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Gibbard–Satterthwaite theorem

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1792:. 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 2516: 25: 67: 257:: 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. 2009:
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
2449:. 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. 2010:
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.
3350: 2676:(April 1975). "Strategy-proofness and Arrow's conditions: Existence and correspondence theorems for voting procedures and social welfare functions". 2500:
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
1259:: an element of this set can represent the preferences of a voter, where a voter may be indifferent regarding the ordering of some alternatives. A 85: 1761:. If the dictator has several equally most-liked alternatives among the possible outcomes, then the winning alternative is simply one of them. 2333:
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
113: 3024:"An interview with Michael Dummett: From analytical philosophy to voting analysis and beyond" 2589:"An Interview with Michael Dummett: From analytical philosophy to voting analysis and beyond" 1108:: there exists situations where a sincere ballot does not defend a voter's preferences best. 149:
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".
2515: 2077:. We give a sketch of proof in the simplified case where some voting rule 3312: 3261: 3050: 2932: 2715:"Alternatives vs. Outcomes: A Note on the Gibbard-Satterthwaite Theorem" 3296: 3226: 3191: 3132: 2983: 2916: 2656: 1666:
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
2635:(1973). "Manipulation of voting schemes: A general result". 2038: 1979: 1963: 1928: 1900: 1682: 1598: 1454: 1358: 1295: 1279: 1244: 1216: 1164: 1132: 2815:"Another Direct Proof of the Gibbard-Satterthwaite Theorem" 1468:{\displaystyle (P_{1},\ldots ,P_{n})\in {\mathcal {P}}^{n}} 1372:{\displaystyle (P_{1},\ldots ,P_{n})\in {\mathcal {P}}^{n}} 38:
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
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The Gibbard–Satterthwaite theorem states that every
2369: 2345: 2325: 2305: 2282: 2262: 2242: 2222: 2202: 2182: 2162: 2142: 2116: 2104:It is possible to build a social ranking function 2089: 2045: 1986: 1935: 1907: 1875: 1855: 1834: 1745: 1721: 1698: 1658: 1634: 1614: 1571: 1544: 1514: 1487: 1467: 1394: 1371: 1302: 1251: 1223: 1195: 1139: 1093: 1073: 1053: 1033: 965: 945: 920: 899: 878: 857: 831: 810: 789: 768: 742: 721: 700: 679: 631: 611: 538: 517: 496: 475: 449: 428: 407: 386: 360: 339: 318: 297: 245: 225: 205: 185: 1788:Consider a three-candidate election conducted by 2587:Rudolf Farra and Maurice Salles (October 2006). 2719:Technical Report (University Library of Munich) 2668: 2666: 1196:{\displaystyle {\mathcal {N}}=\{1,\ldots ,n\}} 260:Assume that their preferences are as follows. 108:. It was first conjectured by the philosopher 2882:. Cambridge, UK: Cambridge University Press. 2445:from 1951 to prove the result we now know as 1863:wins if it gets two thirds of the votes, and 1759:regardless of the preferences of other voters 34:needs attention from an expert in game theory 8: 2006:have natural adaptations to this framework. 1190: 1172: 2014: 1765: 1646:for the election. For example, we say that 933:Alice has strategically upgraded candidate 3166:"Straightforwardness in voting procedures" 2170:function creates new preferences in which 3181: 2748: 2689: 2627: 2625: 2362: 2338: 2318: 2298: 2275: 2255: 2235: 2215: 2195: 2175: 2155: 2129: 2124:, as follows: in order to decide whether 2109: 2082: 2037: 2036: 2034: 1978: 1977: 1968: 1962: 1961: 1952: 1927: 1926: 1924: 1899: 1898: 1896: 1868: 1848: 1827: 1738: 1714: 1687: 1681: 1680: 1671: 1651: 1627: 1603: 1597: 1596: 1587: 1563: 1557: 1533: 1527: 1506: 1500: 1480: 1459: 1453: 1452: 1439: 1420: 1411: 1387: 1363: 1357: 1356: 1343: 1324: 1315: 1294: 1293: 1284: 1278: 1277: 1268: 1243: 1242: 1240: 1215: 1214: 1212: 1163: 1162: 1160: 1131: 1130: 1128: 1086: 1066: 1046: 978: 958: 938: 913: 892: 871: 850: 824: 803: 782: 761: 735: 714: 693: 672: 624: 556: 531: 510: 489: 468: 442: 421: 400: 379: 353: 332: 311: 290: 238: 218: 198: 178: 2770: 2768: 2313:is non-manipulable and non-dictatorial, 1310:. Its input is a profile of preferences 644: 262: 2579: 2565: 1151:(which is assumed finite), also called 3148:The theory of committees and elections 3022:Fara, Rudolf; Salles, Maurice (2006). 2730: 2728: 2441:. In a 1973 article, Gibbard exploits 1406:if and only if there exists a profile 44:may be able to help recruit an expert. 3078:Axioms of Cooperative Decision Making 2853: 2851: 2808: 2806: 2346:{\displaystyle \operatorname {Rank} } 2326:{\displaystyle \operatorname {Rank} } 2223:{\displaystyle \operatorname {Rank} } 2163:{\displaystyle \operatorname {Rank} } 2117:{\displaystyle \operatorname {Rank} } 1699:{\displaystyle f({\mathcal {P}}^{n})} 1615:{\displaystyle f({\mathcal {P}}^{n})} 124:in 1975. It deals with deterministic 7: 1733:if and only if there exists a voter 3183:10.1093/oxfordjournals.oep.a042255 14: 3112:The American Mathematical Monthly 2293:It is possible to prove that, if 1034:{\displaystyle (a:2,b:7,c:6,d:3)} 612:{\displaystyle (a:3,b:6,c:7,d:2)} 3351:Theorems in discrete mathematics 2514: 639:will be elected, with 7 points. 65: 23: 1104:We say that the Borda count is 3150:. Cambridge: University Press. 3081:. Cambridge University Press. 2046:{\displaystyle {\mathcal {A}}} 1974: 1936:{\displaystyle {\mathcal {A}}} 1908:{\displaystyle {\mathcal {L}}} 1693: 1676: 1609: 1592: 1445: 1413: 1349: 1317: 1290: 1252:{\displaystyle {\mathcal {A}}} 1224:{\displaystyle {\mathcal {P}}} 1140:{\displaystyle {\mathcal {A}}} 1028: 980: 606: 558: 147:Gibbard's proof of the theorem 1: 2956:International Economic Review 2834:10.1016/S0165-1765(00)00362-1 2789:10.1016/S0165-1765(00)00312-8 2759:10.1016/S0165-1765(00)00332-3 2530:Arrow's impossibility theorem 2502:Arrow's impossibility theorem 2443:Arrow's impossibility theorem 2377:must also be a dictatorship. 2071:Arrow's impossibility theorem 1776:Counterexamples and loopholes 1766:Gibbard–Satterthwaite theorem 102:Gibbard–Satterthwaite theorem 91:Proposed since November 2023. 2700:10.1016/0022-0531(75)90050-2 2357:. Hence, such a voting rule 3001:. Oxford University Press. 253:. Assume that they use the 74:It has been suggested that 36:. The specific problem is: 3372: 2678:Journal of Economic Theory 2388:Excessive citations inline 1495:, by replacing her ballot 3285:Social Choice and Welfare 3254:10.1007/s00355-005-0014-x 3242:Social Choice and Welfare 3043:10.1007/s00355-006-0128-9 3031:Social Choice and Welfare 2997:Dummett, Michael (1984). 2674:Satterthwaite, Mark Allen 2608:10.1007/s00355-006-0128-9 2596:Social Choice and Welfare 953:and downgraded candidate 126:ordinal electoral systems 2491:describes this relation: 2143:{\displaystyle a\prec b} 2075:social ranking functions 2876:Algorithmic Game Theory 2540:Duggan–Schwartz theorem 2473:Duggan–Schwartz theorem 2393:considered for deletion 2029:sometimes assumed that 973:. Now, the scores are: 163:Duggan–Schwartz theorem 42:WikiProject Game theory 3170:Oxford Economic Papers 3146:Black, Duncan (1958). 2498: 2462:Gibbard's 1978 theorem 2419: 2371: 2347: 2327: 2307: 2284: 2264: 2244: 2224: 2204: 2184: 2164: 2144: 2118: 2091: 2047: 1988: 1937: 1909: 1877: 1857: 1836: 1747: 1723: 1700: 1660: 1636: 1616: 1573: 1546: 1545:{\displaystyle P_{i}'} 1516: 1489: 1469: 1396: 1373: 1304: 1253: 1225: 1197: 1141: 1095: 1075: 1055: 1035: 967: 947: 922: 901: 880: 859: 833: 812: 791: 770: 744: 723: 702: 681: 633: 613: 540: 519: 498: 477: 451: 430: 409: 388: 362: 341: 320: 299: 247: 227: 207: 187: 155:Gibbard's 1978 theorem 120:in 1973 and economist 112:and the mathematician 2813:Sen, Arunava (2001). 2713:Weber, Tjark (2009). 2493: 2415: 2372: 2348: 2328: 2308: 2285: 2265: 2245: 2225: 2205: 2185: 2165: 2145: 2119: 2092: 2048: 1994:. The definitions of 1989: 1938: 1910: 1878: 1858: 1837: 1748: 1724: 1701: 1661: 1637: 1617: 1574: 1572:{\displaystyle P_{i}} 1547: 1517: 1515:{\displaystyle P_{i}} 1490: 1470: 1397: 1374: 1305: 1254: 1226: 1198: 1142: 1096: 1076: 1056: 1036: 968: 948: 923: 902: 881: 860: 834: 813: 792: 771: 745: 724: 703: 682: 634: 614: 541: 520: 499: 478: 452: 431: 410: 389: 363: 342: 321: 300: 248: 228: 208: 188: 3356:Social choice theory 2561:Notes and references 2361: 2337: 2317: 2297: 2274: 2254: 2234: 2214: 2194: 2174: 2154: 2128: 2108: 2081: 2033: 1951: 1923: 1895: 1867: 1847: 1826: 1817:Simple majority vote 1737: 1713: 1670: 1650: 1626: 1586: 1556: 1526: 1522:with another ballot 1499: 1479: 1410: 1386: 1314: 1267: 1239: 1211: 1159: 1127: 1113:ranked-choice voting 1085: 1065: 1045: 977: 957: 937: 912: 891: 870: 849: 823: 802: 781: 760: 734: 713: 692: 671: 623: 555: 530: 509: 488: 467: 441: 420: 399: 378: 352: 331: 310: 289: 237: 217: 197: 177: 169:Informal description 140:always-best strategy 84:into this article. ( 2353:function must be a 2018: —  1917:strict total orders 1806:serial dictatorship 1800:Serial dictatorship 1769: —  1541: 619:. Hence, candidate 3346:Economics theorems 3297:10.1007/PL00007177 3162:Farquharson, Robin 2917:10.1007/bf01718676 2859:Vazirani, Vijay V. 2439:Mark Satterthwaite 2421:During the 1950s, 2367: 2343: 2323: 2303: 2280: 2260: 2240: 2220: 2200: 2180: 2160: 2140: 2114: 2087: 2043: 2016: 1984: 1945:strict voting rule 1933: 1905: 1873: 1853: 1832: 1767: 1743: 1719: 1696: 1656: 1642:, i.e. the set of 1632: 1612: 1569: 1542: 1529: 1512: 1485: 1465: 1392: 1369: 1300: 1249: 1233:strict weak orders 1221: 1193: 1137: 1091: 1071: 1051: 1031: 963: 943: 918: 897: 876: 855: 829: 808: 787: 766: 740: 719: 698: 677: 629: 609: 536: 515: 494: 473: 447: 426: 405: 384: 358: 337: 316: 295: 243: 223: 203: 183: 122:Mark Satterthwaite 3164:(February 1956). 2999:Voting Procedures 2822:Economics Letters 2777:Economics Letters 2737:Economics Letters 2545:Gibbard's theorem 2466:Hylland's theorem 2458:Gibbard's theorem 2447:Gibbard's theorem 2423:Robin Farquharson 2370:{\displaystyle f} 2306:{\displaystyle f} 2283:{\displaystyle b} 2263:{\displaystyle a} 2243:{\displaystyle f} 2230:examines whether 2203:{\displaystyle b} 2183:{\displaystyle a} 2097:is assumed to be 2090:{\displaystyle f} 2026:possible outcomes 1996:possible outcomes 1876:{\displaystyle b} 1856:{\displaystyle a} 1835:{\displaystyle a} 1794:Gibbard's theorem 1746:{\displaystyle i} 1722:{\displaystyle f} 1659:{\displaystyle f} 1644:possible outcomes 1635:{\displaystyle f} 1488:{\displaystyle i} 1475:where some voter 1395:{\displaystyle f} 1094:{\displaystyle c} 1074:{\displaystyle b} 1054:{\displaystyle b} 966:{\displaystyle c} 946:{\displaystyle b} 931: 930: 921:{\displaystyle a} 900:{\displaystyle d} 879:{\displaystyle b} 858:{\displaystyle c} 832:{\displaystyle a} 811:{\displaystyle d} 790:{\displaystyle b} 769:{\displaystyle c} 743:{\displaystyle c} 722:{\displaystyle d} 701:{\displaystyle a} 680:{\displaystyle b} 632:{\displaystyle c} 549: 548: 539:{\displaystyle a} 518:{\displaystyle d} 497:{\displaystyle b} 476:{\displaystyle c} 450:{\displaystyle a} 429:{\displaystyle d} 408:{\displaystyle b} 387:{\displaystyle c} 361:{\displaystyle d} 340:{\displaystyle c} 319:{\displaystyle b} 298:{\displaystyle a} 246:{\displaystyle d} 226:{\displaystyle c} 206:{\displaystyle b} 186:{\displaystyle a} 159:Hylland's theorem 114:Robin Farquharson 98: 97: 93: 77:Gibbard's theorem 59: 58: 3363: 3325: 3324: 3280: 3274: 3273: 3237: 3231: 3230: 3202: 3196: 3195: 3185: 3158: 3152: 3151: 3143: 3137: 3136: 3106: 3100: 3099: 3097: 3095: 3069: 3063: 3062: 3028: 3019: 3013: 3012: 2994: 2988: 2987: 2951: 2945: 2944: 2900: 2894: 2893: 2881: 2867:Roughgarden, Tim 2855: 2846: 2845: 2819: 2810: 2801: 2800: 2772: 2763: 2762: 2752: 2732: 2723: 2722: 2710: 2704: 2703: 2693: 2670: 2661: 2660: 2629: 2620: 2619: 2593: 2584: 2573: 2570: 2555:Strategic voting 2524: 2519: 2518: 2485:mechanism design 2396: 2376: 2374: 2373: 2368: 2352: 2350: 2349: 2344: 2332: 2330: 2329: 2324: 2312: 2310: 2309: 2304: 2289: 2287: 2286: 2281: 2269: 2267: 2266: 2261: 2249: 2247: 2246: 2241: 2229: 2227: 2226: 2221: 2209: 2207: 2206: 2201: 2189: 2187: 2186: 2181: 2169: 2167: 2166: 2161: 2149: 2147: 2146: 2141: 2123: 2121: 2120: 2115: 2099:Pareto-efficient 2096: 2094: 2093: 2088: 2052: 2050: 2049: 2044: 2042: 2041: 2019: 1993: 1991: 1990: 1985: 1983: 1982: 1973: 1972: 1967: 1966: 1943:and we define a 1942: 1940: 1939: 1934: 1932: 1931: 1914: 1912: 1911: 1906: 1904: 1903: 1883:wins otherwise. 1882: 1880: 1879: 1874: 1862: 1860: 1859: 1854: 1841: 1839: 1838: 1833: 1770: 1752: 1750: 1749: 1744: 1728: 1726: 1725: 1720: 1705: 1703: 1702: 1697: 1692: 1691: 1686: 1685: 1665: 1663: 1662: 1657: 1641: 1639: 1638: 1633: 1621: 1619: 1618: 1613: 1608: 1607: 1602: 1601: 1578: 1576: 1575: 1570: 1568: 1567: 1551: 1549: 1548: 1543: 1537: 1521: 1519: 1518: 1513: 1511: 1510: 1494: 1492: 1491: 1486: 1474: 1472: 1471: 1466: 1464: 1463: 1458: 1457: 1444: 1443: 1425: 1424: 1401: 1399: 1398: 1393: 1378: 1376: 1375: 1370: 1368: 1367: 1362: 1361: 1348: 1347: 1329: 1328: 1309: 1307: 1306: 1301: 1299: 1298: 1289: 1288: 1283: 1282: 1258: 1256: 1255: 1250: 1248: 1247: 1230: 1228: 1227: 1222: 1220: 1219: 1202: 1200: 1199: 1194: 1168: 1167: 1146: 1144: 1143: 1138: 1136: 1135: 1119:Formal statement 1100: 1098: 1097: 1092: 1080: 1078: 1077: 1072: 1060: 1058: 1057: 1052: 1040: 1038: 1037: 1032: 972: 970: 969: 964: 952: 950: 949: 944: 927: 925: 924: 919: 906: 904: 903: 898: 885: 883: 882: 877: 864: 862: 861: 856: 838: 836: 835: 830: 817: 815: 814: 809: 796: 794: 793: 788: 775: 773: 772: 767: 749: 747: 746: 741: 728: 726: 725: 720: 707: 705: 704: 699: 686: 684: 683: 678: 645: 638: 636: 635: 630: 618: 616: 615: 610: 545: 543: 542: 537: 524: 522: 521: 516: 503: 501: 500: 495: 482: 480: 479: 474: 456: 454: 453: 448: 435: 433: 432: 427: 414: 412: 411: 406: 393: 391: 390: 385: 367: 365: 364: 359: 346: 344: 343: 338: 325: 323: 322: 317: 304: 302: 301: 296: 263: 252: 250: 249: 244: 232: 230: 229: 224: 212: 210: 209: 204: 192: 190: 189: 184: 104:is a theorem in 89: 69: 68: 61: 54: 51: 45: 27: 26: 19: 3371: 3370: 3366: 3365: 3364: 3362: 3361: 3360: 3331: 3330: 3329: 3328: 3282: 3281: 3277: 3239: 3238: 3234: 3219:10.2307/1907685 3204: 3203: 3199: 3160: 3159: 3155: 3145: 3144: 3140: 3125:10.2307/2695497 3108: 3107: 3103: 3093: 3091: 3089: 3071: 3070: 3066: 3026: 3021: 3020: 3016: 3009: 2996: 2995: 2991: 2968:10.2307/2648754 2953: 2952: 2948: 2902: 2901: 2897: 2890: 2879: 2857: 2856: 2849: 2817: 2812: 2811: 2804: 2774: 2773: 2766: 2750:10.1.1.130.1704 2734: 2733: 2726: 2712: 2711: 2707: 2691:10.1.1.471.9842 2672: 2671: 2664: 2649:10.2307/1914083 2631: 2630: 2623: 2591: 2586: 2585: 2581: 2576: 2571: 2567: 2563: 2535:Condorcet cycle 2520: 2513: 2510: 2481: 2455: 2453:Related results 2431:tactical voting 2427:Michael Dummett 2403: 2381: 2359: 2358: 2335: 2334: 2315: 2314: 2295: 2294: 2272: 2271: 2252: 2251: 2232: 2231: 2212: 2211: 2192: 2191: 2172: 2171: 2152: 2151: 2126: 2125: 2106: 2105: 2079: 2078: 2067: 2065:Sketch of proof 2031: 2030: 2022: 2017: 1960: 1949: 1948: 1921: 1920: 1893: 1892: 1889: 1865: 1864: 1845: 1844: 1824: 1823: 1819: 1802: 1786: 1784:Cardinal voting 1778: 1773: 1768: 1735: 1734: 1711: 1710: 1679: 1668: 1667: 1648: 1647: 1624: 1623: 1595: 1584: 1583: 1559: 1554: 1553: 1524: 1523: 1502: 1497: 1496: 1477: 1476: 1451: 1435: 1416: 1408: 1407: 1384: 1383: 1355: 1339: 1320: 1312: 1311: 1276: 1265: 1264: 1237: 1236: 1209: 1208: 1157: 1156: 1125: 1124: 1121: 1083: 1082: 1063: 1062: 1043: 1042: 975: 974: 955: 954: 935: 934: 910: 909: 889: 888: 868: 867: 847: 846: 821: 820: 800: 799: 779: 778: 758: 757: 732: 731: 711: 710: 690: 689: 669: 668: 621: 620: 553: 552: 528: 527: 507: 506: 486: 485: 465: 464: 439: 438: 418: 417: 397: 396: 376: 375: 350: 349: 329: 328: 308: 307: 287: 286: 235: 234: 215: 214: 195: 194: 175: 174: 171: 151:cardinal voting 110:Michael Dummett 94: 70: 66: 55: 49: 46: 40: 28: 24: 17: 12: 11: 5: 3369: 3367: 3359: 3358: 3353: 3348: 3343: 3333: 3332: 3327: 3326: 3275: 3248:(2): 475–483. 3232: 3197: 3172:. New Series. 3153: 3138: 3119:(4): 321–337. 3101: 3087: 3064: 3037:(2): 347–364. 3014: 3008:978-0198761884 3007: 2989: 2962:(2): 413–417. 2946: 2895: 2888: 2847: 2828:(3): 381–385. 2802: 2783:(3): 319–322. 2764: 2724: 2705: 2684:(2): 187–217. 2662: 2643:(4): 587–601. 2633:Gibbard, Allan 2621: 2602:(2): 347–364. 2578: 2577: 2575: 2574: 2564: 2562: 2559: 2558: 2557: 2552: 2547: 2542: 2537: 2532: 2526: 2525: 2522:Economy portal 2509: 2506: 2480: 2477: 2454: 2451: 2402: 2399: 2366: 2342: 2322: 2302: 2279: 2259: 2239: 2219: 2199: 2179: 2159: 2139: 2136: 2133: 2113: 2086: 2066: 2063: 2040: 2012: 1981: 1976: 1971: 1965: 1959: 1956: 1947:as a function 1930: 1902: 1888: 1885: 1872: 1852: 1831: 1818: 1815: 1801: 1798: 1785: 1782: 1777: 1774: 1763: 1742: 1718: 1706:is 3 or more. 1695: 1690: 1684: 1678: 1675: 1655: 1631: 1611: 1606: 1600: 1594: 1591: 1566: 1562: 1540: 1536: 1532: 1509: 1505: 1484: 1462: 1456: 1450: 1447: 1442: 1438: 1434: 1431: 1428: 1423: 1419: 1415: 1391: 1366: 1360: 1354: 1351: 1346: 1342: 1338: 1335: 1332: 1327: 1323: 1319: 1297: 1292: 1287: 1281: 1275: 1272: 1263:is a function 1246: 1231:be the set of 1218: 1192: 1189: 1186: 1183: 1180: 1177: 1174: 1171: 1166: 1147:be the set of 1134: 1120: 1117: 1090: 1070: 1050: 1030: 1027: 1024: 1021: 1018: 1015: 1012: 1009: 1006: 1003: 1000: 997: 994: 991: 988: 985: 982: 962: 942: 929: 928: 917: 907: 896: 886: 875: 865: 854: 844: 840: 839: 828: 818: 807: 797: 786: 776: 765: 755: 751: 750: 739: 729: 718: 708: 697: 687: 676: 666: 662: 661: 658: 655: 652: 649: 628: 608: 605: 602: 599: 596: 593: 590: 587: 584: 581: 578: 575: 572: 569: 566: 563: 560: 547: 546: 535: 525: 514: 504: 493: 483: 472: 462: 458: 457: 446: 436: 425: 415: 404: 394: 383: 373: 369: 368: 357: 347: 336: 326: 315: 305: 294: 284: 280: 279: 276: 273: 270: 267: 242: 222: 202: 182: 170: 167: 144: 143: 136: 133: 96: 95: 73: 71: 64: 57: 56: 31: 29: 22: 15: 13: 10: 9: 6: 4: 3: 2: 3368: 3357: 3354: 3352: 3349: 3347: 3344: 3342: 3341:Voting theory 3339: 3338: 3336: 3322: 3318: 3314: 3310: 3306: 3302: 3298: 3294: 3290: 3286: 3279: 3276: 3271: 3267: 3263: 3259: 3255: 3251: 3247: 3243: 3236: 3233: 3228: 3224: 3220: 3216: 3212: 3208: 3201: 3198: 3193: 3189: 3184: 3179: 3175: 3171: 3167: 3163: 3157: 3154: 3149: 3142: 3139: 3134: 3130: 3126: 3122: 3118: 3114: 3113: 3105: 3102: 3090: 3088:9780521424585 3084: 3080: 3079: 3074: 3073:Moulin, Hervé 3068: 3065: 3060: 3056: 3052: 3048: 3044: 3040: 3036: 3032: 3025: 3018: 3015: 3010: 3004: 3000: 2993: 2990: 2985: 2981: 2977: 2973: 2969: 2965: 2961: 2957: 2950: 2947: 2942: 2938: 2934: 2930: 2926: 2922: 2918: 2914: 2910: 2906: 2905:Public Choice 2899: 2896: 2891: 2889:0-521-87282-0 2885: 2878: 2877: 2872: 2868: 2864: 2860: 2854: 2852: 2848: 2843: 2839: 2835: 2831: 2827: 2823: 2816: 2809: 2807: 2803: 2798: 2794: 2790: 2786: 2782: 2778: 2771: 2769: 2765: 2760: 2756: 2751: 2746: 2743:(1): 99–105. 2742: 2738: 2731: 2729: 2725: 2720: 2716: 2709: 2706: 2701: 2697: 2692: 2687: 2683: 2679: 2675: 2669: 2667: 2663: 2658: 2654: 2650: 2646: 2642: 2638: 2634: 2628: 2626: 2622: 2617: 2613: 2609: 2605: 2601: 2597: 2590: 2583: 2580: 2569: 2566: 2560: 2556: 2553: 2551: 2550:Ranked voting 2548: 2546: 2543: 2541: 2538: 2536: 2533: 2531: 2528: 2527: 2523: 2517: 2512: 2507: 2505: 2503: 2497: 2492: 2490: 2486: 2478: 2476: 2474: 2469: 2467: 2463: 2459: 2452: 2450: 2448: 2444: 2440: 2436: 2435:Allan Gibbard 2432: 2428: 2424: 2418: 2414: 2412: 2408: 2407:Lewis Carroll 2400: 2398: 2394: 2390: 2389: 2385: 2378: 2364: 2356: 2340: 2320: 2300: 2291: 2277: 2257: 2237: 2217: 2197: 2177: 2157: 2137: 2134: 2131: 2111: 2102: 2100: 2084: 2076: 2072: 2064: 2062: 2060: 2056: 2027: 2021: 2011: 2007: 2005: 2001: 1997: 1969: 1957: 1954: 1946: 1918: 1886: 1884: 1870: 1850: 1829: 1816: 1814: 1810: 1807: 1799: 1797: 1795: 1791: 1783: 1781: 1775: 1772: 1762: 1760: 1756: 1740: 1732: 1716: 1707: 1688: 1673: 1653: 1645: 1629: 1622:the image of 1604: 1589: 1582:We denote by 1580: 1564: 1560: 1538: 1534: 1530: 1507: 1503: 1482: 1460: 1448: 1440: 1436: 1432: 1429: 1426: 1421: 1417: 1405: 1389: 1380: 1364: 1352: 1344: 1340: 1336: 1333: 1330: 1325: 1321: 1285: 1273: 1270: 1262: 1234: 1206: 1187: 1184: 1181: 1178: 1175: 1169: 1154: 1150: 1118: 1116: 1114: 1109: 1107: 1102: 1088: 1068: 1048: 1025: 1022: 1019: 1016: 1013: 1010: 1007: 1004: 1001: 998: 995: 992: 989: 986: 983: 960: 940: 915: 908: 894: 887: 873: 866: 852: 845: 842: 841: 826: 819: 805: 798: 784: 777: 763: 756: 753: 752: 737: 730: 716: 709: 695: 688: 674: 667: 664: 663: 659: 656: 653: 650: 647: 646: 643: 640: 626: 603: 600: 597: 594: 591: 588: 585: 582: 579: 576: 573: 570: 567: 564: 561: 533: 526: 512: 505: 491: 484: 470: 463: 460: 459: 444: 437: 423: 416: 402: 395: 381: 374: 371: 370: 355: 348: 334: 327: 313: 306: 292: 285: 282: 281: 277: 274: 271: 268: 265: 264: 261: 258: 256: 240: 220: 200: 180: 168: 166: 164: 160: 156: 152: 148: 141: 137: 134: 131: 130: 129: 127: 123: 119: 118:Allan Gibbard 115: 111: 107: 106:voting theory 103: 92: 87: 83: 79: 78: 72: 63: 62: 53: 43: 39: 35: 32:This article 30: 21: 20: 3291:(1): 85–93. 3288: 3284: 3278: 3245: 3241: 3235: 3213:(1): 33–43. 3210: 3207:Econometrica 3206: 3200: 3176:(1): 80–89. 3173: 3169: 3156: 3147: 3141: 3116: 3110: 3104: 3092:. Retrieved 3077: 3067: 3034: 3030: 3017: 2998: 2992: 2959: 2955: 2949: 2908: 2904: 2898: 2875: 2825: 2821: 2780: 2776: 2740: 2736: 2718: 2708: 2681: 2677: 2640: 2637:Econometrica 2636: 2599: 2595: 2582: 2568: 2499: 2494: 2482: 2470: 2456: 2420: 2416: 2411:Duncan Black 2404: 2386: 2379: 2355:dictatorship 2292: 2103: 2068: 2058: 2054: 2025: 2023: 2013: 2008: 2003: 1999: 1995: 1944: 1890: 1820: 1813:among them. 1811: 1805: 1803: 1790:score voting 1787: 1779: 1764: 1758: 1754: 1730: 1709:We say that 1708: 1643: 1581: 1403: 1382:We say that 1381: 1260: 1204: 1152: 1149:alternatives 1148: 1122: 1110: 1105: 1103: 932: 641: 550: 259: 172: 145: 101: 99: 90: 75: 47: 37: 33: 2911:: 137–142. 2871:Tardos, Éva 2863:Nisan, Noam 2004:dictatorial 2000:manipulable 1915:the set of 1731:dictatorial 1404:manipulable 1261:voting rule 1203:the set of 1106:manipulable 255:Borda count 3335:Categories 3094:10 January 2489:Noam Nisan 2479:Importance 1153:candidates 3305:0176-1714 2976:0020-6598 2941:153421058 2925:0048-5829 2842:0165-1765 2797:0165-1765 2745:CiteSeerX 2686:CiteSeerX 2391:is being 2135:≺ 2059:unanimous 1975:→ 1887:Corollary 1753:who is a 1449:∈ 1430:… 1353:∈ 1334:… 1291:→ 1182:… 1041:. Hence, 660:Choice 4 278:Choice 4 50:June 2024 3313:41106341 3270:27639067 3262:41106711 3075:(1991). 3059:46164353 3051:41106783 2933:30023000 2873:(2007). 2616:46164353 2508:See also 2384:template 2250:chooses 1755:dictator 1539:′ 657:Choice 3 654:Choice 2 651:Choice 1 275:Choice 3 272:Choice 2 269:Choice 1 3227:1907685 3192:2662065 3133:2695497 2984:2648754 2657:1914083 2401:History 2397:  2015:Theorem 86:Discuss 3321:271833 3319:  3311:  3303:  3268:  3260:  3225:  3190:  3131:  3085:  3057:  3049:  3005:  2982:  2974:  2939:  2931:  2923:  2886:  2840:  2795:  2747:  2688:  2655:  2614:  2496:model. 2150:, the 1207:. Let 1205:voters 82:merged 3317:S2CID 3309:JSTOR 3266:S2CID 3258:JSTOR 3223:JSTOR 3188:JSTOR 3129:JSTOR 3055:S2CID 3047:JSTOR 3027:(PDF) 2980:JSTOR 2937:S2CID 2929:JSTOR 2880:(PDF) 2818:(PDF) 2653:JSTOR 2612:S2CID 2592:(PDF) 2382:‹The 1919:over 1235:over 843:Carol 665:Alice 648:Voter 461:Carol 283:Alice 266:Voter 3301:ISSN 3096:2016 3083:ISBN 3003:ISBN 2972:ISSN 2921:ISSN 2884:ISBN 2838:ISSN 2793:ISSN 2471:The 2464:and 2437:and 2341:Rank 2321:Rank 2218:Rank 2190:and 2158:Rank 2112:Rank 2073:for 2055:onto 1804:The 1123:Let 233:and 157:and 100:The 3293:doi 3250:doi 3215:doi 3178:doi 3121:doi 3117:109 3039:doi 2964:doi 2913:doi 2830:doi 2785:doi 2755:doi 2696:doi 2645:doi 2604:doi 2270:or 2101:. 1729:is 1579:). 1402:is 1081:to 754:Bob 372:Bob 80:be 3337:: 3315:. 3307:. 3299:. 3289:17 3287:. 3264:. 3256:. 3246:25 3244:. 3221:. 3211:29 3209:. 3186:. 3168:. 3127:. 3115:. 3053:. 3045:. 3035:27 3033:. 3029:. 2978:. 2970:. 2960:24 2958:. 2935:. 2927:. 2919:. 2909:32 2907:. 2869:; 2865:; 2861:; 2850:^ 2836:. 2826:70 2824:. 2820:. 2805:^ 2791:. 2781:69 2779:. 2767:^ 2753:. 2741:70 2739:. 2727:^ 2717:. 2694:. 2682:10 2680:. 2665:^ 2651:. 2641:41 2639:. 2624:^ 2610:. 2600:27 2598:. 2594:. 2504:. 2395:.› 2290:. 2002:, 1998:, 1796:. 213:, 193:, 153:. 3323:. 3295:: 3272:. 3252:: 3229:. 3217:: 3194:. 3180:: 3174:8 3135:. 3123:: 3098:. 3061:. 3041:: 3011:. 2986:. 2966:: 2943:. 2915:: 2892:. 2844:. 2832:: 2799:. 2787:: 2761:. 2757:: 2721:. 2702:. 2698:: 2659:. 2647:: 2618:. 2606:: 2413:: 2365:f 2301:f 2278:b 2258:a 2238:f 2198:b 2178:a 2138:b 2132:a 2085:f 2039:A 1980:A 1970:n 1964:L 1958:: 1955:f 1929:A 1901:L 1871:b 1851:a 1830:a 1741:i 1717:f 1694:) 1689:n 1683:P 1677:( 1674:f 1654:f 1630:f 1610:) 1605:n 1599:P 1593:( 1590:f 1565:i 1561:P 1535:i 1531:P 1508:i 1504:P 1483:i 1461:n 1455:P 1446:) 1441:n 1437:P 1433:, 1427:, 1422:1 1418:P 1414:( 1390:f 1365:n 1359:P 1350:) 1345:n 1341:P 1337:, 1331:, 1326:1 1322:P 1318:( 1296:A 1286:n 1280:P 1274:: 1271:f 1245:A 1217:P 1191:} 1188:n 1185:, 1179:, 1176:1 1173:{ 1170:= 1165:N 1133:A 1089:c 1069:b 1049:b 1029:) 1026:3 1023:: 1020:d 1017:, 1014:6 1011:: 1008:c 1005:, 1002:7 999:: 996:b 993:, 990:2 987:: 984:a 981:( 961:c 941:b 916:a 895:d 874:b 853:c 827:a 806:d 785:b 764:c 738:c 717:d 696:a 675:b 627:c 607:) 604:2 601:: 598:d 595:, 592:7 589:: 586:c 583:, 580:6 577:: 574:b 571:, 568:3 565:: 562:a 559:( 534:a 513:d 492:b 471:c 445:a 424:d 403:b 382:c 356:d 335:c 314:b 293:a 241:d 221:c 201:b 181:a 88:) 52:) 48:(

Index

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
template
Excessive citations inline
considered for deletion
Lewis Carroll

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