 719:δ 684:∅ 633:σ 602:real line 582:δ 489:μ 483:∅ 480:≠ 454:∈ 427:μ 377:Σ 348:μ 306:σ 284:Σ 214:σ 193:Σ 180:Hausdorff 31:does not 2152:Category 1975:Fubini's 1965:Egorov's 1933:Monotone 1892:variable 1870:Random: 1821:Strongly 1746:Lebesgue 1731:Harmonic 1721:Gaussian 1706:Counting 1673:Spectral 1668:Singular 1658:s-finite 1653:σ-finite 1536:Discrete 1511:Complete 1468:Measures 1442:Null set 1330:function 1221:See also 1205:as well. 519:Examples 443:for all 318:-algebra 270:open set 226:-algebra 185:and let 1887:process 1882:measure 1877:element 1816:Bochner 1790:Trivial 1785:Tangent 1763:Product 1621:Regular 1599:)  1586:Perfect 1559:)  1524:)  1516:Content 1506:Complex 1447:Support 1420:-system 1309:Measure 600:on the 88:scholar 52:removed 37:sources 1953:Jordan 1938:Vitali 1897:vector 1826:Weakly 1688:Vector 1663:Signed 1616:Random 1557:Quasi- 1546:Finite 1526:Convex 1486:Banach 1476:Atomic 1304:spaces 1289:  298:Borel 276:, and 90:  83:  76:  69:  61:  1795:Young 1716:Euler 1711:Dirac 1683:Tight 1611:Radon 1581:Outer 1551:Inner 1501:Brown 1496:Borel 1491:Besov 1481:Baire 1066:then 1019:with 710:then 272:is a 205:be a 178:be a 95:JSTOR 81:books 2059:For 1948:Hahn 1804:Maps 1726:Haar 1597:Sub- 1351:Atom 1339:Sets 1190:> 1152:> 964:and 890:The 501:> 146:Let 67:news 35:any 33:cite 944:If 838:on 743:on 360:on 320:on 228:on 126:In 46:by 2154:: 504:0. 1595:( 1555:( 1520:( 1418:π 1328:/ 1302:L 1265:e 1258:t 1251:v 1216:. 1193:0 1187:) 1184:U 1181:( 1158:; 1155:0 1149:) 1146:U 1143:( 1100:X 1094:U 1054:, 1007:, 1004:) 998:, 995:X 992:( 922:X 902:X 853:n 848:R 816:n 811:R 761:n 756:R 723:0 698:, 695:} 691:R 687:, 681:{ 678:= 675:T 654:R 612:R 586:0 561:T 535:X 498:) 495:U 492:( 486:, 477:U 457:T 451:U 404:X 380:) 374:, 371:X 368:( 328:X 256:T 236:X 166:) 163:T 160:, 157:X 154:( 117:) 111:( 106:) 102:( 92:· 85:· 78:· 71:· 54:. 40:.

Index


cite
sources
improve this article
adding citations to reliable sources
removed
"Strictly positive measure"
news
newspapers
books
scholar
JSTOR
Learn how and when to remove this message
mathematics
measure theory
Hausdorff
topological space
σ {\displaystyle \sigma } -algebra
open set
measurable set
Borel σ {\displaystyle \sigma } -algebra
if and only if
Counting measure
Dirac measure
real line
Gaussian measure
Euclidean space
Wiener measure
Lebesgue measure
trivial measure

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