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Lovász number

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3692: 4259: 2396: 4071: 558: 3430: 814: 2247: 2053: 2654: 4254:{\displaystyle u_{k}={\begin{pmatrix}\cos {\theta }\\\sin {\theta }\cos {\varphi _{k}}\\\sin {\theta }\sin {\varphi _{k}}\end{pmatrix}},\quad \cos {\theta }={\frac {1}{\sqrt{5}}},\quad \varphi _{k}={\frac {2\pi k}{5}}} 2799: 4469:
A representation of vertices by standard basis vectors will not be faithful, meaning that adjacent vertices are represented by non-orthogonal vectors, unless the graph is edgeless. A faithful representation in
3016: 444: 1761: 3687: 272: 1459: 2909: 2549: 3311: 3885: 4349: 4005: 1078: 2234: 2179: 4395: 3818: 3625: 3932: 1649: 1796: 708: 4066: 3274: 3236: 2455: 1922: 2120: 1351: 932: 863: 617: 325: 3768: 3178: 71: 2690: 4400:
However, there exist graphs for which the Lovász number and Shannon capacity differ, so the Lovász number cannot in general be used to compute exact Shannon capacities.
3459: 3045: 2830: 1956: 1951: 1851: 683: 4303: 1695: 1507: 1210: 3102: 1547: 1249: 4496:
is also possible by associating each vertex to a basis vector as before, but mapping each vertex to the sum of basis vectors associated with its closed neighbourhood.
1144: 160: 4529: 4576: 3959: 3724: 3537: 1022: 379: 352: 2391:{\displaystyle \vartheta (C_{n})={\begin{cases}{\frac {n\cos(\pi /n)}{1+\cos(\pi /n)}}&{\text{for odd }}n,\\{\frac {n}{2}}&{\text{for even }}n\end{cases}}} 5152: 4494: 1275: 978: 584: 4596: 4549: 3581: 3561: 3510: 3486: 3306: 3146: 3126: 3069: 2929: 2850: 2734: 2714: 1871: 1816: 1669: 1611: 1587: 1567: 1481: 1395: 1375: 1315: 1295: 1184: 1164: 1098: 1002: 952: 903: 883: 834: 703: 657: 637: 439: 419: 399: 296: 204: 184: 2739: 2950: 1703: 2562: 5124: 5001: 4855: 3630: 1400: 2855: 3934:, since "11", "23", "35", "54", "42" are five mutually non-confusable messages (forming a five-vertex independent set in the strong square of 5164: 4977: 5026:
Howard, Mark; Wallman, Joel; Veitch, Victor; Emerson, Joseph (19 June 2014), "Contextuality supplies the 'magic' for quantum computation",
3276:
and then rounding to the nearest integer value, the chromatic number and clique number of these graphs can be computed in polynomial time.
5087: 211: 2468: 3489: 553:{\displaystyle u_{i}^{\mathrm {T} }u_{j}={\begin{cases}1,&{\text{if }}i=j,\\0,&{\text{if }}ij\notin E.\end{cases}}} 4905: 3826: 3466: 1510: 163: 25: 4308: 5286: 3285: 2555: 37: 3964: 1027: 4996: 2193: 2133: 5281: 4853:(2013), "Zero-error communication via quantum channels, non-commutative graphs and a quantum Lovász ϑ function", 4354: 3777: 3425:{\displaystyle \Theta (G)=\sup _{k}{\sqrt{\alpha (G^{k})}}=\lim _{k\rightarrow \infty }{\sqrt{\alpha (G^{k})}},} 5228:
Todd, Mike; Cheung, Sin-Shuen (February 21, 2012), "Lecture 9: SDP formulations of the Lovász theta function",
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The Lovász "sandwich theorem" states that the Lovász number always lies between two other numbers that are
1876: 1590: 5173: 5140: 5119: 4951: 4897: 2083: 1320: 78: 4413: 908: 839: 593: 301: 5047: 3540: 3181: 2693: 112:
of the graph, and can be used to compute these numbers on graphs for which they are equal, including
3737: 2278: 483: 77:
to contrast with the upright theta used for Shannon capacity. This quantity was first introduced by
4955: 4947: 4901: 4893: 3462: 3154: 47: 2669: 5096: 5071: 5037: 4928: 4882: 4864: 4834: 4808: 4437: 3435: 3021: 2806: 1927: 1827: 809:{\displaystyle \vartheta (G)=\min _{c,U}\max _{i\in V}{\frac {1}{(c^{\mathrm {T} }u_{i})^{2}}},} 668: 4264: 1674: 1486: 1189: 5250: 5229: 5160: 5063: 4973: 4959: 4826: 4417: 3078: 1516: 1218: 5156: 3627:. However, the Lovász number provides an upper bound on the Shannon capacity of graph, hence 1111: 127: 5217: 5194: 5129: 5106: 5055: 5028: 5010: 4965: 4920: 4874: 4818: 4508: 4436:
that can be computed in polynomial time and has been used to prove lower bounds in monotone
4433: 3185: 3105: 1822: 1212: 105: 101: 97: 4987: 4554: 3937: 3702: 3515: 1007: 357: 330: 4983: 4846: 4794: 4786: 4429: 4409: 3189: 981: 89: 4473: 1254: 957: 563: 5051: 5205: 5145: 4850: 4790: 4581: 4534: 3566: 3546: 3495: 3471: 3291: 3131: 3111: 3054: 2914: 2835: 2719: 2699: 2402: 2076: 1856: 1801: 1697: 1654: 1596: 1572: 1552: 1466: 1380: 1360: 1300: 1280: 1169: 1149: 1083: 987: 937: 888: 868: 819: 688: 642: 622: 587: 424: 404: 384: 281: 189: 169: 4408:
The Lovász number has been generalized for "non-commutative graphs" in the context of
5275: 4964:, Algorithms and Combinatorics, vol. 2 (2nd ed.), Springer-Verlag, Berlin, 3197: 3048: 113: 109: 5258: 4932: 4838: 3200:, the chromatic number and clique number are equal, and therefore are both equal to 5082: 5075: 4886: 4822: 2461: 2048:{\displaystyle \vartheta (G)=\max _{d,U}\sum _{i\in V}(d^{\mathrm {T} }u_{i})^{2}.} 17: 5254: 2944: 2240: 2126: 206: 33: 29: 4936: 4969: 1354: 5221: 5133: 5014: 4878: 2649:{\displaystyle \vartheta (K_{n_{1},\dots ,n_{k}})=\max _{1\leq i\leq k}n_{i}} 980:. Intuitively, this corresponds to minimizing the half-angle of a rotational 5263: 3691: 5177: 5067: 4830: 4305:. By using this choice in the initial definition of Lovász number, we get 5190:
Sandwich Theorem and Calculation of the Theta Function for Several Graphs
5188: 4906:"The ellipsoid method and its consequences in combinatorial optimization" 3727: 2185: 5059: 5018: 984:
containing all representing vectors of an orthonormal representation of
5198: 4997:"On Some Problems of Lovász Concerning the Shannon Capacity of a Graph" 4924: 5143:(1986), "Chapter 3.2: Chromatic number, cliques, and perfect graphs", 5101: 4531:
then one can always achieve a smaller objective value by restricting
3072: 2794:{\displaystyle \vartheta (G\boxtimes H)=\vartheta (G)\vartheta (H).} 934:. Here minimization implicitly is performed also over the dimension 88:
Accurate numerical approximations to this number can be computed in
3011:{\displaystyle \omega (G)\leq \vartheta ({\bar {G}})\leq \chi (G),} 5111: 5042: 4869: 4813: 74: 3128:(the smallest number of colors needed to color the vertices of 1756:{\displaystyle \vartheta (G)=\max _{B}\operatorname {Tr} (BJ).} 560:
Clearly, every graph admits an orthonormal representation with
2062:
The Lovász number has been computed for the following graphs:
4068:
be the following orthonormal representation of the pentagon:
954:, however without loss of generality it suffices to consider 3682:{\displaystyle \alpha (G)\leq \Theta (G)\leq \vartheta (G).} 1377:. Then an alternative way of computing the Lovász number of 267:{\displaystyle U=(u_{i}\mid i\in V)\subset \mathbb {R} ^{N}} 3699:
For example, let the confusability graph of the channel be
2384: 1454:{\displaystyle \vartheta (G)=\min _{A}\lambda _{\max }(A).} 546: 4767: 3148:
so that no two adjacent vertices receive the same color).
2904:{\displaystyle \vartheta (G)\vartheta ({\bar {G}})\geq n,} 4703: 2544:{\displaystyle \vartheta (KG_{n,k})={\binom {n-1}{k-1}}} 4432:, a monotone approximation to the Lovász number of the 1821:
The Lovász number can be computed also in terms of the
586:: just represent vertices by distinct vectors from the 5208:(1956), "The zero error capacity of a noisy channel", 5147:
An Algorithmic Theory of Numbers, Graphs and Convexity
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The following method is dual to the previous one. Let
639:
considerably smaller than the number of vertices 
619:. Depending on the graph it might be possible to take 4755: 4584: 4557: 4537: 4511: 4476: 4357: 4311: 4267: 4074: 4016: 3967: 3940: 3893: 3829: 3780: 3740: 3705: 3633: 3589: 3569: 3549: 3518: 3498: 3474: 3438: 3314: 3294: 3244: 3206: 3157: 3134: 3114: 3081: 3057: 3024: 2953: 2917: 2858: 2838: 2809: 2742: 2722: 2702: 2672: 2565: 2471: 2412: 2250: 2196: 2136: 2086: 1959: 1930: 1879: 1859: 1830: 1804: 1769: 1706: 1677: 1657: 1619: 1599: 1575: 1555: 1519: 1489: 1469: 1403: 1383: 1363: 1323: 1303: 1283: 1257: 1221: 1192: 1172: 1152: 1114: 1086: 1030: 1010: 990: 960: 940: 911: 891: 871: 842: 822: 711: 691: 671: 645: 625: 596: 566: 447: 427: 407: 387: 360: 333: 304: 284: 214: 192: 172: 130: 50: 5179:
Semidefinite programs and combinatorial optimization
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Geometric algorithms and combinatorial optimization
3880:{\displaystyle \Theta (C_{5})\geq \alpha (C_{5})=2} 5231:Lecture Notes for OR6327, Semidefinite Programming 5144: 4795:"Graph-theoretic approach to quantum correlations" 4743: 4590: 4570: 4543: 4523: 4488: 4389: 4343: 4297: 4253: 4060: 3999: 3953: 3926: 3879: 3812: 3762: 3718: 3681: 3619: 3575: 3555: 3531: 3504: 3480: 3453: 3424: 3300: 3268: 3230: 3172: 3140: 3120: 3096: 3063: 3039: 3010: 2923: 2903: 2844: 2824: 2793: 2728: 2708: 2684: 2648: 2543: 2449: 2390: 2228: 2173: 2114: 2047: 1945: 1916: 1865: 1845: 1810: 1790: 1755: 1689: 1663: 1643: 1605: 1581: 1561: 1541: 1501: 1475: 1453: 1389: 1369: 1345: 1309: 1289: 1269: 1243: 1204: 1178: 1158: 1138: 1092: 1072: 1016: 996: 972: 946: 926: 897: 877: 857: 828: 808: 697: 677: 651: 631: 611: 578: 552: 433: 413: 393: 373: 346: 319: 290: 266: 198: 178: 154: 65: 4344:{\displaystyle \vartheta (C_{5})\leq {\sqrt {5}}} 3734:it was an open problem to determine the value of 2535: 2506: 3374: 3331: 2615: 1976: 1723: 1434: 1420: 1329: 744: 728: 5153:Society for Industrial and Applied Mathematics 5122:(1979), "On the Shannon capacity of a graph", 4000:{\displaystyle \Theta (C_{5})\geq {\sqrt {5}}} 1100:corresponds to the symmetry axis of the cone. 1073:{\displaystyle \vartheta (G)=1/\cos ^{2}\phi } 2229:{\displaystyle \vartheta (C_{5})={\sqrt {5}}} 8: 2174:{\displaystyle \vartheta ({\bar {K}}_{n})=n} 4607: 4707: 4390:{\displaystyle \Theta (C_{5})={\sqrt {5}}} 3813:{\displaystyle \Theta (C_{5})={\sqrt {5}}} 73:, using a script form of the Greek letter 5193:(M.S. thesis), Brigham Young University, 5110: 5100: 5041: 4868: 4812: 4583: 4562: 4556: 4536: 4510: 4475: 4380: 4368: 4356: 4334: 4322: 4310: 4266: 4233: 4224: 4208: 4199: 4191: 4166: 4161: 4150: 4133: 4128: 4117: 4102: 4088: 4079: 4073: 4049: 4030: 4015: 3990: 3978: 3966: 3945: 3939: 3909: 3904: 3892: 3862: 3840: 3828: 3803: 3791: 3779: 3751: 3739: 3710: 3704: 3632: 3620:{\displaystyle \Theta (G)\geq \alpha (G)} 3588: 3568: 3548: 3523: 3517: 3497: 3473: 3437: 3412: 3402: 3389: 3377: 3363: 3353: 3340: 3334: 3313: 3293: 3252: 3251: 3243: 3214: 3213: 3205: 3156: 3133: 3113: 3080: 3056: 3023: 2976: 2975: 2952: 2916: 2878: 2877: 2857: 2837: 2811: 2810: 2808: 2741: 2721: 2701: 2671: 2640: 2618: 2600: 2581: 2576: 2564: 2534: 2505: 2503: 2485: 2470: 2426: 2411: 2373: 2361: 2346: 2330: 2299: 2281: 2273: 2261: 2249: 2219: 2207: 2195: 2156: 2145: 2144: 2135: 2097: 2085: 2036: 2026: 2015: 2014: 1995: 1979: 1958: 1932: 1931: 1929: 1893: 1878: 1858: 1832: 1831: 1829: 1803: 1768: 1726: 1705: 1676: 1656: 1618: 1598: 1574: 1554: 1524: 1518: 1488: 1468: 1433: 1423: 1402: 1382: 1362: 1328: 1322: 1302: 1282: 1256: 1226: 1220: 1191: 1171: 1151: 1113: 1085: 1058: 1049: 1029: 1009: 989: 959: 939: 918: 914: 913: 910: 890: 870: 849: 845: 844: 841: 821: 794: 784: 773: 772: 759: 747: 731: 710: 690: 670: 644: 624: 603: 599: 598: 595: 565: 523: 494: 478: 469: 458: 457: 452: 446: 426: 406: 386: 365: 359: 338: 332: 311: 307: 306: 303: 283: 258: 254: 253: 228: 213: 191: 171: 129: 49: 4704:Grötschel, Lovász & Schrijver (1981) 3927:{\displaystyle \alpha (C_{5}^{2})\geq 5} 3690: 2064: 1644:{\displaystyle \operatorname {Tr} (B)=1} 5125:IEEE Transactions on Information Theory 5002:IEEE Transactions on Information Theory 4856:IEEE Transactions on Information Theory 4731: 4450: 3731: 1791:{\displaystyle \operatorname {Tr} (BJ)} 104:of any graph is sandwiched between the 5210:IRE Transactions on Information Theory 4719: 4679: 4667: 4655: 4643: 4631: 4619: 4457: 4416:in an attempt to explain the power of 4061:{\displaystyle U=(u_{1},\dots ,u_{5})} 4010:To show that this bound is tight, let 3771: 3269:{\displaystyle \vartheta ({\bar {G}})} 3231:{\displaystyle \vartheta ({\bar {G}})} 2450:{\displaystyle \vartheta (KG_{5,2})=4} 4756:Cabello, Severini & Winter (2014) 4691: 7: 3184:and numerically approximated by the 1924:be an orthonormal representation of 1917:{\displaystyle U=(u_{i}\mid i\in V)} 885:is an orthonormal representation of 5088:Electronic Journal of Combinatorics 4551:to the subspace spanned by vectors 4412:. The Lovasz number also arises in 3238:. By computing an approximation of 2115:{\displaystyle \vartheta (K_{n})=1} 1346:{\displaystyle \lambda _{\max }(A)} 4744:Duan, Severini & Winter (2013) 4358: 3968: 3830: 3781: 3741: 3649: 3590: 3384: 3315: 2510: 2016: 1798:is just the sum of all entries of 774: 459: 83:On the Shannon Capacity of a Graph 40:of the graph. It is also known as 14: 381:are orthogonal whenever vertices 5085:(1994), "The sandwich theorem", 1589:are adjacent, and such that the 927:{\displaystyle \mathbb {R} ^{N}} 858:{\displaystyle \mathbb {R} ^{N}} 612:{\displaystyle \mathbb {R} ^{N}} 320:{\displaystyle \mathbb {R} ^{N}} 4219: 4184: 4823:10.1103/PhysRevLett.112.040401 4374: 4361: 4328: 4315: 4292: 4274: 4055: 4023: 3984: 3971: 3915: 3897: 3868: 3855: 3846: 3833: 3797: 3784: 3770:. It was first established by 3763:{\displaystyle \Theta (C_{5})} 3757: 3744: 3730:. Since the original paper of 3673: 3667: 3658: 3652: 3643: 3637: 3614: 3608: 3599: 3593: 3448: 3442: 3408: 3395: 3381: 3359: 3346: 3324: 3318: 3263: 3257: 3248: 3225: 3219: 3210: 3167: 3161: 3091: 3085: 3034: 3028: 3002: 2996: 2987: 2981: 2972: 2963: 2957: 2889: 2883: 2874: 2868: 2862: 2816: 2785: 2779: 2773: 2767: 2758: 2746: 2608: 2569: 2497: 2475: 2438: 2416: 2338: 2324: 2307: 2293: 2267: 2254: 2213: 2200: 2162: 2150: 2140: 2103: 2090: 2033: 2007: 1969: 1963: 1937: 1911: 1886: 1837: 1785: 1776: 1747: 1738: 1716: 1710: 1632: 1626: 1511:positive semidefinite matrices 1445: 1439: 1413: 1407: 1340: 1334: 1133: 1121: 1040: 1034: 791: 765: 721: 715: 246: 221: 149: 137: 60: 54: 1: 3192:in the number of vertices of 3173:{\displaystyle \vartheta (G)} 1593:(sum of diagonal entries) of 66:{\displaystyle \vartheta (G)} 5187:Riddle, Marcia Ling (2003), 4682:, Corollary 2 and Theorem 8. 3280:Relation to Shannon capacity 2947:to compute. More precisely, 2685:{\displaystyle G\boxtimes H} 2556:Complete multipartite graphs 186:vertices. An ordered set of 4995:Haemers, Willem H. (1979), 4578:; this subspace is at most 2058:Value for well-known graphs 100:. The Lovász number of the 44:and is commonly denoted by 5303: 3454:{\displaystyle \alpha (G)} 3040:{\displaystyle \omega (G)} 2825:{\displaystyle {\bar {G}}} 1946:{\displaystyle {\bar {G}}} 1846:{\displaystyle {\bar {G}}} 1317:are not adjacent, and let 1004:. If the optimal angle is 678:{\displaystyle \vartheta } 276:orthonormal representation 4970:10.1007/978-3-642-78240-4 4610:, Proposition 5.1, p. 28. 4298:{\displaystyle c=(1,0,0)} 3071:(the size of the largest 2939:Lovász "sandwich theorem" 1690:{\displaystyle n\times n} 1502:{\displaystyle n\times n} 1205:{\displaystyle n\times n} 5222:10.1109/TIT.1956.1056798 5134:10.1109/tit.1979.1055985 5015:10.1109/tit.1979.1056027 4879:10.1109/TIT.2012.2221677 4708:Todd & Cheung (2012) 4670:, Lemma 2 and Theorem 7. 3097:{\displaystyle \chi (G)} 1542:{\displaystyle b_{ij}=0} 1244:{\displaystyle a_{ij}=1} 94:semidefinite programming 4800:Physical Review Letters 3488:(the size of a largest 3308:is defined as follows: 3180:can be formulated as a 1139:{\displaystyle G=(V,E)} 705:is defined as follows: 155:{\displaystyle G=(V,E)} 4592: 4572: 4545: 4525: 4524:{\displaystyle N>n} 4490: 4391: 4345: 4299: 4255: 4062: 4001: 3955: 3928: 3881: 3814: 3764: 3720: 3696: 3683: 3621: 3577: 3557: 3533: 3506: 3482: 3455: 3426: 3302: 3270: 3232: 3174: 3142: 3122: 3098: 3065: 3041: 3012: 2925: 2905: 2846: 2826: 2795: 2730: 2710: 2686: 2650: 2545: 2451: 2392: 2230: 2175: 2116: 2049: 1947: 1918: 1867: 1847: 1812: 1792: 1757: 1691: 1665: 1645: 1607: 1583: 1563: 1543: 1503: 1477: 1455: 1391: 1371: 1347: 1311: 1291: 1271: 1245: 1206: 1180: 1160: 1140: 1104:Equivalent expressions 1094: 1074: 1018: 998: 974: 948: 928: 899: 879: 859: 830: 810: 699: 679: 653: 633: 613: 580: 554: 435: 415: 395: 375: 348: 321: 292: 268: 200: 180: 156: 67: 4593: 4573: 4571:{\displaystyle u_{i}} 4546: 4526: 4491: 4414:quantum contextuality 4410:quantum communication 4392: 4346: 4300: 4256: 4063: 4002: 3956: 3954:{\displaystyle C_{5}} 3929: 3882: 3815: 3765: 3721: 3719:{\displaystyle C_{5}} 3694: 3684: 3622: 3578: 3558: 3534: 3532:{\displaystyle G^{k}} 3507: 3483: 3456: 3427: 3303: 3271: 3233: 3188:in time bounded by a 3175: 3143: 3123: 3099: 3066: 3042: 3013: 2926: 2906: 2847: 2832:is the complement of 2827: 2796: 2731: 2711: 2687: 2651: 2546: 2452: 2393: 2231: 2176: 2117: 2050: 1948: 1919: 1873:be a unit vector and 1868: 1848: 1813: 1793: 1758: 1692: 1666: 1646: 1608: 1584: 1564: 1544: 1504: 1478: 1456: 1392: 1372: 1348: 1312: 1292: 1272: 1246: 1207: 1181: 1161: 1141: 1095: 1075: 1019: 1017:{\displaystyle \phi } 999: 975: 949: 929: 900: 880: 860: 831: 811: 700: 680: 654: 634: 614: 581: 555: 436: 416: 396: 376: 374:{\displaystyle u_{j}} 349: 347:{\displaystyle u_{i}} 322: 293: 269: 201: 181: 157: 68: 42:Lovász theta function 5237:, Cornell University 4956:Schrijver, Alexander 4902:Schrijver, Alexander 4793:(January 27, 2014), 4768:Howard et al. (2014) 4582: 4555: 4535: 4509: 4474: 4355: 4309: 4265: 4072: 4014: 3965: 3938: 3891: 3827: 3778: 3738: 3703: 3631: 3587: 3567: 3547: 3541:strong graph product 3516: 3496: 3472: 3436: 3312: 3292: 3242: 3204: 3182:semidefinite program 3155: 3132: 3112: 3079: 3055: 3022: 2951: 2915: 2856: 2836: 2807: 2740: 2720: 2700: 2694:strong graph product 2670: 2563: 2469: 2410: 2248: 2194: 2134: 2084: 1957: 1928: 1877: 1857: 1828: 1802: 1767: 1704: 1675: 1655: 1617: 1597: 1573: 1553: 1517: 1487: 1467: 1401: 1381: 1361: 1321: 1301: 1281: 1255: 1219: 1190: 1170: 1150: 1112: 1084: 1028: 1008: 988: 958: 938: 909: 889: 869: 840: 836:is a unit vector in 820: 709: 689: 669: 643: 623: 594: 564: 445: 425: 421:are not adjacent in 405: 385: 358: 331: 302: 282: 212: 190: 170: 128: 48: 5060:10.1038/nature13460 5052:2014Natur.510..351H 4489:{\displaystyle N=n} 3914: 3463:independence number 1353:denote the largest 1270:{\displaystyle i=j} 973:{\displaystyle N=n} 579:{\displaystyle N=n} 464: 5287:Information theory 5251:Weisstein, Eric W. 5128:, IT-25 (1): 1–7, 4925:10.1007/BF02579273 4608:Lovász (1995–2001) 4588: 4568: 4541: 4521: 4486: 4438:circuit complexity 4387: 4341: 4295: 4251: 4175: 4058: 3997: 3951: 3924: 3900: 3877: 3810: 3760: 3716: 3697: 3679: 3617: 3573: 3553: 3529: 3502: 3478: 3451: 3422: 3388: 3339: 3298: 3266: 3228: 3170: 3138: 3118: 3094: 3061: 3037: 3008: 2921: 2901: 2842: 2822: 2791: 2726: 2706: 2682: 2646: 2635: 2541: 2447: 2388: 2383: 2226: 2171: 2112: 2045: 2006: 1990: 1943: 1914: 1863: 1843: 1808: 1788: 1753: 1731: 1687: 1661: 1641: 1603: 1579: 1559: 1549:whenever vertices 1539: 1499: 1473: 1451: 1428: 1387: 1367: 1343: 1307: 1287: 1267: 1241: 1213:symmetric matrices 1202: 1176: 1156: 1136: 1090: 1070: 1014: 994: 970: 944: 924: 895: 875: 855: 826: 806: 758: 742: 695: 675: 649: 629: 609: 576: 550: 545: 448: 431: 411: 391: 371: 344: 317: 288: 264: 196: 176: 152: 81:in his 1979 paper 63: 5166:978-0-89871-203-2 4979:978-3-642-78242-8 4948:Grötschel, Martin 4894:Grötschel, Martin 4591:{\displaystyle n} 4544:{\displaystyle c} 4418:quantum computers 4385: 4339: 4249: 4214: 4213: 3995: 3808: 3576:{\displaystyle k} 3556:{\displaystyle G} 3505:{\displaystyle G} 3481:{\displaystyle G} 3417: 3373: 3368: 3330: 3301:{\displaystyle G} 3260: 3222: 3141:{\displaystyle G} 3121:{\displaystyle G} 3064:{\displaystyle G} 2984: 2933:vertex-transitive 2924:{\displaystyle G} 2911:with equality if 2886: 2845:{\displaystyle G} 2819: 2729:{\displaystyle H} 2709:{\displaystyle G} 2659: 2658: 2614: 2533: 2376: 2369: 2349: 2342: 2224: 2153: 1991: 1975: 1940: 1866:{\displaystyle d} 1840: 1811:{\displaystyle B} 1722: 1664:{\displaystyle J} 1606:{\displaystyle B} 1582:{\displaystyle j} 1562:{\displaystyle i} 1476:{\displaystyle B} 1419: 1390:{\displaystyle G} 1370:{\displaystyle A} 1310:{\displaystyle j} 1290:{\displaystyle i} 1179:{\displaystyle A} 1159:{\displaystyle n} 1093:{\displaystyle c} 997:{\displaystyle G} 947:{\displaystyle N} 898:{\displaystyle G} 878:{\displaystyle U} 829:{\displaystyle c} 801: 743: 727: 698:{\displaystyle G} 652:{\displaystyle n} 632:{\displaystyle N} 526: 497: 434:{\displaystyle G} 414:{\displaystyle j} 394:{\displaystyle i} 291:{\displaystyle G} 199:{\displaystyle n} 179:{\displaystyle n} 5294: 5282:Graph invariants 5268: 5259:Sandwich Theorem 5238: 5236: 5224: 5201: 5183: 5169: 5150: 5136: 5115: 5114: 5104: 5083:Knuth, Donald E. 5078: 5045: 5022: 5017:, archived from 4990: 4943: 4941: 4935:, archived from 4910: 4889: 4872: 4863:(2): 1164–1174, 4847:Severini, Simone 4841: 4816: 4787:Severini, Simone 4771: 4765: 4759: 4753: 4747: 4741: 4735: 4729: 4723: 4717: 4711: 4701: 4695: 4689: 4683: 4677: 4671: 4665: 4659: 4653: 4647: 4641: 4635: 4629: 4623: 4617: 4611: 4605: 4599: 4597: 4595: 4594: 4589: 4577: 4575: 4574: 4569: 4567: 4566: 4550: 4548: 4547: 4542: 4530: 4528: 4527: 4522: 4503: 4497: 4495: 4493: 4492: 4487: 4467: 4461: 4455: 4434:complement graph 4396: 4394: 4393: 4388: 4386: 4381: 4373: 4372: 4350: 4348: 4347: 4342: 4340: 4335: 4327: 4326: 4304: 4302: 4301: 4296: 4260: 4258: 4257: 4252: 4250: 4245: 4234: 4229: 4228: 4215: 4212: 4204: 4200: 4195: 4180: 4179: 4172: 4171: 4170: 4154: 4139: 4138: 4137: 4121: 4106: 4084: 4083: 4067: 4065: 4064: 4059: 4054: 4053: 4035: 4034: 4006: 4004: 4003: 3998: 3996: 3991: 3983: 3982: 3960: 3958: 3957: 3952: 3950: 3949: 3933: 3931: 3930: 3925: 3913: 3908: 3886: 3884: 3883: 3878: 3867: 3866: 3845: 3844: 3819: 3817: 3816: 3811: 3809: 3804: 3796: 3795: 3769: 3767: 3766: 3761: 3756: 3755: 3725: 3723: 3722: 3717: 3715: 3714: 3688: 3686: 3685: 3680: 3626: 3624: 3623: 3618: 3583:times. Clearly, 3582: 3580: 3579: 3574: 3562: 3560: 3559: 3554: 3538: 3536: 3535: 3530: 3528: 3527: 3511: 3509: 3508: 3503: 3487: 3485: 3484: 3479: 3460: 3458: 3457: 3452: 3431: 3429: 3428: 3423: 3418: 3416: 3411: 3407: 3406: 3390: 3387: 3369: 3367: 3362: 3358: 3357: 3341: 3338: 3307: 3305: 3304: 3299: 3286:Shannon capacity 3275: 3273: 3272: 3267: 3262: 3261: 3253: 3237: 3235: 3234: 3229: 3224: 3223: 3215: 3186:ellipsoid method 3179: 3177: 3176: 3171: 3147: 3145: 3144: 3139: 3127: 3125: 3124: 3119: 3106:chromatic number 3103: 3101: 3100: 3095: 3070: 3068: 3067: 3062: 3046: 3044: 3043: 3038: 3017: 3015: 3014: 3009: 2986: 2985: 2977: 2930: 2928: 2927: 2922: 2910: 2908: 2907: 2902: 2888: 2887: 2879: 2851: 2849: 2848: 2843: 2831: 2829: 2828: 2823: 2821: 2820: 2812: 2800: 2798: 2797: 2792: 2735: 2733: 2732: 2727: 2715: 2713: 2712: 2707: 2691: 2689: 2688: 2683: 2655: 2653: 2652: 2647: 2645: 2644: 2634: 2607: 2606: 2605: 2604: 2586: 2585: 2550: 2548: 2547: 2542: 2540: 2539: 2538: 2532: 2521: 2509: 2496: 2495: 2456: 2454: 2453: 2448: 2437: 2436: 2397: 2395: 2394: 2389: 2387: 2386: 2377: 2374: 2370: 2362: 2350: 2347: 2343: 2341: 2334: 2310: 2303: 2282: 2266: 2265: 2235: 2233: 2232: 2227: 2225: 2220: 2212: 2211: 2180: 2178: 2177: 2172: 2161: 2160: 2155: 2154: 2146: 2121: 2119: 2118: 2113: 2102: 2101: 2065: 2054: 2052: 2051: 2046: 2041: 2040: 2031: 2030: 2021: 2020: 2019: 2005: 1989: 1952: 1950: 1949: 1944: 1942: 1941: 1933: 1923: 1921: 1920: 1915: 1898: 1897: 1872: 1870: 1869: 1864: 1852: 1850: 1849: 1844: 1842: 1841: 1833: 1823:complement graph 1817: 1815: 1814: 1809: 1797: 1795: 1794: 1789: 1762: 1760: 1759: 1754: 1730: 1696: 1694: 1693: 1688: 1670: 1668: 1667: 1662: 1650: 1648: 1647: 1642: 1612: 1610: 1609: 1604: 1588: 1586: 1585: 1580: 1568: 1566: 1565: 1560: 1548: 1546: 1545: 1540: 1532: 1531: 1508: 1506: 1505: 1500: 1482: 1480: 1479: 1474: 1460: 1458: 1457: 1452: 1438: 1437: 1427: 1396: 1394: 1393: 1388: 1376: 1374: 1373: 1368: 1352: 1350: 1349: 1344: 1333: 1332: 1316: 1314: 1313: 1308: 1296: 1294: 1293: 1288: 1276: 1274: 1273: 1268: 1250: 1248: 1247: 1242: 1234: 1233: 1211: 1209: 1208: 1203: 1185: 1183: 1182: 1177: 1165: 1163: 1162: 1157: 1145: 1143: 1142: 1137: 1099: 1097: 1096: 1091: 1079: 1077: 1076: 1071: 1063: 1062: 1053: 1023: 1021: 1020: 1015: 1003: 1001: 1000: 995: 979: 977: 976: 971: 953: 951: 950: 945: 933: 931: 930: 925: 923: 922: 917: 904: 902: 901: 896: 884: 882: 881: 876: 864: 862: 861: 856: 854: 853: 848: 835: 833: 832: 827: 815: 813: 812: 807: 802: 800: 799: 798: 789: 788: 779: 778: 777: 760: 757: 741: 704: 702: 701: 696: 684: 682: 681: 676: 658: 656: 655: 650: 638: 636: 635: 630: 618: 616: 615: 610: 608: 607: 602: 585: 583: 582: 577: 559: 557: 556: 551: 549: 548: 527: 524: 498: 495: 474: 473: 463: 462: 456: 440: 438: 437: 432: 420: 418: 417: 412: 400: 398: 397: 392: 380: 378: 377: 372: 370: 369: 353: 351: 350: 345: 343: 342: 326: 324: 323: 318: 316: 315: 310: 297: 295: 294: 289: 273: 271: 270: 265: 263: 262: 257: 233: 232: 205: 203: 202: 197: 185: 183: 182: 177: 161: 159: 158: 153: 106:chromatic number 98:ellipsoid method 72: 70: 69: 64: 38:Shannon capacity 5302: 5301: 5297: 5296: 5295: 5293: 5292: 5291: 5272: 5271: 5249: 5246: 5241: 5234: 5227: 5206:Shannon, Claude 5204: 5186: 5182:(lecture notes) 5172: 5167: 5139: 5118: 5081: 5036:(7505): 351–5, 5025: 4994: 4980: 4946: 4939: 4908: 4892: 4851:Winter, Andreas 4844: 4791:Winter, Andreas 4785:Cabello, Adán; 4784: 4780: 4775: 4774: 4766: 4762: 4754: 4750: 4742: 4738: 4730: 4726: 4718: 4714: 4702: 4698: 4690: 4686: 4678: 4674: 4666: 4662: 4654: 4650: 4642: 4638: 4630: 4626: 4618: 4614: 4606: 4602: 4580: 4579: 4558: 4553: 4552: 4533: 4532: 4507: 4506: 4504: 4500: 4472: 4471: 4468: 4464: 4456: 4452: 4447: 4430:Tardos function 4426: 4406: 4404:Quantum physics 4364: 4353: 4352: 4318: 4307: 4306: 4263: 4262: 4235: 4220: 4174: 4173: 4162: 4141: 4140: 4129: 4108: 4107: 4089: 4075: 4070: 4069: 4045: 4026: 4012: 4011: 3974: 3963: 3962: 3941: 3936: 3935: 3889: 3888: 3858: 3836: 3825: 3824: 3787: 3776: 3775: 3747: 3736: 3735: 3706: 3701: 3700: 3629: 3628: 3585: 3584: 3565: 3564: 3545: 3544: 3519: 3514: 3513: 3494: 3493: 3490:independent set 3470: 3469: 3434: 3433: 3398: 3391: 3349: 3342: 3310: 3309: 3290: 3289: 3282: 3240: 3239: 3202: 3201: 3153: 3152: 3130: 3129: 3110: 3109: 3077: 3076: 3053: 3052: 3020: 3019: 2949: 2948: 2941: 2913: 2912: 2854: 2853: 2834: 2833: 2805: 2804: 2738: 2737: 2718: 2717: 2698: 2697: 2668: 2667: 2664: 2636: 2596: 2577: 2572: 2561: 2560: 2522: 2511: 2504: 2481: 2467: 2466: 2422: 2408: 2407: 2382: 2381: 2371: 2358: 2357: 2344: 2311: 2283: 2274: 2257: 2246: 2245: 2203: 2192: 2191: 2143: 2132: 2131: 2093: 2082: 2081: 2060: 2032: 2022: 2010: 1955: 1954: 1926: 1925: 1889: 1875: 1874: 1855: 1854: 1826: 1825: 1800: 1799: 1765: 1764: 1702: 1701: 1673: 1672: 1653: 1652: 1615: 1614: 1595: 1594: 1571: 1570: 1551: 1550: 1520: 1515: 1514: 1485: 1484: 1483:range over all 1465: 1464: 1429: 1399: 1398: 1397:is as follows: 1379: 1378: 1359: 1358: 1324: 1319: 1318: 1299: 1298: 1279: 1278: 1253: 1252: 1222: 1217: 1216: 1188: 1187: 1186:range over all 1168: 1167: 1148: 1147: 1110: 1109: 1106: 1082: 1081: 1054: 1026: 1025: 1006: 1005: 986: 985: 956: 955: 936: 935: 912: 907: 906: 887: 886: 867: 866: 843: 838: 837: 818: 817: 790: 780: 768: 764: 707: 706: 687: 686: 667: 666: 641: 640: 621: 620: 597: 592: 591: 562: 561: 544: 543: 521: 512: 511: 492: 479: 465: 443: 442: 423: 422: 403: 402: 383: 382: 361: 356: 355: 334: 329: 328: 305: 300: 299: 280: 279: 252: 224: 210: 209: 188: 187: 168: 167: 126: 125: 122: 90:polynomial time 46: 45: 12: 11: 5: 5300: 5298: 5290: 5289: 5284: 5274: 5273: 5270: 5269: 5245: 5244:External links 5242: 5240: 5239: 5225: 5202: 5184: 5174:Lovász, László 5170: 5165: 5141:Lovász, László 5137: 5120:Lovász, László 5116: 5079: 5023: 5009:(2): 231–232, 4992: 4978: 4952:Lovász, László 4944: 4919:(2): 169–197, 4898:Lovász, László 4890: 4845:Duan, Runyao; 4842: 4781: 4779: 4776: 4773: 4772: 4760: 4748: 4736: 4732:Haemers (1979) 4724: 4712: 4696: 4684: 4672: 4660: 4648: 4636: 4624: 4612: 4600: 4587: 4565: 4561: 4540: 4520: 4517: 4514: 4498: 4485: 4482: 4479: 4462: 4449: 4448: 4446: 4443: 4442: 4441: 4425: 4422: 4405: 4402: 4384: 4379: 4376: 4371: 4367: 4363: 4360: 4338: 4333: 4330: 4325: 4321: 4317: 4314: 4294: 4291: 4288: 4285: 4282: 4279: 4276: 4273: 4270: 4248: 4244: 4241: 4238: 4232: 4227: 4223: 4218: 4211: 4207: 4203: 4198: 4194: 4190: 4187: 4183: 4178: 4169: 4165: 4160: 4157: 4153: 4149: 4146: 4143: 4142: 4136: 4132: 4127: 4124: 4120: 4116: 4113: 4110: 4109: 4105: 4101: 4098: 4095: 4094: 4092: 4087: 4082: 4078: 4057: 4052: 4048: 4044: 4041: 4038: 4033: 4029: 4025: 4022: 4019: 3994: 3989: 3986: 3981: 3977: 3973: 3970: 3948: 3944: 3923: 3920: 3917: 3912: 3907: 3903: 3899: 3896: 3876: 3873: 3870: 3865: 3861: 3857: 3854: 3851: 3848: 3843: 3839: 3835: 3832: 3807: 3802: 3799: 3794: 3790: 3786: 3783: 3759: 3754: 3750: 3746: 3743: 3732:Shannon (1956) 3713: 3709: 3695:Pentagon graph 3678: 3675: 3672: 3669: 3666: 3663: 3660: 3657: 3654: 3651: 3648: 3645: 3642: 3639: 3636: 3616: 3613: 3610: 3607: 3604: 3601: 3598: 3595: 3592: 3572: 3552: 3526: 3522: 3501: 3477: 3450: 3447: 3444: 3441: 3421: 3415: 3410: 3405: 3401: 3397: 3394: 3386: 3383: 3380: 3376: 3372: 3366: 3361: 3356: 3352: 3348: 3345: 3337: 3333: 3329: 3326: 3323: 3320: 3317: 3297: 3281: 3278: 3265: 3259: 3256: 3250: 3247: 3227: 3221: 3218: 3212: 3209: 3198:perfect graphs 3169: 3166: 3163: 3160: 3137: 3117: 3093: 3090: 3087: 3084: 3060: 3036: 3033: 3030: 3027: 3007: 3004: 3001: 2998: 2995: 2992: 2989: 2983: 2980: 2974: 2971: 2968: 2965: 2962: 2959: 2956: 2940: 2937: 2920: 2900: 2897: 2894: 2891: 2885: 2882: 2876: 2873: 2870: 2867: 2864: 2861: 2841: 2818: 2815: 2790: 2787: 2784: 2781: 2778: 2775: 2772: 2769: 2766: 2763: 2760: 2757: 2754: 2751: 2748: 2745: 2725: 2705: 2681: 2678: 2675: 2663: 2660: 2657: 2656: 2643: 2639: 2633: 2630: 2627: 2624: 2621: 2617: 2613: 2610: 2603: 2599: 2595: 2592: 2589: 2584: 2580: 2575: 2571: 2568: 2558: 2552: 2551: 2537: 2531: 2528: 2525: 2520: 2517: 2514: 2508: 2502: 2499: 2494: 2491: 2488: 2484: 2480: 2477: 2474: 2464: 2458: 2457: 2446: 2443: 2440: 2435: 2432: 2429: 2425: 2421: 2418: 2415: 2405: 2403:Petersen graph 2399: 2398: 2385: 2380: 2375:for even  2372: 2368: 2365: 2360: 2359: 2356: 2353: 2345: 2340: 2337: 2333: 2329: 2326: 2323: 2320: 2317: 2314: 2309: 2306: 2302: 2298: 2295: 2292: 2289: 2286: 2280: 2279: 2277: 2272: 2269: 2264: 2260: 2256: 2253: 2243: 2237: 2236: 2223: 2218: 2215: 2210: 2206: 2202: 2199: 2189: 2182: 2181: 2170: 2167: 2164: 2159: 2152: 2149: 2142: 2139: 2129: 2123: 2122: 2111: 2108: 2105: 2100: 2096: 2092: 2089: 2079: 2077:Complete graph 2073: 2072: 2071:Lovász number 2069: 2059: 2056: 2044: 2039: 2035: 2029: 2025: 2018: 2013: 2009: 2004: 2001: 1998: 1994: 1988: 1985: 1982: 1978: 1974: 1971: 1968: 1965: 1962: 1939: 1936: 1913: 1910: 1907: 1904: 1901: 1896: 1892: 1888: 1885: 1882: 1862: 1839: 1836: 1807: 1787: 1784: 1781: 1778: 1775: 1772: 1752: 1749: 1746: 1743: 1740: 1737: 1734: 1729: 1725: 1721: 1718: 1715: 1712: 1709: 1698:matrix of ones 1686: 1683: 1680: 1660: 1640: 1637: 1634: 1631: 1628: 1625: 1622: 1602: 1578: 1558: 1538: 1535: 1530: 1527: 1523: 1498: 1495: 1492: 1472: 1450: 1447: 1444: 1441: 1436: 1432: 1426: 1422: 1418: 1415: 1412: 1409: 1406: 1386: 1366: 1342: 1339: 1336: 1331: 1327: 1306: 1286: 1266: 1263: 1260: 1240: 1237: 1232: 1229: 1225: 1201: 1198: 1195: 1175: 1166:vertices. Let 1155: 1146:be a graph on 1135: 1132: 1129: 1126: 1123: 1120: 1117: 1105: 1102: 1089: 1069: 1066: 1061: 1057: 1052: 1048: 1045: 1042: 1039: 1036: 1033: 1013: 993: 969: 966: 963: 943: 921: 916: 894: 874: 852: 847: 825: 805: 797: 793: 787: 783: 776: 771: 767: 763: 756: 753: 750: 746: 740: 737: 734: 730: 726: 723: 720: 717: 714: 694: 674: 648: 628: 606: 601: 588:standard basis 575: 572: 569: 547: 542: 539: 536: 533: 530: 522: 520: 517: 514: 513: 510: 507: 504: 501: 493: 491: 488: 485: 484: 482: 477: 472: 468: 461: 455: 451: 430: 410: 390: 368: 364: 341: 337: 314: 309: 287: 261: 256: 251: 248: 245: 242: 239: 236: 231: 227: 223: 220: 217: 195: 175: 151: 148: 145: 142: 139: 136: 133: 121: 118: 114:perfect graphs 62: 59: 56: 53: 13: 10: 9: 6: 4: 3: 2: 5299: 5288: 5285: 5283: 5280: 5279: 5277: 5266: 5265: 5260: 5256: 5255:Lovász Number 5252: 5248: 5247: 5243: 5233: 5232: 5226: 5223: 5219: 5215: 5211: 5207: 5203: 5200: 5196: 5192: 5191: 5185: 5181: 5180: 5176:(1995–2001), 5175: 5171: 5168: 5162: 5158: 5154: 5149: 5148: 5142: 5138: 5135: 5131: 5127: 5126: 5121: 5117: 5113: 5112:10.37236/1193 5108: 5103: 5098: 5094: 5090: 5089: 5084: 5080: 5077: 5073: 5069: 5065: 5061: 5057: 5053: 5049: 5044: 5039: 5035: 5031: 5030: 5024: 5021:on 2012-03-05 5020: 5016: 5012: 5008: 5004: 5003: 4998: 4993: 4989: 4985: 4981: 4975: 4971: 4967: 4963: 4962: 4957: 4953: 4949: 4945: 4942:on 2011-07-18 4938: 4934: 4930: 4926: 4922: 4918: 4914: 4913:Combinatorica 4907: 4903: 4899: 4895: 4891: 4888: 4884: 4880: 4876: 4871: 4866: 4862: 4858: 4857: 4852: 4848: 4843: 4840: 4836: 4832: 4828: 4824: 4820: 4815: 4810: 4807:(4): 040401, 4806: 4802: 4801: 4796: 4792: 4788: 4783: 4782: 4777: 4769: 4764: 4761: 4757: 4752: 4749: 4745: 4740: 4737: 4733: 4728: 4725: 4721: 4720:Lovász (1979) 4716: 4713: 4709: 4705: 4700: 4697: 4693: 4688: 4685: 4681: 4680:Lovász (1979) 4676: 4673: 4669: 4668:Lovász (1979) 4664: 4661: 4657: 4656:Riddle (2003) 4652: 4649: 4645: 4644:Lovász (1979) 4640: 4637: 4633: 4632:Lovász (1979) 4628: 4625: 4621: 4620:Lovász (1979) 4616: 4613: 4609: 4604: 4601: 4598:-dimensional. 4585: 4563: 4559: 4538: 4518: 4515: 4512: 4502: 4499: 4483: 4480: 4477: 4466: 4463: 4459: 4458:Lovász (1979) 4454: 4451: 4444: 4439: 4435: 4431: 4428: 4427: 4423: 4421: 4419: 4415: 4411: 4403: 4401: 4398: 4382: 4377: 4369: 4365: 4336: 4331: 4323: 4319: 4312: 4289: 4286: 4283: 4280: 4277: 4271: 4268: 4246: 4242: 4239: 4236: 4230: 4225: 4221: 4216: 4209: 4205: 4201: 4196: 4192: 4188: 4185: 4181: 4176: 4167: 4163: 4158: 4155: 4151: 4147: 4144: 4134: 4130: 4125: 4122: 4118: 4114: 4111: 4103: 4099: 4096: 4090: 4085: 4080: 4076: 4050: 4046: 4042: 4039: 4036: 4031: 4027: 4020: 4017: 4008: 3992: 3987: 3979: 3975: 3946: 3942: 3921: 3918: 3910: 3905: 3901: 3894: 3874: 3871: 3863: 3859: 3852: 3849: 3841: 3837: 3821: 3805: 3800: 3792: 3788: 3773: 3772:Lovász (1979) 3752: 3748: 3733: 3729: 3711: 3707: 3693: 3689: 3676: 3670: 3664: 3661: 3655: 3646: 3640: 3634: 3611: 3605: 3602: 3596: 3570: 3550: 3542: 3524: 3520: 3499: 3491: 3475: 3468: 3464: 3445: 3439: 3419: 3413: 3403: 3399: 3392: 3378: 3370: 3364: 3354: 3350: 3343: 3335: 3327: 3321: 3295: 3287: 3279: 3277: 3254: 3245: 3216: 3207: 3199: 3195: 3191: 3187: 3183: 3164: 3158: 3151:The value of 3149: 3135: 3115: 3107: 3088: 3082: 3074: 3058: 3050: 3049:clique number 3031: 3025: 3005: 2999: 2993: 2990: 2978: 2969: 2966: 2960: 2954: 2946: 2938: 2936: 2934: 2918: 2898: 2895: 2892: 2880: 2871: 2865: 2859: 2839: 2813: 2801: 2788: 2782: 2776: 2770: 2764: 2761: 2755: 2752: 2749: 2743: 2723: 2703: 2695: 2679: 2676: 2673: 2661: 2641: 2637: 2631: 2628: 2625: 2622: 2619: 2611: 2601: 2597: 2593: 2590: 2587: 2582: 2578: 2573: 2566: 2559: 2557: 2554: 2553: 2529: 2526: 2523: 2518: 2515: 2512: 2500: 2492: 2489: 2486: 2482: 2478: 2472: 2465: 2463: 2462:Kneser graphs 2460: 2459: 2444: 2441: 2433: 2430: 2427: 2423: 2419: 2413: 2406: 2404: 2401: 2400: 2378: 2366: 2363: 2354: 2351: 2348:for odd  2335: 2331: 2327: 2321: 2318: 2315: 2312: 2304: 2300: 2296: 2290: 2287: 2284: 2275: 2270: 2262: 2258: 2251: 2244: 2242: 2239: 2238: 2221: 2216: 2208: 2204: 2197: 2190: 2187: 2184: 2183: 2168: 2165: 2157: 2147: 2137: 2130: 2128: 2125: 2124: 2109: 2106: 2098: 2094: 2087: 2080: 2078: 2075: 2074: 2070: 2067: 2066: 2063: 2057: 2055: 2042: 2037: 2027: 2023: 2011: 2002: 1999: 1996: 1992: 1986: 1983: 1980: 1972: 1966: 1960: 1934: 1908: 1905: 1902: 1899: 1894: 1890: 1883: 1880: 1860: 1834: 1824: 1819: 1805: 1782: 1779: 1773: 1770: 1750: 1744: 1741: 1735: 1732: 1727: 1719: 1713: 1707: 1699: 1684: 1681: 1678: 1658: 1638: 1635: 1629: 1623: 1620: 1600: 1592: 1576: 1556: 1536: 1533: 1528: 1525: 1521: 1512: 1496: 1493: 1490: 1470: 1461: 1448: 1442: 1430: 1424: 1416: 1410: 1404: 1384: 1364: 1356: 1337: 1325: 1304: 1284: 1264: 1261: 1258: 1238: 1235: 1230: 1227: 1223: 1214: 1199: 1196: 1193: 1173: 1153: 1130: 1127: 1124: 1118: 1115: 1103: 1101: 1087: 1067: 1064: 1059: 1055: 1050: 1046: 1043: 1037: 1031: 1011: 991: 983: 967: 964: 961: 941: 919: 892: 872: 850: 823: 803: 795: 785: 781: 769: 761: 754: 751: 748: 738: 735: 732: 724: 718: 712: 692: 672: 665: 664:Lovász number 660: 646: 626: 604: 589: 573: 570: 567: 540: 537: 534: 531: 528: 518: 515: 508: 505: 502: 499: 489: 486: 480: 475: 470: 466: 453: 449: 428: 408: 388: 366: 362: 339: 335: 312: 285: 277: 274:is called an 259: 249: 243: 240: 237: 234: 229: 225: 218: 215: 208: 193: 173: 165: 146: 143: 140: 134: 131: 119: 117: 115: 111: 110:clique number 107: 103: 99: 95: 91: 86: 84: 80: 79:László Lovász 76: 57: 51: 43: 39: 35: 31: 27: 23: 22:Lovász number 19: 5262: 5230: 5213: 5209: 5189: 5178: 5146: 5123: 5102:math/9312214 5092: 5086: 5033: 5027: 5019:the original 5006: 5000: 4960: 4937:the original 4916: 4912: 4860: 4854: 4804: 4798: 4763: 4751: 4739: 4727: 4722:, Theorem 1. 4715: 4699: 4692:Knuth (1994) 4687: 4675: 4663: 4651: 4646:, Theorem 5. 4639: 4634:, Theorem 4. 4627: 4622:, Theorem 3. 4615: 4603: 4501: 4465: 4453: 4407: 4399: 4009: 3822: 3698: 3563:with itself 3283: 3193: 3150: 2942: 2802: 2692:denotes the 2665: 2241:Cycle graphs 2061: 1820: 1462: 1277:or vertices 1107: 663: 661: 275: 207:unit vectors 123: 87: 82: 41: 21: 18:graph theory 15: 5216:(3): 8–19, 5199:1877/etd181 3887:. However, 2945:NP-complete 2127:Empty graph 34:upper bound 32:that is an 30:real number 5276:Categories 5155:, p.  4991:, page 285 4778:References 3190:polynomial 2696:of graphs 2662:Properties 1513:such that 1509:symmetric 1355:eigenvalue 1215:such that 120:Definition 102:complement 5264:MathWorld 5043:1401.4174 4870:1002.2514 4814:1401.7081 4359:Θ 4351:. Hence, 4332:≤ 4313:ϑ 4240:π 4222:φ 4193:θ 4189:⁡ 4164:φ 4159:⁡ 4152:θ 4148:⁡ 4131:φ 4126:⁡ 4119:θ 4115:⁡ 4104:θ 4100:⁡ 4040:… 3988:≥ 3969:Θ 3919:≥ 3895:α 3853:α 3850:≥ 3831:Θ 3823:Clearly, 3782:Θ 3742:Θ 3665:ϑ 3662:≤ 3650:Θ 3647:≤ 3635:α 3606:α 3603:≥ 3591:Θ 3440:α 3393:α 3385:∞ 3382:→ 3344:α 3316:Θ 3288:of graph 3258:¯ 3246:ϑ 3220:¯ 3208:ϑ 3159:ϑ 3083:χ 3026:ω 2994:χ 2991:≤ 2982:¯ 2970:ϑ 2967:≤ 2955:ω 2893:≥ 2884:¯ 2872:ϑ 2860:ϑ 2817:¯ 2777:ϑ 2765:ϑ 2753:⊠ 2744:ϑ 2677:⊠ 2629:≤ 2623:≤ 2591:… 2567:ϑ 2527:− 2516:− 2473:ϑ 2414:ϑ 2328:π 2322:⁡ 2297:π 2291:⁡ 2252:ϑ 2198:ϑ 2151:¯ 2138:ϑ 2088:ϑ 2000:∈ 1993:∑ 1961:ϑ 1938:¯ 1906:∈ 1900:∣ 1838:¯ 1774:⁡ 1736:⁡ 1708:ϑ 1682:× 1624:⁡ 1494:× 1431:λ 1405:ϑ 1326:λ 1251:whenever 1197:× 1068:ϕ 1065:⁡ 1032:ϑ 1012:ϕ 752:∈ 713:ϑ 685:of graph 673:ϑ 535:∉ 250:⊂ 241:∈ 235:∣ 52:ϑ 5068:24919152 4958:(1993), 4933:43787103 4904:(1981), 4839:34998358 4831:24580419 4424:See also 4261:and let 3961:), thus 3728:pentagon 2186:Pentagon 525:if  496:if  96:and the 5076:4463585 5048:Bibcode 4988:1261419 4887:4690143 3539:is the 3461:is the 3104:is the 3047:is the 2852:, then 2736:, then 1953:. Then 1700:. Then 1671:be the 1024:, then 36:on the 5261:") at 5163:  5095:: A1, 5074:  5066:  5029:Nature 4986:  4976:  4931:  4885:  4837:  4829:  3512:) and 3432:where 3196:. For 3075:) and 3073:clique 3018:where 1853:. Let 1763:Here, 1651:. Let 816:where 20:, the 5235:(PDF) 5097:arXiv 5072:S2CID 5038:arXiv 4940:(PDF) 4929:S2CID 4909:(PDF) 4883:S2CID 4865:arXiv 4835:S2CID 4809:arXiv 4445:Notes 3774:that 3467:graph 2188:graph 2068:Graph 1591:trace 327:, if 164:graph 162:be a 75:theta 28:is a 26:graph 24:of a 5257:" (" 5161:ISBN 5064:PMID 4974:ISBN 4827:PMID 4516:> 3726:, a 3284:The 2716:and 1569:and 1297:and 1108:Let 1080:and 982:cone 865:and 662:The 401:and 354:and 124:Let 108:and 5253:, " 5218:doi 5195:hdl 5130:doi 5107:doi 5056:doi 5034:510 5011:doi 4966:doi 4921:doi 4875:doi 4819:doi 4805:112 4505:If 4186:cos 4156:sin 4145:sin 4123:cos 4112:sin 4097:cos 3543:of 3492:of 3465:of 3375:lim 3332:sup 3108:of 3051:of 2931:is 2803:If 2666:If 2616:max 2319:cos 2288:cos 1977:max 1724:max 1613:is 1435:max 1421:min 1357:of 1330:max 1056:cos 905:in 745:max 729:min 590:of 298:in 278:of 166:on 92:by 16:In 5278:: 5212:, 5159:, 5157:75 5151:, 5105:, 5091:, 5070:, 5062:, 5054:, 5046:, 5032:, 5007:25 5005:, 4999:, 4984:MR 4982:, 4972:, 4954:; 4950:; 4927:, 4915:, 4911:, 4900:; 4896:; 4881:, 4873:, 4861:59 4859:, 4849:; 4833:, 4825:, 4817:, 4803:, 4797:, 4789:; 4706:; 4420:. 4397:. 4007:. 3820:. 2935:. 1818:. 1771:Tr 1733:Tr 1621:Tr 659:. 441:: 116:. 85:. 5267:. 5220:: 5214:2 5197:: 5132:: 5109:: 5099:: 5093:1 5058:: 5050:: 5040:: 5013:: 4968:: 4923:: 4917:1 4877:: 4867:: 4821:: 4811:: 4770:. 4758:. 4746:. 4734:. 4710:. 4694:. 4658:. 4586:n 4564:i 4560:u 4539:c 4519:n 4513:N 4484:n 4481:= 4478:N 4460:. 4440:. 4383:5 4378:= 4375:) 4370:5 4366:C 4362:( 4337:5 4329:) 4324:5 4320:C 4316:( 4293:) 4290:0 4287:, 4284:0 4281:, 4278:1 4275:( 4272:= 4269:c 4247:5 4243:k 4237:2 4231:= 4226:k 4217:, 4210:4 4206:5 4202:1 4197:= 4182:, 4177:) 4168:k 4135:k 4091:( 4086:= 4081:k 4077:u 4056:) 4051:5 4047:u 4043:, 4037:, 4032:1 4028:u 4024:( 4021:= 4018:U 3993:5 3985:) 3980:5 3976:C 3972:( 3947:5 3943:C 3922:5 3916:) 3911:2 3906:5 3902:C 3898:( 3875:2 3872:= 3869:) 3864:5 3860:C 3856:( 3847:) 3842:5 3838:C 3834:( 3806:5 3801:= 3798:) 3793:5 3789:C 3785:( 3758:) 3753:5 3749:C 3745:( 3712:5 3708:C 3677:. 3674:) 3671:G 3668:( 3659:) 3656:G 3653:( 3644:) 3641:G 3638:( 3615:) 3612:G 3609:( 3600:) 3597:G 3594:( 3571:k 3551:G 3525:k 3521:G 3500:G 3476:G 3449:) 3446:G 3443:( 3420:, 3414:k 3409:) 3404:k 3400:G 3396:( 3379:k 3371:= 3365:k 3360:) 3355:k 3351:G 3347:( 3336:k 3328:= 3325:) 3322:G 3319:( 3296:G 3264:) 3255:G 3249:( 3226:) 3217:G 3211:( 3194:G 3168:) 3165:G 3162:( 3136:G 3116:G 3092:) 3089:G 3086:( 3059:G 3035:) 3032:G 3029:( 3006:, 3003:) 3000:G 2997:( 2988:) 2979:G 2973:( 2964:) 2961:G 2958:( 2919:G 2899:, 2896:n 2890:) 2881:G 2875:( 2869:) 2866:G 2863:( 2840:G 2814:G 2789:. 2786:) 2783:H 2780:( 2774:) 2771:G 2768:( 2762:= 2759:) 2756:H 2750:G 2747:( 2724:H 2704:G 2680:H 2674:G 2642:i 2638:n 2632:k 2626:i 2620:1 2612:= 2609:) 2602:k 2598:n 2594:, 2588:, 2583:1 2579:n 2574:K 2570:( 2536:) 2530:1 2524:k 2519:1 2513:n 2507:( 2501:= 2498:) 2493:k 2490:, 2487:n 2483:G 2479:K 2476:( 2445:4 2442:= 2439:) 2434:2 2431:, 2428:5 2424:G 2420:K 2417:( 2379:n 2367:2 2364:n 2355:, 2352:n 2339:) 2336:n 2332:/ 2325:( 2316:+ 2313:1 2308:) 2305:n 2301:/ 2294:( 2285:n 2276:{ 2271:= 2268:) 2263:n 2259:C 2255:( 2222:5 2217:= 2214:) 2209:5 2205:C 2201:( 2169:n 2166:= 2163:) 2158:n 2148:K 2141:( 2110:1 2107:= 2104:) 2099:n 2095:K 2091:( 2043:. 2038:2 2034:) 2028:i 2024:u 2017:T 2012:d 2008:( 2003:V 1997:i 1987:U 1984:, 1981:d 1973:= 1970:) 1967:G 1964:( 1935:G 1912:) 1909:V 1903:i 1895:i 1891:u 1887:( 1884:= 1881:U 1861:d 1835:G 1806:B 1786:) 1783:J 1780:B 1777:( 1751:. 1748:) 1745:J 1742:B 1739:( 1728:B 1720:= 1717:) 1714:G 1711:( 1685:n 1679:n 1659:J 1639:1 1636:= 1633:) 1630:B 1627:( 1601:B 1577:j 1557:i 1537:0 1534:= 1529:j 1526:i 1522:b 1497:n 1491:n 1471:B 1449:. 1446:) 1443:A 1440:( 1425:A 1417:= 1414:) 1411:G 1408:( 1385:G 1365:A 1341:) 1338:A 1335:( 1305:j 1285:i 1265:j 1262:= 1259:i 1239:1 1236:= 1231:j 1228:i 1224:a 1200:n 1194:n 1174:A 1154:n 1134:) 1131:E 1128:, 1125:V 1122:( 1119:= 1116:G 1088:c 1060:2 1051:/ 1047:1 1044:= 1041:) 1038:G 1035:( 992:G 968:n 965:= 962:N 942:N 920:N 915:R 893:G 873:U 851:N 846:R 824:c 804:, 796:2 792:) 786:i 782:u 775:T 770:c 766:( 762:1 755:V 749:i 739:U 736:, 733:c 725:= 722:) 719:G 716:( 693:G 647:n 627:N 605:N 600:R 574:n 571:= 568:N 541:. 538:E 532:j 529:i 519:, 516:0 509:, 506:j 503:= 500:i 490:, 487:1 481:{ 476:= 471:j 467:u 460:T 454:i 450:u 429:G 409:j 389:i 367:j 363:u 340:i 336:u 313:N 308:R 286:G 260:N 255:R 247:) 244:V 238:i 230:i 226:u 222:( 219:= 216:U 194:n 174:n 150:) 147:E 144:, 141:V 138:( 135:= 132:G 61:) 58:G 55:(

Index

graph theory
graph
real number
upper bound
Shannon capacity
theta
László Lovász
polynomial time
semidefinite programming
ellipsoid method
complement
chromatic number
clique number
perfect graphs
graph
unit vectors
standard basis
cone
symmetric matrices
eigenvalue
positive semidefinite matrices
trace
matrix of ones
complement graph
Complete graph
Empty graph
Pentagon
Cycle graphs
Petersen graph
Kneser graphs

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