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Cardinality

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A crude sense of cardinality, an awareness that groups of things or events compare with other groups by containing more, fewer, or the same number of instances, is observed in a variety of present-day animal species, suggesting an origin millions of years ago. Human expression of cardinality is seen
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From the 6th century BCE, the writings of Greek philosophers show hints of the cardinality of infinite sets. While they considered the notion of infinity as an endless series of actions, such as adding 1 to a number repeatedly, they did not consider the size of an infinite set of numbers to be a
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While the cardinality of a finite set is simply comparable to its number of elements, extending the notion to infinite sets usually starts with defining the notion of comparison of arbitrary sets (some of which are possibly infinite).
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years ago, with equating the size of a group with a group of recorded notches, or a representative collection of other things, such as sticks and shells. The abstraction of cardinality as a number is evident by 3000 BCE, in Sumerian
4040: 3237:. Cantor introduced the cardinal numbers, and showed—according to his bijection-based definition of size—that some infinite sets are greater than others. The smallest infinite cardinality is that of the natural numbers ( 4191: 5406: 593:, it was seen that even the infinite set of all rational numbers was not enough to describe the length of every possible line segment. Still, there was no concept of infinite sets as something that had cardinality. 2689: 3900: 3233:. Indeed, Dedekind defined an infinite set as one that can be placed into a one-to-one correspondence with a strict subset (that is, having the same size in Cantor's sense); this notion of infinity is called 3745: 3852: 4934: 3396: 4601: 3912: 3545:
of that line, but that this is equal to the number of points on a plane and, indeed, in any finite-dimensional space. These results are highly counterintuitive, because they imply that there exist
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In the above section, "cardinality" of a set was defined functionally. In other words, it was not defined as a specific object itself. However, such an object can be defined as follows.
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thing. The ancient Greek notion of infinity also considered the division of things into parts repeated without limit. In Euclid's
6972: 3589: 3230: 4680:{\displaystyle \left\vert C\cup D\right\vert +\left\vert C\cap D\right\vert =\left\vert C\right\vert +\left\vert D\right\vert .} 3344: 615:, a one-to-one correspondence between the elements of two sets based on a unique relationship. In 1891, with the publication of 5378: 4029:{\displaystyle {\mathfrak {c}}^{2}=\left(2^{\aleph _{0}}\right)^{2}=2^{2\times {\aleph _{0}}}=2^{\aleph _{0}}={\mathfrak {c}},} 3758: 3459: 2543: 7130: 5189: 5918: 7744: 7557: 6985: 6308: 1000: 3763: 3639: 4856:{\displaystyle |A|:={\mbox{Ord}}\cap \bigcap \{\alpha \in {\mbox{Ord}}|\exists (f:A\to \alpha ):(f{\mbox{ injective}})\}} 5712: 8072: 6990: 6980: 6717: 6570: 5923: 17: 5914: 4971: 7126: 5741: 5733: 5681: 5516: 3052: 2895: 6468: 3408: 2858: 1974: 7223: 6967: 5792: 2448: 2383: 2277: 8050: 7644: 6528: 6221: 3480: 2946: 2603: 7930: 5962: 5096:
This definition is natural since it agrees with the axiom of limitation of size which implies bijection between
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on them. There are two notions often used when referring to cardinality: one which compares sets directly using
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and others rejected the view that the whole cannot be the same size as the part. One example of this is
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The second result was first demonstrated by Cantor in 1878, but it became more apparent in 1890, when
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and the manipulation of numbers without reference to a specific group of things or events.
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between the cardinality of the reals and the cardinality of the natural numbers, that is,
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under this relation, then, consists of all those sets which have the same cardinality as
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Kurt Von Fritz (1945). "The Discovery of Incommensurability by Hippasus of Metapontum".
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However, this hypothesis can neither be proved nor disproved within the widely accepted
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that contain more elements than there are in the infinite set of natural numbers.
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Cardinal arithmetic can be used to show not only that the number of points in a
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Proceedings of the National Academy of Sciences of the United States of America
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Proceedings of the National Academy of Sciences of the United States of America
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is injective, but not surjective since 2, for instance, is not mapped to, and
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Applied Abstract Algebra, K.H. Kim, F.W. Roush, Ellis Horwood Series, 1983,
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set is designated for each equivalence class. The most common choice is the
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To better understand infinite sets, a notion of cardinality was formulated
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contains elements that do not belong to its subsets, and the supersets of
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The first of these results is apparent by considering, for instance, the
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was described as the ability to compare the length of two line segments,
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Georg Cantor (1932), Adolf Fraenkel (Lebenslauf); Ernst Zermelo (eds.),
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that has the same cardinality as the set of the natural numbers, or |
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This definition allows also obtain a cardinality of any proper class
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Cantor also showed that sets with cardinality strictly greater than
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holds for cardinality. Thus we can make the following definitions:
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Gesammelte Abhandlungen mathematischen und philosophischen Inhalts
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The Road to Reality: A Complete guide to the Laws of the Universe
3895:{\displaystyle {\mathfrak {c}}^{\mathfrak {c}}=2^{\mathfrak {c}}} 5696:
Georg Cantor (1887), "Mitteilungen zur Lehre vom Transfiniten",
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with cardinality greater than that of the natural numbers, or |
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Animals Count and Use Zero. How Far Does Their Number Sense Go?
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From this, one can show that in general, the cardinalities of
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has cardinality strictly less than the cardinality of the set
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which compares their relative size. For example, the sets
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is defined as its equivalence class under equinumerosity.
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has cardinality less than or equal to the cardinality of
5379:"Ueber eine elementare Frage der Mannigfaltigkeitslehre" 5204: 4866:
We use the intersection of a class which is defined by
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can be bijective (see picture). By a similar argument,
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The relation of having the same cardinality is called
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has cardinality strictly less than the cardinality of
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Zeitschrift fĂŒr Philosophie und philosophische Kritik
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Two sets have the same cardinality if there exists a
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Jahresbericht der Deutschen Mathematiker-Vereinigung
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include the set of all real numbers, the set of all
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One of Cantor's most important results was that the
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is a bijection. This is no longer true for infinite
611:. He examined the process of equating two sets with 729:cannot be surjective. The picture shows an example 5604:"The Independence of the Continuum Hypothesis, II" 5108: 5085: 5042: 5018: 4957: 4928: 4855: 4739: 4715: 4679: 4576: 4479: 4298: 4179: 4028: 3894: 3846: 3796: 3739: 3630: 3516: 3444: 3390: 3325: 3298: 3256: 3184: 3137: 3043: 3016: 2982: 2928: 2884: 2835: 2807: 2769: 2742: 2709: 2683: 2524: 2498: 2472: 2433: 2407: 2368: 2344: 2301: 2255: 2226: 2202: 2178: 2154: 2111: 2087: 2065: 2019: 1965: 1919: 1873: 1822: 1798: 1774: 1750: 1707: 1685: 1635: 1611: 1585: 1528: 1504: 1478: 1456: 1416: 1392: 1366: 1342: 1318: 1294: 1270: 1242: 1218: 1190: 1166: 1139: 1115: 1091: 1049: 985: 900: 876: 848: 824: 530: 507: 474: 453: 424: 396: 366: 342: 294: 270: 249:. The cardinality of a set may also be called its 217: 173: 113: 77: 53: 5231:"Cardinality | Brilliant Math & Science Wiki" 3060: 8197: 5019:{\displaystyle (x\mapsto |x|):V\to {\mbox{Ord}}} 5497: 3306:) is greater than that of the natural numbers ( 3267: 2929:{\displaystyle {\mathfrak {c}}=2^{\aleph _{0}}} 5537:"The Independence of the Continuum Hypothesis" 5361: 3569:contain elements that are not included in it. 3445:{\displaystyle 2^{\aleph _{0}}>\aleph _{0}} 2885:{\displaystyle {\mathfrak {c}}>\aleph _{0}} 7551: 5793: 2606:. This is usually taken as the definition of 2124: 1784:, if there exists an injective function from 27:Definition of the number of elements in a set 5710: 5695: 5505:; Srishti D. Chatterji; et al. (eds.), 5376: 4850: 4786: 4367:, peaches)} is a bijection between the sets 3024:is the smallest cardinal number bigger than 2473:{\displaystyle {\mathcal {P}}(\mathbb {N} )} 2417:, and it can be shown that no function from 2408:{\displaystyle {\mathcal {P}}(\mathbb {N} )} 2339: 2333: 2302:{\displaystyle {\mathcal {P}}(\mathbb {N} )} 1693:, which was established by the existence of 1044: 1012: 980: 948: 212: 194: 168: 150: 5689: 5464:(4), Leipzig: B. G. Teubner: 438–443, 4691:Definition of cardinality in class theory ( 3517:{\displaystyle 2^{\aleph _{0}}=\aleph _{1}} 2983:{\displaystyle \aleph _{1}=2^{\aleph _{0}}} 408:on each side; this is the same notation as 7558: 7544: 5985: 5800: 5786: 4895: 4891: 4747:denotes the class of all ordinal numbers. 4309: 2750:is the least cardinal number greater than 1720: 986:{\displaystyle E=\{0,2,4,6,{\text{...}}\}} 789: 666:does not have the same cardinality as its 5645: 5627: 5578: 5560: 5184:. San Francisco, CA: Dover Publications. 4491: 2518: 2492: 2463: 2427: 2398: 2362: 2292: 2249: 1674: 1586:{\displaystyle h(n)=n-(n{\text{ mod }}2)} 1498: 1386: 1109: 1005: 810:(a.k.a., one-to-one correspondence) from 225:are the same size as they each contain 3 3541:is equal to the number of points in any 3333:); that is, there are more real numbers 658: 630: 508:{\displaystyle \operatorname {card} (A)} 65:has 5 elements. Thus the cardinality of 36: 5668: 4595:are related by the following equation: 3087:with cardinality less than that of the 2269:has cardinality strictly less than its 14: 8198: 5807: 4449:Sets with cardinality of the continuum 3067:Finite, countable and uncountable sets 1256:injective or surjective function from 655:, both sets have the same cardinality. 8211:Basic concepts in infinite set theory 7539: 5781: 5601: 5534: 5401: 5399: 5324: 5205: 2847:"c"), and is also referred to as the 1981:is equivalent to the statement that 5717:, Berlin: Springer, pp. 378–439 5535:Cohen, Paul J. (December 15, 1963). 5318: 4958:{\displaystyle \bigcap \emptyset =V} 4335:= {apples, oranges, peaches}, where 3590:Hilbert's paradox of the Grand Hotel 3231:Hilbert's paradox of the Grand Hotel 997:has the same cardinality as the set 5602:Cohen, Paul J. (January 15, 1964). 4287: 4258: 4242: 4205: 4198: 4169: 4047: 4018: 3919: 3886: 3871: 3864: 3836: 3813: 3786: 3770: 3732: 3708: 3623: 3460:Cantor's first uncountability proof 3350: 3291: 3177: 2901: 2864: 2828: 2743:{\displaystyle \aleph _{\alpha +1}} 2549: 2544:Cantor's first uncountability proof 717:)} disagrees with every set in the 24: 5452:"Über das Problem der Wohlordnung" 5396: 4946: 4899: 4807: 4443:Cantor–Bernstein–Schroeder theorem 4267: 4225: 4153: 4132: 4117: 4096: 4079: 4054: 4002: 3981: 3944: 3820: 3505: 3490: 3433: 3418: 3364: 3314: 3245: 3126: 3032: 3003: 2969: 2951: 2915: 2873: 2796: 2758: 2725: 2663: 2650: 2637: 2454: 2389: 2283: 1686:{\displaystyle |E|=|\mathbb {N} |} 522: 25: 8222: 5179: 2770:{\displaystyle \aleph _{\alpha }} 626: 133:describes a relationship between 7589: 7519: 5086:{\displaystyle |P|={\mbox{Ord}}} 4723:denote a class of all sets, and 3204: 2815:), while the cardinality of the 432:may alternatively be denoted by 5722: 5662: 5595: 5528: 5491: 5424: 5407:"Infinite Sets and Cardinality" 5370: 3646:). They include, for instance: 3631:{\displaystyle {\mathfrak {c}}} 3299:{\displaystyle {\mathfrak {c}}} 3185:{\displaystyle {\mathfrak {c}}} 3017:{\displaystyle 2^{\aleph _{0}}} 2836:{\displaystyle {\mathfrak {c}}} 350:; however, if referring to the 85:is 5 or, written symbolically, 7565: 5753: 5355: 5290: 5266: 5247: 5223: 5198: 5173: 5069: 5061: 5006: 4997: 4993: 4985: 4981: 4975: 4923: 4896: 4892: 4888: 4873: 4847: 4834: 4828: 4822: 4810: 4803: 4766: 4758: 4474: 4462: 3213:breaks down when dealing with 3061:§ Cardinality of the continuum 2467: 2459: 2402: 2394: 2352:is an injective function from 2327: 2321: 2296: 2288: 2059: 2051: 2043: 2035: 2013: 2005: 1997: 1989: 1959: 1951: 1943: 1935: 1913: 1905: 1897: 1889: 1867: 1859: 1851: 1843: 1679: 1669: 1661: 1653: 1580: 1566: 1554: 1548: 1442: 1436: 1077: 1071: 502: 496: 448: 442: 390: 382: 336: 328: 320: 312: 101: 93: 13: 1: 7480:History of mathematical logic 5166: 4498:Inclusion-exclusion principle 4375:. The cardinality of each of 3640:generalized diagonal argument 3341:. Namely, Cantor showed that 2604:initial ordinal in that class 597: 7405:Primitive recursive function 5309:Third Millennium Mathematics 5274:"Early Human Counting Tools" 4740:{\displaystyle {\mbox{Ord}}} 3280:cardinality of the continuum 3274:Cardinality of the continuum 3268:Cardinality of the continuum 2849:cardinality of the continuum 2525:{\displaystyle \mathbb {R} } 2499:{\displaystyle \mathbb {N} } 2434:{\displaystyle \mathbb {N} } 2369:{\displaystyle \mathbb {N} } 2256:{\displaystyle \mathbb {N} } 1505:{\displaystyle \mathbb {N} } 1393:{\displaystyle \mathbb {N} } 1352:. For example, the function 1116:{\displaystyle \mathbb {N} } 589:. But with the discovery of 32:Cardinality (disambiguation) 7: 5298:Third Millennium Chronology 5296:Duncan J. Melville (2003). 5119: 3557:that have the same size as 3326:{\displaystyle \aleph _{0}} 3257:{\displaystyle \aleph _{0}} 3217:. In the late 19th century 3138:{\displaystyle \aleph _{0}} 3044:{\displaystyle \aleph _{0}} 2851:. Cantor showed, using the 2808:{\displaystyle \aleph _{0}} 2622:, the cardinalities of the 2066:{\displaystyle |B|\leq |A|} 2020:{\displaystyle |A|\leq |B|} 1920:{\displaystyle |B|\leq |A|} 1874:{\displaystyle |A|\leq |B|} 918:. Such sets are said to be 218:{\displaystyle B=\{2,4,6\}} 174:{\displaystyle A=\{1,2,3\}} 10: 8227: 8056:von Neumann–Bernays–Gödel 6469:Schröder–Bernstein theorem 6196:Monadic predicate calculus 5855:Foundations of mathematics 4495: 3902:can be demonstrated using 3652:the set of all subsets of 3456:Cantor's diagonal argument 3271: 3209:Our intuition gained from 2553: 2540:Cantor's diagonal argument 2345:{\displaystyle g(n)=\{n\}} 1975:Schröder–Bernstein theorem 617:Cantor's diagonal argument 541: 29: 8120: 8083: 7995: 7885: 7857:One-to-one correspondence 7773: 7714: 7598: 7587: 7573: 7515: 7502:Philosophy of mathematics 7451:Automated theorem proving 7433: 7328: 7160: 7053: 6905: 6622: 6598: 6576:Von Neumann–Bernays–Gödel 6521: 6415: 6319: 6217: 6208: 6135: 6070: 5976: 5898: 5815: 5508:GrundzĂŒge der Mengenlehre 5364:The Annals of Mathematics 5334:Texas A&M Mathematics 5327:"The History of Infinity" 3578:one-to-one correspondence 2591:The cardinality of a set 245:, and another which uses 3534:, if ZFC is consistent. 3470:states that there is no 635:Bijective function from 7152:Self-verifying theories 6973:Tarski's axiomatization 5924:Tarski's undefinability 5919:incompleteness theorems 5524:Original edition (1914) 5313:St. Lawrence University 4310:Examples and properties 2780:The cardinality of the 2710:{\displaystyle \alpha } 1966:{\displaystyle |A|=|B|} 1457:{\displaystyle g(n)=4n} 1092:{\displaystyle f(n)=2n} 374:, it is simply denoted 343:{\displaystyle |A|=|B|} 7815:Constructible universe 7635:Constructibility (V=L) 7526:Mathematics portal 7137:Proof of impossibility 6785:propositional variable 6095:Propositional calculus 5562:10.1073/pnas.50.6.1143 5411:Mathematics LibreTexts 5325:Allen, Donald (2003). 5253:Cepelewicz, Jordana 5116:and any proper class. 5110: 5087: 5044: 5020: 4959: 4930: 4857: 4741: 4717: 4681: 4578: 4492:Union and intersection 4481: 4300: 4181: 4030: 3896: 3848: 3798: 3741: 3692:Both have cardinality 3679:of all functions from 3632: 3518: 3446: 3392: 3327: 3300: 3258: 3186: 3139: 3045: 3018: 2984: 2930: 2886: 2837: 2809: 2771: 2744: 2711: 2685: 2526: 2500: 2474: 2435: 2409: 2370: 2346: 2303: 2257: 2228: 2204: 2180: 2156: 2113: 2089: 2067: 2021: 1967: 1921: 1875: 1824: 1800: 1776: 1752: 1709: 1687: 1637: 1613: 1587: 1530: 1506: 1480: 1458: 1418: 1394: 1368: 1344: 1320: 1296: 1272: 1244: 1220: 1204:bijection exists from 1192: 1168: 1141: 1117: 1093: 1051: 987: 902: 878: 850: 826: 782: 733:and the corresponding 677:): For every function 656: 651:is a proper subset of 532: 509: 476: 455: 426: 398: 368: 344: 296: 272: 219: 175: 122: 115: 79: 55: 8038:Principia Mathematica 7872:Transfinite induction 7731:(i.e. set difference) 7395:Kolmogorov complexity 7348:Computably enumerable 7248:Model complete theory 7040:Principia Mathematica 6100:Propositional formula 5929:Banach–Tarski paradox 5629:10.1073/pnas.51.1.105 5457:Mathematische Annalen 5377:Georg Cantor (1891). 5111: 5088: 5045: 5021: 4960: 4931: 4858: 4742: 4718: 4682: 4579: 4482: 4394:|, then there exists 4347:are distinct, then | 4301: 4182: 4031: 3897: 3849: 3799: 3742: 3633: 3519: 3447: 3393: 3337:than natural numbers 3328: 3301: 3259: 3187: 3140: 3046: 3019: 2985: 2931: 2887: 2838: 2810: 2772: 2745: 2712: 2686: 2527: 2501: 2475: 2436: 2410: 2371: 2347: 2304: 2258: 2239:For example, the set 2229: 2205: 2181: 2157: 2114: 2090: 2068: 2022: 1968: 1922: 1876: 1825: 1801: 1777: 1753: 1710: 1688: 1638: 1614: 1588: 1531: 1507: 1481: 1459: 1419: 1395: 1369: 1345: 1321: 1297: 1273: 1245: 1221: 1193: 1169: 1142: 1118: 1094: 1061:, since the function 1052: 988: 935:For example, the set 903: 879: 851: 827: 662: 634: 533: 510: 477: 456: 427: 399: 369: 354:of an individual set 345: 297: 273: 220: 176: 116: 114:{\displaystyle |S|=5} 80: 56: 40: 8112:Burali-Forti paradox 7867:Set-builder notation 7820:Continuum hypothesis 7760:Symmetric difference 7343:Church–Turing thesis 7330:Computability theory 6539:continuum hypothesis 6057:Square of opposition 5915:Gödel's completeness 5432:Friedrich M. Hartogs 5182:Set Theory and Logic 5161:Pigeonhole principle 5100: 5057: 5034: 4972: 4940: 4870: 4754: 4727: 4707: 4602: 4521: 4459: 4192: 4041: 3913: 3858: 3807: 3764: 3699: 3618: 3601:space-filling curves 3532:axiomatic set theory 3481: 3468:continuum hypothesis 3409: 3345: 3310: 3286: 3241: 3172: 3122: 3028: 2994: 2947: 2941:continuum hypothesis 2896: 2859: 2823: 2792: 2754: 2721: 2701: 2633: 2612:axiomatic set theory 2569:equivalence relation 2514: 2488: 2449: 2423: 2384: 2358: 2315: 2278: 2245: 2218: 2194: 2170: 2146: 2125:Definition 3: | 2103: 2079: 2031: 1985: 1931: 1885: 1839: 1814: 1790: 1766: 1742: 1721:Definition 2: | 1699: 1649: 1627: 1603: 1542: 1520: 1494: 1470: 1430: 1408: 1382: 1358: 1334: 1310: 1286: 1262: 1234: 1210: 1182: 1158: 1131: 1105: 1099:is a bijection from 1065: 1001: 939: 892: 868: 840: 816: 790:Definition 1: | 607:, the originator of 519: 487: 466: 454:{\displaystyle n(A)} 436: 416: 378: 358: 308: 286: 262: 185: 141: 89: 69: 45: 30:For other uses, see 8073:Tarski–Grothendieck 7497:Mathematical object 7388:P versus NP problem 7353:Computable function 7147:Reverse mathematics 7073:Logical consequence 6950:primitive recursive 6945:elementary function 6718:Free/bound variable 6571:Tarski–Grothendieck 6090:Logical connectives 6020:Logical equivalence 5870:Logical consequence 5736:(student edition), 5620:1964PNAS...51..105C 5553:1963PNAS...50.1143C 3904:cardinal arithmetic 3759:cardinal equalities 3576:, which provides a 3553:of an infinite set 3099:|, is said to be a 2892:. We can show that 531:{\displaystyle \#A} 397:{\displaystyle |A|} 7662:Limitation of size 7295:Transfer principle 7258:Semantics of logic 7243:Categorical theory 7219:Non-standard model 6733:Logical connective 5860:Information theory 5809:Mathematical logic 5719:Here: p.413 bottom 5470:10.1007/bf01458215 5303:2018-07-07 at the 5207:Weisstein, Eric W. 5106: 5083: 5081: 5040: 5016: 5014: 4955: 4926: 4853: 4845: 4800: 4778: 4737: 4735: 4713: 4677: 4574: 4477: 4453:irrational numbers 4296: 4177: 4026: 3892: 3844: 3794: 3737: 3628: 3514: 3442: 3388: 3323: 3296: 3254: 3182: 3147:countably infinite 3145:, is said to be a 3135: 3041: 3014: 2980: 2926: 2882: 2833: 2805: 2767: 2740: 2707: 2681: 2538:. For proofs, see 2522: 2496: 2470: 2431: 2405: 2366: 2342: 2299: 2253: 2224: 2200: 2176: 2152: 2131:| < | 2109: 2085: 2063: 2017: 1963: 1917: 1871: 1820: 1796: 1772: 1748: 1705: 1683: 1633: 1609: 1583: 1526: 1502: 1476: 1454: 1414: 1390: 1364: 1340: 1316: 1292: 1268: 1240: 1216: 1188: 1164: 1137: 1113: 1089: 1047: 983: 898: 874: 846: 822: 783: 657: 591:irrational numbers 528: 505: 472: 451: 422: 394: 364: 340: 292: 268: 215: 171: 123: 111: 75: 51: 18:Finite cardinality 8193: 8192: 8102:Russell's paradox 8051:Zermelo–Fraenkel 7952:Dedekind-infinite 7825:Diagonal argument 7724:Cartesian product 7581:Set (mathematics) 7533: 7532: 7465:Abstract category 7268:Theories of truth 7078:Rule of inference 7068:Natural deduction 7049: 7048: 6594: 6593: 6299:Cartesian product 6204: 6203: 6110:Many-valued logic 6085:Boolean functions 5968:Russell's paradox 5943:diagonal argument 5840:First-order logic 5744:(library edition) 5676:, Vintage Books, 5343:on August 1, 2020 5210:"Cardinal Number" 5191:978-0-486-63829-4 5180:Stoll, Robert R. 5109:{\displaystyle V} 5080: 5043:{\displaystyle P} 5013: 4844: 4799: 4777: 4734: 4716:{\displaystyle V} 4455:and the interval 3235:Dedekind infinite 3196:|, is said to be 3164:|, for example | 3077:law of trichotomy 2853:diagonal argument 2577:equivalence class 2575:of all sets. The 2567:, and this is an 2227:{\displaystyle B} 2203:{\displaystyle A} 2179:{\displaystyle B} 2155:{\displaystyle A} 2112:{\displaystyle B} 2088:{\displaystyle A} 1973:(a fact known as 1823:{\displaystyle B} 1799:{\displaystyle A} 1775:{\displaystyle B} 1751:{\displaystyle A} 1708:{\displaystyle f} 1636:{\displaystyle h} 1612:{\displaystyle g} 1575: 1529:{\displaystyle E} 1479:{\displaystyle h} 1417:{\displaystyle E} 1367:{\displaystyle g} 1343:{\displaystyle B} 1319:{\displaystyle A} 1295:{\displaystyle B} 1271:{\displaystyle A} 1243:{\displaystyle B} 1219:{\displaystyle A} 1191:{\displaystyle B} 1167:{\displaystyle A} 1140:{\displaystyle E} 1042: 978: 901:{\displaystyle B} 877:{\displaystyle A} 849:{\displaystyle B} 825:{\displaystyle A} 475:{\displaystyle A} 425:{\displaystyle A} 367:{\displaystyle A} 295:{\displaystyle B} 271:{\displaystyle A} 78:{\displaystyle S} 54:{\displaystyle S} 16:(Redirected from 8218: 8206:Cardinal numbers 8175:Bertrand Russell 8165:John von Neumann 8150:Abraham Fraenkel 8145:Richard Dedekind 8107:Suslin's problem 8018:Cantor's theorem 7735:De Morgan's laws 7593: 7560: 7553: 7546: 7537: 7536: 7524: 7523: 7475:History of logic 7470:Category of sets 7363:Decision problem 7142:Ordinal analysis 7083:Sequent calculus 6981:Boolean algebras 6921: 6920: 6895: 6866:logical/constant 6620: 6619: 6606: 6529:Zermelo–Fraenkel 6280:Set operations: 6215: 6214: 6152: 5983: 5982: 5963:Löwenheim–Skolem 5850:Formal semantics 5802: 5795: 5788: 5779: 5778: 5772: 5757: 5745: 5726: 5720: 5718: 5707: 5693: 5687: 5686: 5666: 5660: 5659: 5649: 5631: 5599: 5593: 5592: 5582: 5564: 5547:(6): 1143–1148. 5532: 5526: 5521: 5503:Egbert Brieskorn 5495: 5489: 5488: 5440:Walther von Dyck 5428: 5422: 5421: 5419: 5418: 5403: 5394: 5393: 5383: 5374: 5368: 5367: 5359: 5353: 5352: 5350: 5348: 5342: 5336:. Archived from 5331: 5322: 5316: 5294: 5288: 5287: 5285: 5284: 5270: 5264: 5263:, August 9, 2021 5251: 5245: 5244: 5242: 5241: 5227: 5221: 5220: 5219: 5202: 5196: 5195: 5177: 5141:Cantor's theorem 5136:Cantor's paradox 5115: 5113: 5112: 5107: 5092: 5090: 5089: 5084: 5082: 5078: 5072: 5064: 5050:, in particular 5049: 5047: 5046: 5041: 5025: 5023: 5022: 5017: 5015: 5011: 4996: 4988: 4965:. In this case 4964: 4962: 4961: 4956: 4935: 4933: 4932: 4927: 4862: 4860: 4859: 4854: 4846: 4842: 4806: 4801: 4797: 4779: 4775: 4769: 4761: 4746: 4744: 4743: 4738: 4736: 4732: 4722: 4720: 4719: 4714: 4686: 4684: 4683: 4678: 4673: 4659: 4645: 4641: 4623: 4619: 4583: 4581: 4580: 4575: 4570: 4556: 4542: 4538: 4486: 4484: 4483: 4480:{\displaystyle } 4478: 4305: 4303: 4302: 4297: 4292: 4291: 4290: 4277: 4276: 4275: 4274: 4262: 4261: 4247: 4246: 4245: 4239: 4235: 4234: 4233: 4232: 4210: 4209: 4208: 4202: 4201: 4186: 4184: 4183: 4178: 4173: 4172: 4163: 4162: 4161: 4160: 4143: 4142: 4141: 4140: 4139: 4126: 4125: 4124: 4106: 4105: 4104: 4103: 4093: 4089: 4088: 4087: 4086: 4064: 4063: 4062: 4061: 4051: 4050: 4035: 4033: 4032: 4027: 4022: 4021: 4012: 4011: 4010: 4009: 3992: 3991: 3990: 3989: 3988: 3964: 3963: 3958: 3954: 3953: 3952: 3951: 3929: 3928: 3923: 3922: 3901: 3899: 3898: 3893: 3891: 3890: 3889: 3876: 3875: 3874: 3868: 3867: 3853: 3851: 3850: 3845: 3840: 3839: 3830: 3829: 3828: 3827: 3817: 3816: 3803: 3801: 3800: 3795: 3790: 3789: 3780: 3779: 3774: 3773: 3746: 3744: 3743: 3738: 3736: 3735: 3726: 3725: 3713: 3712: 3711: 3637: 3635: 3634: 3629: 3627: 3626: 3574:tangent function 3551:proper supersets 3539:real number line 3523: 3521: 3520: 3515: 3513: 3512: 3500: 3499: 3498: 3497: 3451: 3449: 3448: 3443: 3441: 3440: 3428: 3427: 3426: 3425: 3397: 3395: 3394: 3389: 3387: 3386: 3374: 3373: 3372: 3371: 3354: 3353: 3332: 3330: 3329: 3324: 3322: 3321: 3305: 3303: 3302: 3297: 3295: 3294: 3263: 3261: 3260: 3255: 3253: 3252: 3227:Richard Dedekind 3191: 3189: 3188: 3183: 3181: 3180: 3144: 3142: 3141: 3136: 3134: 3133: 3050: 3048: 3047: 3042: 3040: 3039: 3023: 3021: 3020: 3015: 3013: 3012: 3011: 3010: 2989: 2987: 2986: 2981: 2979: 2978: 2977: 2976: 2959: 2958: 2935: 2933: 2932: 2927: 2925: 2924: 2923: 2922: 2905: 2904: 2891: 2889: 2888: 2883: 2881: 2880: 2868: 2867: 2842: 2840: 2839: 2834: 2832: 2831: 2814: 2812: 2811: 2806: 2804: 2803: 2776: 2774: 2773: 2768: 2766: 2765: 2749: 2747: 2746: 2741: 2739: 2738: 2716: 2714: 2713: 2708: 2690: 2688: 2687: 2682: 2671: 2670: 2658: 2657: 2645: 2644: 2550:Cardinal numbers 2533: 2531: 2529: 2528: 2523: 2521: 2507: 2505: 2503: 2502: 2497: 2495: 2481: 2479: 2477: 2476: 2471: 2466: 2458: 2457: 2442: 2440: 2438: 2437: 2432: 2430: 2416: 2414: 2412: 2411: 2406: 2401: 2393: 2392: 2377: 2375: 2373: 2372: 2367: 2365: 2351: 2349: 2348: 2343: 2310: 2308: 2306: 2305: 2300: 2295: 2287: 2286: 2264: 2262: 2260: 2259: 2254: 2252: 2235: 2233: 2231: 2230: 2225: 2211: 2209: 2207: 2206: 2201: 2187: 2185: 2183: 2182: 2177: 2163: 2161: 2159: 2158: 2153: 2136: 2130: 2120: 2118: 2116: 2115: 2110: 2096: 2094: 2092: 2091: 2086: 2072: 2070: 2069: 2064: 2062: 2054: 2046: 2038: 2026: 2024: 2023: 2018: 2016: 2008: 2000: 1992: 1972: 1970: 1969: 1964: 1962: 1954: 1946: 1938: 1926: 1924: 1923: 1918: 1916: 1908: 1900: 1892: 1880: 1878: 1877: 1872: 1870: 1862: 1854: 1846: 1831: 1829: 1827: 1826: 1821: 1807: 1805: 1803: 1802: 1797: 1783: 1781: 1779: 1778: 1773: 1759: 1757: 1755: 1754: 1749: 1732: 1726: 1716: 1714: 1712: 1711: 1706: 1692: 1690: 1689: 1684: 1682: 1677: 1672: 1664: 1656: 1644: 1642: 1640: 1639: 1634: 1620: 1618: 1616: 1615: 1610: 1595:modulo operation 1592: 1590: 1589: 1584: 1576: 1573: 1537: 1535: 1533: 1532: 1527: 1513: 1511: 1509: 1508: 1503: 1501: 1487: 1485: 1483: 1482: 1477: 1463: 1461: 1460: 1455: 1425: 1423: 1421: 1420: 1415: 1401: 1399: 1397: 1396: 1391: 1389: 1375: 1373: 1371: 1370: 1365: 1351: 1349: 1347: 1346: 1341: 1327: 1325: 1323: 1322: 1317: 1303: 1301: 1299: 1298: 1293: 1279: 1277: 1275: 1274: 1269: 1251: 1249: 1247: 1246: 1241: 1227: 1225: 1223: 1222: 1217: 1199: 1197: 1195: 1194: 1189: 1175: 1173: 1171: 1170: 1165: 1152:For finite sets 1148: 1146: 1144: 1143: 1138: 1124: 1122: 1120: 1119: 1114: 1112: 1098: 1096: 1095: 1090: 1056: 1054: 1053: 1048: 1043: 1040: 1008: 993:of non-negative 992: 990: 989: 984: 979: 976: 909: 907: 905: 904: 899: 885: 883: 881: 880: 875: 857: 855: 853: 852: 847: 833: 831: 829: 828: 823: 801: 795: 764: 742: 621:uncountable sets 602: 599: 571:commensurability 553: 552: 537: 535: 534: 529: 514: 512: 511: 506: 482: 481: 479: 478: 473: 460: 458: 457: 452: 431: 429: 428: 423: 403: 401: 400: 395: 393: 385: 373: 371: 370: 365: 349: 347: 346: 341: 339: 331: 323: 315: 303: 301: 299: 298: 293: 279: 277: 275: 274: 269: 247:cardinal numbers 224: 222: 221: 216: 180: 178: 177: 172: 120: 118: 117: 112: 104: 96: 84: 82: 81: 76: 60: 58: 57: 52: 21: 8226: 8225: 8221: 8220: 8219: 8217: 8216: 8215: 8196: 8195: 8194: 8189: 8116: 8095: 8079: 8044:New Foundations 7991: 7881: 7800:Cardinal number 7783: 7769: 7710: 7594: 7585: 7569: 7564: 7534: 7529: 7518: 7511: 7456:Category theory 7446:Algebraic logic 7429: 7400:Lambda calculus 7338:Church encoding 7324: 7300:Truth predicate 7156: 7122:Complete theory 7045: 6914: 6910: 6906: 6901: 6893: 6613: and  6609: 6604: 6590: 6566:New Foundations 6534:axiom of choice 6517: 6479:Gödel numbering 6419: and  6411: 6315: 6200: 6150: 6131: 6080:Boolean algebra 6066: 6030:Equiconsistency 5995:Classical logic 5972: 5953:Halting problem 5941: and  5917: and  5905: and  5904: 5899:Theorems ( 5894: 5811: 5806: 5776: 5775: 5758: 5754: 5749: 5748: 5727: 5723: 5708: 5694: 5690: 5684: 5667: 5663: 5600: 5596: 5533: 5529: 5519: 5499:Felix Hausdorff 5496: 5492: 5448:Otto Blumenthal 5429: 5425: 5416: 5414: 5405: 5404: 5397: 5381: 5375: 5371: 5360: 5356: 5346: 5344: 5340: 5329: 5323: 5319: 5305:Wayback Machine 5295: 5291: 5282: 5280: 5272: 5271: 5267: 5252: 5248: 5239: 5237: 5229: 5228: 5224: 5203: 5199: 5192: 5178: 5174: 5169: 5122: 5101: 5098: 5097: 5076: 5068: 5060: 5058: 5055: 5054: 5035: 5032: 5031: 5009: 4992: 4984: 4973: 4970: 4969: 4941: 4938: 4937: 4871: 4868: 4867: 4843: injective 4840: 4802: 4795: 4773: 4765: 4757: 4755: 4752: 4751: 4730: 4728: 4725: 4724: 4708: 4705: 4704: 4701: 4663: 4649: 4631: 4627: 4609: 4605: 4603: 4600: 4599: 4560: 4546: 4528: 4524: 4522: 4519: 4518: 4500: 4494: 4460: 4457: 4456: 4312: 4286: 4285: 4281: 4270: 4266: 4257: 4256: 4255: 4251: 4241: 4240: 4228: 4224: 4223: 4219: 4215: 4214: 4204: 4203: 4197: 4196: 4195: 4193: 4190: 4189: 4168: 4167: 4156: 4152: 4151: 4147: 4135: 4131: 4130: 4120: 4116: 4115: 4114: 4110: 4099: 4095: 4094: 4082: 4078: 4077: 4073: 4069: 4068: 4057: 4053: 4052: 4046: 4045: 4044: 4042: 4039: 4038: 4017: 4016: 4005: 4001: 4000: 3996: 3984: 3980: 3979: 3972: 3968: 3959: 3947: 3943: 3942: 3938: 3934: 3933: 3924: 3918: 3917: 3916: 3914: 3911: 3910: 3885: 3884: 3880: 3870: 3869: 3863: 3862: 3861: 3859: 3856: 3855: 3835: 3834: 3823: 3819: 3818: 3812: 3811: 3810: 3808: 3805: 3804: 3785: 3784: 3775: 3769: 3768: 3767: 3765: 3762: 3761: 3731: 3730: 3721: 3717: 3707: 3706: 3702: 3700: 3697: 3696: 3638:exist (see his 3622: 3621: 3619: 3616: 3615: 3599:introduced the 3508: 3504: 3493: 3489: 3488: 3484: 3482: 3479: 3478: 3472:cardinal number 3436: 3432: 3421: 3417: 3416: 3412: 3410: 3407: 3406: 3382: 3378: 3367: 3363: 3362: 3358: 3349: 3348: 3346: 3343: 3342: 3317: 3313: 3311: 3308: 3307: 3290: 3289: 3287: 3284: 3283: 3276: 3270: 3248: 3244: 3242: 3239: 3238: 3207: 3176: 3175: 3173: 3170: 3169: 3129: 3125: 3123: 3120: 3119: 3089:natural numbers 3073:axiom of choice 3069: 3035: 3031: 3029: 3026: 3025: 3006: 3002: 3001: 2997: 2995: 2992: 2991: 2972: 2968: 2967: 2963: 2954: 2950: 2948: 2945: 2944: 2918: 2914: 2913: 2909: 2900: 2899: 2897: 2894: 2893: 2876: 2872: 2863: 2862: 2860: 2857: 2856: 2843:" (a lowercase 2827: 2826: 2824: 2821: 2820: 2819:is denoted by " 2799: 2795: 2793: 2790: 2789: 2782:natural numbers 2761: 2757: 2755: 2752: 2751: 2728: 2724: 2722: 2719: 2718: 2702: 2699: 2698: 2666: 2662: 2653: 2649: 2640: 2636: 2634: 2631: 2630: 2620:axiom of choice 2608:cardinal number 2558: 2556:Cardinal number 2552: 2517: 2515: 2512: 2511: 2509: 2491: 2489: 2486: 2485: 2483: 2462: 2453: 2452: 2450: 2447: 2446: 2444: 2426: 2424: 2421: 2420: 2418: 2397: 2388: 2387: 2385: 2382: 2381: 2379: 2361: 2359: 2356: 2355: 2353: 2316: 2313: 2312: 2291: 2282: 2281: 2279: 2276: 2275: 2273: 2267:natural numbers 2248: 2246: 2243: 2242: 2240: 2219: 2216: 2215: 2213: 2195: 2192: 2191: 2189: 2171: 2168: 2167: 2165: 2147: 2144: 2143: 2141: 2139: 2132: 2126: 2104: 2101: 2100: 2098: 2080: 2077: 2076: 2074: 2058: 2050: 2042: 2034: 2032: 2029: 2028: 2012: 2004: 1996: 1988: 1986: 1983: 1982: 1979:axiom of choice 1958: 1950: 1942: 1934: 1932: 1929: 1928: 1912: 1904: 1896: 1888: 1886: 1883: 1882: 1866: 1858: 1850: 1842: 1840: 1837: 1836: 1815: 1812: 1811: 1809: 1791: 1788: 1787: 1785: 1767: 1764: 1763: 1761: 1743: 1740: 1739: 1737: 1735: 1728: 1727:| ≀ | 1722: 1700: 1697: 1696: 1694: 1678: 1673: 1668: 1660: 1652: 1650: 1647: 1646: 1628: 1625: 1624: 1622: 1604: 1601: 1600: 1598: 1574: mod  1572: 1543: 1540: 1539: 1521: 1518: 1517: 1515: 1497: 1495: 1492: 1491: 1489: 1471: 1468: 1467: 1465: 1431: 1428: 1427: 1409: 1406: 1405: 1403: 1385: 1383: 1380: 1379: 1377: 1359: 1356: 1355: 1353: 1335: 1332: 1331: 1329: 1311: 1308: 1307: 1305: 1287: 1284: 1283: 1281: 1263: 1260: 1259: 1257: 1235: 1232: 1231: 1229: 1211: 1208: 1207: 1205: 1183: 1180: 1179: 1177: 1159: 1156: 1155: 1153: 1149:(see picture). 1132: 1129: 1128: 1126: 1108: 1106: 1103: 1102: 1100: 1066: 1063: 1062: 1059:natural numbers 1039: 1004: 1002: 999: 998: 975: 940: 937: 936: 893: 890: 889: 887: 869: 866: 865: 863: 841: 838: 837: 835: 817: 814: 813: 811: 804: 797: 796:| = | 791: 760: 738: 629: 600: 550: 548: 544: 520: 517: 516: 488: 485: 484: 467: 464: 463: 462: 437: 434: 433: 417: 414: 413: 389: 381: 379: 376: 375: 359: 356: 355: 352:cardinal number 335: 327: 319: 311: 309: 306: 305: 287: 284: 283: 281: 263: 260: 259: 257: 256:When two sets, 186: 183: 182: 142: 139: 138: 100: 92: 90: 87: 86: 70: 67: 66: 63:Platonic solids 46: 43: 42: 35: 28: 23: 22: 15: 12: 11: 5: 8224: 8214: 8213: 8208: 8191: 8190: 8188: 8187: 8182: 8180:Thoralf Skolem 8177: 8172: 8167: 8162: 8157: 8152: 8147: 8142: 8137: 8132: 8126: 8124: 8118: 8117: 8115: 8114: 8109: 8104: 8098: 8096: 8094: 8093: 8090: 8084: 8081: 8080: 8078: 8077: 8076: 8075: 8070: 8065: 8064: 8063: 8048: 8047: 8046: 8034: 8033: 8032: 8021: 8020: 8015: 8010: 8005: 7999: 7997: 7993: 7992: 7990: 7989: 7984: 7979: 7974: 7965: 7960: 7955: 7945: 7940: 7939: 7938: 7933: 7928: 7918: 7908: 7903: 7898: 7892: 7890: 7883: 7882: 7880: 7879: 7874: 7869: 7864: 7862:Ordinal number 7859: 7854: 7849: 7844: 7843: 7842: 7837: 7827: 7822: 7817: 7812: 7807: 7797: 7792: 7786: 7784: 7782: 7781: 7778: 7774: 7771: 7770: 7768: 7767: 7762: 7757: 7752: 7747: 7742: 7740:Disjoint union 7737: 7732: 7726: 7720: 7718: 7712: 7711: 7709: 7708: 7707: 7706: 7701: 7690: 7689: 7687:Martin's axiom 7684: 7679: 7674: 7669: 7664: 7659: 7654: 7652:Extensionality 7649: 7648: 7647: 7637: 7632: 7631: 7630: 7625: 7620: 7610: 7604: 7602: 7596: 7595: 7588: 7586: 7584: 7583: 7577: 7575: 7571: 7570: 7563: 7562: 7555: 7548: 7540: 7531: 7530: 7516: 7513: 7512: 7510: 7509: 7504: 7499: 7494: 7489: 7488: 7487: 7477: 7472: 7467: 7458: 7453: 7448: 7443: 7441:Abstract logic 7437: 7435: 7431: 7430: 7428: 7427: 7422: 7420:Turing machine 7417: 7412: 7407: 7402: 7397: 7392: 7391: 7390: 7385: 7380: 7375: 7370: 7360: 7358:Computable set 7355: 7350: 7345: 7340: 7334: 7332: 7326: 7325: 7323: 7322: 7317: 7312: 7307: 7302: 7297: 7292: 7287: 7286: 7285: 7280: 7275: 7265: 7260: 7255: 7253:Satisfiability 7250: 7245: 7240: 7239: 7238: 7228: 7227: 7226: 7216: 7215: 7214: 7209: 7204: 7199: 7194: 7184: 7183: 7182: 7177: 7170:Interpretation 7166: 7164: 7158: 7157: 7155: 7154: 7149: 7144: 7139: 7134: 7124: 7119: 7118: 7117: 7116: 7115: 7105: 7100: 7090: 7085: 7080: 7075: 7070: 7065: 7059: 7057: 7051: 7050: 7047: 7046: 7044: 7043: 7035: 7034: 7033: 7032: 7027: 7026: 7025: 7020: 7015: 6995: 6994: 6993: 6991:minimal axioms 6988: 6977: 6976: 6975: 6964: 6963: 6962: 6957: 6952: 6947: 6942: 6937: 6924: 6922: 6903: 6902: 6900: 6899: 6898: 6897: 6885: 6880: 6879: 6878: 6873: 6868: 6863: 6853: 6848: 6843: 6838: 6837: 6836: 6831: 6821: 6820: 6819: 6814: 6809: 6804: 6794: 6789: 6788: 6787: 6782: 6777: 6767: 6766: 6765: 6760: 6755: 6750: 6745: 6740: 6730: 6725: 6720: 6715: 6714: 6713: 6708: 6703: 6698: 6688: 6683: 6681:Formation rule 6678: 6673: 6672: 6671: 6666: 6656: 6655: 6654: 6644: 6639: 6634: 6629: 6623: 6617: 6600:Formal systems 6596: 6595: 6592: 6591: 6589: 6588: 6583: 6578: 6573: 6568: 6563: 6558: 6553: 6548: 6543: 6542: 6541: 6536: 6525: 6523: 6519: 6518: 6516: 6515: 6514: 6513: 6503: 6498: 6497: 6496: 6489:Large cardinal 6486: 6481: 6476: 6471: 6466: 6452: 6451: 6450: 6445: 6440: 6425: 6423: 6413: 6412: 6410: 6409: 6408: 6407: 6402: 6397: 6387: 6382: 6377: 6372: 6367: 6362: 6357: 6352: 6347: 6342: 6337: 6332: 6326: 6324: 6317: 6316: 6314: 6313: 6312: 6311: 6306: 6301: 6296: 6291: 6286: 6278: 6277: 6276: 6271: 6261: 6256: 6254:Extensionality 6251: 6249:Ordinal number 6246: 6236: 6231: 6230: 6229: 6218: 6212: 6206: 6205: 6202: 6201: 6199: 6198: 6193: 6188: 6183: 6178: 6173: 6168: 6167: 6166: 6156: 6155: 6154: 6141: 6139: 6133: 6132: 6130: 6129: 6128: 6127: 6122: 6117: 6107: 6102: 6097: 6092: 6087: 6082: 6076: 6074: 6068: 6067: 6065: 6064: 6059: 6054: 6049: 6044: 6039: 6034: 6033: 6032: 6022: 6017: 6012: 6007: 6002: 5997: 5991: 5989: 5980: 5974: 5973: 5971: 5970: 5965: 5960: 5955: 5950: 5945: 5933:Cantor's  5931: 5926: 5921: 5911: 5909: 5896: 5895: 5893: 5892: 5887: 5882: 5877: 5872: 5867: 5862: 5857: 5852: 5847: 5842: 5837: 5832: 5831: 5830: 5819: 5817: 5813: 5812: 5805: 5804: 5797: 5790: 5782: 5774: 5773: 5751: 5750: 5747: 5746: 5721: 5709:Reprinted in: 5688: 5682: 5661: 5614:(1): 105–110. 5594: 5527: 5517: 5490: 5423: 5395: 5369: 5354: 5317: 5289: 5265: 5246: 5222: 5197: 5190: 5171: 5170: 5168: 5165: 5164: 5163: 5158: 5153: 5148: 5143: 5138: 5133: 5128: 5121: 5118: 5105: 5094: 5093: 5075: 5071: 5067: 5063: 5039: 5028: 5027: 5008: 5005: 5002: 4999: 4995: 4991: 4987: 4983: 4980: 4977: 4954: 4951: 4948: 4945: 4925: 4922: 4919: 4916: 4913: 4910: 4907: 4904: 4901: 4898: 4894: 4890: 4887: 4884: 4881: 4878: 4875: 4864: 4863: 4852: 4849: 4839: 4836: 4833: 4830: 4827: 4824: 4821: 4818: 4815: 4812: 4809: 4805: 4794: 4791: 4788: 4785: 4782: 4772: 4768: 4764: 4760: 4712: 4700: 4689: 4688: 4687: 4676: 4672: 4669: 4666: 4662: 4658: 4655: 4652: 4648: 4644: 4640: 4637: 4634: 4630: 4626: 4622: 4618: 4615: 4612: 4608: 4585: 4584: 4573: 4569: 4566: 4563: 4559: 4555: 4552: 4549: 4545: 4541: 4537: 4534: 4531: 4527: 4496:Main article: 4493: 4490: 4489: 4488: 4476: 4473: 4470: 4467: 4464: 4446: 4415: 4384: 4311: 4308: 4307: 4306: 4295: 4289: 4284: 4280: 4273: 4269: 4265: 4260: 4254: 4250: 4244: 4238: 4231: 4227: 4222: 4218: 4213: 4207: 4200: 4187: 4176: 4171: 4166: 4159: 4155: 4150: 4146: 4138: 4134: 4129: 4123: 4119: 4113: 4109: 4102: 4098: 4092: 4085: 4081: 4076: 4072: 4067: 4060: 4056: 4049: 4036: 4025: 4020: 4015: 4008: 4004: 3999: 3995: 3987: 3983: 3978: 3975: 3971: 3967: 3962: 3957: 3950: 3946: 3941: 3937: 3932: 3927: 3921: 3888: 3883: 3879: 3873: 3866: 3843: 3838: 3833: 3826: 3822: 3815: 3793: 3788: 3783: 3778: 3772: 3755: 3754: 3747: 3734: 3729: 3724: 3720: 3716: 3710: 3705: 3690: 3689: 3688: 3687: 3673: 3625: 3597:Giuseppe Peano 3584:(−œπ, Ϲ) and 3547:proper subsets 3525: 3524: 3511: 3507: 3503: 3496: 3492: 3487: 3464: 3463: 3452: 3439: 3435: 3431: 3424: 3420: 3415: 3385: 3381: 3377: 3370: 3366: 3361: 3357: 3352: 3320: 3316: 3293: 3272:Main article: 3269: 3266: 3251: 3247: 3206: 3203: 3202: 3201: 3179: 3150: 3132: 3128: 3104: 3068: 3065: 3038: 3034: 3009: 3005: 3000: 2975: 2971: 2966: 2962: 2957: 2953: 2921: 2917: 2912: 2908: 2903: 2879: 2875: 2871: 2866: 2845:fraktur script 2830: 2802: 2798: 2764: 2760: 2737: 2734: 2731: 2727: 2706: 2692: 2691: 2680: 2677: 2674: 2669: 2665: 2661: 2656: 2652: 2648: 2643: 2639: 2616: 2615: 2600:representative 2596: 2565:equinumerosity 2554:Main article: 2551: 2548: 2520: 2494: 2469: 2465: 2461: 2456: 2429: 2404: 2400: 2396: 2391: 2364: 2341: 2338: 2335: 2332: 2329: 2326: 2323: 2320: 2298: 2294: 2290: 2285: 2251: 2223: 2199: 2175: 2151: 2138: 2123: 2108: 2084: 2061: 2057: 2053: 2049: 2045: 2041: 2037: 2015: 2011: 2007: 2003: 1999: 1995: 1991: 1961: 1957: 1953: 1949: 1945: 1941: 1937: 1915: 1911: 1907: 1903: 1899: 1895: 1891: 1869: 1865: 1861: 1857: 1853: 1849: 1845: 1819: 1795: 1771: 1747: 1734: 1719: 1704: 1681: 1676: 1671: 1667: 1663: 1659: 1655: 1645:can challenge 1632: 1608: 1582: 1579: 1571: 1568: 1565: 1562: 1559: 1556: 1553: 1550: 1547: 1525: 1500: 1475: 1453: 1450: 1447: 1444: 1441: 1438: 1435: 1413: 1388: 1363: 1339: 1315: 1291: 1267: 1239: 1215: 1187: 1163: 1136: 1111: 1088: 1085: 1082: 1079: 1076: 1073: 1070: 1046: 1038: 1035: 1032: 1029: 1026: 1023: 1020: 1017: 1014: 1011: 1007: 982: 974: 971: 968: 965: 962: 959: 956: 953: 950: 947: 944: 897: 873: 845: 821: 803: 788: 628: 627:Comparing sets 625: 543: 540: 527: 524: 504: 501: 498: 495: 492: 471: 450: 447: 444: 441: 421: 410:absolute value 392: 388: 384: 363: 338: 334: 330: 326: 322: 318: 314: 291: 267: 214: 211: 208: 205: 202: 199: 196: 193: 190: 170: 167: 164: 161: 158: 155: 152: 149: 146: 110: 107: 103: 99: 95: 74: 50: 26: 9: 6: 4: 3: 2: 8223: 8212: 8209: 8207: 8204: 8203: 8201: 8186: 8185:Ernst Zermelo 8183: 8181: 8178: 8176: 8173: 8171: 8170:Willard Quine 8168: 8166: 8163: 8161: 8158: 8156: 8153: 8151: 8148: 8146: 8143: 8141: 8138: 8136: 8133: 8131: 8128: 8127: 8125: 8123: 8122:Set theorists 8119: 8113: 8110: 8108: 8105: 8103: 8100: 8099: 8097: 8091: 8089: 8086: 8085: 8082: 8074: 8071: 8069: 8068:Kripke–Platek 8066: 8062: 8059: 8058: 8057: 8054: 8053: 8052: 8049: 8045: 8042: 8041: 8040: 8039: 8035: 8031: 8028: 8027: 8026: 8023: 8022: 8019: 8016: 8014: 8011: 8009: 8006: 8004: 8001: 8000: 7998: 7994: 7988: 7985: 7983: 7980: 7978: 7975: 7973: 7971: 7966: 7964: 7961: 7959: 7956: 7953: 7949: 7946: 7944: 7941: 7937: 7934: 7932: 7929: 7927: 7924: 7923: 7922: 7919: 7916: 7912: 7909: 7907: 7904: 7902: 7899: 7897: 7894: 7893: 7891: 7888: 7884: 7878: 7875: 7873: 7870: 7868: 7865: 7863: 7860: 7858: 7855: 7853: 7850: 7848: 7845: 7841: 7838: 7836: 7833: 7832: 7831: 7828: 7826: 7823: 7821: 7818: 7816: 7813: 7811: 7808: 7805: 7801: 7798: 7796: 7793: 7791: 7788: 7787: 7785: 7779: 7776: 7775: 7772: 7766: 7763: 7761: 7758: 7756: 7753: 7751: 7748: 7746: 7743: 7741: 7738: 7736: 7733: 7730: 7727: 7725: 7722: 7721: 7719: 7717: 7713: 7705: 7704:specification 7702: 7700: 7697: 7696: 7695: 7692: 7691: 7688: 7685: 7683: 7680: 7678: 7675: 7673: 7670: 7668: 7665: 7663: 7660: 7658: 7655: 7653: 7650: 7646: 7643: 7642: 7641: 7638: 7636: 7633: 7629: 7626: 7624: 7621: 7619: 7616: 7615: 7614: 7611: 7609: 7606: 7605: 7603: 7601: 7597: 7592: 7582: 7579: 7578: 7576: 7572: 7568: 7561: 7556: 7554: 7549: 7547: 7542: 7541: 7538: 7528: 7527: 7522: 7514: 7508: 7505: 7503: 7500: 7498: 7495: 7493: 7490: 7486: 7483: 7482: 7481: 7478: 7476: 7473: 7471: 7468: 7466: 7462: 7459: 7457: 7454: 7452: 7449: 7447: 7444: 7442: 7439: 7438: 7436: 7432: 7426: 7423: 7421: 7418: 7416: 7415:Recursive set 7413: 7411: 7408: 7406: 7403: 7401: 7398: 7396: 7393: 7389: 7386: 7384: 7381: 7379: 7376: 7374: 7371: 7369: 7366: 7365: 7364: 7361: 7359: 7356: 7354: 7351: 7349: 7346: 7344: 7341: 7339: 7336: 7335: 7333: 7331: 7327: 7321: 7318: 7316: 7313: 7311: 7308: 7306: 7303: 7301: 7298: 7296: 7293: 7291: 7288: 7284: 7281: 7279: 7276: 7274: 7271: 7270: 7269: 7266: 7264: 7261: 7259: 7256: 7254: 7251: 7249: 7246: 7244: 7241: 7237: 7234: 7233: 7232: 7229: 7225: 7224:of arithmetic 7222: 7221: 7220: 7217: 7213: 7210: 7208: 7205: 7203: 7200: 7198: 7195: 7193: 7190: 7189: 7188: 7185: 7181: 7178: 7176: 7173: 7172: 7171: 7168: 7167: 7165: 7163: 7159: 7153: 7150: 7148: 7145: 7143: 7140: 7138: 7135: 7132: 7131:from ZFC 7128: 7125: 7123: 7120: 7114: 7111: 7110: 7109: 7106: 7104: 7101: 7099: 7096: 7095: 7094: 7091: 7089: 7086: 7084: 7081: 7079: 7076: 7074: 7071: 7069: 7066: 7064: 7061: 7060: 7058: 7056: 7052: 7042: 7041: 7037: 7036: 7031: 7030:non-Euclidean 7028: 7024: 7021: 7019: 7016: 7014: 7013: 7009: 7008: 7006: 7003: 7002: 7000: 6996: 6992: 6989: 6987: 6984: 6983: 6982: 6978: 6974: 6971: 6970: 6969: 6965: 6961: 6958: 6956: 6953: 6951: 6948: 6946: 6943: 6941: 6938: 6936: 6933: 6932: 6930: 6926: 6925: 6923: 6918: 6912: 6907:Example  6904: 6896: 6891: 6890: 6889: 6886: 6884: 6881: 6877: 6874: 6872: 6869: 6867: 6864: 6862: 6859: 6858: 6857: 6854: 6852: 6849: 6847: 6844: 6842: 6839: 6835: 6832: 6830: 6827: 6826: 6825: 6822: 6818: 6815: 6813: 6810: 6808: 6805: 6803: 6800: 6799: 6798: 6795: 6793: 6790: 6786: 6783: 6781: 6778: 6776: 6773: 6772: 6771: 6768: 6764: 6761: 6759: 6756: 6754: 6751: 6749: 6746: 6744: 6741: 6739: 6736: 6735: 6734: 6731: 6729: 6726: 6724: 6721: 6719: 6716: 6712: 6709: 6707: 6704: 6702: 6699: 6697: 6694: 6693: 6692: 6689: 6687: 6684: 6682: 6679: 6677: 6674: 6670: 6667: 6665: 6664:by definition 6662: 6661: 6660: 6657: 6653: 6650: 6649: 6648: 6645: 6643: 6640: 6638: 6635: 6633: 6630: 6628: 6625: 6624: 6621: 6618: 6616: 6612: 6607: 6601: 6597: 6587: 6584: 6582: 6579: 6577: 6574: 6572: 6569: 6567: 6564: 6562: 6559: 6557: 6554: 6552: 6551:Kripke–Platek 6549: 6547: 6544: 6540: 6537: 6535: 6532: 6531: 6530: 6527: 6526: 6524: 6520: 6512: 6509: 6508: 6507: 6504: 6502: 6499: 6495: 6492: 6491: 6490: 6487: 6485: 6482: 6480: 6477: 6475: 6472: 6470: 6467: 6464: 6460: 6456: 6453: 6449: 6446: 6444: 6441: 6439: 6436: 6435: 6434: 6430: 6427: 6426: 6424: 6422: 6418: 6414: 6406: 6403: 6401: 6398: 6396: 6395:constructible 6393: 6392: 6391: 6388: 6386: 6383: 6381: 6378: 6376: 6373: 6371: 6368: 6366: 6363: 6361: 6358: 6356: 6353: 6351: 6348: 6346: 6343: 6341: 6338: 6336: 6333: 6331: 6328: 6327: 6325: 6323: 6318: 6310: 6307: 6305: 6302: 6300: 6297: 6295: 6292: 6290: 6287: 6285: 6282: 6281: 6279: 6275: 6272: 6270: 6267: 6266: 6265: 6262: 6260: 6257: 6255: 6252: 6250: 6247: 6245: 6241: 6237: 6235: 6232: 6228: 6225: 6224: 6223: 6220: 6219: 6216: 6213: 6211: 6207: 6197: 6194: 6192: 6189: 6187: 6184: 6182: 6179: 6177: 6174: 6172: 6169: 6165: 6162: 6161: 6160: 6157: 6153: 6148: 6147: 6146: 6143: 6142: 6140: 6138: 6134: 6126: 6123: 6121: 6118: 6116: 6113: 6112: 6111: 6108: 6106: 6103: 6101: 6098: 6096: 6093: 6091: 6088: 6086: 6083: 6081: 6078: 6077: 6075: 6073: 6072:Propositional 6069: 6063: 6060: 6058: 6055: 6053: 6050: 6048: 6045: 6043: 6040: 6038: 6035: 6031: 6028: 6027: 6026: 6023: 6021: 6018: 6016: 6013: 6011: 6008: 6006: 6003: 6001: 6000:Logical truth 5998: 5996: 5993: 5992: 5990: 5988: 5984: 5981: 5979: 5975: 5969: 5966: 5964: 5961: 5959: 5956: 5954: 5951: 5949: 5946: 5944: 5940: 5936: 5932: 5930: 5927: 5925: 5922: 5920: 5916: 5913: 5912: 5910: 5908: 5902: 5897: 5891: 5888: 5886: 5883: 5881: 5878: 5876: 5873: 5871: 5868: 5866: 5863: 5861: 5858: 5856: 5853: 5851: 5848: 5846: 5843: 5841: 5838: 5836: 5833: 5829: 5826: 5825: 5824: 5821: 5820: 5818: 5814: 5810: 5803: 5798: 5796: 5791: 5789: 5784: 5783: 5780: 5770: 5766: 5762: 5756: 5752: 5743: 5742:0-85312-563-5 5739: 5735: 5734:0-85312-612-7 5731: 5725: 5716: 5715: 5705: 5701: 5700: 5692: 5685: 5683:0-09-944068-7 5679: 5675: 5671: 5665: 5657: 5653: 5648: 5643: 5639: 5635: 5630: 5625: 5621: 5617: 5613: 5609: 5605: 5598: 5590: 5586: 5581: 5576: 5572: 5568: 5563: 5558: 5554: 5550: 5546: 5542: 5538: 5531: 5525: 5520: 5518:3-540-42224-2 5514: 5510: 5509: 5504: 5500: 5494: 5487: 5483: 5479: 5475: 5471: 5467: 5463: 5459: 5458: 5453: 5449: 5445: 5444:David Hilbert 5441: 5437: 5433: 5427: 5412: 5408: 5402: 5400: 5391: 5387: 5380: 5373: 5365: 5358: 5339: 5335: 5328: 5321: 5314: 5310: 5306: 5302: 5299: 5293: 5279: 5278:Math Timeline 5275: 5269: 5262: 5258: 5257: 5250: 5236: 5235:brilliant.org 5232: 5226: 5217: 5216: 5211: 5208: 5201: 5193: 5187: 5183: 5176: 5172: 5162: 5159: 5157: 5154: 5152: 5149: 5147: 5146:Countable set 5144: 5142: 5139: 5137: 5134: 5132: 5129: 5127: 5124: 5123: 5117: 5103: 5073: 5065: 5053: 5052: 5051: 5037: 5003: 5000: 4989: 4978: 4968: 4967: 4966: 4952: 4949: 4943: 4920: 4917: 4914: 4911: 4908: 4905: 4902: 4885: 4882: 4879: 4876: 4837: 4831: 4825: 4819: 4816: 4813: 4792: 4789: 4783: 4780: 4770: 4762: 4750: 4749: 4748: 4710: 4698: 4694: 4674: 4670: 4667: 4664: 4660: 4656: 4653: 4650: 4646: 4642: 4638: 4635: 4632: 4628: 4624: 4620: 4616: 4613: 4610: 4606: 4598: 4597: 4596: 4594: 4593:intersections 4590: 4571: 4567: 4564: 4561: 4557: 4553: 4550: 4547: 4543: 4539: 4535: 4532: 4529: 4525: 4517: 4516: 4515: 4513: 4512:disjoint sets 4509: 4505: 4499: 4471: 4468: 4465: 4454: 4450: 4447: 4444: 4440: 4436: 4432: 4428: 4424: 4420: 4416: 4413: 4409: 4405: 4401: 4397: 4393: 4389: 4385: 4382: 4378: 4374: 4370: 4366: 4363:, oranges), ( 4362: 4358: 4355:| because { ( 4354: 4350: 4346: 4342: 4338: 4334: 4330: 4326: 4322: 4318: 4314: 4313: 4293: 4282: 4278: 4271: 4263: 4252: 4248: 4236: 4229: 4220: 4216: 4211: 4188: 4174: 4164: 4157: 4148: 4144: 4136: 4127: 4121: 4111: 4107: 4100: 4090: 4083: 4074: 4070: 4065: 4058: 4037: 4023: 4013: 4006: 3997: 3993: 3985: 3976: 3973: 3969: 3965: 3960: 3955: 3948: 3939: 3935: 3930: 3925: 3909: 3908: 3907: 3905: 3881: 3877: 3841: 3831: 3824: 3791: 3781: 3776: 3760: 3752: 3748: 3727: 3722: 3718: 3714: 3703: 3695: 3694: 3693: 3686: 3682: 3678: 3674: 3671: 3667: 3663: 3659: 3655: 3651: 3650: 3649: 3648: 3647: 3645: 3641: 3612: 3610: 3606: 3602: 3598: 3593: 3591: 3587: 3583: 3579: 3575: 3570: 3568: 3564: 3560: 3556: 3552: 3548: 3544: 3540: 3535: 3533: 3530: 3509: 3501: 3494: 3485: 3477: 3476: 3475: 3473: 3469: 3461: 3457: 3453: 3437: 3429: 3422: 3413: 3405: 3404: 3403: 3402:) satisfies: 3401: 3383: 3379: 3375: 3368: 3359: 3355: 3340: 3336: 3318: 3281: 3275: 3265: 3249: 3236: 3232: 3228: 3224: 3223:Gottlob Frege 3220: 3216: 3215:infinite sets 3212: 3205:Infinite sets 3199: 3195: 3167: 3163: 3159: 3155: 3151: 3148: 3130: 3117: 3113: 3109: 3105: 3102: 3098: 3094: 3090: 3086: 3082: 3081: 3080: 3078: 3074: 3064: 3062: 3058: 3054: 3036: 3007: 2998: 2973: 2964: 2960: 2955: 2942: 2937: 2919: 2910: 2906: 2877: 2869: 2854: 2850: 2846: 2818: 2800: 2787: 2783: 2778: 2762: 2735: 2732: 2729: 2704: 2697: 2678: 2675: 2672: 2667: 2659: 2654: 2646: 2641: 2629: 2628: 2627: 2625: 2624:infinite sets 2621: 2618:Assuming the 2613: 2609: 2605: 2601: 2597: 2594: 2590: 2589: 2588: 2586: 2582: 2578: 2574: 2570: 2566: 2561: 2557: 2547: 2545: 2541: 2537: 2336: 2330: 2324: 2318: 2272: 2268: 2237: 2221: 2197: 2173: 2149: 2135: 2129: 2122: 2106: 2082: 2055: 2047: 2039: 2009: 2001: 1993: 1980: 1976: 1955: 1947: 1939: 1909: 1901: 1893: 1863: 1855: 1847: 1833: 1817: 1793: 1769: 1745: 1731: 1725: 1718: 1702: 1665: 1657: 1630: 1606: 1596: 1577: 1569: 1563: 1560: 1557: 1551: 1545: 1538:, defined by 1523: 1473: 1451: 1448: 1445: 1439: 1433: 1426:, defined by 1411: 1361: 1337: 1313: 1289: 1265: 1255: 1237: 1213: 1203: 1185: 1161: 1150: 1134: 1086: 1083: 1080: 1074: 1068: 1060: 1036: 1033: 1030: 1027: 1024: 1021: 1018: 1015: 1009: 996: 972: 969: 966: 963: 960: 957: 954: 951: 945: 942: 933: 931: 930: 925: 921: 917: 913: 910:that is both 895: 871: 861: 858:, that is, a 843: 819: 809: 800: 794: 787: 780: 776: 772: 768: 763: 758: 754: 750: 746: 741: 736: 732: 728: 724: 720: 716: 712: 708: 704: 700: 696: 692: 688: 684: 680: 676: 672: 669: 665: 661: 654: 650: 646: 642: 638: 633: 624: 622: 618: 614: 610: 606: 594: 592: 588: 584: 580: 576: 572: 568: 567: 560: 558: 539: 525: 499: 493: 490: 469: 445: 439: 419: 411: 407: 386: 361: 353: 332: 324: 316: 289: 265: 254: 252: 248: 244: 240: 236: 232: 231:infinite sets 228: 209: 206: 203: 200: 197: 191: 188: 165: 162: 159: 156: 153: 147: 144: 136: 132: 128: 108: 105: 97: 72: 64: 48: 39: 33: 19: 8135:Georg Cantor 8130:Paul Bernays 8061:Morse–Kelley 8036: 7969: 7968:Subset  7915:hereditarily 7877:Venn diagram 7835:ordered pair 7794: 7750:Intersection 7694:Axiom schema 7517: 7315:Ultraproduct 7162:Model theory 7127:Independence 7063:Formal proof 7055:Proof theory 7038: 7011: 6968:real numbers 6940:second-order 6851:Substitution 6728:Metalanguage 6669:conservative 6642:Axiom schema 6586:Constructive 6556:Morse–Kelley 6522:Set theories 6501:Aleph number 6494:inaccessible 6420: 6400:Grothendieck 6284:intersection 6171:Higher-order 6159:Second-order 6105:Truth tables 6062:Venn diagram 5845:Formal proof 5834: 5755: 5724: 5713: 5703: 5697: 5691: 5673: 5664: 5611: 5607: 5597: 5544: 5540: 5530: 5507: 5493: 5461: 5455: 5426: 5415:. Retrieved 5413:. 2019-12-05 5410: 5389: 5385: 5372: 5363: 5357: 5345:. Retrieved 5338:the original 5333: 5320: 5308: 5292: 5281:. Retrieved 5277: 5268: 5254: 5249: 5238:. Retrieved 5234: 5225: 5213: 5200: 5181: 5175: 5126:Aleph number 5095: 5029: 4936:, therefore 4865: 4702: 4586: 4507: 4503: 4501: 4438: 4434: 4430: 4426: 4422: 4418: 4411: 4407: 4403: 4399: 4398:such that | 4395: 4391: 4387: 4380: 4376: 4372: 4368: 4364: 4360: 4359:, apples), ( 4356: 4352: 4348: 4344: 4340: 4336: 4332: 4328: 4324: 4320: 4316: 3756: 3691: 3684: 3680: 3676: 3669: 3665: 3661: 3656:, i.e., the 3653: 3613: 3609:such a proof 3594: 3585: 3580:between the 3571: 3566: 3562: 3558: 3554: 3536: 3526: 3465: 3338: 3334: 3277: 3219:Georg Cantor 3208: 3193: 3165: 3161: 3157: 3153: 3115: 3111: 3107: 3096: 3092: 3084: 3070: 2938: 2817:real numbers 2779: 2693: 2626:are denoted 2617: 2592: 2584: 2580: 2562: 2559: 2536:real numbers 2238: 2140: 2133: 2127: 1834: 1736: 1729: 1723: 1253: 1201: 1151: 995:even numbers 934: 929:equinumerous 927: 923: 919: 805: 798: 792: 784: 778: 774: 770: 766: 761: 756: 752: 748: 744: 739: 734: 730: 726: 722: 714: 710: 706: 702: 698: 694: 690: 686: 682: 678: 674: 670: 663: 652: 648: 645:even numbers 640: 636: 605:Georg Cantor 595: 586: 582: 578: 574: 564: 561: 547:as early as 545: 406:vertical bar 351: 255: 250: 130: 124: 8160:Thomas Jech 8003:Alternative 7982:Uncountable 7936:Ultrafilter 7795:Cardinality 7699:replacement 7640:Determinacy 7425:Type theory 7373:undecidable 7305:Truth value 7192:equivalence 6871:non-logical 6484:Enumeration 6474:Isomorphism 6421:cardinality 6405:Von Neumann 6370:Ultrafilter 6335:Uncountable 6269:equivalence 6186:Quantifiers 6176:Fixed-point 6145:First-order 6025:Consistency 6010:Proposition 5987:Traditional 5958:Lindström's 5948:Compactness 5890:Type theory 5835:Cardinality 5436:Felix Klein 5131:Beth number 3561:, although 3211:finite sets 3198:uncountable 3075:holds, the 3053:independent 2784:is denoted 924:equipollent 693:), the set 647:. Although 639:to the set 601: 1880 557:mathematics 131:cardinality 127:mathematics 8200:Categories 8155:Kurt Gödel 8140:Paul Cohen 7977:Transitive 7745:Identities 7729:Complement 7716:Operations 7677:Regularity 7645:projective 7608:Adjunction 7567:Set theory 7236:elementary 6929:arithmetic 6797:Quantifier 6775:functional 6647:Expression 6365:Transitive 6309:identities 6294:complement 6227:hereditary 6210:Set theory 5670:Penrose, R 5417:2020-08-23 5283:2018-04-26 5240:2020-08-23 5167:References 5156:Ordinality 4433:|, then | 3664:, written 3588:(see also 3101:finite set 2943:says that 2786:aleph-null 2311:, because 2073:for every 920:equipotent 916:surjective 609:set theory 243:injections 239:bijections 235:arithmetic 8088:Paradoxes 8008:Axiomatic 7987:Universal 7963:Singleton 7958:Recursive 7901:Countable 7896:Amorphous 7755:Power set 7672:Power set 7623:dependent 7618:countable 7507:Supertask 7410:Recursion 7368:decidable 7202:saturated 7180:of models 7103:deductive 7098:axiomatic 7018:Hilbert's 7005:Euclidean 6986:canonical 6909:axiomatic 6841:Signature 6770:Predicate 6659:Extension 6581:Ackermann 6506:Operation 6385:Universal 6375:Recursive 6350:Singleton 6345:Inhabited 6330:Countable 6320:Types of 6304:power set 6274:partition 6191:Predicate 6137:Predicate 6052:Syllogism 6042:Soundness 6015:Inference 6005:Tautology 5907:paradoxes 5486:121598654 5478:0025-5831 5215:MathWorld 5007:→ 4982:↦ 4947:∅ 4944:⋂ 4918:∈ 4906:∈ 4900:∀ 4893:⟺ 4883:⋂ 4880:∈ 4826:α 4823:→ 4808:∃ 4793:∈ 4790:α 4784:⋂ 4781:∩ 4636:∩ 4614:∪ 4533:∪ 4268:ℵ 4264:× 4226:ℵ 4154:ℵ 4133:ℵ 4128:× 4118:ℵ 4097:ℵ 4080:ℵ 4055:ℵ 4003:ℵ 3982:ℵ 3977:× 3945:ℵ 3821:ℵ 3719:ℶ 3658:power set 3605:hypercube 3506:ℵ 3491:ℵ 3434:ℵ 3419:ℵ 3380:ℶ 3365:ℵ 3315:ℵ 3246:ℵ 3160:| > | 3127:ℵ 3095:| < | 3033:ℵ 3004:ℵ 2970:ℵ 2952:ℵ 2916:ℵ 2874:ℵ 2797:ℵ 2763:α 2759:ℵ 2730:α 2726:ℵ 2705:α 2694:For each 2676:… 2664:ℵ 2651:ℵ 2638:ℵ 2579:of a set 2271:power set 2048:≤ 2002:≤ 1902:≤ 1856:≤ 1564:− 912:injective 808:bijection 668:power set 613:bijection 523:# 494:⁡ 404:, with a 8092:Problems 7996:Theories 7972:Superset 7948:Infinite 7777:Concepts 7657:Infinity 7574:Overview 7492:Logicism 7485:timeline 7461:Concrete 7320:Validity 7290:T-schema 7283:Kripke's 7278:Tarski's 7273:semantic 7263:Strength 7212:submodel 7207:spectrum 7175:function 7023:Tarski's 7012:Elements 6999:geometry 6955:Robinson 6876:variable 6861:function 6834:spectrum 6824:Sentence 6780:variable 6723:Language 6676:Relation 6637:Automata 6627:Alphabet 6611:language 6465:-jection 6443:codomain 6429:Function 6390:Universe 6360:Infinite 6264:Relation 6047:Validity 6037:Argument 5935:theorem, 5769:geometry 5759:Such as 5706:: 81–125 5672:(2005), 5656:16591132 5589:16578557 5501:(2002), 5450:(eds.), 5434:(1915), 5392:: 75–78. 5301:Archived 5151:Counting 5120:See also 4425:| and | 3751:Beth two 3675:the set 3582:interval 3400:Beth one 3152:Any set 3106:Any set 3083:Any set 860:function 725:, hence 566:Elements 227:elements 41:The set 8030:General 8025:Zermelo 7931:subbase 7913: ( 7852:Forcing 7830:Element 7802: ( 7780:Methods 7667:Pairing 7434:Related 7231:Diagram 7129: ( 7108:Hilbert 7093:Systems 7088:Theorem 6966:of the 6911:systems 6691:Formula 6686:Grammar 6602: ( 6546:General 6259:Forcing 6244:Element 6164:Monadic 5939:paradox 5880:Theorem 5816:General 5616:Bibcode 5549:Bibcode 5347:Nov 15, 4514:, then 3644:theorem 3543:segment 3192:> | 3091:, or | 3071:If the 3063:below. 2990:, i.e. 2855:, that 2696:ordinal 2571:on the 2534:of all 2532:⁠ 2510:⁠ 2506:⁠ 2484:⁠ 2480:⁠ 2445:⁠ 2441:⁠ 2419:⁠ 2415:⁠ 2380:⁠ 2376:⁠ 2354:⁠ 2309:⁠ 2274:⁠ 2265:of all 2263:⁠ 2241:⁠ 2234:⁠ 2214:⁠ 2210:⁠ 2190:⁠ 2186:⁠ 2166:⁠ 2162:⁠ 2142:⁠ 2119:⁠ 2099:⁠ 2095:⁠ 2075:⁠ 1977:). The 1927:, then 1830:⁠ 1810:⁠ 1806:⁠ 1786:⁠ 1782:⁠ 1762:⁠ 1758:⁠ 1738:⁠ 1715:⁠ 1695:⁠ 1643:⁠ 1623:⁠ 1619:⁠ 1599:⁠ 1536:⁠ 1516:⁠ 1512:⁠ 1490:⁠ 1486:⁠ 1466:⁠ 1424:⁠ 1404:⁠ 1400:⁠ 1378:⁠ 1374:⁠ 1354:⁠ 1350:⁠ 1330:⁠ 1326:⁠ 1306:⁠ 1302:⁠ 1282:⁠ 1278:⁠ 1258:⁠ 1252:, then 1250:⁠ 1230:⁠ 1226:⁠ 1206:⁠ 1198:⁠ 1178:⁠ 1174:⁠ 1154:⁠ 1147:⁠ 1127:⁠ 1123:⁠ 1101:⁠ 908:⁠ 888:⁠ 884:⁠ 864:⁠ 856:⁠ 836:⁠ 832:⁠ 812:⁠ 542:History 302:⁠ 282:⁠ 278:⁠ 258:⁠ 61:of all 7921:Filter 7911:Finite 7847:Family 7790:Almost 7628:global 7613:Choice 7600:Axioms 7197:finite 6960:Skolem 6913:  6888:Theory 6856:Symbol 6846:String 6829:atomic 6706:ground 6701:closed 6696:atomic 6652:ground 6615:syntax 6511:binary 6438:domain 6355:Finite 6120:finite 5978:Logics 5937:  5885:Theory 5761:length 5740:  5732:  5680:  5654:  5647:300611 5644:  5636:  5587:  5580:221287 5577:  5569:  5515:  5484:  5476:  5261:Quanta 5188:  4589:unions 4437:| = | 4429:| ≀ | 4421:| ≀ | 4406:| and 4402:| = | 4390:| ≀ | 4351:| = | 4343:, and 4331:} and 3672:) or 2 3114:| = | 2137:| 1733:| 1593:(see: 802:| 8013:Naive 7943:Fuzzy 7906:Empty 7889:types 7840:tuple 7810:Class 7804:large 7765:Union 7682:Union 7187:Model 6935:Peano 6792:Proof 6632:Arity 6561:Naive 6448:image 6380:Fuzzy 6340:Empty 6289:union 6234:Class 5875:Model 5865:Lemma 5823:Axiom 5638:72252 5634:JSTOR 5571:71858 5567:JSTOR 5482:S2CID 5382:(PDF) 5341:(PDF) 5330:(PDF) 4703:Here 4591:and 4417:If | 4386:If | 4383:is 3. 3749:(see 3454:(see 3398:(see 2573:class 1808:into 1488:from 1376:from 1200:, if 926:, or 862:from 719:range 681:from 515:, or 7926:base 7310:Type 7113:list 6917:list 6894:list 6883:Term 6817:rank 6711:open 6605:list 6417:Maps 6322:sets 6181:Free 6151:list 5901:list 5828:list 5765:area 5763:and 5738:ISBN 5730:ISBN 5678:ISBN 5652:PMID 5585:PMID 5513:ISBN 5474:ISSN 5349:2019 5186:ISBN 4510:are 4506:and 4379:and 4371:and 3854:and 3757:The 3728:> 3642:and 3549:and 3466:The 3430:> 3168:| = 3149:set. 3118:| = 2939:The 2870:> 2673:< 2660:< 2647:< 2097:and 1881:and 1621:nor 1328:and 1254:each 1202:some 1176:and 914:and 762:blue 585:and 577:and 491:card 280:and 251:size 241:and 181:and 135:sets 7887:Set 6997:of 6979:of 6927:of 6459:Sur 6433:Map 6240:Ur- 6222:Set 5767:in 5642:PMC 5624:doi 5575:PMC 5557:doi 5466:doi 5079:Ord 5012:Ord 4798:Ord 4776:Ord 4733:Ord 4695:or 4693:NBG 4502:If 4319:= { 4315:If 3683:to 3660:of 3592:). 3529:ZFC 3458:or 3264:). 3057:ZFC 3055:of 2610:in 2542:or 2443:to 2378:to 2212:to 2027:or 1835:If 1514:to 1402:to 1280:to 1228:to 1125:to 1057:of 1041:... 977:... 932:. 886:to 834:to 740:red 721:of 697:= { 685:to 643:of 603:by 551:000 125:In 8202:: 7383:NP 7007:: 7001:: 6931:: 6608:), 6463:Bi 6455:In 5704:91 5702:, 5650:. 5640:. 5632:. 5622:. 5612:51 5610:. 5606:. 5583:. 5573:. 5565:. 5555:. 5545:50 5543:. 5539:. 5522:- 5480:, 5472:, 5462:76 5460:, 5454:, 5446:; 5442:; 5438:; 5409:. 5398:^ 5388:. 5384:. 5332:. 5311:. 5307:, 5276:. 5259:, 5233:. 5212:. 4771::= 4697:MK 4410:⊆ 4339:, 4327:, 4323:, 3906:: 3753:). 3611:. 3462:). 3225:, 3221:, 2777:. 2717:, 2598:A 2546:. 2236:. 2121:. 1832:. 1717:. 922:, 781:). 759:, 755:)\ 743:: 737:; 705:: 598:c. 569:, 549:40 538:. 483:, 461:, 129:, 7970:· 7954:) 7950:( 7917:) 7806:) 7559:e 7552:t 7545:v 7463:/ 7378:P 7133:) 6919:) 6915:( 6812:∀ 6807:! 6802:∃ 6763:= 6758:↔ 6753:→ 6748:∧ 6743:√ 6738:ÂŹ 6461:/ 6457:/ 6431:/ 6242:) 6238:( 6125:∞ 6115:3 5903:) 5801:e 5794:t 5787:v 5658:. 5626:: 5618:: 5591:. 5559:: 5551:: 5468:: 5420:. 5390:1 5366:. 5351:. 5315:. 5286:. 5243:. 5218:. 5194:. 5104:V 5074:= 5070:| 5066:P 5062:| 5038:P 5026:. 5004:V 5001:: 4998:) 4994:| 4990:x 4986:| 4979:x 4976:( 4953:V 4950:= 4924:) 4921:q 4915:x 4912:: 4909:Q 4903:q 4897:( 4889:) 4886:Q 4877:x 4874:( 4851:} 4848:) 4838:f 4835:( 4832:: 4829:) 4820:A 4817:: 4814:f 4811:( 4804:| 4787:{ 4767:| 4763:A 4759:| 4711:V 4699:) 4675:. 4671:| 4668:D 4665:| 4661:+ 4657:| 4654:C 4651:| 4647:= 4643:| 4639:D 4633:C 4629:| 4625:+ 4621:| 4617:D 4611:C 4607:| 4572:. 4568:| 4565:B 4562:| 4558:+ 4554:| 4551:A 4548:| 4544:= 4540:| 4536:B 4530:A 4526:| 4508:B 4504:A 4487:. 4475:] 4472:1 4469:, 4466:0 4463:[ 4445:. 4439:Y 4435:X 4431:X 4427:Y 4423:Y 4419:X 4414:. 4412:Y 4408:Z 4404:Z 4400:X 4396:Z 4392:Y 4388:X 4381:Y 4377:X 4373:Y 4369:X 4365:c 4361:b 4357:a 4353:Y 4349:X 4345:c 4341:b 4337:a 4333:Y 4329:c 4325:b 4321:a 4317:X 4294:. 4288:c 4283:2 4279:= 4272:0 4259:c 4253:2 4249:= 4243:c 4237:) 4230:0 4221:2 4217:( 4212:= 4206:c 4199:c 4175:, 4170:c 4165:= 4158:0 4149:2 4145:= 4137:0 4122:0 4112:2 4108:= 4101:0 4091:) 4084:0 4075:2 4071:( 4066:= 4059:0 4048:c 4024:, 4019:c 4014:= 4007:0 3998:2 3994:= 3986:0 3974:2 3970:2 3966:= 3961:2 3956:) 3949:0 3940:2 3936:( 3931:= 3926:2 3920:c 3887:c 3882:2 3878:= 3872:c 3865:c 3842:, 3837:c 3832:= 3825:0 3814:c 3792:, 3787:c 3782:= 3777:2 3771:c 3733:c 3723:2 3715:= 3709:c 3704:2 3685:R 3681:R 3677:R 3670:R 3668:( 3666:P 3662:R 3654:R 3624:c 3586:R 3567:S 3563:S 3559:S 3555:S 3510:1 3502:= 3495:0 3486:2 3438:0 3423:0 3414:2 3384:1 3376:= 3369:0 3360:2 3356:= 3351:c 3339:N 3335:R 3319:0 3292:c 3282:( 3250:0 3200:. 3194:N 3178:c 3166:R 3162:N 3158:X 3154:X 3131:0 3116:N 3112:X 3108:X 3103:. 3097:N 3093:X 3085:X 3037:0 3008:0 2999:2 2974:0 2965:2 2961:= 2956:1 2920:0 2911:2 2907:= 2902:c 2878:0 2865:c 2829:c 2801:0 2788:( 2736:1 2733:+ 2679:. 2668:2 2655:1 2642:0 2614:. 2593:A 2585:A 2581:A 2519:R 2493:N 2468:) 2464:N 2460:( 2455:P 2428:N 2403:) 2399:N 2395:( 2390:P 2363:N 2340:} 2337:n 2334:{ 2331:= 2328:) 2325:n 2322:( 2319:g 2297:) 2293:N 2289:( 2284:P 2250:N 2222:B 2198:A 2174:B 2150:A 2134:B 2128:A 2107:B 2083:A 2060:| 2056:A 2052:| 2044:| 2040:B 2036:| 2014:| 2010:B 2006:| 1998:| 1994:A 1990:| 1960:| 1956:B 1952:| 1948:= 1944:| 1940:A 1936:| 1914:| 1910:A 1906:| 1898:| 1894:B 1890:| 1868:| 1864:B 1860:| 1852:| 1848:A 1844:| 1818:B 1794:A 1770:B 1746:A 1730:B 1724:A 1703:f 1680:| 1675:N 1670:| 1666:= 1662:| 1658:E 1654:| 1631:h 1607:g 1581:) 1578:2 1570:n 1567:( 1561:n 1558:= 1555:) 1552:n 1549:( 1546:h 1524:E 1499:N 1474:h 1452:n 1449:4 1446:= 1443:) 1440:n 1437:( 1434:g 1412:E 1387:N 1362:g 1338:B 1314:A 1290:B 1266:A 1238:B 1214:A 1186:B 1162:A 1135:E 1110:N 1087:n 1084:2 1081:= 1078:) 1075:n 1072:( 1069:f 1045:} 1037:, 1034:3 1031:, 1028:2 1025:, 1022:1 1019:, 1016:0 1013:{ 1010:= 1006:N 981:} 973:, 970:6 967:, 964:4 961:, 958:2 955:, 952:0 949:{ 946:= 943:E 896:B 872:A 844:B 820:A 799:B 793:A 779:n 777:( 775:f 773:\ 771:T 769:∈ 767:n 765:: 757:T 753:n 751:( 749:f 747:∈ 745:n 735:T 731:f 727:f 723:f 715:n 713:( 711:f 709:∉ 707:n 703:N 701:∈ 699:n 695:T 691:N 689:( 687:P 683:N 679:f 675:N 673:( 671:P 664:N 653:N 649:E 641:E 637:N 587:b 583:a 579:b 575:a 526:A 503:) 500:A 497:( 470:A 449:) 446:A 443:( 440:n 420:A 391:| 387:A 383:| 362:A 337:| 333:B 329:| 325:= 321:| 317:A 313:| 290:B 266:A 213:} 210:6 207:, 204:4 201:, 198:2 195:{ 192:= 189:B 169:} 166:3 163:, 160:2 157:, 154:1 151:{ 148:= 145:A 121:. 109:5 106:= 102:| 98:S 94:| 73:S 49:S 34:. 20:)

Index

Finite cardinality
Cardinality (disambiguation)

Platonic solids
mathematics
sets
elements
infinite sets
arithmetic
bijections
injections
cardinal numbers
vertical bar
absolute value
mathematics
Elements
commensurability
irrational numbers
Georg Cantor
set theory
bijection
Cantor's diagonal argument
uncountable sets

even numbers

power set
range
bijection
function

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