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Gale diagram

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1632:, a 4-dimensional polytope with 8 vertices, 10 tetrahedral facets, and one octahedral facet, constructed by Peter Kleinschmidt. Although the octahedral facet has the same combinatorial structure as a regular octahedron, it is not possible for it to be regular. Two copies of this polytope can be glued together on their octahedral facets to produce a 10-vertex polytope in which some pairs of realizations cannot be continuously deformed into each other. 1221:. In the affine diagram, the points are zero-dimensional, so they can be represented only by their signs or colors without any location value. In order to represent a polytope, the diagram must have at least two points with each nonzero sign. Two diagrams represent the same combinatorial equivalence class of polytopes when they have the same numbers of points of each sign, or when they can be obtained from each other by negating all of the signs. 1625:(nine points and nine lines in the plane that cannot be realized with rational coordinates) by doubling three of the points, assigning signs to the resulting 12 points, and treating the resulting signed configuration as the Gale diagram of a polytope. Although irrational polytopes are known with dimension as low as four, none are known with fewer vertices. 33: 1003:. As with the linear diagram, a subset of vertices forms a face if and only if there is no affine function (a linear function with a possibly nonzero constant term) that assigns a non-negative value to each positive vector in the complementary set and a non-positive value to each negative vector in the complementary set. 98:
of the polytope. It can be used to describe high-dimensional polytopes with few vertices, by transforming them into sets with the same number of points, but in a space of a much lower dimension. The process can also be reversed, to construct polytopes with desired properties from their Gale diagrams.
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and which lie below it, but this information can be represented by assigning a sign (positive, negative, or zero) or equivalently a color (black, white, or gray) to each point. The resulting set of signed or colored points is the affine Gale diagram of the given polytope. This construction has the
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has linear Gale diagram comprising six points on the circle, in three diametrically opposed pairs, with each pair representing vertices of the prism that are adjacent on two square faces of the prism. The corresponding affine Gale diagram has three pairs of points on a line, like the regular
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have these properties, but in 16 or more dimensions there exist illuminated polytopes with fewer vertices, and in 6 or more dimensions the illuminated polytopes with the fewest vertices need not be simplicial. The construction involves Gale
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Three-dimensional polyhedra with six vertices provide natural examples where the original polyhedron is of a low enough dimension to visualize, but where the Gale diagram still provides a dimension-reducing effect.
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has linear Gale diagram comprising three pairs of equal points on the unit circle (representing pairs of opposite vertices of the octahedron), dividing the circle into arcs of angle less than
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A proper subset of the vertices of a polytope forms the vertex set of a face of the polytope, if and only if the complementary set of vectors of the Gale transform has a
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The Gale diagram is particularly effective in describing polyhedra whose numbers of vertices are only slightly larger than their dimensions.
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The bipyramid over a square pyramid is a 4-dimensional polytope with 7 vertices having the dual property, that the shape of one of its
1650:, and "illuminated polytopes", in which every vertex is incident to a diagonal that passes through the interior of the polytope. The 2073: 2047: 1964: 69: 1155:
vertices, the linear Gale diagram is one-dimensional, with the vector representing each point being one of the three numbers
755:. The linear Gale diagram is a normalized version of the Gale transform, in which all the vectors are zero or unit vectors. 713:
Because the Gale transform is defined only up to a linear transformation, its nonzero vectors can be normalized to all be
1280:, there are two possible Gale diagrams: the diagram with two points of each nonzero sign and one zero point represents a 1639:(the apex of its central pyramid) cannot be prescribed. Originally found by David W. Barnette, it was rediscovered by 1075:. In this case, the linear Gale diagram is 0-dimensional, consisting only of zero vectors. The affine diagram has 992:
advantage, over the Gale transform, of using one less dimension to represent the structure of the given polytope.
1951:, Student Mathematical Library, vol. 33, Institute for Advanced Study (IAS), Princeton, NJ, pp. 37–45, 1550: 1981:
Wotzlaw, Ronald F.; Ziegler, Günter M. (2011), "A lost counterexample and a problem on illuminated polytopes",
83: 1366: 1284:, while the diagram with two points of one nonzero sign and three points with the other sign represents the 360: 1629: 1990: 1902:, Annals of Mathematics Studies, no. 38, Princeton University Press, Princeton, N.J., pp. 255–263, 1500:
vertices, it is not completely trivial to determine when two Gale diagrams represent the same polytope.
1836:, Section 6.5(b) "Facets of 4-polytopes cannot be prescribed", pp. 173–175, and Exercise 6.18, p. 188; 2027: 1914:
Sturmfels, Bernd (1988), "Some applications of affine Gale diagrams to polytopes with few vertices",
1622: 1614: 1610: 1285: 698: 478: 201: 161: 1995: 246: 104: 2016: 1509: 905: 2043: 1960: 702: 664: 2034:, Graduate Texts in Mathematics, vol. 152, New York: Springer-Verlag, pp. 149–190, 936: 824: 786: 716: 2035: 2000: 1952: 1923: 1647: 1536: 1000: 2057: 2012: 1974: 1935: 1907: 1576: 1471: 1435: 1294: 1126: 1042: 589: 406: 304: 167: 2053: 2008: 1970: 1942: 1931: 1903: 1640: 1515: 91: 2004: 1257: 1227: 971:-dimensional points. This projection loses the information about which vectors lie above 336: 1201: 1158: 911: 882: 1651: 1556: 1415: 1346: 1326: 1281: 1181: 1106: 1078: 1022: 974: 862: 766: 644: 624: 566: 546: 526: 458: 438: 386: 366: 284: 226: 206: 143: 123: 995:
Gale transforms and linear and affine Gale diagrams can also be described through the
2067: 1636: 1251: 197: 2020: 1618: 1613:, an 8-dimensional polytope with 12 vertices that cannot be realized with rational 996: 1646:
The construction of small "unneighborly polytopes", that is, polytopes without a
1250:, the only possibility is two points of each nonzero sign, representing a convex 661:-dimensional polytope, but the dimension of the Gale diagram is smaller whenever 2039: 1465: 752: 694: 403:
original vertices with coefficients summing to zero; this kernel has dimension
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vertices, and to construct polytopes with unusual properties. These include:
1864:, Section 6.5(b) "Facets of 4-polytopes cannot be prescribed", pp. 173–175; 621:
Note that the vectors in the Gale diagram are in natural bijection with the
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through the origin that avoids all of the vectors, and a parallel subspace
1852:, Section 6.5(d) "Polytopes violating the isotopy conjecture", pp. 177–179 94:
into a set of vectors or points in a space of a different dimension, the
1956: 1072: 1927: 1898:
Gale, David (1956), "Neighboring vertices on a convex polyhedron",
2030:(1995), "Chapter 6: Duality, Gale Diagrams, and Applications", 26: 1464:
vertices, the linear Gale diagram consists of points on the
1820:, Section 6.5(a) "A nonrational 8-polytope", pp. 172–173; 1540:
octahedron, but with one point of each sign in each pair.
1323:, and the number of combinatorial equivalence classes of 47: 1291:
In general, the number of distinct Gale diagrams with
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Given a Gale diagram of a polytope, that is, a set of
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The Gale transform and Gale diagram are named after
1549:Gale diagrams have been used to provide a complete 42:
may be too technical for most readers to understand
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Then, a 1881: 8: 1391: 1370: 1994: 1865: 1837: 1801: 1708: 1578: 1558: 1517: 1473: 1437: 1417: 1383: 1377: 1368: 1348: 1328: 1296: 1259: 1229: 1203: 1183: 1160: 1128: 1108: 1080: 1044: 1024: 976: 938: 913: 884: 864: 826: 788: 768: 718: 666: 646: 626: 591: 568: 548: 528: 480: 460: 440: 408: 388: 368: 338: 306: 286: 248: 228: 208: 169: 145: 125: 70:Learn how and when to remove this message 54:, without removing the technical details. 383:describes linear dependencies among the 1861: 1849: 1833: 1817: 1805: 1777: 1765: 1744: 1732: 1665: 1397:{\displaystyle \lfloor d^{2}/4\rfloor } 1900:Linear inequalities and related system 1869: 1821: 1789: 1761: 1759: 1757: 1755: 1753: 1720: 1696: 1684: 1071:vertices, the minimum possible, is a 821:-dimensional space, one can choose a 523:are a chosen basis for the kernel of 52:make it understandable to non-experts 7: 2005:10.4169/amer.math.monthly.118.06.534 1945:(2006), "Chapter 5: Gale Diagrams", 1916:SIAM Journal on Discrete Mathematics 1672: 1948:Lectures in Geometric Combinatorics 82:In the mathematical discipline of 25: 281:, defining a linear mapping from 31: 512:{\displaystyle n\times (n-d-1)} 958: 940: 846: 828: 808: 790: 738: 720: 506: 488: 320: 308: 262: 250: 243:column vectors has dimensions 183: 171: 1: 1983:American Mathematical Monthly 333:-space, surjective with rank 274:{\displaystyle (d+1)\times n} 1882:Wotzlaw & Ziegler (2011) 1573:-dimensional polytopes with 1343:-dimensional polytopes with 164:of each vertex, to obtain a 140:-dimensional polytope, with 2040:10.1007/978-1-4613-8431-1_6 1868:, Proposition 5.1, p. 130; 1432:-dimensional polytope with 1123:-dimensional polytope with 1039:-dimensional polytope with 2090: 160:vertices, adjoin 1 to the 90:turns the vertices of any 1872:, Theorem 6.12, pp. 53–55 1824:, Theorem 6.11, pp. 51–52 1735:, Definition 6.17, p. 168 1551:combinatorial enumeration 641:vertices of the original 2074:Polyhedral combinatorics 1621:constructed it from the 683:{\displaystyle n\leq 2d} 435:. The Gale transform of 84:polyhedral combinatorics 1687:, Definition 5.2, p. 38 1408:Two additional vertices 964:{\displaystyle (n-d-2)} 852:{\displaystyle (n-d-2)} 814:{\displaystyle (n-d-1)} 744:{\displaystyle (n-d-1)} 1780:, Example 6.18, p. 169 1599: 1567: 1526: 1494: 1458: 1426: 1398: 1357: 1337: 1317: 1274: 1244: 1215: 1192: 1172: 1149: 1117: 1089: 1065: 1033: 985: 965: 933:will produce a set of 927: 898: 873: 859:-dimensional subspace 853: 815: 777: 745: 684: 655: 635: 612: 577: 557: 537: 513: 469: 449: 429: 397: 377: 353: 327: 295: 275: 237: 217: 190: 154: 134: 2032:Lectures on Polytopes 1630:Kleinschmidt polytope 1615:Cartesian coordinates 1600: 1598:{\displaystyle n=d+3} 1568: 1527: 1495: 1493:{\displaystyle n=d+2} 1459: 1457:{\displaystyle n=d+3} 1427: 1399: 1358: 1338: 1318: 1316:{\displaystyle n=d+2} 1275: 1245: 1216: 1193: 1173: 1150: 1148:{\displaystyle n=d+2} 1118: 1099:One additional vertex 1090: 1066: 1064:{\displaystyle n=d+1} 1034: 986: 966: 928: 899: 874: 854: 816: 778: 746: 685: 656: 636: 613: 611:{\displaystyle n-d-1} 578: 558: 538: 514: 470: 450: 430: 428:{\displaystyle n-d-1} 398: 378: 354: 328: 326:{\displaystyle (d+1)} 296: 276: 238: 218: 191: 189:{\displaystyle (d+1)} 162:Cartesian coordinates 155: 135: 1699:, Theorem 5.6, p. 41 1643:using Gale diagrams. 1623:Perles configuration 1577: 1557: 1525:{\displaystyle \pi } 1516: 1472: 1436: 1416: 1367: 1347: 1327: 1295: 1286:triangular bipyramid 1258: 1228: 1202: 1182: 1159: 1127: 1107: 1079: 1043: 1023: 975: 937: 912: 883: 863: 825: 787: 767: 717: 665: 645: 625: 590: 567: 547: 527: 479: 459: 439: 407: 387: 367: 337: 305: 285: 247: 227: 207: 168: 144: 124: 105:neighborly polytopes 1273:{\displaystyle d=3} 1243:{\displaystyle d=2} 908:from the origin to 783:unit vectors in an 352:{\displaystyle d+1} 2028:Ziegler, Günter M. 1595: 1563: 1522: 1510:regular octahedron 1490: 1454: 1422: 1394: 1353: 1333: 1313: 1270: 1240: 1214:{\displaystyle +1} 1211: 1188: 1171:{\displaystyle -1} 1168: 1145: 1113: 1085: 1061: 1029: 981: 961: 926:{\displaystyle S'} 923: 906:central projection 897:{\displaystyle S'} 894: 869: 849: 811: 773: 741: 697:that contains the 680: 651: 631: 608: 573: 553: 533: 509: 465: 445: 425: 393: 373: 349: 323: 291: 271: 233: 213: 186: 150: 130: 1566:{\displaystyle d} 1425:{\displaystyle d} 1356:{\displaystyle n} 1336:{\displaystyle d} 1191:{\displaystyle 0} 1116:{\displaystyle d} 1088:{\displaystyle n} 1032:{\displaystyle d} 1001:oriented matroids 984:{\displaystyle S} 872:{\displaystyle S} 776:{\displaystyle n} 703:relative interior 654:{\displaystyle d} 634:{\displaystyle n} 576:{\displaystyle n} 556:{\displaystyle B} 536:{\displaystyle A} 468:{\displaystyle B} 448:{\displaystyle A} 396:{\displaystyle n} 376:{\displaystyle A} 294:{\displaystyle n} 236:{\displaystyle n} 216:{\displaystyle A} 153:{\displaystyle n} 133:{\displaystyle d} 80: 79: 72: 16:(Redirected from 2081: 2060: 2023: 1998: 1977: 1957:10.1090/stml/033 1943:Thomas, Rekha R. 1938: 1910: 1885: 1879: 1873: 1866:Sturmfels (1988) 1859: 1853: 1847: 1841: 1838:Sturmfels (1988) 1831: 1825: 1815: 1809: 1802:Sturmfels (1988) 1799: 1793: 1787: 1781: 1775: 1769: 1763: 1748: 1742: 1736: 1730: 1724: 1718: 1712: 1709:Sturmfels (1988) 1706: 1700: 1694: 1688: 1682: 1676: 1670: 1648:universal vertex 1604: 1602: 1601: 1596: 1572: 1570: 1569: 1564: 1537:triangular prism 1531: 1529: 1528: 1523: 1499: 1497: 1496: 1491: 1463: 1461: 1460: 1455: 1431: 1429: 1428: 1423: 1403: 1401: 1400: 1395: 1387: 1382: 1381: 1362: 1360: 1359: 1354: 1342: 1340: 1339: 1334: 1322: 1320: 1319: 1314: 1279: 1277: 1276: 1271: 1249: 1247: 1246: 1241: 1220: 1218: 1217: 1212: 1197: 1195: 1194: 1189: 1177: 1175: 1174: 1169: 1154: 1152: 1151: 1146: 1122: 1120: 1119: 1114: 1094: 1092: 1091: 1086: 1070: 1068: 1067: 1062: 1038: 1036: 1035: 1030: 990: 988: 987: 982: 970: 968: 967: 962: 932: 930: 929: 924: 922: 903: 901: 900: 895: 893: 878: 876: 875: 870: 858: 856: 855: 850: 820: 818: 817: 812: 782: 780: 779: 774: 750: 748: 747: 742: 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1733:Ziegler (1995) 1725: 1713: 1701: 1689: 1677: 1664: 1663: 1661: 1658: 1657: 1656: 1644: 1637:vertex figures 1633: 1626: 1594: 1591: 1588: 1585: 1582: 1562: 1546: 1543: 1542: 1541: 1533: 1521: 1489: 1486: 1483: 1480: 1477: 1453: 1450: 1447: 1444: 1441: 1421: 1409: 1406: 1393: 1390: 1386: 1380: 1376: 1372: 1352: 1332: 1312: 1309: 1306: 1303: 1300: 1282:square pyramid 1269: 1266: 1263: 1239: 1236: 1233: 1210: 1207: 1187: 1167: 1164: 1144: 1141: 1138: 1135: 1132: 1112: 1100: 1097: 1084: 1060: 1057: 1054: 1051: 1048: 1028: 1016: 1013: 1008: 1005: 980: 960: 957: 954: 951: 948: 945: 942: 921: 918: 892: 889: 868: 848: 845: 842: 839: 836: 833: 830: 810: 807: 804: 801: 798: 795: 792: 772: 760: 759:Affine diagram 757: 740: 737: 734: 731: 728: 725: 722: 710: 709:Linear diagram 707: 679: 676: 673: 670: 650: 630: 607: 604: 601: 598: 595: 572: 552: 532: 521:column vectors 508: 505: 502: 499: 496: 493: 490: 487: 484: 464: 444: 424: 421: 418: 415: 412: 392: 372: 348: 345: 342: 322: 319: 316: 313: 310: 290: 270: 267: 264: 261: 258: 255: 252: 232: 212: 185: 182: 179: 176: 173: 149: 129: 117: 114: 112: 109: 88:Gale transform 78: 77: 39: 37: 30: 24: 18:Gale transform 14: 13: 10: 9: 6: 4: 3: 2: 2086: 2075: 2072: 2071: 2069: 2059: 2055: 2051: 2049:0-387-94365-X 2045: 2041: 2037: 2033: 2029: 2025: 2022: 2018: 2014: 2010: 2006: 2002: 1997: 1992: 1988: 1984: 1979: 1976: 1972: 1968: 1966:0-8218-4140-8 1962: 1958: 1954: 1950: 1949: 1944: 1940: 1937: 1933: 1929: 1925: 1921: 1917: 1912: 1909: 1905: 1901: 1896: 1895: 1891: 1883: 1878: 1875: 1871: 1870:Thomas (2006) 1867: 1863: 1858: 1855: 1851: 1846: 1843: 1840:, pp. 129–130 1839: 1835: 1830: 1827: 1823: 1822:Thomas (2006) 1819: 1814: 1811: 1807: 1803: 1798: 1795: 1791: 1790:Thomas (2006) 1786: 1783: 1779: 1774: 1771: 1767: 1762: 1760: 1758: 1756: 1754: 1750: 1746: 1741: 1738: 1734: 1729: 1726: 1722: 1721:Thomas (2006) 1717: 1714: 1710: 1705: 1702: 1698: 1697:Thomas (2006) 1693: 1690: 1686: 1685:Thomas (2006) 1681: 1678: 1674: 1669: 1666: 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419: 416: 413: 410: 390: 370: 362: 346: 343: 340: 317: 314: 311: 288: 268: 265: 259: 256: 253: 230: 210: 203: 199: 198:column vector 196:-dimensional 180: 177: 174: 163: 147: 127: 115: 110: 108: 106: 102: 97: 93: 89: 85: 74: 71: 63: 53: 49: 43: 40:This article 38: 29: 28: 19: 2031: 1986: 1982: 1947: 1919: 1915: 1899: 1877: 1857: 1845: 1829: 1813: 1797: 1785: 1773: 1740: 1728: 1716: 1704: 1692: 1680: 1668: 1619:Micha Perles 1548: 1545:Applications 1502: 1411: 1290: 1223: 1102: 1018: 1010: 994: 762: 753:unit vectors 712: 692: 620: 583: 520: 455:is a matrix 119: 96:Gale diagram 95: 87: 81: 66: 60:October 2022 57: 41: 1723:, p. 43–44. 1673:Gale (1956) 1466:unit circle 695:convex hull 584:row vectors 111:Definitions 1892:References 1804:, p. 121; 301:-space to 101:David Gale 1991:CiteSeerX 1768:, p. 171. 1655:diagrams. 1520:π 1392:⌋ 1371:⌊ 1163:− 1015:Simplices 953:− 947:− 841:− 835:− 803:− 797:− 733:− 727:− 672:≤ 603:− 597:− 501:− 495:− 486:× 420:− 414:− 266:× 223:of these 116:Transform 2068:Category 2021:15007113 1808:, p. 172 1747:, p. 170 1007:Examples 920:′ 891:′ 519:, whose 120:Given a 2058:1311028 2013:2812284 1975:2237292 1936:0936614 1908:0085552 1553:of the 1073:simplex 997:duality 701:in its 543:. Then 46:Please 2056:  2046:  2019:  2011:  1993:  1973:  1963:  1934:  1906:  1254:. For 699:origin 361:kernel 359:. The 202:matrix 200:. The 86:, the 2017:S2CID 1660:Notes 1412:In a 1198:, or 1103:In a 2044:ISBN 1961:ISBN 1628:The 1609:The 1224:For 563:has 2036:doi 2001:doi 1987:118 1953:doi 1924:doi 999:of 363:of 50:to 2070:: 2054:MR 2052:, 2042:, 2015:, 2009:MR 2007:, 1999:, 1985:, 1971:MR 1969:, 1959:, 1932:MR 1930:, 1918:, 1904:MR 1752:^ 1617:. 1535:A 1508:A 1404:. 1288:. 1178:, 1019:A 690:. 107:. 2038:: 2003:: 1955:: 1926:: 1920:1 1884:. 1711:. 1675:. 1593:3 1590:+ 1587:d 1584:= 1581:n 1561:d 1488:2 1485:+ 1482:d 1479:= 1476:n 1452:3 1449:+ 1446:d 1443:= 1440:n 1420:d 1389:4 1385:/ 1379:2 1375:d 1351:n 1331:d 1311:2 1308:+ 1305:d 1302:= 1299:n 1268:3 1265:= 1262:d 1238:2 1235:= 1232:d 1209:1 1206:+ 1186:0 1166:1 1143:2 1140:+ 1137:d 1134:= 1131:n 1111:d 1083:n 1059:1 1056:+ 1053:d 1050:= 1047:n 1027:d 979:S 959:) 956:2 950:d 944:n 941:( 917:S 888:S 867:S 847:) 844:2 838:d 832:n 829:( 809:) 806:1 800:d 794:n 791:( 771:n 739:) 736:1 730:d 724:n 721:( 678:d 675:2 669:n 649:d 629:n 606:1 600:d 594:n 571:n 551:B 531:A 507:) 504:1 498:d 492:n 489:( 483:n 463:B 443:A 423:1 417:d 411:n 391:n 371:A 347:1 344:+ 341:d 321:) 318:1 315:+ 312:d 309:( 289:n 269:n 263:) 260:1 257:+ 254:d 251:( 231:n 211:A 184:) 181:1 178:+ 175:d 172:( 148:n 128:d 73:) 67:( 62:) 58:( 44:. 20:)

Index

Gale transform
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polyhedral combinatorics
convex polytope
David Gale
neighborly polytopes
Cartesian coordinates
column vector
matrix
kernel
convex hull
origin
relative interior
unit vectors
central projection
duality
oriented matroids
simplex
quadrilateral
square pyramid
triangular bipyramid
unit circle
regular octahedron
triangular prism
combinatorial enumeration
Perles polytope
Cartesian coordinates
Micha Perles

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