Knowledge (XXG)

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1085:
s are obviously linearly independent and they are in the center, so they form a basis. The proof is kind of obvious if you've been working with these sums long enough, but probably not if you never seen them before. My group theory book (W.R. Scott) gives the proof in 7 lines, slightly different than
620:
If we know f(n)=(1/n^2) for all integers n, and f is analytic in the complex plane except for possibly at some singularities, then what more would we need to know in order to establish g exactly? Obviously you could have g(z)=cos(2piz)/(z^2) or something similar so it needn't necessarily be
456:. However, it's not really defined like that, it's a primitive notion: you are given a set of worlds, an accessibility relation, and truth values of atomic statements in each world, and all this together determines the truth values of compound statements (which may involve the 1215:(ec)Variables are useful here. When you want to manipulate some number, but you don't know what the number is, place a variable in its stead; this gives you information about the variable which later may allow you to determine its value. 1226:. How much did the 65 cents stamps she purchased cost? How many 50 cent stamps did she purchase? How much did they cost? What is the total cost (before tax) of all the stamps she purchased? How much did she spend (after tax)? 621:
g(z)=1/z^2 at this point - but I can't see how we can classify all possible g which take the appropriate values at integers, in order to work out what more information we need to know to identify g. Could anyone suggest anything?
1121:
Arriana bought two kinds of stamps, 50cent stamps, and 65cent stamps. She bought 40% more 50cent stamps then 65 cent stamps, spending a total of $ 50.56. How many of each type did she buy? There is a 7% tax on stamp sales.
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Indeed I must admit I was wondering why they couldn't just ask Arriana or look at the stamps, and why did they want to know anyway? Surely you'd only want to know how any stamps you've got left.
59: 444:". You can ask whether a statement (formula) is possible in a world, but there is no concept of a world being possible in another world. The intuitive meaning of the accessibility relation 783:), but I can't seem to string it altogether. The notes I'm working with only dedicate one line to the explanation, so I feel I'm missing something pretty obvious. Thanks, as always! 1007: 1071: 841: 769: 548: 360: 494: 161: 521: 317: 474: 25: 389: 207: 1355: 1332: 412: 337: 294: 272: 247: 227: 181: 129: 85:
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the
671:(assuming that's what you mean by "analytic except for possibly at some singularities") which vanishes in all integer points. You can thus ignore the 1/ 37: 586:⊨ is read 'models' rather than 'is', where models here means the right hand side proposition is true for the world given by the left hand side. 1242: 1132: 421: 21: 1229:
You know that the answer to the last question is $ 50.56 from the problem statement. Once you've answered the last question in terms of
1377: 625: 1409: 1385: 1250: 1208: 1140: 1102: 792: 717:? I've tried it out for a few concrete examples, and it worked, but I can't really see why. The closest I could come was taking 686: 633: 607: 573: 429: 852: 598:
as implementing the most common system, what the article calls the strongest logic S5, but this isn't necessarily so.
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has an inverse in the algebra. I know also that the class sums are invariant under conjugation by the elements of
1296:
after she left and found out that the total number of guests receiving invitations happens to be the same as the
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or not. The accessibility relation can be an arbitrary binary relation, in general it does not have to be
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instead of the actual amounts in each of the other statements as well and you've got some equations.
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be the number of 65 cent stamps that she bought. Then answer the following questions in terms of
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Start by giving a name to everything you dont know. these are called variable for some reason
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will suffice. (I suppose that's what you get when you ask such a question in a mathematics
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Yes- I realize you won't help me with my homework, but I have no idea where to start here.
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part, and concentrate on the (less messy, if not really easier) task of classifying such
368: 186: 1405: 1265: 1204: 603: 1340: 1317: 397: 322: 279: 257: 232: 212: 166: 114: 1362: 1285: 1373: 1301: 1094: 784: 1357:. Moreover, the number of guests who lived locally, and not over the border in 1277: 1257: 594:
is a world. I think your business about inclusion is where you are thinking of
1261: 706: 680: 567: 1401: 1293: 1273: 1200: 599: 74: 500:. Your example does not make much sense as is, but even if we read it as " 1304: 1289: 1365: 1334: 1297: 414:
is like an equality relation, or a kind of "is a subset of" relation?
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where the second sum is obtained by reindexing the first one. But
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566:, hence neither equality nor "subset of" is an adequate analogy.— 1233:(using your previous answers), you will have an equation for 1260:
is the only way to solve these problems, when sometimes the
616:
What more do we need to know in order to Identify a function
1164:
and then write them in like 40% more 50c stamps means take
108:
From the article, just trying to understand the semantics.
931:{\displaystyle z^{h}=\sum z_{g}g^{h}=\sum z_{g^{h^{-1}}}g} 771:, which introduces conjugation, but that's only true when 554:", this is insufficient information to determine whether 1343: 1320: 1040: 958: 855: 810: 735: 533: 506: 482: 462: 400: 371: 345: 325: 302: 282: 260: 235: 215: 189: 169: 137: 117: 1284:, and she crossed a name off her list as she put a 1349: 1326: 1065: 1001: 930: 835: 763: 542: 515: 488: 468: 406: 383: 354: 331: 311: 288: 266: 241: 221: 201: 175: 155: 123: 448:is actually that every statement that is true in 802:be in the center of the group algebra and write 1077:where the sum runs over the conjugacy classes 798:I think you're over thinking the problem. Let 163:are worlds. We have a accessibility relation 8: 1241:and solve the problem from there. Eric. 1342: 1319: 1276:work will do. I followed Arriana to the 1054: 1039: 986: 981: 976: 963: 957: 912: 907: 902: 886: 876: 860: 854: 824: 809: 746: 734: 532: 505: 481: 461: 399: 370: 344: 324: 301: 281: 259: 234: 214: 188: 168: 136: 116: 1093:A-hah, I see now - thanks for the help. 49: 36: 1024:depends only on the conjugacy class of 65: 43: 7: 1237:. This will allow you to calculate 1002:{\displaystyle z_{g}=z_{g^{h^{-1}}}} 705:, form a basis of the center of the 436:It does not make sense to say that " 1118:Can someone give me the equations? 32: 1292:. I pulled that list out of the 111:We have a non-empty set (frame) 1376:of the total number of guests. 1361:(and thus requiring the higher 1272:, ...) In this case a little 1017:. In other words the value of 667:is a function meromorphic in 18:Knowledge (XXG):Reference desk 1: 1410:12:00, 23 February 2010 (UTC) 1386:01:50, 23 February 2010 (UTC) 1251:22:11, 22 February 2010 (UTC) 1209:22:07, 22 February 2010 (UTC) 1191:All you do is write down the 1141:21:55, 22 February 2010 (UTC) 1103:21:37, 22 February 2010 (UTC) 1066:{\displaystyle z=\sum z_{C}C} 836:{\displaystyle z=\sum z_{g}g} 793:18:02, 22 February 2010 (UTC) 687:14:59, 22 February 2010 (UTC) 634:13:34, 22 February 2010 (UTC) 608:15:16, 22 February 2010 (UTC) 574:14:52, 22 February 2010 (UTC) 430:10:29, 22 February 2010 (UTC) 33: 1268:. When your only tool is a 1159:for the number of 65c stamps 1153:for the number of 50c stamps 779:(i.e. the basis elements of 721:to be in the centre - then 1431: 764:{\displaystyle h=z^{-1}hz} 543:{\displaystyle \Diamond p} 355:{\displaystyle \Diamond p} 950:so matching coefficients 693:Centre of a group algebra 489:{\displaystyle \Diamond } 1280:when she mailed off her 156:{\displaystyle v,w\in G} 1351: 1328: 1067: 1003: 932: 837: 765: 624:Thanks all very much! 544: 517: 516:{\displaystyle \Box p} 490: 470: 408: 385: 356: 333: 313: 312:{\displaystyle \Box p} 290: 268: 243: 223: 203: 177: 157: 125: 87:current reference desk 1352: 1329: 1068: 1004: 933: 838: 766: 590:is a proposition and 545: 518: 491: 471: 469:{\displaystyle \Box } 409: 386: 357: 334: 314: 291: 269: 244: 224: 204: 178: 158: 126: 1341: 1318: 1256:Everyone acts as if 1125:Thanks in advance. 1038: 956: 853: 808: 733: 699:conjugacy class sums 531: 504: 480: 460: 398: 369: 343: 323: 300: 280: 258: 233: 213: 187: 167: 135: 115: 1309:mapping class group 1282:wedding invitations 729:in the algebra, so 384:{\displaystyle vRw} 202:{\displaystyle vRw} 1347: 1324: 1081:of the group. The 1063: 999: 928: 833: 761: 639:Your condition on 540: 513: 486: 466: 404: 381: 352: 329: 309: 286: 264: 239: 219: 199: 173: 153: 121: 1412: 1388: 1350:{\displaystyle g} 1327:{\displaystyle g} 1131:comment added by 713:, for some field 643:is equivalent to 420:comment added by 407:{\displaystyle R} 332:{\displaystyle v} 289:{\displaystyle w} 267:{\displaystyle p} 242:{\displaystyle w} 222:{\displaystyle v} 176:{\displaystyle R} 124:{\displaystyle G} 93: 92: 73: 72: 1422: 1399: 1356: 1354: 1353: 1348: 1333: 1331: 1330: 1325: 1255: 1143: 1072: 1070: 1069: 1064: 1059: 1058: 1008: 1006: 1005: 1000: 998: 997: 996: 995: 994: 993: 968: 967: 937: 935: 934: 929: 924: 923: 922: 921: 920: 919: 891: 890: 881: 880: 865: 864: 842: 840: 839: 834: 829: 828: 770: 768: 767: 762: 754: 753: 584:double turnstile 549: 547: 546: 541: 522: 520: 519: 514: 498:Kripke semantics 496:operators), see 495: 493: 492: 487: 475: 473: 472: 467: 432: 413: 411: 410: 405: 390: 388: 387: 382: 361: 359: 358: 353: 338: 336: 335: 330: 318: 316: 315: 310: 295: 293: 292: 287: 274:= it is snowing 273: 271: 270: 265: 248: 246: 245: 240: 228: 226: 225: 220: 208: 206: 205: 200: 182: 180: 179: 174: 162: 160: 159: 154: 130: 128: 127: 122: 75: 38:Mathematics desk 34: 1430: 1429: 1425: 1424: 1423: 1421: 1420: 1419: 1372:of the largest 1339: 1338: 1316: 1315: 1300:of the largest 1243:131.215.159.171 1126: 1113: 1050: 1036: 1035: 1032:can be written 1022: 982: 977: 972: 959: 954: 953: 908: 903: 898: 882: 872: 856: 851: 850: 820: 806: 805: 742: 731: 730: 695: 618: 529: 528: 502: 501: 478: 477: 458: 457: 452:is possible in 440:is possible in 415: 396: 395: 394:Does this mean 367: 366: 341: 340: 321: 320: 298: 297: 278: 277: 256: 255: 252:As an example: 231: 230: 229:is possible in 211: 210: 185: 184: 165: 164: 133: 132: 113: 112: 106: 101: 30: 29: 28: 12: 11: 5: 1428: 1426: 1418: 1417: 1416: 1415: 1414: 1413: 1392: 1391: 1390: 1389: 1346: 1323: 1227: 1216: 1212: 1211: 1189: 1188: 1187: 1162: 1161: 1160: 1154: 1133:174.112.38.185 1112: 1109: 1108: 1107: 1106: 1105: 1088: 1087: 1075: 1074: 1073: 1062: 1057: 1053: 1049: 1046: 1043: 1020: 1011: 1010: 1009: 992: 989: 985: 980: 975: 971: 966: 962: 940: 939: 938: 927: 918: 915: 911: 906: 901: 897: 894: 889: 885: 879: 875: 871: 868: 863: 859: 845: 844: 843: 832: 827: 823: 819: 816: 813: 760: 757: 752: 749: 745: 741: 738: 694: 691: 690: 689: 617: 614: 613: 612: 611: 610: 577: 576: 539: 536: 512: 509: 485: 465: 422:81.149.255.225 403: 380: 377: 374: 351: 348: 328: 308: 305: 285: 263: 238: 218: 198: 195: 192: 172: 152: 149: 146: 143: 140: 120: 105: 102: 100: 97: 95: 91: 90: 82: 81: 71: 70: 64: 48: 41: 40: 31: 15: 14: 13: 10: 9: 6: 4: 3: 2: 1427: 1411: 1407: 1403: 1398: 1397: 1396: 1395: 1394: 1393: 1387: 1383: 1379: 1378:58.147.60.130 1375: 1371: 1367: 1364: 1363:international 1360: 1344: 1336: 1321: 1314: 1310: 1306: 1303: 1299: 1295: 1291: 1287: 1283: 1279: 1275: 1271: 1267: 1263: 1259: 1254: 1253: 1252: 1248: 1244: 1240: 1236: 1232: 1228: 1225: 1221: 1217: 1214: 1213: 1210: 1206: 1202: 1198: 1194: 1190: 1186: 1182: 1178: 1177: 1175: 1171: 1167: 1163: 1158: 1155: 1152: 1149: 1148: 1146: 1145: 1144: 1142: 1138: 1134: 1130: 1123: 1119: 1116: 1110: 1104: 1100: 1096: 1092: 1091: 1090: 1089: 1086:the one here. 1084: 1080: 1076: 1060: 1055: 1051: 1047: 1044: 1041: 1034: 1033: 1031: 1027: 1023: 1016: 1012: 990: 987: 983: 978: 973: 969: 964: 960: 952: 951: 949: 945: 941: 925: 916: 913: 909: 904: 899: 895: 892: 887: 883: 877: 873: 869: 866: 861: 857: 849: 848: 846: 830: 825: 821: 817: 814: 811: 804: 803: 801: 797: 796: 795: 794: 790: 786: 782: 778: 774: 758: 755: 750: 747: 743: 739: 736: 728: 724: 720: 716: 712: 708: 707:group algebra 704: 700: 692: 688: 685: 682: 678: 674: 670: 666: 662: 658: 654: 650: 646: 642: 638: 637: 636: 635: 631: 627: 622: 615: 609: 605: 601: 597: 593: 589: 585: 581: 580: 579: 578: 575: 572: 569: 565: 561: 557: 553: 537: 534: 526: 510: 507: 499: 483: 463: 455: 451: 447: 443: 439: 435: 434: 433: 431: 427: 423: 419: 401: 392: 378: 375: 372: 363: 349: 346: 326: 306: 303: 283: 275: 261: 253: 250: 236: 216: 196: 193: 190: 170: 150: 147: 144: 141: 138: 118: 109: 103: 98: 96: 88: 84: 83: 80: 77: 76: 68: 61: 57: 53: 47: 42: 39: 35: 27: 23: 19: 1374:prime factor 1238: 1234: 1230: 1223: 1219: 1196: 1192: 1184: 1180: 1179:(1 + 40/100) 1173: 1172:and you get 1169: 1165: 1156: 1150: 1124: 1120: 1117: 1114: 1082: 1078: 1029: 1025: 1018: 1014: 947: 943: 799: 780: 776: 772: 726: 722: 718: 714: 710: 702: 701:of a group, 696: 676: 672: 668: 664: 660: 656: 652: 648: 644: 640: 623: 619: 595: 591: 587: 555: 551: 524: 453: 449: 445: 441: 437: 393: 364: 276: 254: 251: 183:, such that 110: 107: 94: 78: 1368:), was the 1337:divided by 1278:post office 1258:mathematics 1176:or shorter 1168:and 40% of 1127:—Preceding 697:Why do the 550:is true in 523:is true in 416:—Preceding 209:means that 104:Modal logic 99:February 22 67:February 23 46:February 21 26:Mathematics 1262:humanities 626:82.6.96.22 560:transitive 365:Therefore 1274:detective 1111:Math Help 663:), where 564:reflexive 50:<< 1305:subgroup 1290:envelope 1288:on each 1129:unsigned 1013:for all 946:for all 725:for all 418:unsigned 56:February 24:‎ | 22:Archives 20:‎ | 1366:postage 1335:surface 1307:of the 1298:lim sup 1095:Icthyos 785:Icthyos 723:hz = zh 89:pages. 1370:square 1359:Canada 1302:finite 1270:hammer 651:) = 1/ 131:, and 1313:genus 1311:of a 1294:trash 1286:stamp 1266:forum 1028:. So 847:Then 556:v R w 446:v R w 69:: --> 63:: --> 62:: --> 44:< 16:< 1406:talk 1402:Dmcq 1382:talk 1247:talk 1218:Let 1205:talk 1201:Dmcq 1137:talk 1099:talk 789:talk 681:Emil 630:talk 604:talk 600:Dmcq 582:The 568:Emil 527:and 476:and 426:talk 944:z=z 562:or 339:is 296:is 60:Mar 52:Jan 1408:) 1384:) 1249:) 1207:) 1195:or 1183:= 1139:) 1101:) 1048:∑ 988:− 914:− 896:∑ 870:∑ 818:∑ 791:) 781:FG 748:− 711:FG 709:, 684:J. 679:.— 655:+ 632:) 606:) 571:J. 535:◊ 508:◻ 484:◊ 464:◻ 428:) 391:. 362:. 347:◊ 319:. 304:◻ 249:. 148:∈ 58:| 54:| 1404:( 1380:( 1345:g 1322:g 1245:( 1239:x 1235:x 1231:x 1224:x 1220:x 1203:( 1197:y 1193:x 1185:x 1181:y 1174:x 1170:y 1166:y 1157:y 1151:x 1135:( 1097:( 1083:C 1079:C 1061:C 1056:C 1052:z 1045:= 1042:z 1030:z 1026:g 1021:g 1019:z 1015:h 991:1 984:h 979:g 974:z 970:= 965:g 961:z 948:h 926:g 917:1 910:h 905:g 900:z 893:= 888:h 884:g 878:g 874:z 867:= 862:h 858:z 831:g 826:g 822:z 815:= 812:z 800:z 787:( 777:G 773:z 759:z 756:h 751:1 744:z 740:= 737:h 727:z 719:h 715:F 703:G 677:h 673:z 669:C 665:h 661:z 659:( 657:h 653:z 649:z 647:( 645:g 641:g 628:( 602:( 596:R 592:w 588:p 552:v 538:p 525:w 511:p 454:v 450:w 442:w 438:v 424:( 402:R 379:w 376:R 373:v 350:p 327:v 307:p 284:w 262:p 237:w 217:v 197:w 194:R 191:v 171:R 151:G 145:w 142:, 139:v 119:G

Index

Knowledge (XXG):Reference desk
Archives
Mathematics
Mathematics desk
February 21
Jan
February
Mar
February 23
current reference desk
unsigned
81.149.255.225
talk
10:29, 22 February 2010 (UTC)
Kripke semantics
transitive
reflexive
Emil
J.
14:52, 22 February 2010 (UTC)
double turnstile
Dmcq
talk
15:16, 22 February 2010 (UTC)
82.6.96.22
talk
13:34, 22 February 2010 (UTC)
Emil
J.
14:59, 22 February 2010 (UTC)

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