Knowledge (XXG)

Zig-zag product

Source đź“ť

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Roughly speaking, in order to solve the undirected s-t connectivity problem in logarithmic space, the input graph is transformed, using a combination of powering and the zigzag product, into a constant-degree regular graph with a logarithmic diameter. The power product increases the expansion (hence
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In 2002 Omer Reingold, Salil Vadhan, and Avi Wigderson gave a simple, explicit combinatorial construction of constant-degree expander graphs. The construction is iterative, and needs as a basic building block a single, expander of constant size. In each iteration the zigzag product is used in order
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From the properties of the zigzag product mentioned above, we see that the product of a large graph with a small graph, inherits a size similar to the large graph, and degree similar to the small graph, while preserving its expansion properties from both, thus enabling to increase the size of the
1735: 1642: 945: 864: 783: 701: 2044: 254:, and connects the vertices by moving a small step (zig) inside a cloud, followed by a big step (zag) between two clouds, and finally performs another small step inside the destination cloud. 2208:
problem, the problem of testing whether there is a path between two given vertices in an undirected graph, using only logarithmic space. The algorithm relies heavily on the zigzag product.
1503: 1417: 1014: 620: 261:. When the zig-zag product was first introduced, it was used for the explicit construction of constant degree expanders and extractors. Later on, the zig-zag product was used in 488: 387: 1543: 1268: 1956: 1769: 1328: 514: 212: 91: 579: 2076: 1444: 1358: 1075: 541: 65: 2192:
to generate another graph whose size is increased but its degree and expansion remains unchanged. This process continues, yielding arbitrarily large expanders.
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reduces the diameter) at the price of increasing the degree, and the zigzag product is used to reduce the degree while preserving the expansion.
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is a “good enough” expander (has a large spectral gap) then the expansion of the zigzag product is close to the original expansion of
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the product in fact splits the edges of each original vertex between the vertices of the cloud that replace it.
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vertices, whose second largest eigenvalue (of the associated random walk) has absolute value at most
1189:, with an important property of the zigzag product the preservation of the spectral gap. That is, if 953: 1235: 2279: 2252: 1929: 1748: 1313: 493: 191: 70: 546: 2318: 2288: 2262: 2221: 2049: 94: 1422: 1336: 1053: 519: 2205: 1730:{\displaystyle f(\lambda _{1},\lambda _{2})<\lambda _{1}+\lambda _{2}+\lambda _{2}^{2}} 266: 165:, then the expansion of the resulting graph is only slightly worse than the expansion of 44: 17: 2161: 2141: 2121: 2101: 2081: 1961: 1883: 1863: 1817: 1797: 1774: 1293: 1273: 1212: 1192: 1160: 1140: 1120: 1100: 1080: 1033: 412: 392: 308: 288: 270: 237: 217: 168: 162: 144: 120: 100: 1903: 1837: 432: 328: 2333: 2304: 2300: 2274: 2242: 2234: 1030:
It is immediate from the definition of the zigzag product that it transforms a graph
137:) and produces a graph that approximately inherits the size of the large one but the 39: 2308: 2238: 1186: 352: 31: 2266: 2322: 2292: 2311:(2006), "Pseudorandom walks on regular digraphs and the RL vs. L problem", 141:
of the small one. An important property of the zig-zag product is that if
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In 2005 Omer Reingold introduced an algorithm that solves the undirected
1637:{\displaystyle (N_{1}\cdot D_{1},D_{2}^{2},f(\lambda _{1},\lambda _{2}))} 2257: 2200:
Solving the undirected s-t connectivity problem in logarithmic space
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Proc. 41st IEEE Symposium on Foundations of Computer Science (FOCS)
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Proc. 38th ACM Symposium on Theory of Computing (STOC)
696:{\displaystyle \mathrm {Rot} _{G\circ H}((v,a),(i,j))} 2164: 2144: 2124: 2104: 2084: 2052: 1984: 1964: 1932: 1906: 1886: 1866: 1840: 1820: 1800: 1777: 1751: 1650: 1551: 1511: 1452: 1425: 1366: 1339: 1316: 1296: 1276: 1238: 1215: 1195: 1163: 1143: 1123: 1103: 1083: 1056: 1036: 956: 875: 794: 713: 629: 587: 549: 522: 496: 461: 435: 415: 395: 360: 331: 311: 291: 240: 220: 194: 171: 147: 123: 103: 73: 47: 2039:{\displaystyle G|_{S}\circ H=G\circ H|_{S\times D}} 1771:operates separately on each connected component of 2170: 2150: 2130: 2110: 2090: 2070: 2038: 1970: 1950: 1918: 1892: 1872: 1852: 1826: 1806: 1783: 1763: 1729: 1636: 1537: 1497: 1438: 1411: 1352: 1322: 1302: 1282: 1262: 1221: 1201: 1169: 1149: 1129: 1109: 1089: 1069: 1042: 1008: 939: 858: 777: 695: 614: 573: 535: 508: 482: 447: 421: 401: 381: 343: 317: 297: 246: 226: 206: 177: 153: 129: 109: 85: 59: 1137:. Roughly speaking, by amplifying each vertex of 2277:(2008), "Undirected connectivity in log-space", 1185:The expansion of a graph can be measured by its 1117:, the zigzag product will reduce the degree of 940:{\displaystyle (b,j')=\mathrm {Rot} _{H}(b',j)} 859:{\displaystyle (w,b')=\mathrm {Rot} _{G}(v,a')} 778:{\displaystyle (a',i')=\mathrm {Rot} _{H}(a,i)} 8: 1498:{\displaystyle (D_{1},D_{2},\lambda _{2})} 1412:{\displaystyle (N_{1},D_{1},\lambda _{1})} 2256: 2187:Construction of constant degree expanders 2163: 2143: 2123: 2103: 2083: 2062: 2057: 2051: 2024: 2019: 1994: 1989: 1983: 1963: 1931: 1905: 1885: 1865: 1839: 1819: 1799: 1776: 1750: 1721: 1716: 1703: 1690: 1674: 1661: 1649: 1622: 1609: 1590: 1585: 1572: 1559: 1550: 1529: 1516: 1510: 1486: 1473: 1460: 1451: 1430: 1424: 1400: 1387: 1374: 1365: 1344: 1338: 1315: 1295: 1275: 1237: 1214: 1194: 1162: 1142: 1122: 1102: 1082: 1061: 1055: 1035: 955: 911: 900: 874: 830: 819: 793: 754: 743: 712: 642: 631: 628: 615:{\displaystyle \mathrm {Rot} _{G\circ H}} 600: 589: 586: 548: 527: 521: 495: 474: 463: 460: 434: 414: 394: 373: 362: 359: 330: 310: 290: 239: 219: 193: 170: 146: 122: 102: 72: 46: 274: 259:Reingold, Vadhan & Wigderson (2000) 2196:expander without deleterious effects. 188:Roughly speaking, the zig-zag product 1794:Formally speaking, given two graphs: 257:The zigzag product was introduced by 7: 2138:which contains all of the edges in 907: 904: 901: 826: 823: 820: 750: 747: 744: 638: 635: 632: 596: 593: 590: 483:{\displaystyle \mathrm {Rot} _{H}} 470: 467: 464: 382:{\displaystyle \mathrm {Rot} _{G}} 369: 366: 363: 25: 1538:{\displaystyle G_{1}\circ G_{2}} 27:Binary operation in graph theory 1097:is a significantly larger than 1009:{\displaystyle ((w,b),(j',i'))} 263:computational complexity theory 2058: 2020: 1990: 1945: 1939: 1913: 1907: 1847: 1841: 1680: 1654: 1631: 1628: 1602: 1552: 1492: 1453: 1406: 1367: 1263:{\displaystyle (N,D,\lambda )} 1257: 1239: 1003: 1000: 978: 972: 960: 957: 934: 917: 893: 876: 853: 836: 812: 795: 772: 760: 736: 714: 690: 687: 675: 669: 657: 654: 568: 562: 556: 550: 442: 436: 338: 332: 1: 1958:is a connected component of 1157:into a cloud of the size of 2287:(4): Article 17, 24 pages, 1951:{\displaystyle S\subseteq } 97:which takes a large graph ( 2356: 1741:Connectivity preservation 1181:Spectral gap preservation 18:Zig-zag product of graphs 2267:10.1109/SFCS.2000.892006 1764:{\displaystyle G\circ H} 1323:{\displaystyle \lambda } 1050:to a new graph which is 509:{\displaystyle G\circ H} 214:replaces each vertex of 207:{\displaystyle G\circ H} 86:{\displaystyle G\circ H} 2323:10.1145/1132516.1132583 2293:10.1145/1391289.1391291 1026:Reduction of the degree 574:{\displaystyle \times } 234:with a copy (cloud) of 2172: 2152: 2132: 2112: 2092: 2072: 2071:{\displaystyle G|_{S}} 2040: 1972: 1952: 1920: 1894: 1874: 1854: 1828: 1808: 1785: 1765: 1731: 1638: 1539: 1499: 1440: 1413: 1354: 1324: 1304: 1284: 1264: 1223: 1203: 1171: 1151: 1131: 1111: 1091: 1071: 1044: 1010: 941: 860: 779: 697: 616: 575: 537: 510: 490:. The zig-zag product 484: 449: 423: 403: 383: 345: 319: 299: 248: 228: 208: 179: 155: 131: 111: 87: 61: 2173: 2153: 2133: 2113: 2093: 2073: 2041: 1973: 1953: 1921: 1895: 1875: 1855: 1829: 1809: 1786: 1766: 1732: 1639: 1540: 1500: 1441: 1439:{\displaystyle G_{2}} 1414: 1355: 1353:{\displaystyle G_{1}} 1325: 1305: 1285: 1265: 1224: 1204: 1172: 1152: 1132: 1112: 1092: 1072: 1070:{\displaystyle d^{2}} 1045: 1011: 942: 861: 780: 698: 617: 576: 538: 536:{\displaystyle d^{2}} 516:is defined to be the 511: 485: 450: 424: 404: 384: 346: 320: 300: 249: 229: 209: 180: 156: 132: 117:) and a small graph ( 112: 88: 62: 2317:, pp. 457–466, 2162: 2158:between vertices in 2142: 2122: 2118:(i.e., the graph on 2102: 2082: 2050: 1982: 1962: 1930: 1904: 1884: 1864: 1838: 1818: 1798: 1775: 1749: 1648: 1549: 1509: 1450: 1423: 1364: 1337: 1314: 1294: 1274: 1236: 1213: 1193: 1161: 1141: 1121: 1101: 1081: 1054: 1034: 954: 873: 792: 711: 627: 585: 547: 520: 494: 459: 433: 413: 393: 358: 329: 309: 289: 238: 218: 192: 169: 145: 121: 101: 71: 45: 2078:is the subgraph of 1745:The zigzag product 1726: 1595: 1232:Formally: Define a 581:whose rotation map 60:{\displaystyle G,H} 2280:Journal of the ACM 2168: 2148: 2128: 2108: 2088: 2068: 2036: 1968: 1948: 1916: 1900:-regular graph on 1890: 1870: 1850: 1834:-regular graph on 1824: 1804: 1781: 1761: 1727: 1712: 1634: 1581: 1535: 1495: 1436: 1409: 1350: 1320: 1300: 1290:-regular graph on 1280: 1260: 1219: 1199: 1167: 1147: 1127: 1107: 1087: 1077:-regular. Thus if 1067: 1040: 1006: 937: 856: 775: 693: 612: 571: 543:-regular graph on 533: 506: 480: 455:with rotation map 445: 429:-regular graph on 419: 399: 379: 341: 325:-regular graph on 315: 295: 267:symmetric logspace 244: 224: 204: 175: 151: 127: 107: 83: 57: 2251:, pp. 3–13, 2171:{\displaystyle S} 2151:{\displaystyle G} 2131:{\displaystyle S} 2111:{\displaystyle S} 2091:{\displaystyle G} 1971:{\displaystyle G} 1893:{\displaystyle d} 1873:{\displaystyle H} 1827:{\displaystyle D} 1807:{\displaystyle G} 1784:{\displaystyle G} 1303:{\displaystyle N} 1283:{\displaystyle D} 1222:{\displaystyle G} 1202:{\displaystyle H} 1170:{\displaystyle H} 1150:{\displaystyle G} 1130:{\displaystyle G} 1110:{\displaystyle H} 1090:{\displaystyle G} 1043:{\displaystyle G} 422:{\displaystyle d} 402:{\displaystyle H} 318:{\displaystyle D} 298:{\displaystyle G} 247:{\displaystyle H} 227:{\displaystyle G} 178:{\displaystyle G} 154:{\displaystyle H} 130:{\displaystyle H} 110:{\displaystyle G} 16:(Redirected from 2347: 2325: 2295: 2269: 2260: 2222:Graph operations 2177: 2175: 2174: 2169: 2157: 2155: 2154: 2149: 2137: 2135: 2134: 2129: 2117: 2115: 2114: 2109: 2097: 2095: 2094: 2089: 2077: 2075: 2074: 2069: 2067: 2066: 2061: 2045: 2043: 2042: 2037: 2035: 2034: 2023: 1999: 1998: 1993: 1977: 1975: 1974: 1969: 1957: 1955: 1954: 1949: 1925: 1923: 1922: 1919:{\displaystyle } 1917: 1899: 1897: 1896: 1891: 1879: 1877: 1876: 1871: 1859: 1857: 1856: 1853:{\displaystyle } 1851: 1833: 1831: 1830: 1825: 1813: 1811: 1810: 1805: 1790: 1788: 1787: 1782: 1770: 1768: 1767: 1762: 1736: 1734: 1733: 1728: 1725: 1720: 1708: 1707: 1695: 1694: 1679: 1678: 1666: 1665: 1643: 1641: 1640: 1635: 1627: 1626: 1614: 1613: 1594: 1589: 1577: 1576: 1564: 1563: 1544: 1542: 1541: 1536: 1534: 1533: 1521: 1520: 1504: 1502: 1501: 1496: 1491: 1490: 1478: 1477: 1465: 1464: 1445: 1443: 1442: 1437: 1435: 1434: 1418: 1416: 1415: 1410: 1405: 1404: 1392: 1391: 1379: 1378: 1359: 1357: 1356: 1351: 1349: 1348: 1329: 1327: 1326: 1321: 1309: 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90: 89: 84: 66: 64: 63: 58: 21: 2355: 2354: 2350: 2349: 2348: 2346: 2345: 2344: 2330: 2329: 2299: 2273: 2233: 2230: 2218: 2206:st-connectivity 2202: 2189: 2184: 2160: 2159: 2140: 2139: 2120: 2119: 2100: 2099: 2080: 2079: 2056: 2048: 2047: 2018: 1988: 1980: 1979: 1960: 1959: 1928: 1927: 1902: 1901: 1882: 1881: 1862: 1861: 1836: 1835: 1816: 1815: 1796: 1795: 1773: 1772: 1747: 1746: 1743: 1699: 1686: 1670: 1657: 1646: 1645: 1618: 1605: 1568: 1555: 1547: 1546: 1525: 1512: 1507: 1506: 1482: 1469: 1456: 1448: 1447: 1426: 1421: 1420: 1396: 1383: 1370: 1362: 1361: 1340: 1335: 1334: 1312: 1311: 1292: 1291: 1272: 1271: 1234: 1233: 1211: 1210: 1191: 1190: 1183: 1159: 1158: 1139: 1138: 1119: 1118: 1099: 1098: 1079: 1078: 1057: 1052: 1051: 1032: 1031: 1028: 1023: 992: 981: 952: 951: 920: 899: 885: 871: 870: 845: 818: 804: 790: 789: 742: 728: 717: 709: 708: 630: 625: 624: 623: 588: 583: 582: 545: 544: 523: 518: 517: 492: 491: 462: 457: 456: 431: 430: 411: 410: 391: 390: 361: 356: 355: 327: 326: 307: 306: 287: 286: 283: 236: 235: 216: 215: 190: 189: 167: 166: 143: 142: 119: 118: 99: 98: 69: 68: 43: 42: 36:zig-zag product 28: 23: 22: 15: 12: 11: 5: 2353: 2351: 2343: 2342: 2340:Graph products 2332: 2331: 2328: 2327: 2297: 2271: 2229: 2226: 2225: 2224: 2217: 2214: 2201: 2198: 2188: 2185: 2183: 2180: 2167: 2147: 2127: 2107: 2087: 2065: 2060: 2055: 2033: 2030: 2027: 2022: 2017: 2014: 2011: 2008: 2005: 2002: 1997: 1992: 1987: 1967: 1947: 1944: 1941: 1938: 1935: 1915: 1912: 1909: 1889: 1869: 1849: 1846: 1843: 1823: 1803: 1780: 1760: 1757: 1754: 1742: 1739: 1724: 1719: 1715: 1711: 1706: 1702: 1698: 1693: 1689: 1685: 1682: 1677: 1673: 1669: 1664: 1660: 1656: 1653: 1644:-graph, where 1633: 1630: 1625: 1621: 1617: 1612: 1608: 1604: 1601: 1598: 1593: 1588: 1584: 1580: 1575: 1571: 1567: 1562: 1558: 1554: 1532: 1528: 1524: 1519: 1515: 1494: 1489: 1485: 1481: 1476: 1472: 1468: 1463: 1459: 1455: 1433: 1429: 1408: 1403: 1399: 1395: 1390: 1386: 1382: 1377: 1373: 1369: 1347: 1343: 1319: 1299: 1279: 1270:-graph as any 1259: 1256: 1253: 1250: 1247: 1244: 1241: 1218: 1198: 1182: 1179: 1166: 1146: 1126: 1106: 1086: 1064: 1060: 1039: 1027: 1024: 1022: 1019: 1018: 1017: 1005: 1002: 998: 995: 991: 987: 984: 980: 977: 974: 971: 968: 965: 962: 959: 948: 936: 933: 930: 926: 923: 919: 914: 909: 906: 903: 898: 895: 891: 888: 884: 881: 878: 867: 855: 851: 848: 844: 841: 838: 833: 828: 825: 822: 817: 814: 810: 807: 803: 800: 797: 786: 774: 771: 768: 765: 762: 757: 752: 749: 746: 741: 738: 734: 731: 727: 723: 720: 716: 692: 689: 686: 683: 680: 677: 674: 671: 668: 665: 662: 659: 656: 651: 648: 645: 640: 637: 634: 622:is as follows: 609: 606: 603: 598: 595: 592: 570: 567: 564: 561: 558: 555: 552: 530: 526: 505: 502: 499: 477: 472: 469: 466: 444: 441: 438: 418: 398: 376: 371: 368: 365: 340: 337: 334: 314: 294: 282: 279: 265:to prove that 243: 223: 203: 200: 197: 174: 150: 126: 106: 82: 79: 76: 56: 53: 50: 40:regular graphs 26: 24: 14: 13: 10: 9: 6: 4: 3: 2: 2352: 2341: 2338: 2337: 2335: 2324: 2320: 2316: 2315: 2310: 2306: 2302: 2298: 2294: 2290: 2286: 2282: 2281: 2276: 2272: 2268: 2264: 2259: 2254: 2250: 2249: 2244: 2243:Wigderson, A. 2240: 2236: 2232: 2231: 2227: 2223: 2220: 2219: 2215: 2213: 2209: 2207: 2199: 2197: 2193: 2186: 2181: 2179: 2165: 2145: 2125: 2105: 2085: 2063: 2053: 2031: 2028: 2025: 2015: 2012: 2009: 2006: 2003: 2000: 1995: 1985: 1965: 1942: 1936: 1933: 1910: 1887: 1867: 1844: 1821: 1801: 1792: 1778: 1758: 1755: 1752: 1740: 1738: 1722: 1717: 1713: 1709: 1704: 1700: 1696: 1691: 1687: 1683: 1675: 1671: 1667: 1662: 1658: 1651: 1623: 1619: 1615: 1610: 1606: 1599: 1596: 1591: 1586: 1582: 1578: 1573: 1569: 1565: 1560: 1556: 1530: 1526: 1522: 1517: 1513: 1505:-graph, then 1487: 1483: 1479: 1474: 1470: 1466: 1461: 1457: 1431: 1427: 1401: 1397: 1393: 1388: 1384: 1380: 1375: 1371: 1345: 1341: 1331: 1317: 1297: 1277: 1254: 1251: 1248: 1245: 1242: 1230: 1216: 1196: 1188: 1180: 1178: 1164: 1144: 1124: 1104: 1084: 1062: 1058: 1037: 1025: 1020: 996: 993: 989: 985: 982: 975: 969: 966: 963: 949: 931: 928: 924: 921: 912: 896: 889: 886: 882: 879: 868: 849: 846: 842: 839: 831: 815: 808: 805: 801: 798: 787: 769: 766: 763: 755: 739: 732: 729: 725: 721: 718: 706: 705: 704: 684: 681: 678: 672: 666: 663: 660: 649: 646: 643: 607: 604: 601: 565: 559: 553: 528: 524: 503: 500: 497: 475: 439: 416: 396: 374: 354: 335: 312: 292: 280: 278: 276: 275:Reingold 2008 272: 268: 264: 260: 255: 241: 221: 201: 198: 195: 186: 172: 164: 148: 140: 124: 104: 96: 80: 77: 74: 67:, denoted by 54: 51: 48: 41: 37: 33: 19: 2312: 2305:Trevisan, L. 2301:Reingold, O. 2284: 2278: 2258:math/0406038 2246: 2235:Reingold, O. 2210: 2203: 2194: 2190: 2182:Applications 1793: 1744: 1332: 1231: 1187:spectral gap 1184: 1029: 353:rotation map 284: 256: 187: 35: 32:graph theory 29: 2275:Reingold, O 2098:induced by 1419:-graph and 273:are equal ( 2309:Vadhan, S. 2239:Vadhan, S. 2228:References 1021:Properties 281:Definition 161:is a good 2029:× 2013:∘ 2001:∘ 1937:⊆ 1756:∘ 1714:λ 1701:λ 1688:λ 1672:λ 1659:λ 1620:λ 1607:λ 1566:⋅ 1523:∘ 1484:λ 1398:λ 1318:λ 1255:λ 647:∘ 605:∘ 560:× 501:∘ 199:∘ 78:∘ 2334:Category 2216:See also 2046:, where 997:′ 986:′ 925:′ 890:′ 850:′ 809:′ 733:′ 722:′ 389:and let 271:logspace 163:expander 950:Output 93:, is a 139:degree 34:, the 2253:arXiv 1978:then 1926:- if 1545:is a 1446:be a 1360:be a 409:be a 351:with 305:be a 1880:, a 1860:and 1814:, a 1684:< 1333:Let 869:Let 788:Let 707:Let 285:Let 269:and 2319:doi 2289:doi 2263:doi 2178:). 1229:. 277:). 38:of 30:In 2336:: 2307:; 2303:; 2285:55 2283:, 2261:, 2241:; 2237:; 1791:. 1737:. 1330:. 703:: 185:. 2326:. 2321:: 2296:. 2291:: 2270:. 2265:: 2255:: 2166:S 2146:G 2126:S 2106:S 2086:G 2064:S 2059:| 2054:G 2032:D 2026:S 2021:| 2016:H 2010:G 2007:= 2004:H 1996:S 1991:| 1986:G 1966:G 1946:] 1943:N 1940:[ 1934:S 1914:] 1911:D 1908:[ 1888:d 1868:H 1848:] 1845:N 1842:[ 1822:D 1802:G 1779:G 1759:H 1753:G 1723:2 1718:2 1710:+ 1705:2 1697:+ 1692:1 1681:) 1676:2 1668:, 1663:1 1655:( 1652:f 1632:) 1629:) 1624:2 1616:, 1611:1 1603:( 1600:f 1597:, 1592:2 1587:2 1583:D 1579:, 1574:1 1570:D 1561:1 1557:N 1553:( 1531:2 1527:G 1518:1 1514:G 1493:) 1488:2 1480:, 1475:2 1471:D 1467:, 1462:1 1458:D 1454:( 1432:2 1428:G 1407:) 1402:1 1394:, 1389:1 1385:D 1381:, 1376:1 1372:N 1368:( 1346:1 1342:G 1298:N 1278:D 1258:) 1252:, 1249:D 1246:, 1243:N 1240:( 1217:G 1197:H 1165:H 1145:G 1125:G 1105:H 1085:G 1063:2 1059:d 1038:G 1016:. 1004:) 1001:) 994:i 990:, 983:j 979:( 976:, 973:) 970:b 967:, 964:w 961:( 958:( 947:. 935:) 932:j 929:, 922:b 918:( 913:H 908:t 905:o 902:R 897:= 894:) 887:j 883:, 880:b 877:( 866:. 854:) 847:a 843:, 840:v 837:( 832:G 827:t 824:o 821:R 816:= 813:) 806:b 802:, 799:w 796:( 785:. 773:) 770:i 767:, 764:a 761:( 756:H 751:t 748:o 745:R 740:= 737:) 730:i 726:, 719:a 715:( 691:) 688:) 685:j 682:, 679:i 676:( 673:, 670:) 667:a 664:, 661:v 658:( 655:( 650:H 644:G 639:t 636:o 633:R 608:H 602:G 597:t 594:o 591:R 569:] 566:D 563:[ 557:] 554:N 551:[ 529:2 525:d 504:H 498:G 476:H 471:t 468:o 465:R 443:] 440:D 437:[ 417:d 397:H 375:G 370:t 367:o 364:R 339:] 336:N 333:[ 313:D 293:G 242:H 222:G 202:H 196:G 173:G 149:H 125:H 105:G 81:H 75:G 55:H 52:, 49:G 20:)

Index

Zig-zag product of graphs
graph theory
regular graphs
binary operation
degree
expander
Reingold, Vadhan & Wigderson (2000)
computational complexity theory
symmetric logspace
logspace
Reingold 2008
rotation map
spectral gap
st-connectivity
Graph operations
Reingold, O.
Vadhan, S.
Wigderson, A.
Proc. 41st IEEE Symposium on Foundations of Computer Science (FOCS)
arXiv
math/0406038
doi
10.1109/SFCS.2000.892006
Reingold, O
Journal of the ACM
doi
10.1145/1391289.1391291
Reingold, O.
Trevisan, L.
Vadhan, S.

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