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Rigidity matroid

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668: 691:(two triangles sharing an edge) is rigid in two dimensions, but it is not uniquely realizable because it has two different realizations, one in which the triangles are on opposite sides of the shared edge and one in which they are both on the same side. Uniquely realizable graphs are important in applications that involve reconstruction of shapes from distances, such as 687:-dimensional space if every placement of the same graph with the same edge lengths is congruent to it. Such a framework must necessarily be rigid, because otherwise there exists a continuous motion bringing it to a non-congruent placement with the same edge lengths, but unique realizability is stronger than rigidity. For instance, the 359:, a vector for each vertex specifying its speed and direction. The gradient describes a linearized approximation to the actual motion of the points, in which each point moves at constant velocity in a straight line. The gradient may be described as a row vector that has one real number coordinate for each pair 658:
Although defined in different terms (column vectors versus row vectors, or forces versus motions) static rigidity and first-order rigidity reduce to the same properties of the underlying matrix and therefore coincide with each other. In two dimensions, the generic rigidity matroid also describes the
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If the edges of the framework are assumed to be rigid bars that can neither expand nor contract (but can freely rotate) then any motion respecting this rigidity must preserve the lengths of the edges: the derivative of length, as a function of the time over which the motion occurs, must remain zero.
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showed that the same characterization is true: the independent sets form the edge sets of (2,3)-sparse graphs and the independent rigid sets form the edge sets of (2,3)-tight graphs. Based on this work the (2,3)-tight graphs (the graphs of minimally rigid generic frameworks in two dimensions) have
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number of degrees of freedom of a different kind of motion, in which each edge is constrained to stay parallel to its original position rather than being constrained to maintain the same length; however, the equivalence between rigidity and parallel motion breaks down in higher dimensions.
806:, redundantly rigid graph, and he conjectured that this is an exact characterization of the uniquely realizable frameworks. The conjecture is true for one and two dimensions; in the one-dimensional case, for instance, a graph is uniquely realizable if and only if it is connected and 1054:-sparse graph, for if not there would exist a subgraph whose number of edges would exceed the dimension of its space of equilibrium loads, from which it follows that it would have a self-stress. By similar reasoning, a set of edges that is both independent and rigid forms a 463:
of the rigidity matrix. For frameworks that are not in generic position, it is possible that some infinitesimally rigid motions (vectors in the nullspace of the rigidity matrix) are not the gradients of any continuous motion, but this cannot happen for generic frameworks.
1113:-tight graph. For instance, in one dimension, the independent sets form the edge sets of forests, (1,1)-sparse graphs, and the independent rigid sets form the edge sets of trees, (1,1)-tight graphs. In this case the rigidity matroid of a framework is the same as the 220:, an assignment of equal and opposite forces to the endpoints of each edge that is not identically zero but that adds to zero at every vertex. Thus, a set of edges forms an independent set in the rigidity matroid if and only if it has no self-stress. 575:, and when it does have this rank the only motions that preserve the lengths of the edges of the framework are the rigid motions. In this case the framework is said to be first-order (or infinitesimally) rigid. More generally, an edge 211:
is a special case of a load, in which equal and opposite forces are applied to the two endpoints of each edge (which may be imagined as a spring) and the forces formed in this way are added at each vertex. Every stress is an
216:, a load that does not impose any translational force on the whole system (the sum of its force vectors is zero) nor any rotational force. A linear dependence among the rows of the rigidity matrix may be represented as a 471:
to its original configuration. Rigid motions include translations and rotations of Euclidean space; the gradients of rigid motions form a linear space having the translations and rotations as bases, of dimension
343:. If a set has this rank, it follows that its set of stresses is the same as the space of equilibrium loads. Alternatively and equivalently, in this case every equilibrium load on the framework may be 287:. An independent set in the rigidity matroid has a system of equilibrium loads whose dimension equals the cardinality of the set, so the maximum rank that any set in the matroid can have is 810:. However, Henrickson's conjecture is false for three or more dimensions. For frameworks that are not generic, it is NP-hard to determine whether a given framework is uniquely realizable. 1273: 1111: 1052: 764: 573: 341: 285: 1480:
Eren, T.; Goldenberg, O.K.; Whiteley, W.; Yang, Y.R.; Morse, A.S.; Anderson, B.D.O.; Belhumeur, P.N. (2004), "Rigidity, computation, and randomization in network localization",
519:, which must always be a subspace of the nullspace of the rigidity matrix. Because the nullspace always has at least this dimension, the rigidity matroid can have rank at most 517: 68:. A set of edges is independent if and only if, for every edge in the set, removing the edge would increase the number of degrees of freedom of the remaining subgraph. 1275:-tight graph is minimally rigid, and characterizing the minimally rigid graphs (the bases of the rigidity matroid of the complete graph) is an important open problem. 964: 932: 851: 800: 389: 993: 900: 171:
that has as its elements the edges of the graph. A set of edges is independent, in the matroid, if it corresponds to a set of rows of the rigidity matrix that is
1211: 1191: 1171: 1147: 871: 653: 633: 613: 593: 449: 429: 409: 1592:, DIMACS Series on Discrete Mathematics and Theoretical Computer Science, vol. 4, Providence, RI: American Mathematical Society, pp. 147–155, 459:
with the row of the rigidity matrix that represents the given edge. Thus, the family of gradients of (infinitesimally) rigid motions is given by the
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and that the matroid does not have any coloops. Hendrickson proved that every uniquely realizable framework (with generic edge lengths) is either a
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edges. From the consideration of loads and stresses it can be seen that a set of edges that is independent in the rigidity matroid forms a
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This condition may be expressed in linear algebra as a constraint that the gradient vector of the motion of the vertices must have zero
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if it remains rigid after removing any one of its edges. In matroidal terms, this means that the rigidity matroid has the full rank
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If the vertices of a framework are in a motion, then that motion may be described over small scales of distance by its
1643: 1790: 1352:, Encyclopedia of Mathematics and its Applications, vol. 40, Cambridge: Cambridge Univ. Press, pp. 1–53, 347:
by a stress that generates an equal and opposite set of forces, and the framework is said to be statically rigid.
1548: 34: 1403:, Contemporary Mathematics, vol. 197, Providence, RI: American Mathematical Society, pp. 171–311, 451:-dimensional space; that is, the dimension of the gradient is the same as the width of the rigidity matrix. 1482:
Proc. Twenty-third Annual Joint Conference of the IEEE Computer and Communications Societies (INFOCOM 2004)
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Jackson, Bill; Jordán, Tibor (2005), "Connected rigidity matroids and unique realizations of graphs",
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if and only if there does not exist a continuous motion of the framework that changes the length of
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Hendrickson, Bruce (1995), "The molecule problem: exploiting structure in global optimization",
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A rigid motion of the framework is a motion such that, at each point in time, the framework is
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determine the same rigidity matroid, regardless of their specific coordinates. This is the (
1770: 1720: 1700: 1622:, Technical Report, Pittsburgh, PA: Computer Science Department, Carnegie-Mellon University 1597: 1571: 1532: 1466: 1418: 1365: 1326: 937: 905: 824: 773: 362: 93: 969: 876: 8: 172: 22: 1704: 1724: 1670: 1652: 1493: 1196: 1176: 1156: 1132: 856: 638: 618: 598: 578: 434: 414: 394: 1728: 1758: 1708: 1674: 1662: 1557: 1520: 1497: 1485: 1454: 1404: 1353: 1314: 113: 81: 38: 1766: 1743: 1716: 1593: 1585: 1567: 1528: 1462: 1414: 1396: 1361: 1357: 1345: 1322: 1114: 207:
on a framework is a system of forces on the vertices (represented as vectors). A
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that forms a rigid framework in two dimensions, the spanning Laman subgraphs of
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in land surveying, the determination of the positions of the nodes in a
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as endpoints, then the value of the entry is the difference between the
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Hendrickson, Bruce (1992), "Conditions for unique graph realizations",
1641:; Theran, L. (2009), "Sparse hypergraphs and pebble game algorithms", 1657: 460: 1524: 1458: 1318: 1691:(1970), "On graphs and the rigidity of plane skeletal structures", 356: 1751:
International Journal of Computational Geometry & Applications
231:, among which the equilibrium loads form a subspace of dimension 30: 667: 53:-dimensional space, a set of edges that defines a subgraph with 1149:
vertices forms the set of bases of the rigidity matroid of a
1744:"On the rank function of the 3-dimensional rigidity matroid" 699:, and the reconstruction of conformations of molecules via 183:
real numbers. Any two generic frameworks on the same graph
1479: 1399:(1996), "Some matroids from discrete applied geometry", 223:
The vector space of all possible loads, on a system of
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is the index of one of the Cartesian coordinates of
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for each vertex of the graph. From a framework with
1267: 1205: 1185: 1165: 1141: 1105: 1046: 987: 958: 926: 894: 865: 845: 794: 758: 647: 627: 607: 595:belongs to the matroid closure operation of a set 587: 567: 511: 443: 423: 403: 383: 335: 279: 1256: 1235: 1094: 1073: 1035: 1014: 750: 729: 559: 538: 503: 482: 327: 306: 271: 250: 167:The rigidity matroid of the given framework is a 41:with rigid edges of fixed lengths, embedded into 1782: 1129:. The family of Laman graphs on a fixed set of 675:, generically rigid but not uniquely realizable 1741: 1637: 1625: 1545: 1305:Graver, Jack E. (1991), "Rigidity matroids", 818: 88:-dimensional Euclidean space by providing a 1510: 1434: 1430: 1428: 1391: 1389: 1387: 1385: 1383: 1381: 1379: 1377: 1375: 1656: 1590:Applied Geometry and Discrete Mathematics 1561: 1448: 1408: 1348:(1992), "Matroids and rigid structures", 1193:are the bases of the rigidity matroid of 45:. In a rigidity matroid for a graph with 1584: 1395: 1344: 1300: 1298: 1296: 1294: 1292: 1290: 1288: 1216:However, in higher dimensions not every 853:-sparse if every nonempty subgraph with 706:Bruce Hendrickson defined a graph to be 666: 1425: 1372: 813: 701:nuclear magnetic resonance spectroscopy 635:but leaves the lengths of the edges in 179:if the coordinates of its vertices are 18:Abstraction of bar-and-joint frameworks 1783: 1588:(1991), "On generic global rigidity", 1304: 1742:Jackson, Bill; Jordán, Tibor (2006), 1687: 1340: 1338: 1336: 1285: 1268:{\displaystyle (d,{\binom {d+1}{2}})} 1153:, and more generally for every graph 1121: 1106:{\displaystyle (d,{\binom {d+1}{2}})} 1047:{\displaystyle (d,{\binom {d+1}{2}})} 662: 1616:Embeddability of weighted graphs in 1610: 1307:SIAM Journal on Discrete Mathematics 759:{\displaystyle dn-{\binom {d+1}{2}}} 568:{\displaystyle dn-{\binom {d+1}{2}}} 336:{\displaystyle dn-{\binom {d+1}{2}}} 280:{\displaystyle dn-{\binom {d+1}{2}}} 112:columns, an expanded version of the 104:edges, one can define a matrix with 1484:, vol. 4, pp. 2673–2684, 120:. In this matrix, the entry in row 13: 1401:Matroid theory (Seattle, WA, 1995) 1333: 1239: 1077: 1018: 733: 542: 486: 310: 254: 191:-dimensional) rigidity matroid of 14: 1807: 1644:European Journal of Combinatorics 512:{\displaystyle {\binom {d+1}{2}}} 411:is a vertex of the framework and 1735: 1681: 1631: 1549:Journal of Combinatorial Theory 1604: 1578: 1539: 1504: 1473: 1262: 1223: 1100: 1061: 1041: 1002: 953: 941: 921: 909: 840: 828: 789: 777: 378: 366: 140:. If, on the other hand, edge 1: 1278: 350: 71: 33:that describes the number of 1437:SIAM Journal on Optimization 1358:10.1017/CBO9780511662041.002 1117:of the corresponding graph. 7: 1626:Jackson & Jordán (2005) 1490:10.1109/INFCOM.2004.1354686 819:Streinu & Theran (2009) 136:is not an endpoint of edge 10: 1812: 1693:J. Engineering Mathematics 1620:-space is strongly NP-hard 1563:10.1016/j.jctb.2004.11.002 198: 1763:10.1142/S0218195906002117 1667:10.1016/j.ejc.2008.12.018 1513:SIAM Journal on Computing 181:algebraically independent 966:-sparse and has exactly 821:define a graph as being 227:vertices, has dimension 175:. A framework is called 116:of the graph called the 1791:Mathematics of rigidity 697:wireless sensor network 57:degrees of freedom has 1410:10.1090/conm/197/02540 1269: 1207: 1187: 1167: 1143: 1107: 1048: 989: 960: 928: 896: 867: 847: 796: 760: 676: 649: 629: 609: 589: 569: 513: 445: 425: 405: 385: 337: 281: 21:In the mathematics of 1270: 1208: 1188: 1168: 1144: 1108: 1049: 990: 961: 959:{\displaystyle (k,l)} 929: 927:{\displaystyle (k,l)} 897: 873:vertices has at most 868: 848: 846:{\displaystyle (k,l)} 797: 795:{\displaystyle (d+1)} 761: 670: 650: 630: 610: 590: 570: 514: 446: 426: 406: 386: 384:{\displaystyle (v,i)} 338: 282: 94:Cartesian coordinates 1350:Matroid Applications 1220: 1197: 1177: 1157: 1133: 1125:come to be known as 1058: 999: 988:{\displaystyle kn-l} 970: 938: 906: 895:{\displaystyle kn-l} 877: 857: 825: 814:Relation to sparsity 774: 714: 639: 619: 599: 579: 523: 476: 435: 415: 395: 363: 291: 235: 173:linearly independent 1705:1970JEnMa...4..331L 1120:In two dimensions, 64: −  23:structural rigidity 1713:10.1007/BF01534980 1265: 1203: 1183: 1163: 1139: 1103: 1044: 985: 956: 924: 892: 863: 843: 792: 756: 681:unique realization 679:A framework has a 677: 663:Unique realization 645: 625: 605: 585: 565: 509: 441: 421: 401: 381: 333: 277: 156:th coordinates of 35:degrees of freedom 1254: 1206:{\displaystyle G} 1186:{\displaystyle G} 1166:{\displaystyle G} 1142:{\displaystyle n} 1092: 1033: 866:{\displaystyle n} 748: 708:redundantly rigid 648:{\displaystyle S} 628:{\displaystyle e} 608:{\displaystyle S} 588:{\displaystyle e} 557: 501: 444:{\displaystyle d} 424:{\displaystyle i} 404:{\displaystyle v} 325: 269: 1803: 1775: 1773: 1757:(5–6): 415–429, 1748: 1739: 1733: 1731: 1685: 1679: 1677: 1660: 1651:(8): 1944–1964, 1635: 1629: 1623: 1608: 1602: 1600: 1586:Connelly, Robert 1582: 1576: 1574: 1565: 1543: 1537: 1535: 1508: 1502: 1500: 1477: 1471: 1469: 1452: 1432: 1423: 1421: 1412: 1397:Whiteley, Walter 1393: 1370: 1368: 1346:Whiteley, Walter 1342: 1331: 1329: 1302: 1274: 1272: 1271: 1266: 1261: 1260: 1259: 1250: 1238: 1212: 1210: 1209: 1204: 1192: 1190: 1189: 1184: 1172: 1170: 1169: 1164: 1148: 1146: 1145: 1140: 1112: 1110: 1109: 1104: 1099: 1098: 1097: 1088: 1076: 1053: 1051: 1050: 1045: 1040: 1039: 1038: 1029: 1017: 994: 992: 991: 986: 965: 963: 962: 957: 934:-tight if it is 933: 931: 930: 925: 901: 899: 898: 893: 872: 870: 869: 864: 852: 850: 849: 844: 804:vertex-connected 801: 799: 798: 793: 765: 763: 762: 757: 755: 754: 753: 744: 732: 654: 652: 651: 646: 634: 632: 631: 626: 614: 612: 611: 606: 594: 592: 591: 586: 574: 572: 571: 566: 564: 563: 562: 553: 541: 518: 516: 515: 510: 508: 507: 506: 497: 485: 450: 448: 447: 442: 430: 428: 427: 422: 410: 408: 407: 402: 390: 388: 387: 382: 342: 340: 339: 334: 332: 331: 330: 321: 309: 286: 284: 283: 278: 276: 275: 274: 265: 253: 214:equilibrium load 114:incidence matrix 84:, embedded into 82:undirected graph 39:undirected graph 27:rigidity matroid 1811: 1810: 1806: 1805: 1804: 1802: 1801: 1800: 1781: 1780: 1779: 1778: 1746: 1740: 1736: 1686: 1682: 1636: 1632: 1609: 1605: 1583: 1579: 1544: 1540: 1525:10.1137/0221008 1509: 1505: 1478: 1474: 1459:10.1137/0805040 1433: 1426: 1394: 1373: 1343: 1334: 1319:10.1137/0404032 1303: 1286: 1281: 1255: 1240: 1234: 1233: 1232: 1221: 1218: 1217: 1198: 1195: 1194: 1178: 1175: 1174: 1158: 1155: 1154: 1134: 1131: 1130: 1115:graphic matroid 1093: 1078: 1072: 1071: 1070: 1059: 1056: 1055: 1034: 1019: 1013: 1012: 1011: 1000: 997: 996: 971: 968: 967: 939: 936: 935: 907: 904: 903: 878: 875: 874: 858: 855: 854: 826: 823: 822: 816: 775: 772: 771: 749: 734: 728: 727: 726: 715: 712: 711: 665: 640: 637: 636: 620: 617: 616: 600: 597: 596: 580: 577: 576: 558: 543: 537: 536: 535: 524: 521: 520: 502: 487: 481: 480: 479: 477: 474: 473: 436: 433: 432: 416: 413: 412: 396: 393: 392: 364: 361: 360: 353: 326: 311: 305: 304: 303: 292: 289: 288: 270: 255: 249: 248: 247: 236: 233: 232: 201: 118:rigidity matrix 74: 43:Euclidean space 19: 12: 11: 5: 1809: 1799: 1798: 1796:Matroid theory 1793: 1777: 1776: 1734: 1699:(4): 331–340, 1680: 1630: 1624:. As cited by 1603: 1577: 1538: 1503: 1472: 1450:10.1.1.55.2335 1443:(4): 835–857, 1424: 1371: 1332: 1313:(3): 355–368, 1283: 1282: 1280: 1277: 1264: 1258: 1253: 1249: 1246: 1243: 1237: 1231: 1228: 1225: 1202: 1182: 1162: 1151:complete graph 1138: 1102: 1096: 1091: 1087: 1084: 1081: 1075: 1069: 1066: 1063: 1043: 1037: 1032: 1028: 1025: 1022: 1016: 1010: 1007: 1004: 984: 981: 978: 975: 955: 952: 949: 946: 943: 923: 920: 917: 914: 911: 891: 888: 885: 882: 862: 842: 839: 836: 833: 830: 815: 812: 791: 788: 785: 782: 779: 768:complete graph 752: 747: 743: 740: 737: 731: 725: 722: 719: 664: 661: 644: 624: 604: 584: 561: 556: 552: 549: 546: 540: 534: 531: 528: 505: 500: 496: 493: 490: 484: 440: 420: 400: 380: 377: 374: 371: 368: 352: 349: 329: 324: 320: 317: 314: 308: 302: 299: 296: 273: 268: 264: 261: 258: 252: 246: 243: 240: 200: 197: 169:linear matroid 73: 70: 17: 9: 6: 4: 3: 2: 1808: 1797: 1794: 1792: 1789: 1788: 1786: 1772: 1768: 1764: 1760: 1756: 1752: 1745: 1738: 1730: 1726: 1722: 1718: 1714: 1710: 1706: 1702: 1698: 1694: 1690: 1684: 1676: 1672: 1668: 1664: 1659: 1654: 1650: 1646: 1645: 1640: 1634: 1627: 1621: 1617: 1613: 1607: 1599: 1595: 1591: 1587: 1581: 1573: 1569: 1564: 1559: 1555: 1551: 1550: 1542: 1534: 1530: 1526: 1522: 1518: 1514: 1507: 1499: 1495: 1491: 1487: 1483: 1476: 1468: 1464: 1460: 1456: 1451: 1446: 1442: 1438: 1431: 1429: 1420: 1416: 1411: 1406: 1402: 1398: 1392: 1390: 1388: 1386: 1384: 1382: 1380: 1378: 1376: 1367: 1363: 1359: 1355: 1351: 1347: 1341: 1339: 1337: 1328: 1324: 1320: 1316: 1312: 1308: 1301: 1299: 1297: 1295: 1293: 1291: 1289: 1284: 1276: 1251: 1247: 1244: 1241: 1229: 1226: 1214: 1200: 1180: 1160: 1152: 1136: 1128: 1123: 1118: 1116: 1089: 1085: 1082: 1079: 1067: 1064: 1030: 1026: 1023: 1020: 1008: 1005: 982: 979: 976: 973: 950: 947: 944: 918: 915: 912: 889: 886: 883: 880: 860: 837: 834: 831: 820: 811: 809: 805: 786: 783: 780: 769: 745: 741: 738: 735: 723: 720: 717: 709: 704: 702: 698: 694: 693:triangulation 690: 689:diamond graph 686: 682: 674: 673:diamond graph 669: 660: 656: 642: 622: 602: 582: 554: 550: 547: 544: 532: 529: 526: 498: 494: 491: 488: 470: 465: 462: 458: 457:inner product 452: 438: 418: 398: 375: 372: 369: 358: 348: 346: 322: 318: 315: 312: 300: 297: 294: 266: 262: 259: 256: 244: 241: 238: 230: 226: 221: 219: 215: 210: 206: 196: 194: 190: 186: 182: 178: 174: 170: 165: 163: 159: 155: 151: 147: 144:has vertices 143: 139: 135: 132:) is zero if 131: 127: 123: 119: 115: 111: 107: 103: 100:vertices and 99: 95: 91: 87: 83: 79: 69: 67: 63: 60: 56: 52: 48: 44: 40: 36: 32: 28: 24: 16: 1754: 1750: 1737: 1696: 1692: 1683: 1658:math/0703921 1648: 1642: 1633: 1619: 1615: 1606: 1589: 1580: 1553: 1552:, Series B, 1547: 1541: 1519:(1): 65–84, 1516: 1512: 1506: 1481: 1475: 1440: 1436: 1400: 1349: 1310: 1306: 1215: 1127:Laman graphs 1122:Laman (1970) 1119: 817: 707: 705: 684: 680: 678: 657: 466: 453: 354: 344: 228: 224: 222: 217: 213: 208: 204: 202: 192: 188: 184: 176: 166: 161: 157: 153: 149: 145: 141: 137: 133: 129: 125: 124:and column ( 121: 117: 109: 105: 101: 97: 89: 85: 77: 75: 65: 61: 59:matroid rank 54: 50: 49:vertices in 46: 26: 20: 15: 1639:Streinu, I. 1612:Saxe, J. B. 1556:(1): 1–29, 902:edges, and 655:unchanged. 218:self-stress 1785:Categories 1279:References 808:bridgeless 351:Kinematics 92:-tuple of 72:Definition 1729:122631794 1689:Laman, G. 1445:CiteSeerX 980:− 887:− 724:− 533:− 469:congruent 461:nullspace 301:− 245:− 108:rows and 78:framework 1614:(1979), 357:gradient 345:resolved 1771:2269396 1721:0269535 1701:Bibcode 1675:5477763 1598:1116345 1572:2130278 1533:1148818 1498:5674760 1467:1358807 1419:1411692 1366:1165538 1327:1105942 199:Statics 177:generic 31:matroid 1769:  1727:  1719:  1673:  1596:  1570:  1531:  1496:  1465:  1447:  1417:  1364:  1325:  391:where 209:stress 80:is an 37:of an 1747:(PDF) 1725:S2CID 1671:S2CID 1653:arXiv 1494:S2CID 770:or a 29:is a 671:The 205:load 160:and 148:and 25:, a 1759:doi 1709:doi 1663:doi 1558:doi 1521:doi 1486:doi 1455:doi 1405:doi 1354:doi 1315:doi 683:in 1787:: 1767:MR 1765:, 1755:16 1753:, 1749:, 1723:, 1717:MR 1715:, 1707:, 1695:, 1669:, 1661:, 1649:30 1647:, 1594:MR 1568:MR 1566:, 1554:94 1529:MR 1527:, 1517:21 1515:, 1492:, 1463:MR 1461:, 1453:, 1439:, 1427:^ 1415:MR 1413:, 1374:^ 1362:MR 1360:, 1335:^ 1323:MR 1321:, 1309:, 1287:^ 1213:. 703:. 229:dn 203:A 195:. 164:. 110:nd 76:A 62:dn 1774:. 1761:: 1732:. 1711:: 1703:: 1697:4 1678:. 1665:: 1655:: 1628:. 1618:k 1601:. 1575:. 1560:: 1536:. 1523:: 1501:. 1488:: 1470:. 1457:: 1441:5 1422:. 1407:: 1369:. 1356:: 1330:. 1317:: 1311:4 1263:) 1257:) 1252:2 1248:1 1245:+ 1242:d 1236:( 1230:, 1227:d 1224:( 1201:G 1181:G 1161:G 1137:n 1101:) 1095:) 1090:2 1086:1 1083:+ 1080:d 1074:( 1068:, 1065:d 1062:( 1042:) 1036:) 1031:2 1027:1 1024:+ 1021:d 1015:( 1009:, 1006:d 1003:( 983:l 977:n 974:k 954:) 951:l 948:, 945:k 942:( 922:) 919:l 916:, 913:k 910:( 890:l 884:n 881:k 861:n 841:) 838:l 835:, 832:k 829:( 802:- 790:) 787:1 784:+ 781:d 778:( 751:) 746:2 742:1 739:+ 736:d 730:( 721:n 718:d 685:d 643:S 623:e 603:S 583:e 560:) 555:2 551:1 548:+ 545:d 539:( 530:n 527:d 504:) 499:2 495:1 492:+ 489:d 483:( 439:d 419:i 399:v 379:) 376:i 373:, 370:v 367:( 328:) 323:2 319:1 316:+ 313:d 307:( 298:n 295:d 272:) 267:2 263:1 260:+ 257:d 251:( 242:n 239:d 225:n 193:G 189:d 185:G 162:u 158:v 154:i 150:v 146:u 142:e 138:e 134:v 130:i 128:, 126:v 122:e 106:m 102:m 98:n 90:d 86:d 66:k 55:k 51:d 47:n

Index

structural rigidity
matroid
degrees of freedom
undirected graph
Euclidean space
matroid rank
undirected graph
Cartesian coordinates
incidence matrix
linear matroid
linearly independent
algebraically independent
gradient
inner product
nullspace
congruent

diamond graph
diamond graph
triangulation
wireless sensor network
nuclear magnetic resonance spectroscopy
complete graph
vertex-connected
bridgeless
Streinu & Theran (2009)
graphic matroid
Laman (1970)
Laman graphs
complete graph

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