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Radon's theorem

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65: 1714: + 1 of the points; that is, that the given point is part of a Radon partition in which it is a singleton. One proof of CarathĂ©odory's theorem uses a technique of examining solutions to systems of linear equations, similar to the proof of Radon's theorem, to eliminate one point at a time until at most 68:
Two sets of four points in the plane (the vertices of a square and an equilateral triangle with its centroid), the multipliers solving the system of three linear equations for these points, and the Radon partitions formed by separating the points with positive multipliers from the points with
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connecting a pair of vertices in the set. With this definition, every set of ω + 1 vertices in the graph can be partitioned into two subsets whose convex hulls intersect, and ω + 1 is the minimum number for which this is possible, where ω is the
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can be partitioned in one of two ways. It may form a triple and a singleton, where the convex hull of the triple (a triangle) contains the singleton; alternatively, it may form two pairs of points that form the endpoints of two intersecting
335: 184: 745: 348: + 1 equations that they must satisfy (one for each coordinate of the points, together with a final equation requiring the sum of the multipliers to be zero). Fix some particular nonzero solution 1562: + 1 points (for instance, the points of a regular simplex) such that every two nonempty subsets can be separated from each other by a hyperplane. However, no matter which set of 1086: 1017: 952: 1608:
of a set of points is the point minimizing the sum of distances to the points in the set; it generalizes the one-dimensional median and has been studied both from the point of view of
1512: 1461: 1415: 1369: 1692: 512: 421: 389: 1311: 2059: 832: 812: 792: 768: 504: 484: 461: 441: 2407: 1566: + 2 points is given, the two subsets of a Radon partition cannot be linearly separated. Therefore, the VC dimension of this system is exactly 1705: 220: 2437: 2353: 2327: 1934: 97: 2452: 2343: 1949: 2442: 879:
They are equivalent because any affine function on a simplex is uniquely determined by the images of its vertices. Formally, let Ć’ be an
652: 1728:, families of finite sets with the properties that the intersection of any two sets in the family remains in the family, and that the 2357: 1756:
by analogy to their definitions for convex sets in Euclidean spaces, and it can be shown that these numbers satisfy the inequalities
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must then be two disjoint faces whose images have a nonempty intersection. This same general statement, when applied to a
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states that any point in the convex hull of some set of points is also within the convex hull of a subset of at most
1313:, which is a continuous function from S to R. The theorem says that, for any such function, there exists some point 2105: 212: 1547:
on intersections of convex sets; this proof was the motivation for Radon's original discovery of Radon's theorem.
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and the union of all the sets belongs to the family. In this more general context, the convex hull of a set
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The topological Radon theorem follows from the following more general theorem. For any simplicial complex
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of any point set, in an amount of time that is polynomial in both the number of points and the dimension.
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This proof method allows for the efficient construction of a Radon point, in an amount of time that is
636:{\displaystyle p=\sum _{x_{i}\in I}{\frac {a_{i}}{A}}x_{i}=\sum _{x_{j}\in J}{\frac {-a_{j}}{A}}x_{j},} 1887:"A Borsuk theorem for antipodal links and a spectral characterization of linklessly embeddable graphs" 1482: 1431: 1385: 1339: 1961: 1574: 842: 1641: 394: 2183: 1175: 368: 2390: 2292:"Axiomatic convexity theory and relationships between the Carathéodory, Helly, and Radon numbers" 2153: 2122: 1916: 1867: 1748:
points have two subsets whose convex hulls intersect. Similarly, one can define the Helly number
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The topological Radon theorem was originally proved by Bajmoczy and Barany in the following way:
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Says d+2 points in d dimensions can be partitioned into two subsets whose convex hulls intersect
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Using the Borsuk–Ulam Theorem: Lectures on Topological Methods in Combinatorics and Geometry
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to the same point of R. This implies that the images of these two disjoint faces intersect.
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form the required partition of the points into two subsets with intersecting convex hulls.
2315: 2219: 2034: 880: 858: 838: 78: 2008:"Four-point Fermat location problems revisited. New proofs and extensions of old results" 2007: 2402: 2195: 2187: 2003: 1627: 817: 797: 777: 753: 489: 469: 446: 426: 1204: + 1)-dimensional compact convex set, and Ć’ is any continuous function from 2431: 2394: 2267: 2157: 1791: 1787: 1328:
Another proof was given by Lovasz and Schrijver. A third proof is given by Matousek:
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or other efficient algorithms to solve the system of equations for the multipliers.
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Chepoi, V. D. (1986), "Some properties of the d-convexity in triangulated graphs",
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The points g(y) and g(-y) are on two disjoint faces of Δ, and they are mapped by
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is a simplex, the two simplex faces formed by the maximum and minimum points of
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achieves its minimum value are mapped by Ć’ to the same point. In the case where
1188: 885: 871: 794:, and the right hand side expresses it as a convex combination of the points in 50: 41: 2420: 2215: 1782: 28: 1912: 1863: 330:{\displaystyle \sum _{i=1}^{d+2}a_{i}x_{i}=0,\quad \sum _{i=1}^{d+2}a_{i}=0,} 2310: 2253:
Duchet, Pierre (1987), "Convex sets in graphs. II. Minimal path convexity",
2026: 1729: 1558:-dimensional points with respect to linear separations. There exist sets of 1600:. The Radon point of three points in a one-dimensional space is just their 1778:, one may define a convex set to be a set of vertices that includes every 2371:(1921), "Mengen konvexer Körper, die einen gemeinsamen Punkt enthalten", 1257: 20: 1192:, then there are two disjoint faces of Δ whose images under ƒ intersect. 875:, then there are two disjoint faces of Δ whose images under ƒ intersect. 179:{\displaystyle X=\{x_{1},x_{2},\dots ,x_{d+2}\}\subset \mathbf {R} ^{d}} 2386: 2149: 2118: 1855: 1240:, that ƒ must map two opposite points of the sphere to the same point. 1183: 866: 2134:
Bandelt, H.-J.; Pesch, E. (1989), "A Radon theorem for Helly graphs",
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be the set of points with multipliers that are negative or zero. Then
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Shortest Connectivity: An Introduction with Applications in Phylogeny
1839: 1601: 1581: + 2 points by their Radon point can be used to compute an 1540:, the point that minimizes the sum of distances to the other points. 2280:
Eckhoff, J. (1993), "Helly, Radon, and Carathéodory type theorems",
1724:. Concepts related to Radon's theorem have also been considered for 2103:(1979), "A common generalization of Borsuk's and Radon's theorem", 1702:
subsets whose convex hulls intersect in at least one common point.
740:{\displaystyle A=\sum _{x_{i}\in I}a_{i}=-\sum _{x_{j}\in J}a_{j}.} 2204:
International Journal of Computational Geometry & Applications
1982:, Combinatorial Optimization, vol. 17, Springer, p. 6, 1820: 1942:: Lectures on Topological Methods in Combinatorics and Geometry 57:
A point in the intersection of these convex hulls is called a
2284:, vol. A, B, Amsterdam: North-Holland, pp. 389–448 1840:"On a common generalization of Borsuk's and Radon's theorem" 194:-dimensional space. Then there exists a set of multipliers 2356:(2003), "5.1 Nonembeddability Theorems: An Introduction", 1536:
The Radon point of any four points in the plane is their
2200:"Approximating center points with iterated Radon points" 1543:
Radon's theorem forms a key step of a standard proof of
1212:-dimensional space, then there exists a linear function 391:
be the set of points with positive multipliers, and let
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is the intersection of the family members that contain
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to be any continuous function - not necessarily affine:
1158:. These two faces are disjoint, and their images under 1220:
achieves its maximum value and some other point where
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intersect - as claimed by the new formulation. The
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can be partitioned into two disjoint subsets, e.g. (
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belongs to both convex hulls, completing the proof.
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must intersect, because they both contain the point
344: + 2 unknowns (the multipliers) but only 1790:of the given graph. For related results involving 1740:, and the Radon number of a space is the smallest 1686: 1550:Radon's theorem can also be used to calculate the 1506: 1455: 1409: 1363: 1305: 1147:is the image of the face spanned by the vertices ( 1125:is the image of the face spanned by the vertices ( 1080: 1011: 946: 826: 806: 786: 762: 739: 635: 498: 478: 455: 435: 415: 383: 329: 178: 2338:, vol. 212, Springer-Verlag, pp. 9–12, 2330:(2002), "1.3 Radon's Lemma and Helly's Theorem", 1844:Acta Mathematica Academiae Scientiarum Hungaricae 1891:Proceedings of the American Mathematical Society 853:An equivalent formulation of Radon's theorem is: 2405:(1966), "A generalization of Radon's theorem", 77: = 2, any set of four points in the 2239:(1963), "Helly's theorem and its relatives", 1885:Lovász, LászlĂł; Schrijver, Alexander (1998). 1523:|| to R, the images of two disjoint faces of 8: 2273: 2176: 1799: 158: 107: 1519:, then for every continuous mapping from || 2408:Journal of the London Mathematical Society 2062:, Lecture Notes by Marco Pellegrini, 2004. 1838:BajmĂłczy, E. G.; Bárány, I. (1979-09-01). 1081:{\displaystyle x_{1},x_{2},\dots ,x_{d+2}} 1012:{\displaystyle x_{1},x_{2},\dots ,x_{d+2}} 947:{\displaystyle v_{1},v_{2},\dots ,v_{d+2}} 2309: 2290:Kay, David C.; Womble, Eugene W. (1971), 2266: 2255:Journal of Combinatorial Theory, Series A 2071: 1902: 1643: 1495: 1490: 1484: 1444: 1439: 1433: 1398: 1393: 1387: 1352: 1347: 1341: 1292: 1066: 1047: 1034: 1028: 997: 978: 965: 959: 932: 913: 900: 894: 819: 799: 779: 755: 728: 710: 705: 689: 671: 666: 654: 624: 608: 598: 584: 579: 566: 551: 545: 531: 526: 514: 491: 471: 448: 428: 396: 370: 312: 296: 285: 265: 255: 239: 228: 222: 211:, not all of which are zero, solving the 170: 165: 146: 127: 114: 99: 2047: 1631: 1166:generalizes this formluation. It allows 63: 2243:, Proc. Symp. Pure Math., vol. 7, 1816: 1814: 1810: 407: 2083: 1795: 1622:. A generalization for partition into 1110:with overlapping convex hull. Because 750:The left hand side of the formula for 2015:IMA Journal of Management Mathematics 39:Any set of d + 2 points in 7: 1833: 1831: 1829: 1136:, and similarly the convex hull of ( 1317:on S, such that f(g(y)) = f(g(-y)). 1023:. By the original formulation, the 1698:-space, there is a partition into 1491: 1440: 1394: 1348: 1280:) are on two disjoint faces of Δ. 1260:) to Δ, such that for every point 14: 2362:, Springer-Verlag, pp. 88–92 1577:that repeatedly replaces sets of 1638:. It states that for any set of 1507:{\displaystyle K_{\Delta }^{*2}} 1456:{\displaystyle K_{\Delta }^{*2}} 1417:is homeomorphic to the sphere S. 1410:{\displaystyle K_{\Delta }^{*2}} 1364:{\displaystyle K_{\Delta }^{*2}} 1236:instead of a simplex, gives the 166: 1114:is affine, the convex hull of ( 280: 2297:Pacific Journal of Mathematics 1687:{\displaystyle (d+1)(r-1)+1\ } 1672: 1660: 1657: 1645: 954:be the vertices of Δ, and let 416:{\displaystyle J=X\setminus I} 1: 2438:Theorems in discrete geometry 2336:Graduate Texts in Mathematics 2332:Lectures on Discrete Geometry 2245:American Mathematical Society 2060:Epsilon-nets and VC-dimension 1940:Using the Borsuk-Ulam Theorem 1904:10.1090/S0002-9939-98-04244-0 1794:instead of induced paths see 1382:The geometric realization of 2453:Geometric transversal theory 2268:10.1016/0095-8956(88)90039-1 1956:Written in cooperation with 1752:and the CarathĂ©odory number 1182: + 1)-dimensional 865: + 1)-dimensional 384:{\displaystyle I\subseteq X} 2443:Theorems in convex geometry 2282:Handbook of Convex Geometry 1252:Construct a continuous map 1216:such that some point where 841:in the dimension, by using 2469: 2274:Bandelt & Pesch (1989) 2177:Bandelt & Pesch (1989) 2106:Acta Mathematica Hungarica 1800:Bandelt & Pesch (1989) 1336:be the simplex Δ, and let 1256:from S (the d-dimensional 770:expresses this point as a 213:system of linear equations 2216:10.1142/s021819599600023x 1976:Cieslik, Dietmar (2006), 1164:topological Radon theorem 849:Topological Radon theorem 190: + 2 points in 73:For example, in the case 2421:10.1112/jlms/s1-41.1.123 1772:Radon theorem for graphs 1306:{\displaystyle f\circ g} 2311:10.2140/pjm.1971.38.471 2072:Kay & Womble (1971) 1718: + 1 remain. 1821:Clarkson et al. (1996) 1707:CarathĂ©odory's theorem 1688: 1634:) and is now known as 1508: 1457: 1411: 1365: 1307: 1194: 1082: 1019:be their images under 1013: 948: 877: 828: 808: 788: 764: 741: 637: 500: 480: 457: 437: 417: 385: 331: 307: 250: 180: 90:Proof and construction 70: 55: 2374:Mathematische Annalen 2137:Archiv der Mathematik 2027:10.1093/imaman/dpl007 1689: 1509: 1458: 1412: 1366: 1308: 1172: 1083: 1014: 949: 855: 829: 809: 789: 765: 742: 638: 501: 481: 458: 438: 418: 386: 332: 281: 224: 181: 69:negative multipliers. 67: 37: 35:in 1921, states that: 2194:; Sturtivant, Carl; 2184:Clarkson, Kenneth L. 1694:points in Euclidean 1642: 1575:randomized algorithm 1483: 1432: 1386: 1340: 1291: 1027: 958: 893: 843:Gaussian elimination 818: 798: 778: 754: 653: 513: 490: 470: 466:The convex hulls of 447: 427: 395: 369: 221: 98: 49:into two sets whose 1503: 1452: 1406: 1360: 1285:Borsuk–Ulam theorem 1238:Borsuk–Ulam theorem 1196:More generally, if 1176:continuous function 2387:10.1007/BF01464231 2247:, pp. 101–179 2150:10.1007/BF01197978 2119:10.1007/BF01896131 1856:10.1007/BF01896131 1774:. In an arbitrary 1684: 1636:Tverberg's theorem 1628:Helge Tverberg 1626:sets was given by 1620:Tverberg's theorem 1504: 1486: 1453: 1435: 1407: 1389: 1361: 1343: 1303: 1078: 1009: 944: 824: 804: 784: 772:convex combination 760: 737: 723: 684: 633: 597: 544: 496: 476: 453: 433: 413: 381: 340:because there are 327: 176: 71: 2345:978-0-387-95373-1 2099:BajmĂłczy, E. G.; 1962:GĂĽnter M. Ziegler 1951:978-3-540-00362-5 1726:convex geometries 1722:Convex geometries 1683: 1614:robust statistics 1610:facility location 827:{\displaystyle p} 807:{\displaystyle J} 787:{\displaystyle I} 774:of the points in 763:{\displaystyle p} 701: 662: 618: 575: 560: 522: 499:{\displaystyle J} 479:{\displaystyle I} 456:{\displaystyle J} 436:{\displaystyle I} 355:, ...,  201:, ...,  94:Consider any set 2460: 2423: 2397: 2381:(1–2): 113–115, 2363: 2348: 2322: 2313: 2285: 2271: 2270: 2248: 2226: 2174: 2160: 2129: 2113:(3–4): 347–350, 2087: 2081: 2075: 2069: 2063: 2057: 2051: 2045: 2039: 2037: 2012: 2000: 1994: 1992: 1973: 1967: 1965: 1931: 1925: 1924: 1906: 1897:(5): 1275–1285. 1882: 1876: 1875: 1835: 1824: 1818: 1776:undirected graph 1768: + 1. 1760: <  1693: 1691: 1690: 1685: 1681: 1606:geometric median 1598:Geometric median 1593:Related concepts 1570: + 1. 1538:geometric median 1513: 1511: 1510: 1505: 1502: 1494: 1462: 1460: 1459: 1454: 1451: 1443: 1416: 1414: 1413: 1408: 1405: 1397: 1370: 1368: 1367: 1362: 1359: 1351: 1312: 1310: 1309: 1304: 1287:to the function 1087: 1085: 1084: 1079: 1077: 1076: 1052: 1051: 1039: 1038: 1018: 1016: 1015: 1010: 1008: 1007: 983: 982: 970: 969: 953: 951: 950: 945: 943: 942: 918: 917: 905: 904: 833: 831: 830: 825: 813: 811: 810: 805: 793: 791: 790: 785: 769: 767: 766: 761: 746: 744: 743: 738: 733: 732: 722: 715: 714: 694: 693: 683: 676: 675: 642: 640: 639: 634: 629: 628: 619: 614: 613: 612: 599: 596: 589: 588: 571: 570: 561: 556: 555: 546: 543: 536: 535: 505: 503: 502: 497: 485: 483: 482: 477: 462: 460: 459: 454: 442: 440: 439: 434: 422: 420: 419: 414: 390: 388: 387: 382: 336: 334: 333: 328: 317: 316: 306: 295: 270: 269: 260: 259: 249: 238: 185: 183: 182: 177: 175: 174: 169: 157: 156: 132: 131: 119: 118: 2468: 2467: 2463: 2462: 2461: 2459: 2458: 2457: 2428: 2427: 2401: 2367: 2352: 2346: 2326: 2289: 2279: 2252: 2230: 2196:Teng, Shang-Hua 2192:Miller, Gary L. 2188:Eppstein, David 2182: 2164: 2133: 2098: 2095: 2090: 2082: 2078: 2070: 2066: 2058: 2054: 2048:Matoušek (2002) 2046: 2042: 2010: 2004:Plastria, Frank 2002: 2001: 1997: 1990: 1975: 1974: 1970: 1952: 1933: 1932: 1928: 1884: 1883: 1879: 1837: 1836: 1827: 1819: 1812: 1808: 1640: 1639: 1595: 1545:Helly's theorem 1534: 1515:is larger than 1481: 1480: 1477: 1430: 1429: 1425: 1420:Therefore, the 1384: 1383: 1338: 1337: 1289: 1288: 1264:on the sphere, 1246: 1157: 1152: 1146: 1141: 1135: 1130: 1124: 1119: 1109: 1104: 1098: 1093: 1062: 1043: 1030: 1025: 1024: 993: 974: 961: 956: 955: 928: 909: 896: 891: 890: 881:affine function 859:affine function 851: 816: 815: 796: 795: 776: 775: 752: 751: 724: 706: 685: 667: 651: 650: 620: 604: 600: 580: 562: 547: 527: 511: 510: 488: 487: 468: 467: 445: 444: 425: 424: 393: 392: 367: 366: 364: 354: 308: 261: 251: 219: 218: 210: 200: 164: 142: 123: 110: 96: 95: 92: 79:Euclidean plane 31:, published by 25:Radon's theorem 17: 12: 11: 5: 2466: 2464: 2456: 2455: 2450: 2445: 2440: 2430: 2429: 2426: 2425: 2399: 2365: 2350: 2344: 2324: 2304:(2): 471–485, 2287: 2277: 2272:. As cited by 2261:(3): 307–316, 2250: 2228: 2210:(3): 357–377, 2180: 2175:. As cited by 2169:(in Russian), 2162: 2131: 2094: 2091: 2089: 2088: 2076: 2064: 2052: 2040: 2021:(4): 387–396, 1995: 1988: 1968: 1958:Anders Björner 1950: 1935:Matoušek, Jiří 1926: 1877: 1850:(3): 347–350. 1825: 1809: 1807: 1804: 1792:shortest paths 1744:such that any 1680: 1677: 1674: 1671: 1668: 1665: 1662: 1659: 1656: 1653: 1650: 1647: 1594: 1591: 1533: 1530: 1529: 1528: 1501: 1498: 1493: 1489: 1475: 1468: 1450: 1447: 1442: 1438: 1423: 1418: 1404: 1401: 1396: 1392: 1380: 1358: 1355: 1350: 1346: 1326: 1325: 1318: 1302: 1299: 1296: 1281: 1245: 1242: 1155: 1150: 1144: 1139: 1133: 1128: 1122: 1117: 1107: 1102: 1096: 1091: 1075: 1072: 1069: 1065: 1061: 1058: 1055: 1050: 1046: 1042: 1037: 1033: 1006: 1003: 1000: 996: 992: 989: 986: 981: 977: 973: 968: 964: 941: 938: 935: 931: 927: 924: 921: 916: 912: 908: 903: 899: 850: 847: 823: 803: 783: 759: 748: 747: 736: 731: 727: 721: 718: 713: 709: 704: 700: 697: 692: 688: 682: 679: 674: 670: 665: 661: 658: 644: 643: 632: 627: 623: 617: 611: 607: 603: 595: 592: 587: 583: 578: 574: 569: 565: 559: 554: 550: 542: 539: 534: 530: 525: 521: 518: 495: 475: 452: 432: 412: 409: 406: 403: 400: 380: 377: 374: 363: + 2 359: 352: 338: 337: 326: 323: 320: 315: 311: 305: 302: 299: 294: 291: 288: 284: 279: 276: 273: 268: 264: 258: 254: 248: 245: 242: 237: 234: 231: 227: 209: + 2 205: 198: 173: 168: 163: 160: 155: 152: 149: 145: 141: 138: 135: 130: 126: 122: 117: 113: 109: 106: 103: 91: 88: 15: 13: 10: 9: 6: 4: 3: 2: 2465: 2454: 2451: 2449: 2446: 2444: 2441: 2439: 2436: 2435: 2433: 2422: 2418: 2414: 2410: 2409: 2404: 2400: 2396: 2392: 2388: 2384: 2380: 2376: 2375: 2370: 2366: 2361: 2360: 2355: 2351: 2347: 2341: 2337: 2333: 2329: 2325: 2321: 2317: 2312: 2307: 2303: 2299: 2298: 2293: 2288: 2283: 2278: 2275: 2269: 2264: 2260: 2256: 2251: 2246: 2242: 2238: 2234: 2229: 2225: 2221: 2217: 2213: 2209: 2205: 2201: 2197: 2193: 2189: 2185: 2181: 2178: 2172: 2168: 2163: 2159: 2155: 2151: 2147: 2143: 2139: 2138: 2132: 2128: 2124: 2120: 2116: 2112: 2108: 2107: 2102: 2097: 2096: 2092: 2085: 2084:Duchet (1987) 2080: 2077: 2073: 2068: 2065: 2061: 2056: 2053: 2049: 2044: 2041: 2036: 2032: 2028: 2024: 2020: 2016: 2009: 2005: 1999: 1996: 1991: 1989:9780387235394 1985: 1981: 1980: 1972: 1969: 1966:, Section 4.3 1964: 1963: 1959: 1953: 1947: 1943: 1941: 1936: 1930: 1927: 1922: 1918: 1914: 1910: 1905: 1900: 1896: 1892: 1888: 1881: 1878: 1873: 1869: 1865: 1861: 1857: 1853: 1849: 1845: 1841: 1834: 1832: 1830: 1826: 1822: 1817: 1815: 1811: 1805: 1803: 1801: 1797: 1796:Chepoi (1986) 1793: 1789: 1788:clique number 1784: 1781: 1777: 1773: 1769: 1767: 1764: â‰¤  1763: 1759: 1755: 1751: 1747: 1743: 1739: 1735: 1731: 1727: 1723: 1719: 1717: 1713: 1709: 1708: 1703: 1701: 1697: 1678: 1675: 1669: 1666: 1663: 1654: 1651: 1648: 1637: 1633: 1629: 1625: 1621: 1617: 1615: 1611: 1607: 1603: 1599: 1592: 1590: 1588: 1584: 1583:approximation 1580: 1576: 1571: 1569: 1565: 1561: 1557: 1553: 1548: 1546: 1541: 1539: 1531: 1526: 1522: 1518: 1514: 1499: 1496: 1487: 1473: 1469: 1466: 1448: 1445: 1436: 1427: 1419: 1402: 1399: 1390: 1381: 1378: 1374: 1356: 1353: 1344: 1335: 1331: 1330: 1329: 1323: 1319: 1316: 1300: 1297: 1294: 1286: 1282: 1279: 1275: 1271: 1267: 1263: 1259: 1255: 1251: 1250: 1249: 1243: 1241: 1239: 1235: 1231: 1227: 1223: 1219: 1215: 1211: 1207: 1203: 1199: 1193: 1191: 1190: 1185: 1181: 1177: 1171: 1169: 1165: 1161: 1153: 1142: 1131: 1120: 1113: 1105: 1094: 1073: 1070: 1067: 1063: 1059: 1056: 1053: 1048: 1044: 1040: 1035: 1031: 1022: 1004: 1001: 998: 994: 990: 987: 984: 979: 975: 971: 966: 962: 939: 936: 933: 929: 925: 922: 919: 914: 910: 906: 901: 897: 888: 887: 882: 876: 874: 873: 868: 864: 860: 854: 848: 846: 844: 840: 835: 821: 814:. Therefore, 801: 781: 773: 757: 734: 729: 725: 719: 716: 711: 707: 702: 698: 695: 690: 686: 680: 677: 672: 668: 663: 659: 656: 649: 648: 647: 630: 625: 621: 615: 609: 605: 601: 593: 590: 585: 581: 576: 572: 567: 563: 557: 552: 548: 540: 537: 532: 528: 523: 519: 516: 509: 508: 507: 493: 473: 464: 450: 430: 410: 404: 401: 398: 378: 375: 372: 362: 358: 351: 347: 343: 324: 321: 318: 313: 309: 303: 300: 297: 292: 289: 286: 282: 277: 274: 271: 266: 262: 256: 252: 246: 243: 240: 235: 232: 229: 225: 217: 216: 215: 214: 208: 204: 197: 193: 189: 171: 161: 153: 150: 147: 143: 139: 136: 133: 128: 124: 120: 115: 111: 104: 101: 89: 87: 85: 84:line segments 80: 76: 66: 62: 60: 54: 52: 48: 44: 43: 36: 34: 30: 26: 22: 2448:Convex hulls 2412: 2406: 2403:Tverberg, H. 2378: 2372: 2358: 2354:Matoušek, J. 2331: 2328:Matoušek, J. 2301: 2295: 2281: 2258: 2254: 2240: 2233:GrĂĽnbaum, B. 2231:Danzer, L.; 2207: 2203: 2170: 2167:Mat. Issled. 2166: 2144:(1): 95–98, 2141: 2135: 2110: 2104: 2079: 2067: 2055: 2043: 2018: 2014: 1998: 1978: 1971: 1955: 1938: 1929: 1894: 1890: 1880: 1847: 1843: 1771: 1770: 1765: 1761: 1757: 1753: 1749: 1745: 1741: 1737: 1733: 1721: 1720: 1715: 1711: 1706: 1704: 1699: 1695: 1623: 1619: 1618: 1597: 1596: 1578: 1572: 1567: 1563: 1559: 1555: 1552:VC dimension 1549: 1542: 1535: 1532:Applications 1524: 1520: 1516: 1479: 1471: 1464: 1379:with itself. 1376: 1373:deleted join 1333: 1327: 1321: 1314: 1277: 1273: 1269: 1265: 1261: 1253: 1247: 1229: 1225: 1221: 1217: 1213: 1209: 1205: 1201: 1197: 1195: 1187: 1179: 1174:If Ć’ is any 1173: 1167: 1163: 1159: 1148: 1137: 1126: 1115: 1111: 1100: 1089: 1020: 884: 878: 870: 862: 857:If Ć’ is any 856: 852: 836: 749: 645: 465: 360: 356: 349: 345: 341: 339: 206: 202: 195: 191: 187: 93: 74: 72: 58: 56: 51:convex hulls 40: 38: 33:Johann Radon 24: 18: 2415:: 123–128, 1587:centerpoint 1234:hypersphere 61:of the set. 59:Radon point 53:intersect. 47:partitioned 29:convex sets 2432:Categories 2101:Bárány, I. 2093:References 2035:1126.90046 1527:intersect. 1478:-index of 1474:, if the Z 1283:Apply the 883:from Δ to 839:polynomial 2395:121627696 2369:Radon, J. 2241:Convexity 2173:: 164–177 2158:120983560 1913:0002-9939 1864:1588-2632 1730:empty set 1667:− 1497:∗ 1492:Δ 1446:∗ 1441:Δ 1400:∗ 1395:Δ 1354:∗ 1349:Δ 1298:∘ 1057:… 988:… 923:… 717:∈ 703:∑ 699:− 678:∈ 664:∑ 602:− 591:∈ 577:∑ 538:∈ 524:∑ 408:∖ 376:⊆ 283:∑ 226:∑ 162:⊂ 137:… 2237:Klee, V. 2198:(1996), 2127:12971298 2050:, p. 11. 2006:(2006), 1937:(2007). 1872:12971298 1200:is any ( 1178:from a ( 861:from a ( 21:geometry 2320:0310766 2224:1409651 1921:7790459 1780:induced 1630: ( 1463:equals 1371:be the 1184:simplex 1108:j in J, 867:simplex 45:can be 2393:  2342:  2318:  2222:  2156:  2125:  2033:  1986:  1948:  1919:  1911:  1870:  1862:  1682:  1604:. The 1602:median 1426:-index 1272:) and 1258:sphere 1244:Proofs 1134:i in I 1123:i in I 1097:i in I 889:. Let 646:where 365:. Let 2391:S2CID 2154:S2CID 2123:S2CID 2011:(PDF) 1917:S2CID 1868:S2CID 1806:Notes 1585:to a 1186:Δ to 1099:and ( 869:Δ to 2340:ISBN 1984:ISBN 1960:and 1946:ISBN 1909:ISSN 1860:ISSN 1798:and 1783:path 1632:1966 1612:and 1332:Let 1156:in j 1145:in J 486:and 443:and 2417:doi 2383:doi 2306:doi 2263:doi 2212:doi 2146:doi 2115:doi 2031:Zbl 2023:doi 1899:doi 1895:126 1852:doi 1554:of 1467:+1. 1428:of 1375:of 1208:to 1154:)j 1143:)j 186:of 27:on 19:In 2434:: 2413:41 2411:, 2389:, 2379:83 2377:, 2334:, 2316:MR 2314:, 2302:38 2300:, 2294:, 2259:44 2257:, 2235:; 2220:MR 2218:, 2206:, 2202:, 2190:; 2186:; 2171:87 2152:, 2142:52 2140:, 2121:, 2111:34 2109:, 2029:, 2019:17 2017:, 2013:, 1954:. 1915:. 1907:. 1893:. 1889:. 1866:. 1858:. 1848:34 1846:. 1842:. 1828:^ 1813:^ 1802:. 1766:ch 1573:A 1276:(- 86:. 23:, 2424:. 2419:: 2398:. 2385:: 2364:. 2349:. 2323:. 2308:: 2286:. 2276:. 2265:: 2249:. 2227:. 2214:: 2208:6 2179:. 2161:. 2148:: 2130:. 2117:: 2086:. 2074:. 2038:. 2025:: 1993:. 1923:. 1901:: 1874:. 1854:: 1823:. 1762:r 1758:h 1754:c 1750:h 1746:r 1742:r 1738:S 1734:S 1716:d 1712:d 1700:r 1696:d 1679:1 1676:+ 1673:) 1670:1 1664:r 1661:( 1658:) 1655:1 1652:+ 1649:d 1646:( 1624:r 1579:d 1568:d 1564:d 1560:d 1556:d 1525:K 1521:K 1517:d 1500:2 1488:K 1476:2 1472:K 1465:d 1449:2 1437:K 1424:2 1422:Z 1403:2 1391:K 1377:K 1357:2 1345:K 1334:K 1322:f 1315:y 1301:g 1295:f 1278:x 1274:g 1270:x 1268:( 1266:g 1262:x 1254:g 1230:g 1226:K 1222:g 1218:g 1214:g 1210:d 1206:K 1202:d 1198:K 1189:R 1180:d 1168:f 1160:f 1151:j 1149:v 1140:j 1138:x 1132:) 1129:i 1127:v 1121:) 1118:i 1116:x 1112:f 1106:) 1103:j 1101:x 1095:) 1092:i 1090:x 1074:2 1071:+ 1068:d 1064:x 1060:, 1054:, 1049:2 1045:x 1041:, 1036:1 1032:x 1021:Ć’ 1005:2 1002:+ 999:d 995:x 991:, 985:, 980:2 976:x 972:, 967:1 963:x 940:2 937:+ 934:d 930:v 926:, 920:, 915:2 911:v 907:, 902:1 898:v 886:R 872:R 863:d 822:p 802:J 782:I 758:p 735:. 730:j 726:a 720:J 712:j 708:x 696:= 691:i 687:a 681:I 673:i 669:x 660:= 657:A 631:, 626:j 622:x 616:A 610:j 606:a 594:J 586:j 582:x 573:= 568:i 564:x 558:A 553:i 549:a 541:I 533:i 529:x 520:= 517:p 494:J 474:I 451:J 431:I 411:I 405:X 402:= 399:J 379:X 373:I 361:d 357:a 353:1 350:a 346:d 342:d 325:, 322:0 319:= 314:i 310:a 304:2 301:+ 298:d 293:1 290:= 287:i 278:, 275:0 272:= 267:i 263:x 257:i 253:a 247:2 244:+ 241:d 236:1 233:= 230:i 207:d 203:a 199:1 196:a 192:d 188:d 172:d 167:R 159:} 154:2 151:+ 148:d 144:x 140:, 134:, 129:2 125:x 121:, 116:1 112:x 108:{ 105:= 102:X 75:d 42:R

Index

geometry
convex sets
Johann Radon
R
partitioned
convex hulls

Euclidean plane
line segments
system of linear equations
convex combination
polynomial
Gaussian elimination
affine function
simplex
R
affine function
R
continuous function
simplex
R
hypersphere
Borsuk–Ulam theorem
sphere
Borsuk–Ulam theorem
deleted join
Z2-index
geometric median
Helly's theorem
VC dimension

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