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Gibbard–Satterthwaite theorem

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1803:. It is always optimal for a voter to give the best candidate the highest possible score, and the worst candidate the lowest possible score. Then, no matter which score the voter assigns to the middle candidate, it will always fall (non-strictly) between the first and last scores; this implies the voter's score ballot will be weakly consistent with that voter's honest ranking. However, the actual optimal score may depend on the other ballots cast, as indicated by 2510: 36: 78: 268:: each voter communicates his or her preference order over the candidates. For each ballot, 3 points are assigned to the top candidate, 2 points to the second candidate, 1 point to the third one and 0 points to the last one. Once all ballots have been counted, the candidate with the most points is declared the winner. 2020:
For a strict voting rule, the converse of the Gibbard–Satterthwaite theorem is true. Indeed, a strict voting rule is dictatorial if and only if it always selects the most-liked candidate of the dictator among the possible outcomes; in particular, it does not depend on the other voters' ballots. As a
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If there are only 2 possible outcomes, a voting rule may be non-manipulable without being dictatorial. For example, it is the case of the simple majority vote: each voter assigns 1 point to her top alternative and 0 to the other, and the alternative with most points is declared the winner. (If both
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This voting rule is not manipulable: a voter is always better off communicating his or her sincere preferences. It is also dictatorial, and its dictator is voter 1: the winning alternative is always that specific voter's most-liked one or, if there are several most-liked alternatives, it is chosen
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is defined as follows. If voter 1 has a unique most-liked candidate, then this candidate is elected. Otherwise, possible outcomes are restricted to the most-liked candidates, whereas the other candidates are eliminated. Then voter 2's ballot is examined: if there is a unique best-liked candidate
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of the voting rule. It is possible that some other alternatives can be elected in no circumstances: the theorem and the corollary still apply. However, the corollary is sometimes presented under a less general form: instead of assuming that the rule has at least three possible outcomes, it is
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among the non-eliminated ones, then this candidate is elected. Otherwise, the list of possible outcomes is reduced again, etc. If there are still several non-eliminated candidates after all ballots have been examined, then an arbitrary tie-breaking rule is used.
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wins.) This voting rule is not manipulable because a voter is always better off communicating his or her sincere preferences; and it is clearly not dictatorial. Many other rules are neither manipulable nor dictatorial: for example, assume that the alternative
2443:. Independently, Satterthwaite proved the same result in his PhD dissertation in 1973, then published it in a 1975 article. This proof is also based on Arrow's impossibility theorem, but does not involve the more general version given by Gibbard's theorem. 2021:
consequence, it is not manipulable: the dictator is perfectly defended by her sincere ballot, and the other voters have no impact on the outcome, hence they have no incentive to deviate from sincere voting. Thus, we obtain the following equivalence.
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The GS theorem seems to quash any hope of designing incentive-compatible social-choice functions. The whole field of Mechanism Design attempts escaping from this impossibility result using various modifications in the
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In the theorem, as well as in the corollary, it is not needed to assume that any alternative can be elected. It is only assumed that at least three of them can win, i.e. are
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is manipulable, except possibly in two cases: if there is a distinguished voter who has a dictatorial power, or if the rule limits the possible outcomes to two options only.
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deals with processes of collective choice that may not be ordinal, i.e. where a voter's action may not consist in communicating a preference order over the candidates.
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extend these results to non-deterministic mechanisms, i.e. where the outcome may not only depend on the ballots but may also involve a part of chance.
3344: 2670:(April 1975). "Strategy-proofness and Arrow's conditions: Existence and correspondence theorems for voting procedures and social welfare functions". 2494:
The main idea of these "escape routes" is that they allow for a broader class of mechanisms than ranked voting, similarly to the escape routes from
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satisfies independence of irrelevant alternatives. Arrow's impossibility theorem says that, when there are three or more alternatives, such a
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Duggan, John; Schwartz, Thomas (2000). "Strategic manipulability without resoluteness or shared beliefs: Gibbard-Satterthwaite generalized".
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The Gibbard–Satterthwaite theorem is generally presented as a result about voting systems, but it can also be seen as an important result of
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But Alice can vote strategically and change the result. Assume that she modifies her ballot, in order to produce the following situation.
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that choose a single winner, and shows that for every voting rule of this form, at least one of the following three things must hold:
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are even more general and extend these results to non-deterministic processes, where the outcome may depend partly on chance; the
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Gibbard's theorem does not imply that cardinal methods necessarily incentivize reversing one's relative rank of two candidates.
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A variety of "counterexamples" to the Gibbard-Satterthwaite theorem exist when the conditions of the theorem do not apply.
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Barberá, Salvador (1983). "Strategy-Proofness and Pivotal Voters: A Direct Proof of the Gibbard-Satterthwaite Theorem".
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alternatives reach the same number of points, the tie is broken in an arbitrary but deterministic manner, e.g. outcome
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extend this result in another direction, by dealing with deterministic voting rules that choose multiple winners.
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This principle of voting makes an election more of a game of skill than a real test of the wishes of the electors.
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If a strict voting rule has at least 3 possible outcomes, it is non-manipulable if and only if it is dictatorial.
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We now consider the case where by assumption, a voter cannot be indifferent between two candidates. We denote by
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If an ordinal voting rule has at least 3 possible outcomes and is non-dictatorial, then it is manipulable.
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Consider three voters named Alice, Bob and Carol, who wish to select a winner among four candidates named
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Reny, Philip J. (2001). "Arrow's Theorem and the Gibbard-Satterthwaite Theorem: A Unified Approach".
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Gärdenfors, Peter (1977). "A Concise Proof of Theorem on Manipulation of Social Choice Functions".
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The rule is dictatorial, i.e. there exists a distinguished voter who can choose the winner; or
124: 3018:"An interview with Michael Dummett: From analytical philosophy to voting analysis and beyond" 2583:"An Interview with Michael Dummett: From analytical philosophy to voting analysis and beyond" 1119:: there exists situations where a sincere ballot does not defend a voter's preferences best. 160:
is more general and covers processes of collective decision that may not be ordinal, such as
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The strategic aspect of voting is already noticed in 1876 by Charles Dodgson, also known as
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is elected. Alice is satisfied by her ballot modification, because she prefers the outcome
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Benoît, Jean-Pierre (2000). "The Gibbard-Satterthwaite Theorem: A Simple Proof".
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Dummett, Michael; Farquharson, Robin (January 1961). "Stability in voting".
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has at least three possible outcomes if and only if the cardinality of
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Taylor, Alan D. (April 2002). "The manipulability of voting systems".
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published influential articles on voting theory. In an article with
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Dummett, Michael (2005). "The work and life of Robin Farquharson".
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The rule limits the possible outcomes to two alternatives only; or
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contains at least three elements and that the voting rule is
2629:(1973). "Manipulation of voting schemes: A general result". 2049: 1990: 1974: 1939: 1911: 1693: 1609: 1465: 1369: 1306: 1290: 1255: 1227: 1175: 1143: 2809:"Another Direct Proof of the Gibbard-Satterthwaite Theorem" 1479:{\displaystyle (P_{1},\ldots ,P_{n})\in {\mathcal {P}}^{n}} 1383:{\displaystyle (P_{1},\ldots ,P_{n})\in {\mathcal {P}}^{n}} 49:
inadequate description of theorem and practical importance.
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Later authors have developed other variants of the proof.
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If the voters cast sincere ballots, then the scores are:
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The rule is not straightforward, i.e. there is no single
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in 1961 and then proved independently by the philosopher
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extends these results to multiwinner electoral systems.
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are moved to the top of all voters' preferences. Then,
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The Gibbard–Satterthwaite theorem can be proved using
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and it yields the identity of the winning candidate.
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Impossibility result for ranked-choice voting systems
2427:. This conjecture was later proven independently by 1122:
The Gibbard–Satterthwaite theorem states that every
2380: 2356: 2336: 2316: 2293: 2273: 2253: 2233: 2213: 2193: 2173: 2153: 2127: 2115:It is possible to build a social ranking function 2100: 2056: 1997: 1946: 1918: 1886: 1866: 1845: 1756: 1732: 1709: 1669: 1645: 1625: 1582: 1555: 1525: 1498: 1478: 1405: 1382: 1313: 1262: 1234: 1206: 1150: 1104: 1084: 1064: 1044: 976: 956: 931: 910: 889: 868: 842: 821: 800: 779: 753: 732: 711: 690: 642: 622: 549: 528: 507: 486: 460: 439: 418: 397: 371: 350: 329: 308: 256: 236: 216: 196: 1799:Consider a three-candidate election conducted by 2581:Rudolf Farra and Maurice Salles (October 2006). 2713:Technical Report (University Library of Munich) 2662: 2660: 1207:{\displaystyle {\mathcal {N}}=\{1,\ldots ,n\}} 271:Assume that their preferences are as follows. 119:. It was first conjectured by the philosopher 2876:. Cambridge, UK: Cambridge University Press. 2439:from 1951 to prove the result we now know as 1874:wins if it gets two thirds of the votes, and 1770:regardless of the preferences of other voters 45:needs attention from an expert in game theory 8: 2017:have natural adaptations to this framework. 1201: 1183: 2025: 1776: 1657:for the election. For example, we say that 944:Alice has strategically upgraded candidate 3160:"Straightforwardness in voting procedures" 2181:function creates new preferences in which 3175: 2742: 2683: 2621: 2619: 2373: 2349: 2329: 2309: 2286: 2266: 2246: 2226: 2206: 2186: 2166: 2140: 2135:, as follows: in order to decide whether 2120: 2093: 2048: 2047: 2045: 1989: 1988: 1979: 1973: 1972: 1963: 1938: 1937: 1935: 1910: 1909: 1907: 1879: 1859: 1838: 1749: 1725: 1698: 1692: 1691: 1682: 1662: 1638: 1614: 1608: 1607: 1598: 1574: 1568: 1544: 1538: 1517: 1511: 1491: 1470: 1464: 1463: 1450: 1431: 1422: 1398: 1374: 1368: 1367: 1354: 1335: 1326: 1305: 1304: 1295: 1289: 1288: 1279: 1254: 1253: 1251: 1226: 1225: 1223: 1174: 1173: 1171: 1142: 1141: 1139: 1097: 1077: 1057: 989: 969: 949: 924: 903: 882: 861: 835: 814: 793: 772: 746: 725: 704: 683: 635: 567: 542: 521: 500: 479: 453: 432: 411: 390: 364: 343: 322: 301: 249: 229: 209: 189: 2764: 2762: 2324:is non-manipulable and non-dictatorial, 1321:. Its input is a profile of preferences 655: 273: 2573: 2559: 1162:(which is assumed finite), also called 3142:The theory of committees and elections 3016:Fara, Rudolf; Salles, Maurice (2006). 2724: 2722: 2435:. In a 1973 article, Gibbard exploits 1417:if and only if there exists a profile 55:may be able to help recruit an expert. 3072:Axioms of Cooperative Decision Making 2847: 2845: 2802: 2800: 2357:{\displaystyle \operatorname {Rank} } 2337:{\displaystyle \operatorname {Rank} } 2234:{\displaystyle \operatorname {Rank} } 2174:{\displaystyle \operatorname {Rank} } 2128:{\displaystyle \operatorname {Rank} } 1710:{\displaystyle f({\mathcal {P}}^{n})} 1626:{\displaystyle f({\mathcal {P}}^{n})} 135:in 1975. It deals with deterministic 7: 1744:if and only if there exists a voter 3177:10.1093/oxfordjournals.oep.a042255 25: 3106:The American Mathematical Monthly 2304:It is possible to prove that, if 1045:{\displaystyle (a:2,b:7,c:6,d:3)} 623:{\displaystyle (a:3,b:6,c:7,d:2)} 3345:Theorems in discrete mathematics 2508: 650:will be elected, with 7 points. 76: 34: 1115:We say that the Borda count is 3144:. Cambridge: University Press. 3075:. Cambridge University Press. 2057:{\displaystyle {\mathcal {A}}} 1985: 1947:{\displaystyle {\mathcal {A}}} 1919:{\displaystyle {\mathcal {L}}} 1704: 1687: 1620: 1603: 1456: 1424: 1360: 1328: 1301: 1263:{\displaystyle {\mathcal {A}}} 1235:{\displaystyle {\mathcal {P}}} 1151:{\displaystyle {\mathcal {A}}} 1039: 991: 617: 569: 158:Gibbard's proof of the theorem 1: 2950:International Economic Review 2828:10.1016/S0165-1765(00)00362-1 2783:10.1016/S0165-1765(00)00312-8 2753:10.1016/S0165-1765(00)00332-3 2524:Arrow's impossibility theorem 2496:Arrow's impossibility theorem 2437:Arrow's impossibility theorem 2388:must also be a dictatorship. 2082:Arrow's impossibility theorem 1787:Counterexamples and loopholes 1777:Gibbard–Satterthwaite theorem 113:Gibbard–Satterthwaite theorem 102:Proposed since November 2023. 18:Gibbard-Satterthwaite theorem 2694:10.1016/0022-0531(75)90050-2 2368:. Hence, such a voting rule 2995:. Oxford University Press. 264:. Assume that they use the 85:It has been suggested that 47:. The specific problem is: 3366: 2672:Journal of Economic Theory 1506:, by replacing her ballot 3279:Social Choice and Welfare 3248:10.1007/s00355-005-0014-x 3236:Social Choice and Welfare 3037:10.1007/s00355-006-0128-9 3025:Social Choice and Welfare 2991:Dummett, Michael (1984). 2668:Satterthwaite, Mark Allen 2602:10.1007/s00355-006-0128-9 2590:Social Choice and Welfare 964:and downgraded candidate 137:ordinal electoral systems 2485:describes this relation: 2154:{\displaystyle a\prec b} 2086:social ranking functions 2870:Algorithmic Game Theory 2534:Duggan–Schwartz theorem 2467:Duggan–Schwartz theorem 2040:sometimes assumed that 984:. Now, the scores are: 174:Duggan–Schwartz theorem 53:WikiProject Game theory 3164:Oxford Economic Papers 3140:Black, Duncan (1958). 2492: 2456:Gibbard's 1978 theorem 2413: 2382: 2358: 2338: 2318: 2295: 2275: 2255: 2235: 2215: 2195: 2175: 2155: 2129: 2102: 2058: 1999: 1948: 1920: 1888: 1868: 1847: 1758: 1734: 1711: 1671: 1647: 1627: 1584: 1557: 1556:{\displaystyle P_{i}'} 1527: 1500: 1480: 1407: 1384: 1315: 1264: 1236: 1208: 1152: 1106: 1086: 1066: 1046: 978: 958: 933: 912: 891: 870: 844: 823: 802: 781: 755: 734: 713: 692: 644: 624: 551: 530: 509: 488: 462: 441: 420: 399: 373: 352: 331: 310: 258: 238: 218: 198: 166:Gibbard's 1978 theorem 131:in 1973 and economist 123:and the mathematician 2807:Sen, Arunava (2001). 2707:Weber, Tjark (2009). 2487: 2409: 2383: 2359: 2339: 2319: 2296: 2276: 2256: 2236: 2216: 2196: 2176: 2156: 2130: 2103: 2059: 2005:. The definitions of 2000: 1949: 1921: 1889: 1869: 1848: 1759: 1735: 1712: 1672: 1648: 1628: 1585: 1583:{\displaystyle P_{i}} 1558: 1528: 1526:{\displaystyle P_{i}} 1501: 1481: 1408: 1385: 1316: 1265: 1237: 1209: 1153: 1107: 1087: 1067: 1047: 979: 959: 934: 913: 892: 871: 845: 824: 803: 782: 756: 735: 714: 693: 645: 625: 552: 531: 510: 489: 463: 442: 421: 400: 374: 353: 332: 311: 259: 239: 219: 199: 3350:Social choice theory 2555:Notes and references 2372: 2348: 2328: 2308: 2285: 2265: 2245: 2225: 2205: 2185: 2165: 2139: 2119: 2092: 2044: 1962: 1934: 1906: 1878: 1858: 1837: 1828:Simple majority vote 1748: 1724: 1681: 1661: 1637: 1597: 1567: 1537: 1533:with another ballot 1510: 1490: 1421: 1397: 1325: 1278: 1250: 1222: 1170: 1138: 1124:ranked-choice voting 1096: 1076: 1056: 988: 968: 948: 923: 902: 881: 860: 834: 813: 792: 771: 745: 724: 703: 682: 634: 566: 541: 520: 499: 478: 452: 431: 410: 389: 363: 342: 321: 300: 248: 228: 208: 188: 180:Informal description 151:always-best strategy 95:into this article. ( 2364:function must be a 2029: —  1928:strict total orders 1817:serial dictatorship 1811:Serial dictatorship 1780: —  1552: 630:. Hence, candidate 3340:Economics theorems 3291:10.1007/PL00007177 3156:Farquharson, Robin 2911:10.1007/bf01718676 2853:Vazirani, Vijay V. 2433:Mark Satterthwaite 2415:During the 1950s, 2378: 2354: 2334: 2314: 2291: 2271: 2251: 2231: 2211: 2191: 2171: 2151: 2125: 2098: 2054: 2027: 1995: 1956:strict voting rule 1944: 1916: 1884: 1864: 1843: 1778: 1754: 1730: 1707: 1667: 1653:, i.e. the set of 1643: 1623: 1580: 1553: 1540: 1523: 1496: 1476: 1403: 1380: 1311: 1260: 1244:strict weak orders 1232: 1204: 1148: 1102: 1082: 1062: 1042: 974: 954: 929: 908: 887: 866: 840: 819: 798: 777: 751: 730: 709: 688: 640: 620: 547: 526: 505: 484: 458: 437: 416: 395: 369: 348: 327: 306: 254: 234: 214: 194: 133:Mark Satterthwaite 3158:(February 1956). 2993:Voting Procedures 2816:Economics Letters 2771:Economics Letters 2731:Economics Letters 2539:Gibbard's theorem 2460:Hylland's theorem 2452:Gibbard's theorem 2441:Gibbard's theorem 2417:Robin Farquharson 2381:{\displaystyle f} 2317:{\displaystyle f} 2294:{\displaystyle b} 2274:{\displaystyle a} 2254:{\displaystyle f} 2241:examines whether 2214:{\displaystyle b} 2194:{\displaystyle a} 2108:is assumed to be 2101:{\displaystyle f} 2037:possible outcomes 2007:possible outcomes 1887:{\displaystyle b} 1867:{\displaystyle a} 1846:{\displaystyle a} 1805:Gibbard's theorem 1757:{\displaystyle i} 1733:{\displaystyle f} 1670:{\displaystyle f} 1655:possible outcomes 1646:{\displaystyle f} 1499:{\displaystyle i} 1486:where some voter 1406:{\displaystyle f} 1105:{\displaystyle c} 1085:{\displaystyle b} 1065:{\displaystyle b} 977:{\displaystyle c} 957:{\displaystyle b} 942: 941: 932:{\displaystyle a} 911:{\displaystyle d} 890:{\displaystyle b} 869:{\displaystyle c} 843:{\displaystyle a} 822:{\displaystyle d} 801:{\displaystyle b} 780:{\displaystyle c} 754:{\displaystyle c} 733:{\displaystyle d} 712:{\displaystyle a} 691:{\displaystyle b} 643:{\displaystyle c} 560: 559: 550:{\displaystyle a} 529:{\displaystyle d} 508:{\displaystyle b} 487:{\displaystyle c} 461:{\displaystyle a} 440:{\displaystyle d} 419:{\displaystyle b} 398:{\displaystyle c} 372:{\displaystyle d} 351:{\displaystyle c} 330:{\displaystyle b} 309:{\displaystyle a} 257:{\displaystyle d} 237:{\displaystyle c} 217:{\displaystyle b} 197:{\displaystyle a} 170:Hylland's theorem 125:Robin Farquharson 109: 108: 104: 88:Gibbard's theorem 70: 69: 16:(Redirected from 3357: 3319: 3318: 3274: 3268: 3267: 3231: 3225: 3224: 3196: 3190: 3189: 3179: 3152: 3146: 3145: 3137: 3131: 3130: 3100: 3094: 3093: 3091: 3089: 3063: 3057: 3056: 3022: 3013: 3007: 3006: 2988: 2982: 2981: 2945: 2939: 2938: 2894: 2888: 2887: 2875: 2861:Roughgarden, Tim 2849: 2840: 2839: 2813: 2804: 2795: 2794: 2766: 2757: 2756: 2746: 2726: 2717: 2716: 2704: 2698: 2697: 2687: 2664: 2655: 2654: 2623: 2614: 2613: 2587: 2578: 2567: 2564: 2549:Strategic voting 2518: 2513: 2512: 2479:mechanism design 2387: 2385: 2384: 2379: 2363: 2361: 2360: 2355: 2343: 2341: 2340: 2335: 2323: 2321: 2320: 2315: 2300: 2298: 2297: 2292: 2280: 2278: 2277: 2272: 2260: 2258: 2257: 2252: 2240: 2238: 2237: 2232: 2220: 2218: 2217: 2212: 2200: 2198: 2197: 2192: 2180: 2178: 2177: 2172: 2160: 2158: 2157: 2152: 2134: 2132: 2131: 2126: 2110:Pareto-efficient 2107: 2105: 2104: 2099: 2063: 2061: 2060: 2055: 2053: 2052: 2030: 2004: 2002: 2001: 1996: 1994: 1993: 1984: 1983: 1978: 1977: 1954:and we define a 1953: 1951: 1950: 1945: 1943: 1942: 1925: 1923: 1922: 1917: 1915: 1914: 1894:wins otherwise. 1893: 1891: 1890: 1885: 1873: 1871: 1870: 1865: 1852: 1850: 1849: 1844: 1781: 1763: 1761: 1760: 1755: 1739: 1737: 1736: 1731: 1716: 1714: 1713: 1708: 1703: 1702: 1697: 1696: 1676: 1674: 1673: 1668: 1652: 1650: 1649: 1644: 1632: 1630: 1629: 1624: 1619: 1618: 1613: 1612: 1589: 1587: 1586: 1581: 1579: 1578: 1562: 1560: 1559: 1554: 1548: 1532: 1530: 1529: 1524: 1522: 1521: 1505: 1503: 1502: 1497: 1485: 1483: 1482: 1477: 1475: 1474: 1469: 1468: 1455: 1454: 1436: 1435: 1412: 1410: 1409: 1404: 1389: 1387: 1386: 1381: 1379: 1378: 1373: 1372: 1359: 1358: 1340: 1339: 1320: 1318: 1317: 1312: 1310: 1309: 1300: 1299: 1294: 1293: 1269: 1267: 1266: 1261: 1259: 1258: 1241: 1239: 1238: 1233: 1231: 1230: 1213: 1211: 1210: 1205: 1179: 1178: 1157: 1155: 1154: 1149: 1147: 1146: 1130:Formal statement 1111: 1109: 1108: 1103: 1091: 1089: 1088: 1083: 1071: 1069: 1068: 1063: 1051: 1049: 1048: 1043: 983: 981: 980: 975: 963: 961: 960: 955: 938: 936: 935: 930: 917: 915: 914: 909: 896: 894: 893: 888: 875: 873: 872: 867: 849: 847: 846: 841: 828: 826: 825: 820: 807: 805: 804: 799: 786: 784: 783: 778: 760: 758: 757: 752: 739: 737: 736: 731: 718: 716: 715: 710: 697: 695: 694: 689: 656: 649: 647: 646: 641: 629: 627: 626: 621: 556: 554: 553: 548: 535: 533: 532: 527: 514: 512: 511: 506: 493: 491: 490: 485: 467: 465: 464: 459: 446: 444: 443: 438: 425: 423: 422: 417: 404: 402: 401: 396: 378: 376: 375: 370: 357: 355: 354: 349: 336: 334: 333: 328: 315: 313: 312: 307: 274: 263: 261: 260: 255: 243: 241: 240: 235: 223: 221: 220: 215: 203: 201: 200: 195: 115:is a theorem in 100: 80: 79: 72: 65: 62: 56: 38: 37: 30: 21: 3365: 3364: 3360: 3359: 3358: 3356: 3355: 3354: 3325: 3324: 3323: 3322: 3276: 3275: 3271: 3233: 3232: 3228: 3213:10.2307/1907685 3198: 3197: 3193: 3154: 3153: 3149: 3139: 3138: 3134: 3119:10.2307/2695497 3102: 3101: 3097: 3087: 3085: 3083: 3065: 3064: 3060: 3020: 3015: 3014: 3010: 3003: 2990: 2989: 2985: 2962:10.2307/2648754 2947: 2946: 2942: 2896: 2895: 2891: 2884: 2873: 2851: 2850: 2843: 2811: 2806: 2805: 2798: 2768: 2767: 2760: 2744:10.1.1.130.1704 2728: 2727: 2720: 2706: 2705: 2701: 2685:10.1.1.471.9842 2666: 2665: 2658: 2643:10.2307/1914083 2625: 2624: 2617: 2585: 2580: 2579: 2575: 2570: 2565: 2561: 2557: 2529:Condorcet cycle 2514: 2507: 2504: 2475: 2449: 2447:Related results 2425:tactical voting 2421:Michael Dummett 2397: 2370: 2369: 2346: 2345: 2326: 2325: 2306: 2305: 2283: 2282: 2263: 2262: 2243: 2242: 2223: 2222: 2203: 2202: 2183: 2182: 2163: 2162: 2137: 2136: 2117: 2116: 2090: 2089: 2078: 2076:Sketch of proof 2042: 2041: 2033: 2028: 1971: 1960: 1959: 1932: 1931: 1904: 1903: 1900: 1876: 1875: 1856: 1855: 1835: 1834: 1830: 1813: 1797: 1795:Cardinal voting 1789: 1784: 1779: 1746: 1745: 1722: 1721: 1690: 1679: 1678: 1659: 1658: 1635: 1634: 1606: 1595: 1594: 1570: 1565: 1564: 1535: 1534: 1513: 1508: 1507: 1488: 1487: 1462: 1446: 1427: 1419: 1418: 1395: 1394: 1366: 1350: 1331: 1323: 1322: 1287: 1276: 1275: 1248: 1247: 1220: 1219: 1168: 1167: 1136: 1135: 1132: 1094: 1093: 1074: 1073: 1054: 1053: 986: 985: 966: 965: 946: 945: 921: 920: 900: 899: 879: 878: 858: 857: 832: 831: 811: 810: 790: 789: 769: 768: 743: 742: 722: 721: 701: 700: 680: 679: 632: 631: 564: 563: 539: 538: 518: 517: 497: 496: 476: 475: 450: 449: 429: 428: 408: 407: 387: 386: 361: 360: 340: 339: 319: 318: 298: 297: 246: 245: 226: 225: 206: 205: 186: 185: 182: 162:cardinal voting 121:Michael Dummett 105: 81: 77: 66: 60: 57: 51: 39: 35: 28: 23: 22: 15: 12: 11: 5: 3363: 3361: 3353: 3352: 3347: 3342: 3337: 3327: 3326: 3321: 3320: 3269: 3242:(2): 475–483. 3226: 3191: 3166:. New Series. 3147: 3132: 3113:(4): 321–337. 3095: 3081: 3058: 3031:(2): 347–364. 3008: 3002:978-0198761884 3001: 2983: 2956:(2): 413–417. 2940: 2889: 2882: 2841: 2822:(3): 381–385. 2796: 2777:(3): 319–322. 2758: 2718: 2699: 2678:(2): 187–217. 2656: 2637:(4): 587–601. 2627:Gibbard, Allan 2615: 2596:(2): 347–364. 2572: 2571: 2569: 2568: 2558: 2556: 2553: 2552: 2551: 2546: 2541: 2536: 2531: 2526: 2520: 2519: 2516:Economy portal 2503: 2500: 2474: 2471: 2448: 2445: 2396: 2393: 2377: 2353: 2333: 2313: 2290: 2270: 2250: 2230: 2210: 2190: 2170: 2150: 2147: 2144: 2124: 2097: 2077: 2074: 2051: 2023: 1992: 1987: 1982: 1976: 1970: 1967: 1958:as a function 1941: 1913: 1899: 1896: 1883: 1863: 1842: 1829: 1826: 1812: 1809: 1796: 1793: 1788: 1785: 1774: 1753: 1729: 1717:is 3 or more. 1706: 1701: 1695: 1689: 1686: 1666: 1642: 1622: 1617: 1611: 1605: 1602: 1577: 1573: 1551: 1547: 1543: 1520: 1516: 1495: 1473: 1467: 1461: 1458: 1453: 1449: 1445: 1442: 1439: 1434: 1430: 1426: 1402: 1377: 1371: 1365: 1362: 1357: 1353: 1349: 1346: 1343: 1338: 1334: 1330: 1308: 1303: 1298: 1292: 1286: 1283: 1274:is a function 1257: 1242:be the set of 1229: 1203: 1200: 1197: 1194: 1191: 1188: 1185: 1182: 1177: 1158:be the set of 1145: 1131: 1128: 1101: 1081: 1061: 1041: 1038: 1035: 1032: 1029: 1026: 1023: 1020: 1017: 1014: 1011: 1008: 1005: 1002: 999: 996: 993: 973: 953: 940: 939: 928: 918: 907: 897: 886: 876: 865: 855: 851: 850: 839: 829: 818: 808: 797: 787: 776: 766: 762: 761: 750: 740: 729: 719: 708: 698: 687: 677: 673: 672: 669: 666: 663: 660: 639: 619: 616: 613: 610: 607: 604: 601: 598: 595: 592: 589: 586: 583: 580: 577: 574: 571: 558: 557: 546: 536: 525: 515: 504: 494: 483: 473: 469: 468: 457: 447: 436: 426: 415: 405: 394: 384: 380: 379: 368: 358: 347: 337: 326: 316: 305: 295: 291: 290: 287: 284: 281: 278: 253: 233: 213: 193: 181: 178: 155: 154: 147: 144: 107: 106: 84: 82: 75: 68: 67: 42: 40: 33: 26: 24: 14: 13: 10: 9: 6: 4: 3: 2: 3362: 3351: 3348: 3346: 3343: 3341: 3338: 3336: 3335:Voting theory 3333: 3332: 3330: 3316: 3312: 3308: 3304: 3300: 3296: 3292: 3288: 3284: 3280: 3273: 3270: 3265: 3261: 3257: 3253: 3249: 3245: 3241: 3237: 3230: 3227: 3222: 3218: 3214: 3210: 3206: 3202: 3195: 3192: 3187: 3183: 3178: 3173: 3169: 3165: 3161: 3157: 3151: 3148: 3143: 3136: 3133: 3128: 3124: 3120: 3116: 3112: 3108: 3107: 3099: 3096: 3084: 3082:9780521424585 3078: 3074: 3073: 3068: 3067:Moulin, Hervé 3062: 3059: 3054: 3050: 3046: 3042: 3038: 3034: 3030: 3026: 3019: 3012: 3009: 3004: 2998: 2994: 2987: 2984: 2979: 2975: 2971: 2967: 2963: 2959: 2955: 2951: 2944: 2941: 2936: 2932: 2928: 2924: 2920: 2916: 2912: 2908: 2904: 2900: 2899:Public Choice 2893: 2890: 2885: 2883:0-521-87282-0 2879: 2872: 2871: 2866: 2862: 2858: 2854: 2848: 2846: 2842: 2837: 2833: 2829: 2825: 2821: 2817: 2810: 2803: 2801: 2797: 2792: 2788: 2784: 2780: 2776: 2772: 2765: 2763: 2759: 2754: 2750: 2745: 2740: 2737:(1): 99–105. 2736: 2732: 2725: 2723: 2719: 2714: 2710: 2703: 2700: 2695: 2691: 2686: 2681: 2677: 2673: 2669: 2663: 2661: 2657: 2652: 2648: 2644: 2640: 2636: 2632: 2628: 2622: 2620: 2616: 2611: 2607: 2603: 2599: 2595: 2591: 2584: 2577: 2574: 2563: 2560: 2554: 2550: 2547: 2545: 2544:Ranked voting 2542: 2540: 2537: 2535: 2532: 2530: 2527: 2525: 2522: 2521: 2517: 2511: 2506: 2501: 2499: 2497: 2491: 2486: 2484: 2480: 2472: 2470: 2468: 2463: 2461: 2457: 2453: 2446: 2444: 2442: 2438: 2434: 2430: 2429:Allan Gibbard 2426: 2422: 2418: 2412: 2408: 2406: 2402: 2401:Lewis Carroll 2394: 2392: 2389: 2375: 2367: 2351: 2331: 2311: 2302: 2288: 2268: 2248: 2228: 2208: 2188: 2168: 2148: 2145: 2142: 2122: 2113: 2111: 2095: 2087: 2083: 2075: 2073: 2071: 2067: 2038: 2032: 2022: 2018: 2016: 2012: 2008: 1980: 1968: 1965: 1957: 1929: 1897: 1895: 1881: 1861: 1840: 1827: 1825: 1821: 1818: 1810: 1808: 1806: 1802: 1794: 1792: 1786: 1783: 1773: 1771: 1767: 1751: 1743: 1727: 1718: 1699: 1684: 1664: 1656: 1640: 1633:the image of 1615: 1600: 1593:We denote by 1591: 1575: 1571: 1549: 1545: 1541: 1518: 1514: 1493: 1471: 1459: 1451: 1447: 1443: 1440: 1437: 1432: 1428: 1416: 1400: 1391: 1375: 1363: 1355: 1351: 1347: 1344: 1341: 1336: 1332: 1296: 1284: 1281: 1273: 1245: 1217: 1198: 1195: 1192: 1189: 1186: 1180: 1165: 1161: 1129: 1127: 1125: 1120: 1118: 1113: 1099: 1079: 1059: 1036: 1033: 1030: 1027: 1024: 1021: 1018: 1015: 1012: 1009: 1006: 1003: 1000: 997: 994: 971: 951: 926: 919: 905: 898: 884: 877: 863: 856: 853: 852: 837: 830: 816: 809: 795: 788: 774: 767: 764: 763: 748: 741: 727: 720: 706: 699: 685: 678: 675: 674: 670: 667: 664: 661: 658: 657: 654: 651: 637: 614: 611: 608: 605: 602: 599: 596: 593: 590: 587: 584: 581: 578: 575: 572: 544: 537: 523: 516: 502: 495: 481: 474: 471: 470: 455: 448: 434: 427: 413: 406: 392: 385: 382: 381: 366: 359: 345: 338: 324: 317: 303: 296: 293: 292: 288: 285: 282: 279: 276: 275: 272: 269: 267: 251: 231: 211: 191: 179: 177: 175: 171: 167: 163: 159: 152: 148: 145: 142: 141: 140: 138: 134: 130: 129:Allan Gibbard 126: 122: 118: 117:voting theory 114: 103: 98: 94: 90: 89: 83: 74: 73: 64: 54: 50: 46: 43:This article 41: 32: 31: 19: 3285:(1): 85–93. 3282: 3278: 3272: 3239: 3235: 3229: 3207:(1): 33–43. 3204: 3201:Econometrica 3200: 3194: 3170:(1): 80–89. 3167: 3163: 3150: 3141: 3135: 3110: 3104: 3098: 3086:. Retrieved 3071: 3061: 3028: 3024: 3011: 2992: 2986: 2953: 2949: 2943: 2902: 2898: 2892: 2869: 2819: 2815: 2774: 2770: 2734: 2730: 2712: 2702: 2675: 2671: 2634: 2631:Econometrica 2630: 2593: 2589: 2576: 2562: 2493: 2488: 2476: 2464: 2450: 2414: 2410: 2405:Duncan Black 2398: 2390: 2366:dictatorship 2303: 2114: 2079: 2069: 2065: 2036: 2034: 2024: 2019: 2014: 2010: 2006: 1955: 1901: 1831: 1824:among them. 1822: 1816: 1814: 1801:score voting 1798: 1790: 1775: 1769: 1765: 1741: 1720:We say that 1719: 1654: 1592: 1414: 1393:We say that 1392: 1271: 1215: 1163: 1160:alternatives 1159: 1133: 1121: 1116: 1114: 943: 652: 561: 270: 183: 156: 112: 110: 101: 86: 58: 48: 44: 2905:: 137–142. 2865:Tardos, Éva 2857:Nisan, Noam 2015:dictatorial 2011:manipulable 1926:the set of 1742:dictatorial 1415:manipulable 1272:voting rule 1214:the set of 1117:manipulable 266:Borda count 3329:Categories 3088:10 January 2483:Noam Nisan 2473:Importance 1164:candidates 3299:0176-1714 2970:0020-6598 2935:153421058 2919:0048-5829 2836:0165-1765 2791:0165-1765 2739:CiteSeerX 2680:CiteSeerX 2146:≺ 2070:unanimous 1986:→ 1898:Corollary 1764:who is a 1460:∈ 1441:… 1364:∈ 1345:… 1302:→ 1193:… 1052:. Hence, 671:Choice 4 289:Choice 4 61:June 2024 3307:41106341 3264:27639067 3256:41106711 3069:(1991). 3053:46164353 3045:41106783 2927:30023000 2867:(2007). 2610:46164353 2502:See also 2261:chooses 1766:dictator 1550:′ 668:Choice 3 665:Choice 2 662:Choice 1 286:Choice 3 283:Choice 2 280:Choice 1 3221:1907685 3186:2662065 3127:2695497 2978:2648754 2651:1914083 2395:History 2026:Theorem 97:Discuss 3315:271833 3313:  3305:  3297:  3262:  3254:  3219:  3184:  3125:  3079:  3051:  3043:  2999:  2976:  2968:  2933:  2925:  2917:  2880:  2834:  2789:  2741:  2682:  2649:  2608:  2490:model. 2161:, the 1218:. Let 1216:voters 93:merged 3311:S2CID 3303:JSTOR 3260:S2CID 3252:JSTOR 3217:JSTOR 3182:JSTOR 3123:JSTOR 3049:S2CID 3041:JSTOR 3021:(PDF) 2974:JSTOR 2931:S2CID 2923:JSTOR 2874:(PDF) 2812:(PDF) 2647:JSTOR 2606:S2CID 2586:(PDF) 1930:over 1246:over 854:Carol 676:Alice 659:Voter 472:Carol 294:Alice 277:Voter 3295:ISSN 3090:2016 3077:ISBN 2997:ISBN 2966:ISSN 2915:ISSN 2878:ISBN 2832:ISSN 2787:ISSN 2465:The 2458:and 2431:and 2352:Rank 2332:Rank 2229:Rank 2201:and 2169:Rank 2123:Rank 2084:for 2066:onto 1815:The 1134:Let 244:and 168:and 111:The 3287:doi 3244:doi 3209:doi 3172:doi 3115:doi 3111:109 3033:doi 2958:doi 2907:doi 2824:doi 2779:doi 2749:doi 2690:doi 2639:doi 2598:doi 2281:or 2112:. 1740:is 1590:). 1413:is 1092:to 765:Bob 383:Bob 91:be 3331:: 3309:. 3301:. 3293:. 3283:17 3281:. 3258:. 3250:. 3240:25 3238:. 3215:. 3205:29 3203:. 3180:. 3162:. 3121:. 3109:. 3047:. 3039:. 3029:27 3027:. 3023:. 2972:. 2964:. 2954:24 2952:. 2929:. 2921:. 2913:. 2903:32 2901:. 2863:; 2859:; 2855:; 2844:^ 2830:. 2820:70 2818:. 2814:. 2799:^ 2785:. 2775:69 2773:. 2761:^ 2747:. 2735:70 2733:. 2721:^ 2711:. 2688:. 2676:10 2674:. 2659:^ 2645:. 2635:41 2633:. 2618:^ 2604:. 2594:27 2592:. 2588:. 2498:. 2301:. 2013:, 2009:, 1807:. 224:, 204:, 164:. 3317:. 3289:: 3266:. 3246:: 3223:. 3211:: 3188:. 3174:: 3168:8 3129:. 3117:: 3092:. 3055:. 3035:: 3005:. 2980:. 2960:: 2937:. 2909:: 2886:. 2838:. 2826:: 2793:. 2781:: 2755:. 2751:: 2715:. 2696:. 2692:: 2653:. 2641:: 2612:. 2600:: 2407:: 2376:f 2312:f 2289:b 2269:a 2249:f 2209:b 2189:a 2149:b 2143:a 2096:f 2050:A 1991:A 1981:n 1975:L 1969:: 1966:f 1940:A 1912:L 1882:b 1862:a 1841:a 1752:i 1728:f 1705:) 1700:n 1694:P 1688:( 1685:f 1665:f 1641:f 1621:) 1616:n 1610:P 1604:( 1601:f 1576:i 1572:P 1546:i 1542:P 1519:i 1515:P 1494:i 1472:n 1466:P 1457:) 1452:n 1448:P 1444:, 1438:, 1433:1 1429:P 1425:( 1401:f 1376:n 1370:P 1361:) 1356:n 1352:P 1348:, 1342:, 1337:1 1333:P 1329:( 1307:A 1297:n 1291:P 1285:: 1282:f 1256:A 1228:P 1202:} 1199:n 1196:, 1190:, 1187:1 1184:{ 1181:= 1176:N 1144:A 1100:c 1080:b 1060:b 1040:) 1037:3 1034:: 1031:d 1028:, 1025:6 1022:: 1019:c 1016:, 1013:7 1010:: 1007:b 1004:, 1001:2 998:: 995:a 992:( 972:c 952:b 927:a 906:d 885:b 864:c 838:a 817:d 796:b 775:c 749:c 728:d 707:a 686:b 638:c 618:) 615:2 612:: 609:d 606:, 603:7 600:: 597:c 594:, 591:6 588:: 585:b 582:, 579:3 576:: 573:a 570:( 545:a 524:d 503:b 482:c 456:a 435:d 414:b 393:c 367:d 346:c 325:b 304:a 252:d 232:c 212:b 192:a 99:) 63:) 59:( 20:)

Index

Gibbard-Satterthwaite theorem
WikiProject Game theory
Gibbard's theorem
merged
Discuss
voting theory
Michael Dummett
Robin Farquharson
Allan Gibbard
Mark Satterthwaite
ordinal electoral systems
always-best strategy
Gibbard's proof of the theorem
cardinal voting
Gibbard's 1978 theorem
Hylland's theorem
Duggan–Schwartz theorem
Borda count
ranked-choice voting
strict weak orders
score voting
Gibbard's theorem
strict total orders
Arrow's impossibility theorem
social ranking functions
Pareto-efficient
dictatorship
Lewis Carroll
Duncan Black
Robin Farquharson

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