Knowledge (XXG)

Topological space

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6719: 1843: 6502: 6740: 6708: 6777: 6750: 6730: 186:, which in section 3 defines the curved surface in a similar manner to the modern topological understanding: "A curved surface is said to possess continuous curvature at one of its points A, if the direction of all the straight lines drawn from A to points of the surface at an infinitesimal distance from A are deflected infinitesimally from one and the same plane passing through A." 4715: 3817:(also called the indiscrete topology), in which only the empty set and the whole space are open. Every sequence and net in this topology converges to every point of the space. This example shows that in general topological spaces, limits of sequences need not be unique. However, often topological spaces must be 5457:
we can introduce the discrete topology, under which the algebraic operations are continuous functions. For any such structure that is not finite, we often have a natural topology compatible with the algebraic operations, in the sense that the algebraic operations are still continuous. This leads to
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mappings. For example, in finite products, a basis for the product topology consists of all products of open sets. For infinite products, there is the additional requirement that in a basic open set, all but finitely many of its projections are the entire space.
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is strictly finer than the Euclidean topology defined above; a sequence converges to a point in this topology if and only if it converges from above in the Euclidean topology. This example shows that a set may have many distinct topologies defined on it.
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or basis for the topology, meaning that every open set is a union of some collection of sets from the base. In particular, this means that a set is open if there exists an open interval of non zero radius about every point in the set. More generally, the
5429:. A topological property is a property of spaces that is invariant under homeomorphisms. To prove that two spaces are not homeomorphic it is sufficient to find a topological property not shared by them. Examples of such properties include 1386:
The open sets then satisfy the axioms given below in the next definition of a topological space. Conversely, when given the open sets of a topological space, the neighbourhoods satisfying the above axioms can be recovered by defining
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There are many other equivalent ways to define a topological space: in other words the concepts of neighbourhood, or that of open or closed sets can be reconstructed from other starting points and satisfy the correct axioms.
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seem to be the first to realize that the main problem about the topology of (compact) surfaces is to find invariants (preferably numerical) to decide the equivalence of surfaces, that is, to decide whether two surfaces are
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a topology, because (for example) the union of all finite sets not containing zero is not finite and therefore not a member of the family of finite sets. The union of all finite sets not containing zero is also not all of
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A proof that relies only on the existence of certain open sets will also hold for any finer topology, and similarly a proof that relies only on certain sets not being open applies to any coarser topology. The terms
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The first three axioms for neighbourhoods have a clear meaning. The fourth axiom has a very important use in the structure of the theory, that of linking together the neighbourhoods of different points of
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in 1847, although he had used the term in correspondence some years earlier instead of previously used "Analysis situs". The foundation of this science, for a space of any dimension, was created by
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Although very general, the concept of topological spaces is fundamental, and used in virtually every branch of modern mathematics. The study of topological spaces in their own right is called
6219: 4132: 4339:, in which a set is defined as open if it is either empty or its complement is countable. When the set is uncountable, this topology serves as a counterexample in many situations. 743: 5614: 5295: 5117: 4467: 4572: 4506: 4267: 509: 453: 4235: 4042: 3980: 3947: 3709: 2738: 2557: 2349: 2137: 816: 656: 604: 557: 376: 4009: 3880: 2810: 2643: 1206: 4401: 3906: 2780: 1832: 1767: 1248: 4540: 3266: 3205: 3144: 1905: 3232: 3171: 3114: 2698: 1803: 4848: 4635: 3550: 5541: 4592: 4425: 4076: 2053: 2021: 1989: 1494: 772: 156: 5197: 4700: 4612: 4379: 3582: 2833: 1689: 1644: 1595: 955: 6002: 5975: 5405: 5167: 4670: 2968: 2925: 2758: 2079: 1957: 1931: 1864: 1712: 1666: 1621: 1532: 3631: 3809:
A given set may have many different topologies. If a set is given a different topology, it is viewed as a different topological space. Any set can be given the
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in which every subset is open. The only convergent sequences or nets in this topology are those that are eventually constant. Also, any set can be given the
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formalizing the concept of closeness. There are several equivalent definitions of a topology, the most commonly used of which is the definition through
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are also used in the literature, but with little agreement on the meaning, so one should always be sure of an author's convention when reading.
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can be given a metric topology, in which the basic open sets are open balls defined by the metric. This is the standard topology on any
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of every open set is open. This is an attempt to capture the intuition that there are no "jumps" or "separations" in the function. A
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is a variant of the Vietoris topology, and is named after mathematician James Fell. It is generated by the following basis: for every
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are endowed with topologies that are defined by specifying when a particular sequence of functions converges to the zero function.
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if there exists a homeomorphism between them. From the standpoint of topology, homeomorphic spaces are essentially identical.
171: 4318:. Finite spaces are sometimes used to provide examples or counterexamples to conjectures about topological spaces in general. 6337: 6195: 3767: 75: 6660: 6385: 6161: 4293: 6806: 6380: 6312: 5686: 294: 52: 6668: 226: 194: 4105: 6801: 5806: 5617: 4775: 4639: 3007: 3003: 983: 6739: 6467: 6348: 6063: 5630: 5463: 5430: 4767: 4315: 3771: 3084: 607: 5633:– The system of all open sets of a given topological space ordered by inclusion is a complete Heyting algebra. 1866:
be denoted with the circles, here are four examples and two non-examples of topologies on the three-point set
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in which the open sets are the intersections of the open sets of the larger space with the subset. For any
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in which the open sets are the empty set and the sets whose complement is finite. This is the smallest
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Many topologies can be defined on a set to form a topological space. When every open set of a topology
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has a topology native to it, and this can be extended to vector spaces over that field.
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is the simplest non-discrete topological space. It has important relations to the
4285: 4281: 4270: 3851: 3843: 3830: 163: 118: 87: 5837: 4766:, which is generated by the inverse images of open sets of the factors under the 3778:
are continuous functions. The attempt to classify the objects of this category (
6733: 6645: 6132: 6047: 5471: 4171: 3883: 210: 20: 6589: 6520: 6479: 6202:, (Graduate Texts in Mathematics), Springer; 1st edition (September 5, 1997). 4851: 4643: 4311: 4274: 2849: 6614: 6215: 3740: 3015: 2584: 1551: 6139:(Graduate Texts in Mathematics), Springer; 1st edition (October 17, 1997). 5749: 5589:{\displaystyle \operatorname {cl} \{x\}\subseteq \operatorname {cl} \{y\},} 3277:
are sometimes used in place of finer and coarser, respectively. The terms
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A standard example of such a system of neighbourhoods is for the real line
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is shown by the fact that there are several equivalent definitions of this
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Unter einem m e t r i s c h e n   R a u m e verstehen wir eine Menge
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consists of the so-called "marked metric graph structures" of volume 1 on
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Using these axioms, another way to define a topological space is as a set
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has a natural topology that generalizes many of the geometric aspects of
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we construct a basis set consisting of all subsets of the union of the
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This relates easily to the usual definition in analysis. Equivalently,
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suited for the application. The most commonly used is that in terms of
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first expressed the idea that a surface is a topological space that is
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have a standard topology in which the basic open sets are open balls.
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As this definition of a topology is the most commonly used, the set
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is continuous. A common example of a quotient topology is when an
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relating the number of vertices (V), edges (E) and faces (F) of a
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The intersection of any collection of closed sets is also closed.
166:. The study and generalization of this formula, specifically by 6396: 1907:
The bottom-left example is not a topology because the union of
5689: â€“ subset of a topological space whose closure is compact 4708: 3360:{\displaystyle F=\left\{\tau _{\alpha }:\alpha \in A\right\}} 2883:
The union of any finite number of closed sets is also closed.
2847:, the above axioms defining open sets become axioms defining 2246:{\displaystyle \tau =\{\{\},\{1,2,3,4\}\}=\{\varnothing ,X\}} 803: 721: 643: 591: 544: 487: 431: 363: 6392: 5026:
on the set of all non-empty subsets of a topological space
3051:. A topology is completely determined if for every net in 794:
belongs to every one of its neighbourhoods with respect to
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is defined but cannot necessarily be measured by a numeric
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A Guide to the Classification Theorem for Compact Surfaces
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Another way to define a topological space is by using the
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It has been suggested that portions of this section be
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The collection of all topologies on a given fixed set
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Every subset of a topological space can be given the
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Pages displaying wikidata descriptions as a fallback
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Pages displaying wikidata descriptions as a fallback
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of topological spaces, the product can be given the
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The intersection of any finite number of members of
6659: 6623: 6509: 6430: 6056:"Moduli of graphs and automorphisms of free groups" 3461:is the meet of the collection of all topologies on 244:in 1914 in his seminal "Principles of Set Theory". 6259:, Prentice Hall; 2nd edition (December 28, 1999). 5996: 5969: 5799: 5698: â€“ Mathematical set with some added structure 5608: 5588: 5535: 5399: 5372: 5352: 5332: 5309: 5289: 5243: 5223: 5191: 5161: 5134: 5111: 5065: 5041: 5007: 4987: 4960: 4940: 4916: 4889: 4869: 4842: 4810: 4790: 4694: 4664: 4629: 4606: 4586: 4566: 4534: 4500: 4461: 4419: 4395: 4373: 4261: 4229: 4149: 4126: 4094: 4070: 4036: 4003: 3974: 3941: 3900: 3874: 3723: 3703: 3665: 3645: 3625: 3596: 3576: 3544: 3496: 3473: 3453: 3429: 3406: 3382: 3359: 3300: 3260: 3226: 3199: 3165: 3138: 3108: 3063: 3033: 2982: 2962: 2942: 2919: 2899: 2869: 2827: 2804: 2774: 2752: 2732: 2692: 2660: 2637: 2602: 2575: 2551: 2496: 2473: 2453: 2343: 2288: 2265: 2245: 2159: 2131: 2073: 2047: 2015: 1983: 1951: 1925: 1899: 1858: 1826: 1797: 1761: 1733: 1706: 1683: 1660: 1638: 1615: 1589: 1566: 1526: 1488: 1459: 1439: 1419: 1399: 1378: 1355: 1331: 1311: 1289: 1266: 1242: 1220: 1200: 1173: 1146: 1123: 1103: 1083: 1063: 1043: 1021: 998: 972: 949: 919: 896: 876: 853: 833: 810: 786: 766: 737: 698: 678: 650: 626: 598: 573: 551: 527: 503: 470: 447: 414: 394: 370: 354:, though they can be any mathematical object. Let 342: 322: 150: 66:A topological space is the most general type of a 5053:, is generated by the following basis: for every 4185:since it is locally Euclidean. Similarly, every 292:, but perhaps more intuitive is that in terms of 63:, which is easier than the others to manipulate. 6006:Proceedings of the American Mathematical Society 5205:on the set of all non-empty closed subsets of a 4269:the closed sets of the Zariski topology are the 5668: â€“ Semicontinuity for set-valued functions 5015:is then the natural projection onto the set of 3839:, a precise notion of distance between points. 5836:(1914) . "Punktmengen in allgemeinen Räumen". 5421:Topological spaces can be broadly classified, 3857:There are many ways of defining a topology on 2970:are the closed sets, and their complements in 47:, along with an additional structure called a 39:. More specifically, a topological space is a 6408: 5731:Introduction to metric and topological spaces 4310:There exist numerous topologies on any given 82:. Common types of topological spaces include 16:Mathematical space with a notion of closeness 8: 5580: 5574: 5562: 5556: 5169:that have non-empty intersections with each 4127:{\displaystyle \{\varnothing \}\cup \Gamma } 4115: 4109: 2543: 2519: 2448: 2439: 2421: 2415: 2403: 2397: 2385: 2379: 2373: 2364: 2335: 2311: 2240: 2228: 2222: 2219: 2195: 2189: 2186: 2183: 2123: 2099: 2068: 2062: 2042: 2030: 2010: 1998: 1978: 1966: 1946: 1940: 1920: 1914: 1891: 1873: 6241:, McGraw-Hill; 1st edition (June 1, 1968). 5449:Topological spaces with algebraic structure 3747:is also continuous. Two spaces are called 2760:of all finite subsets of the integers plus 2273:required by the axioms forms a topology on 1274:if it includes an open interval containing 330:be a (possibly empty) set. The elements of 270:Axiomatic foundations of topological spaces 6776: 6749: 6415: 6401: 6393: 5380:and have nonempty intersections with each 6231:General investigations of curved surfaces 6182:(3rd edition of differently titled books) 6155:Elements of Mathematics: General Topology 5988: 5982: 5961: 5955: 5950:Anderson, B. A.; Stewart, D. G. (1969). " 5912: 5900: 5789:J. Stillwell, Mathematics and its history 5777: 5601: 5548: 5522: 5391: 5385: 5365: 5345: 5322: 5302: 5281: 5262: 5256: 5236: 5216: 5180: 5174: 5153: 5147: 5124: 5103: 5084: 5078: 5058: 5031: 5000: 4977: 4953: 4933: 4906: 4882: 4862: 4823: 4803: 4783: 4683: 4677: 4656: 4650: 4619: 4599: 4579: 4547: 4512: 4478: 4436: 4412: 4389: 4388: 4386: 4351: 4250: 4246: 4245: 4242: 4221: 4217: 4216: 4213: 4139: 4107: 4087: 4063: 4028: 4024: 4023: 4020: 3994: 3993: 3991: 3966: 3962: 3961: 3958: 3933: 3929: 3928: 3925: 3912:. The set of all open intervals forms a 3894: 3893: 3891: 3865: 3864: 3862: 3854:this topology is the same for all norms. 3789:has motivated areas of research, such as 3716: 3678: 3658: 3638: 3609: 3589: 3563: 3525: 3486: 3466: 3446: 3419: 3399: 3372: 3334: 3317: 3293: 3249: 3243: 3218: 3212: 3188: 3182: 3157: 3151: 3127: 3121: 3100: 3094: 3056: 3023: 2975: 2955: 2932: 2912: 2892: 2862: 2817: 2795: 2794: 2792: 2768: 2767: 2765: 2745: 2723: 2722: 2714: 2673: 2650: 2615: 2592: 2568: 2511: 2486: 2466: 2356: 2303: 2278: 2258: 2175: 2152: 2091: 2060: 2028: 1996: 1964: 1938: 1912: 1871: 1851: 1813: 1778: 1748: 1723: 1699: 1673: 1653: 1628: 1608: 1579: 1559: 1519: 1472: 1452: 1432: 1412: 1392: 1368: 1348: 1324: 1304: 1279: 1259: 1236: 1235: 1233: 1213: 1191: 1190: 1188: 1163: 1136: 1116: 1096: 1076: 1056: 1036: 1011: 991: 962: 936: 909: 889: 866: 846: 826: 802: 801: 799: 779: 750: 720: 719: 711: 691: 671: 642: 641: 639: 619: 590: 589: 587: 566: 543: 542: 540: 520: 486: 485: 483: 460: 430: 429: 427: 407: 387: 362: 361: 359: 335: 315: 240:Topological spaces were first defined by 184:General investigations of curved surfaces 125: 6290:, Macdonald Technical & Scientific, 6274:, Springer; 1st edition (July 6, 2005). 5715: 5662: â€“ Type of topological vector space 5708: 5674: â€“ In mathematics, vector subspace 5478:Topological spaces with order structure 4112: 2367: 2231: 1818: 3047:is a generalisation of the concept of 3006:, which define the closed sets as the 2645:consisting of all possible subsets of 2253:consisting of only the two subsets of 1714:of the open sets is commonly called a 774:In other words, each point of the set 738:{\displaystyle N\in {\mathcal {N}}(x)} 6316:, Holt, Rinehart and Winston (1970). 5888: 5876: 5762: 3552:between topological spaces is called 1546:and satisfying the following axioms: 7: 6239:Schaum's Outline of General Topology 5820:participating institution membership 5411:Classification of topological spaces 4972:is defined on the topological space 4342:The real line can also be given the 1363:is a neighbourhood of all points in 1131:is a neighbourhood of each point of 248:had been defined earlier in 1906 by 5616:denotes an operator satisfying the 5609:{\displaystyle \operatorname {cl} } 5290:{\displaystyle U_{1},\ldots ,U_{n}} 5112:{\displaystyle U_{1},\ldots ,U_{n}} 4462:{\displaystyle \gamma =[0,\gamma )} 4193:inherits a natural topology from . 2668:In this case the topological space 1599:Any arbitrary (finite or infinite) 51:, which can be defined as a set of 6272:A Taste of Topology (Universitext) 6116:Undergraduate Texts in Mathematics 5639: â€“ Type of mathematical space 4121: 4065: 2623: 209:The subject is clearly defined by 70:that allows for the definition of 14: 5656: â€“ Type of topological space 4567:{\displaystyle (\alpha ,\gamma )} 4501:{\displaystyle (\alpha ,\beta ),} 4262:{\displaystyle \mathbb {C} ^{n},} 3982:the basic open sets are the open 3949:can be given a topology. In the 3774:are topological spaces and whose 3367:is a collection of topologies on 1299:Given such a structure, a subset 504:{\displaystyle {\mathcal {N}}(x)} 448:{\displaystyle {\mathcal {N}}(x)} 55:for each point that satisfy some 6775: 6748: 6738: 6728: 6717: 6707: 6706: 6500: 4877:is the collection of subsets of 4857:, then the quotient topology on 4713: 4230:{\displaystyle \mathbb {R} ^{n}} 4200:is defined algebraically on the 4037:{\displaystyle \mathbb {C} ^{n}} 3975:{\displaystyle \mathbb {R} ^{n}} 3942:{\displaystyle \mathbb {R} ^{n}} 3704:{\displaystyle f(M)\subseteq N.} 2740:the set of integers, the family 861:and includes a neighbourhood of 274:The utility of the concept of a 5492:if and only if it is the prime 5441:. For algebraic invariants see 3821:where limit points are unique. 2733:{\displaystyle X=\mathbb {Z} ,} 1514:may be defined as a collection 6229:Gauss, Carl Friedrich (1827). 4834: 4726:out into articles titled 4561: 4549: 4526: 4514: 4492: 4480: 4456: 4444: 4365: 4353: 4332:topology on any infinite set. 3805:Examples of topological spaces 3768:category of topological spaces 3689: 3683: 3620: 3614: 3536: 2950:Thus the sets in the topology 2687: 2675: 2632: 2626: 2552:{\displaystyle X=\{1,2,3,4\},} 2344:{\displaystyle X=\{1,2,3,4\},} 2132:{\displaystyle X=\{1,2,3,4\},} 1792: 1780: 931:of a neighbourhood of a point 811:{\displaystyle {\mathcal {N}}} 732: 726: 651:{\displaystyle {\mathcal {N}}} 614:below are satisfied; and then 599:{\displaystyle {\mathcal {N}}} 552:{\displaystyle {\mathcal {N}}} 498: 492: 442: 436: 371:{\displaystyle {\mathcal {N}}} 306:This axiomatization is due to 235:locally like a Euclidean plane 1: 6328:Vaidyanathaswamy, R. (1960). 5929:. Pearson. pp. 317–319. 4004:{\displaystyle \mathbb {C} ,} 3875:{\displaystyle \mathbb {R} ,} 3743:that is continuous and whose 3481:that contain every member of 2805:{\displaystyle \mathbb {Z} ,} 2638:{\displaystyle \tau =\wp (X)} 1201:{\displaystyle \mathbb {R} ,} 302:Definition via neighbourhoods 5734:. Oxford : Clarendon Press. 4396:{\displaystyle \mathbb {R} } 3901:{\displaystyle \mathbb {R} } 3886:. The standard topology on 3116:is also open for a topology 2775:{\displaystyle \mathbb {Z} } 1827:{\displaystyle X\setminus C} 1762:{\displaystyle C\subseteq X} 1243:{\displaystyle \mathbb {R} } 957:is again a neighbourhood of 298:and so this is given first. 6381:Encyclopedia of Mathematics 6313:Counterexamples in Topology 5687:Relatively compact subspace 4798:is a topological space and 4535:{\displaystyle [0,\beta ),} 4473:generated by the intervals 2907:together with a collection 6823: 6669:Banach fixed-point theorem 6110:Armstrong, M. A. (1983) . 5728:Sutherland, W. A. (1975). 5414: 5407:is a member of the basis. 5340:the set of all subsets of 5317:and for every compact set 4928:is the finest topology on 4778:is defined as follows: if 4051: 3850:. On a finite-dimensional 3828: 3510: 3261:{\displaystyle \tau _{2}.} 3200:{\displaystyle \tau _{1},} 3139:{\displaystyle \tau _{2},} 3082: 2839:Definition via closed sets 2481:forms another topology of 1900:{\displaystyle \{1,2,3\}.} 267: 227:James Waddell Alexander II 43:whose elements are called 6702: 6498: 6347:Willard, Stephen (2004). 6332:. Chelsea Publishing Co. 5925:Munkres, James R (2015). 5839:GrundzĂĽge der Mengenlehre 5807:Oxford English Dictionary 5618:Kuratowski closure axioms 5464:topological vector spaces 4705:Topological constructions 4335:Any set can be given the 4321:Any set can be given the 4316:finite topological spaces 4314:. Such spaces are called 3758:, one of the fundamental 3633:there is a neighbourhood 3227:{\displaystyle \tau _{1}} 3166:{\displaystyle \tau _{2}} 3109:{\displaystyle \tau _{1}} 3004:Kuratowski closure axioms 2693:{\displaystyle (X,\tau )} 1798:{\displaystyle (X,\tau )} 1499:Definition via open sets 1407:to be a neighbourhood of 1071:includes a neighbourhood 986:of two neighbourhoods of 6286:Schubert, Horst (1968), 6192:, Academic Press (1969). 6157:, Addison-Wesley (1966). 6064:Inventiones Mathematicae 5631:Complete Heyting algebra 5425:homeomorphism, by their 4843:{\displaystyle f:X\to Y} 4630:{\displaystyle \gamma .} 4469:may be endowed with the 3584:and every neighbourhood 3545:{\displaystyle f:X\to Y} 3085:Comparison of topologies 3079:Comparison of topologies 27:is, roughly speaking, a 5812:Oxford University Press 5536:{\displaystyle x\leq y} 5509:specialization preorder 5504:Specialization preorder 5360:that are disjoint from 4587:{\displaystyle \alpha } 4420:{\displaystyle \gamma } 4071:{\displaystyle \Gamma } 3835:Metric spaces embody a 3414:is the intersection of 2812:and so it cannot be in 2048:{\displaystyle \{2,3\}} 2016:{\displaystyle \{1,2\}} 1984:{\displaystyle \{2,3\}} 1489:{\displaystyle x\in U.} 767:{\displaystyle x\in N.} 422:a non-empty collection 282:. Thus one chooses the 219:Johann Benedict Listing 151:{\displaystyle V-E+F=2} 6724:Mathematics portal 6624:Metrics and properties 6610:Second-countable space 6353:. Dover Publications. 6308:Seebach, J. Arthur Jr. 6167:Topology and Groupoids 5998: 5971: 5678:Quasitopological space 5610: 5590: 5537: 5427:topological properties 5401: 5374: 5354: 5334: 5311: 5291: 5245: 5225: 5193: 5192:{\displaystyle U_{i}.} 5163: 5136: 5113: 5067: 5043: 5009: 4989: 4962: 4942: 4918: 4891: 4871: 4844: 4812: 4792: 4696: 4695:{\displaystyle F_{n}.} 4666: 4631: 4608: 4607:{\displaystyle \beta } 4588: 4568: 4536: 4502: 4463: 4421: 4397: 4375: 4374:{\displaystyle [a,b).} 4263: 4231: 4151: 4128: 4096: 4072: 4038: 4005: 3976: 3943: 3902: 3876: 3725: 3705: 3667: 3647: 3627: 3598: 3578: 3577:{\displaystyle x\in X} 3546: 3498: 3475: 3455: 3431: 3408: 3384: 3361: 3302: 3262: 3228: 3201: 3167: 3140: 3110: 3065: 3035: 2984: 2964: 2944: 2921: 2901: 2871: 2829: 2828:{\displaystyle \tau .} 2806: 2776: 2754: 2734: 2694: 2662: 2639: 2604: 2577: 2553: 2498: 2475: 2455: 2345: 2290: 2267: 2247: 2161: 2133: 2082: 2075: 2049: 2017: 1985: 1953: 1927: 1901: 1860: 1838:Examples of topologies 1828: 1799: 1763: 1735: 1708: 1685: 1684:{\displaystyle \tau .} 1662: 1640: 1639:{\displaystyle \tau .} 1617: 1591: 1590:{\displaystyle \tau .} 1568: 1528: 1490: 1461: 1441: 1421: 1401: 1380: 1357: 1333: 1313: 1291: 1268: 1244: 1222: 1202: 1175: 1148: 1125: 1105: 1085: 1065: 1045: 1023: 1006:is a neighbourhood of 1000: 974: 951: 950:{\displaystyle x\in X} 921: 904:is a neighbourhood of 898: 878: 855: 835: 812: 788: 768: 739: 700: 686:is a neighbourhood of 680: 652: 628: 608:neighbourhood topology 600: 575: 553: 529: 505: 472: 449: 416: 396: 372: 344: 324: 280:mathematical structure 257: 178:of topology. In 1827, 152: 6137:Topology and Geometry 5999: 5997:{\displaystyle T_{1}} 5972: 5970:{\displaystyle T_{1}} 5778:Gallier & Xu 2013 5611: 5591: 5538: 5402: 5400:{\displaystyle U_{i}} 5375: 5355: 5335: 5312: 5292: 5246: 5226: 5194: 5164: 5162:{\displaystyle U_{i}} 5137: 5114: 5068: 5044: 5010: 4990: 4963: 4943: 4919: 4892: 4872: 4845: 4813: 4793: 4697: 4667: 4665:{\displaystyle F_{n}} 4632: 4609: 4589: 4569: 4537: 4503: 4464: 4422: 4398: 4376: 4305:theory of computation 4264: 4232: 4152: 4129: 4097: 4073: 4039: 4006: 3977: 3944: 3903: 3877: 3731:is continuous if the 3726: 3706: 3668: 3648: 3628: 3599: 3579: 3547: 3499: 3476: 3456: 3432: 3409: 3385: 3362: 3303: 3263: 3229: 3202: 3168: 3141: 3111: 3066: 3036: 2985: 2965: 2963:{\displaystyle \tau } 2945: 2927:of closed subsets of 2922: 2920:{\displaystyle \tau } 2902: 2872: 2830: 2807: 2777: 2755: 2753:{\displaystyle \tau } 2735: 2695: 2663: 2640: 2605: 2578: 2554: 2499: 2476: 2456: 2346: 2291: 2268: 2248: 2162: 2134: 2076: 2074:{\displaystyle \{2\}} 2050: 2018: 1986: 1954: 1952:{\displaystyle \{3\}} 1928: 1926:{\displaystyle \{2\}} 1902: 1861: 1859:{\displaystyle \tau } 1845: 1829: 1800: 1764: 1736: 1709: 1707:{\displaystyle \tau } 1686: 1663: 1661:{\displaystyle \tau } 1641: 1618: 1616:{\displaystyle \tau } 1592: 1569: 1529: 1527:{\displaystyle \tau } 1491: 1462: 1447:includes an open set 1442: 1422: 1402: 1381: 1358: 1334: 1314: 1292: 1269: 1245: 1223: 1203: 1176: 1149: 1126: 1106: 1086: 1066: 1046: 1024: 1001: 975: 952: 922: 899: 879: 856: 836: 813: 789: 769: 740: 701: 681: 653: 629: 601: 576: 554: 530: 506: 473: 450: 417: 397: 373: 345: 325: 153: 6679:Invariance of domain 6631:Euler characteristic 6605:Bundle (mathematics) 6237:Lipschutz, Seymour; 5981: 5954: 5600: 5547: 5521: 5417:Topological property 5384: 5364: 5344: 5321: 5301: 5255: 5235: 5215: 5173: 5146: 5123: 5077: 5057: 5030: 4999: 4976: 4970:equivalence relation 4952: 4932: 4924:In other words, the 4905: 4881: 4861: 4822: 4802: 4782: 4676: 4649: 4618: 4598: 4578: 4546: 4511: 4477: 4435: 4411: 4385: 4350: 4344:lower limit topology 4337:cocountable topology 4241: 4212: 4138: 4106: 4086: 4062: 4019: 3990: 3957: 3924: 3908:is generated by the 3890: 3861: 3766:, which denotes the 3715: 3677: 3657: 3637: 3626:{\displaystyle f(x)} 3608: 3588: 3562: 3524: 3507:Continuous functions 3485: 3465: 3445: 3418: 3398: 3371: 3316: 3292: 3242: 3211: 3181: 3150: 3120: 3093: 3055: 3022: 2974: 2954: 2931: 2911: 2891: 2861: 2816: 2791: 2764: 2744: 2713: 2672: 2649: 2614: 2610:which is the family 2591: 2567: 2510: 2485: 2465: 2355: 2302: 2277: 2257: 2174: 2151: 2090: 2059: 2027: 1995: 1963: 1937: 1911: 1870: 1850: 1812: 1777: 1747: 1722: 1698: 1672: 1652: 1627: 1607: 1578: 1558: 1518: 1471: 1451: 1431: 1411: 1391: 1367: 1347: 1323: 1303: 1278: 1258: 1232: 1212: 1187: 1162: 1135: 1115: 1095: 1075: 1055: 1035: 1010: 990: 961: 935: 908: 888: 865: 845: 825: 798: 778: 749: 710: 690: 670: 638: 618: 586: 565: 539: 519: 482: 459: 426: 406: 386: 358: 334: 314: 180:Carl Friedrich Gauss 124: 6689:Tychonoff's theorem 6684:PoincarĂ© conjecture 6438:General (point-set) 6376:"Topological space" 6077:1986InMat..84...91C 5810:(Online ed.). 5696:Space (mathematics) 5017:equivalence classes 4165:functional analysis 3848:normed vector space 3513:Continuous function 3073:accumulation points 2990:are the open sets. 1250:is defined to be a 350:are usually called 6807:Topological spaces 6674:De Rham cohomology 6595:Polyhedral complex 6585:Simplicial complex 6200:Algebraic Topology 6085:10.1007/BF01388734 5994: 5967: 5606: 5586: 5533: 5513:canonical preorder 5506:: In a space the 5494:spectrum of a ring 5460:topological groups 5443:algebraic topology 5397: 5370: 5350: 5333:{\displaystyle K,} 5330: 5307: 5287: 5241: 5221: 5189: 5159: 5135:{\displaystyle X,} 5132: 5109: 5063: 5042:{\displaystyle X,} 5039: 5005: 4988:{\displaystyle X.} 4985: 4958: 4938: 4917:{\displaystyle f.} 4914: 4887: 4867: 4840: 4808: 4788: 4692: 4662: 4627: 4604: 4584: 4564: 4532: 4498: 4459: 4417: 4393: 4371: 4259: 4227: 4202:spectrum of a ring 4191:simplicial complex 4150:{\displaystyle X.} 4147: 4124: 4092: 4068: 4054:List of topologies 4034: 4001: 3972: 3939: 3898: 3872: 3721: 3701: 3663: 3643: 3623: 3594: 3574: 3542: 3497:{\displaystyle F.} 3494: 3471: 3451: 3430:{\displaystyle F,} 3427: 3404: 3383:{\displaystyle X,} 3380: 3357: 3298: 3258: 3224: 3197: 3163: 3136: 3106: 3061: 3034:{\displaystyle X.} 3031: 2980: 2960: 2943:{\displaystyle X.} 2940: 2917: 2897: 2867: 2857:The empty set and 2825: 2802: 2772: 2750: 2730: 2690: 2661:{\displaystyle X.} 2658: 2635: 2603:{\displaystyle X,} 2600: 2573: 2549: 2497:{\displaystyle X.} 2494: 2471: 2461:of six subsets of 2451: 2341: 2289:{\displaystyle X.} 2286: 2263: 2243: 2157: 2129: 2083: 2071: 2045: 2013: 1981: 1949: 1923: 1897: 1856: 1824: 1795: 1759: 1734:{\displaystyle X.} 1731: 1704: 1681: 1658: 1636: 1613: 1587: 1564: 1524: 1486: 1457: 1437: 1417: 1397: 1379:{\displaystyle U.} 1376: 1353: 1329: 1309: 1290:{\displaystyle x.} 1287: 1264: 1240: 1218: 1198: 1174:{\displaystyle X.} 1171: 1147:{\displaystyle M.} 1144: 1121: 1101: 1081: 1061: 1041: 1031:Any neighbourhood 1022:{\displaystyle x.} 1019: 996: 973:{\displaystyle x.} 970: 947: 920:{\displaystyle x.} 917: 894: 877:{\displaystyle x,} 874: 851: 831: 808: 784: 764: 735: 696: 676: 648: 624: 596: 571: 561:neighbourhoods of 549: 525: 501: 471:{\displaystyle X.} 468: 445: 412: 392: 382:assigning to each 368: 340: 320: 148: 99:point-set topology 68:mathematical space 6789: 6788: 6578:fundamental group 6151:Bourbaki, Nicolas 5936:978-93-325-4953-1 5903:, definition 2.1. 5818:(Subscription or 5643:Convergence space 5468:topological rings 5458:concepts such as 5455:algebraic objects 5439:separation axioms 5373:{\displaystyle K} 5353:{\displaystyle X} 5310:{\displaystyle X} 5244:{\displaystyle n} 5224:{\displaystyle X} 5066:{\displaystyle n} 5024:Vietoris topology 5008:{\displaystyle f} 4961:{\displaystyle f} 4941:{\displaystyle Y} 4926:quotient topology 4890:{\displaystyle Y} 4870:{\displaystyle Y} 4818:is a set, and if 4811:{\displaystyle Y} 4791:{\displaystyle X} 4756:subspace topology 4752: 4751: 4747: 4729:Vietoris topology 4381:This topology on 4323:cofinite topology 4206:algebraic variety 4134:is a topology on 4095:{\displaystyle X} 3811:discrete topology 3724:{\displaystyle f} 3666:{\displaystyle x} 3646:{\displaystyle M} 3597:{\displaystyle N} 3474:{\displaystyle X} 3454:{\displaystyle F} 3407:{\displaystyle F} 3301:{\displaystyle X} 3064:{\displaystyle X} 2994:Other definitions 2983:{\displaystyle X} 2900:{\displaystyle X} 2870:{\displaystyle X} 2576:{\displaystyle X} 2561:discrete topology 2474:{\displaystyle X} 2266:{\displaystyle X} 2160:{\displaystyle X} 1574:itself belong to 1567:{\displaystyle X} 1460:{\displaystyle U} 1440:{\displaystyle N} 1420:{\displaystyle x} 1400:{\displaystyle N} 1356:{\displaystyle U} 1339:is defined to be 1332:{\displaystyle X} 1312:{\displaystyle U} 1267:{\displaystyle x} 1254:of a real number 1221:{\displaystyle N} 1124:{\displaystyle N} 1104:{\displaystyle x} 1084:{\displaystyle M} 1064:{\displaystyle x} 1044:{\displaystyle N} 999:{\displaystyle x} 897:{\displaystyle N} 854:{\displaystyle X} 834:{\displaystyle N} 787:{\displaystyle X} 699:{\displaystyle x} 679:{\displaystyle N} 660:topological space 627:{\displaystyle X} 574:{\displaystyle x} 528:{\displaystyle x} 415:{\displaystyle X} 395:{\displaystyle x} 343:{\displaystyle X} 323:{\displaystyle X} 176:boosted the study 162:, and hence of a 160:convex polyhedron 29:geometrical space 25:topological space 6814: 6802:General topology 6779: 6778: 6752: 6751: 6742: 6732: 6722: 6721: 6710: 6709: 6504: 6417: 6410: 6403: 6394: 6389: 6364: 6350:General Topology 6343: 6300: 6234: 6225: 6181: 6129: 6097: 6096: 6060: 6044: 6038: 6037: 6003: 6001: 6000: 5995: 5993: 5992: 5977:-complements of 5976: 5974: 5973: 5968: 5966: 5965: 5947: 5941: 5940: 5922: 5916: 5910: 5904: 5898: 5892: 5886: 5880: 5874: 5868: 5867: 5858: 5856: 5834:Hausdorff, Felix 5830: 5824: 5823: 5815: 5803: 5796: 5790: 5787: 5781: 5775: 5766: 5760: 5754: 5753: 5725: 5719: 5713: 5692: 5683: 5615: 5613: 5612: 5607: 5595: 5593: 5592: 5587: 5542: 5540: 5539: 5534: 5406: 5404: 5403: 5398: 5396: 5395: 5379: 5377: 5376: 5371: 5359: 5357: 5356: 5351: 5339: 5337: 5336: 5331: 5316: 5314: 5313: 5308: 5297:of open sets in 5296: 5294: 5293: 5288: 5286: 5285: 5267: 5266: 5250: 5248: 5247: 5242: 5230: 5228: 5227: 5222: 5198: 5196: 5195: 5190: 5185: 5184: 5168: 5166: 5165: 5160: 5158: 5157: 5141: 5139: 5138: 5133: 5119:of open sets in 5118: 5116: 5115: 5110: 5108: 5107: 5089: 5088: 5072: 5070: 5069: 5064: 5051:Leopold Vietoris 5048: 5046: 5045: 5040: 5014: 5012: 5011: 5006: 4994: 4992: 4991: 4986: 4967: 4965: 4964: 4959: 4947: 4945: 4944: 4939: 4923: 4921: 4920: 4915: 4896: 4894: 4893: 4888: 4876: 4874: 4873: 4868: 4849: 4847: 4846: 4841: 4817: 4815: 4814: 4809: 4797: 4795: 4794: 4789: 4764:product topology 4743: 4717: 4716: 4709: 4701: 4699: 4698: 4693: 4688: 4687: 4671: 4669: 4668: 4663: 4661: 4660: 4636: 4634: 4633: 4628: 4614:are elements of 4613: 4611: 4610: 4605: 4593: 4591: 4590: 4585: 4573: 4571: 4570: 4565: 4541: 4539: 4538: 4533: 4507: 4505: 4504: 4499: 4468: 4466: 4465: 4460: 4426: 4424: 4423: 4418: 4402: 4400: 4399: 4394: 4392: 4380: 4378: 4377: 4372: 4301:SierpiĹ„ski space 4268: 4266: 4265: 4260: 4255: 4254: 4249: 4236: 4234: 4233: 4228: 4226: 4225: 4220: 4198:Zariski topology 4183:natural topology 4161:linear operators 4156: 4154: 4153: 4148: 4133: 4131: 4130: 4125: 4101: 4099: 4098: 4093: 4077: 4075: 4074: 4069: 4043: 4041: 4040: 4035: 4033: 4032: 4027: 4010: 4008: 4007: 4002: 3997: 3981: 3979: 3978: 3973: 3971: 3970: 3965: 3948: 3946: 3945: 3940: 3938: 3937: 3932: 3919:Euclidean spaces 3907: 3905: 3904: 3899: 3897: 3881: 3879: 3878: 3873: 3868: 3819:Hausdorff spaces 3815:trivial topology 3730: 3728: 3727: 3722: 3710: 3708: 3707: 3702: 3672: 3670: 3669: 3664: 3652: 3650: 3649: 3644: 3632: 3630: 3629: 3624: 3603: 3601: 3600: 3595: 3583: 3581: 3580: 3575: 3551: 3549: 3548: 3543: 3503: 3501: 3500: 3495: 3480: 3478: 3477: 3472: 3460: 3458: 3457: 3452: 3436: 3434: 3433: 3428: 3413: 3411: 3410: 3405: 3389: 3387: 3386: 3381: 3366: 3364: 3363: 3358: 3356: 3352: 3339: 3338: 3310:complete lattice 3307: 3305: 3304: 3299: 3267: 3265: 3264: 3259: 3254: 3253: 3233: 3231: 3230: 3225: 3223: 3222: 3206: 3204: 3203: 3198: 3193: 3192: 3172: 3170: 3169: 3164: 3162: 3161: 3145: 3143: 3142: 3137: 3132: 3131: 3115: 3113: 3112: 3107: 3105: 3104: 3070: 3068: 3067: 3062: 3040: 3038: 3037: 3032: 2989: 2987: 2986: 2981: 2969: 2967: 2966: 2961: 2949: 2947: 2946: 2941: 2926: 2924: 2923: 2918: 2906: 2904: 2903: 2898: 2876: 2874: 2873: 2868: 2845:de Morgan's laws 2834: 2832: 2831: 2826: 2811: 2809: 2808: 2803: 2798: 2781: 2779: 2778: 2773: 2771: 2759: 2757: 2756: 2751: 2739: 2737: 2736: 2731: 2726: 2699: 2697: 2696: 2691: 2667: 2665: 2664: 2659: 2644: 2642: 2641: 2636: 2609: 2607: 2606: 2601: 2582: 2580: 2579: 2574: 2558: 2556: 2555: 2550: 2503: 2501: 2500: 2495: 2480: 2478: 2477: 2472: 2460: 2458: 2457: 2452: 2350: 2348: 2347: 2342: 2295: 2293: 2292: 2287: 2272: 2270: 2269: 2264: 2252: 2250: 2249: 2244: 2166: 2164: 2163: 2158: 2138: 2136: 2135: 2130: 2080: 2078: 2077: 2072: 2054: 2052: 2051: 2046: 2022: 2020: 2019: 2014: 1990: 1988: 1987: 1982: 1958: 1956: 1955: 1950: 1932: 1930: 1929: 1924: 1906: 1904: 1903: 1898: 1865: 1863: 1862: 1857: 1834:is an open set. 1833: 1831: 1830: 1825: 1804: 1802: 1801: 1796: 1768: 1766: 1765: 1760: 1740: 1738: 1737: 1732: 1713: 1711: 1710: 1705: 1690: 1688: 1687: 1682: 1667: 1665: 1664: 1659: 1645: 1643: 1642: 1637: 1622: 1620: 1619: 1614: 1596: 1594: 1593: 1588: 1573: 1571: 1570: 1565: 1541: 1533: 1531: 1530: 1525: 1513: 1495: 1493: 1492: 1487: 1466: 1464: 1463: 1458: 1446: 1444: 1443: 1438: 1426: 1424: 1423: 1418: 1406: 1404: 1403: 1398: 1385: 1383: 1382: 1377: 1362: 1360: 1359: 1354: 1338: 1336: 1335: 1330: 1318: 1316: 1315: 1310: 1296: 1294: 1293: 1288: 1273: 1271: 1270: 1265: 1249: 1247: 1246: 1241: 1239: 1227: 1225: 1224: 1219: 1207: 1205: 1204: 1199: 1194: 1180: 1178: 1177: 1172: 1153: 1151: 1150: 1145: 1130: 1128: 1127: 1122: 1110: 1108: 1107: 1102: 1090: 1088: 1087: 1082: 1070: 1068: 1067: 1062: 1050: 1048: 1047: 1042: 1028: 1026: 1025: 1020: 1005: 1003: 1002: 997: 979: 977: 976: 971: 956: 954: 953: 948: 926: 924: 923: 918: 903: 901: 900: 895: 883: 881: 880: 875: 860: 858: 857: 852: 840: 838: 837: 832: 817: 815: 814: 809: 807: 806: 793: 791: 790: 785: 773: 771: 770: 765: 744: 742: 741: 736: 725: 724: 705: 703: 702: 697: 685: 683: 682: 677: 657: 655: 654: 649: 647: 646: 633: 631: 630: 625: 605: 603: 602: 597: 595: 594: 582:). The function 580: 578: 577: 572: 558: 556: 555: 550: 548: 547: 535:with respect to 534: 532: 531: 526: 510: 508: 507: 502: 491: 490: 478:The elements of 477: 475: 474: 469: 454: 452: 451: 446: 435: 434: 421: 419: 418: 413: 401: 399: 398: 393: 377: 375: 374: 369: 367: 366: 349: 347: 346: 341: 329: 327: 326: 321: 215:Erlangen Program 170:(1789–1857) and 157: 155: 154: 149: 103:general topology 84:Euclidean spaces 6822: 6821: 6817: 6816: 6815: 6813: 6812: 6811: 6792: 6791: 6790: 6785: 6716: 6698: 6694:Urysohn's lemma 6655: 6619: 6505: 6496: 6468:low-dimensional 6426: 6421: 6374: 6371: 6361: 6346: 6340: 6327: 6298: 6285: 6270:Runde, Volker; 6228: 6214:Gallier, Jean; 6213: 6196:Fulton, William 6178: 6160: 6133:Bredon, Glen E. 6126: 6109: 6106: 6101: 6100: 6058: 6052:Vogtmann, Karen 6046: 6045: 6041: 6018:10.2307/2037491 5984: 5979: 5978: 5957: 5952: 5951: 5949: 5948: 5944: 5937: 5924: 5923: 5919: 5911: 5907: 5899: 5895: 5887: 5883: 5875: 5871: 5854: 5852: 5850: 5832: 5831: 5827: 5817: 5798: 5797: 5793: 5788: 5784: 5776: 5769: 5761: 5757: 5742: 5727: 5726: 5722: 5714: 5710: 5705: 5690: 5681: 5672:Linear subspace 5654:Hausdorff space 5627: 5598: 5597: 5545: 5544: 5543:if and only if 5519: 5518: 5480: 5451: 5419: 5413: 5387: 5382: 5381: 5362: 5361: 5342: 5341: 5319: 5318: 5299: 5298: 5277: 5258: 5253: 5252: 5233: 5232: 5213: 5212: 5207:locally compact 5176: 5171: 5170: 5149: 5144: 5143: 5121: 5120: 5099: 5080: 5075: 5074: 5055: 5054: 5028: 5027: 4997: 4996: 4974: 4973: 4950: 4949: 4930: 4929: 4903: 4902: 4897:that have open 4879: 4878: 4859: 4858: 4820: 4819: 4800: 4799: 4780: 4779: 4748: 4718: 4714: 4707: 4679: 4674: 4673: 4652: 4647: 4646: 4616: 4615: 4596: 4595: 4576: 4575: 4544: 4543: 4509: 4508: 4475: 4474: 4433: 4432: 4431:, then the set 4409: 4408: 4383: 4382: 4348: 4347: 4330: 4307:and semantics. 4244: 4239: 4238: 4215: 4210: 4209: 4136: 4135: 4104: 4103: 4084: 4083: 4060: 4059: 4056: 4050: 4022: 4017: 4016: 4013:complex numbers 3988: 3987: 3960: 3955: 3954: 3927: 3922: 3921: 3888: 3887: 3859: 3858: 3833: 3827: 3807: 3795:homology theory 3791:homotopy theory 3756:category theory 3713: 3712: 3675: 3674: 3655: 3654: 3635: 3634: 3606: 3605: 3586: 3585: 3560: 3559: 3522: 3521: 3515: 3509: 3483: 3482: 3463: 3462: 3443: 3442: 3416: 3415: 3396: 3395: 3369: 3368: 3330: 3329: 3325: 3314: 3313: 3290: 3289: 3245: 3240: 3239: 3214: 3209: 3208: 3184: 3179: 3178: 3153: 3148: 3147: 3123: 3118: 3117: 3096: 3091: 3090: 3087: 3081: 3071:the set of its 3053: 3052: 3020: 3019: 2996: 2972: 2971: 2952: 2951: 2929: 2928: 2909: 2908: 2889: 2888: 2859: 2858: 2841: 2814: 2813: 2789: 2788: 2762: 2761: 2742: 2741: 2711: 2710: 2670: 2669: 2647: 2646: 2612: 2611: 2589: 2588: 2565: 2564: 2508: 2507: 2483: 2482: 2463: 2462: 2353: 2352: 2300: 2299: 2275: 2274: 2255: 2254: 2172: 2171: 2149: 2148: 2088: 2087: 2057: 2056: 2025: 2024: 1993: 1992: 1961: 1960: 1935: 1934: 1909: 1908: 1868: 1867: 1848: 1847: 1840: 1810: 1809: 1775: 1774: 1745: 1744: 1720: 1719: 1696: 1695: 1670: 1669: 1650: 1649: 1625: 1624: 1605: 1604: 1576: 1575: 1556: 1555: 1539: 1516: 1515: 1511: 1501: 1469: 1468: 1449: 1448: 1429: 1428: 1409: 1408: 1389: 1388: 1365: 1364: 1345: 1344: 1321: 1320: 1301: 1300: 1276: 1275: 1256: 1255: 1230: 1229: 1210: 1209: 1208:where a subset 1185: 1184: 1160: 1159: 1133: 1132: 1113: 1112: 1093: 1092: 1073: 1072: 1053: 1052: 1033: 1032: 1008: 1007: 988: 987: 959: 958: 933: 932: 906: 905: 886: 885: 863: 862: 843: 842: 841:is a subset of 823: 822: 796: 795: 776: 775: 747: 746: 708: 707: 688: 687: 668: 667: 636: 635: 616: 615: 584: 583: 563: 562: 537: 536: 517: 516: 511:will be called 480: 479: 457: 456: 424: 423: 404: 403: 384: 383: 356: 355: 332: 331: 312: 311: 308:Felix Hausdorff 304: 272: 266: 258:metrischer Raum 250:Maurice FrĂ©chet 242:Felix Hausdorff 231:Hassler Whitney 122: 121: 117:discovered the 111: 17: 12: 11: 5: 6820: 6818: 6810: 6809: 6804: 6794: 6793: 6787: 6786: 6784: 6783: 6773: 6772: 6771: 6766: 6761: 6746: 6736: 6726: 6714: 6703: 6700: 6699: 6697: 6696: 6691: 6686: 6681: 6676: 6671: 6665: 6663: 6657: 6656: 6654: 6653: 6648: 6643: 6641:Winding number 6638: 6633: 6627: 6625: 6621: 6620: 6618: 6617: 6612: 6607: 6602: 6597: 6592: 6587: 6582: 6581: 6580: 6575: 6573:homotopy group 6565: 6564: 6563: 6558: 6553: 6548: 6543: 6533: 6528: 6523: 6513: 6511: 6507: 6506: 6499: 6497: 6495: 6494: 6489: 6484: 6483: 6482: 6472: 6471: 6470: 6460: 6455: 6450: 6445: 6440: 6434: 6432: 6428: 6427: 6422: 6420: 6419: 6412: 6405: 6397: 6391: 6390: 6370: 6369:External links 6367: 6366: 6365: 6359: 6344: 6338: 6325: 6304:Steen, Lynn A. 6301: 6296: 6283: 6268: 6253:Munkres, James 6250: 6235: 6226: 6211: 6193: 6183: 6176: 6158: 6148: 6130: 6124: 6112:Basic Topology 6105: 6102: 6099: 6098: 6039: 5991: 5987: 5964: 5960: 5942: 5935: 5917: 5915:, theorem 2.6. 5913:Armstrong 1983 5905: 5901:Armstrong 1983 5893: 5891:, section 2.2. 5881: 5879:, section 2.1. 5869: 5848: 5825: 5801:"metric space" 5791: 5782: 5767: 5755: 5740: 5720: 5707: 5706: 5704: 5701: 5700: 5699: 5693: 5684: 5675: 5669: 5666:Hemicontinuity 5663: 5657: 5651: 5649:Exterior space 5646: 5640: 5634: 5626: 5623: 5622: 5621: 5605: 5585: 5582: 5579: 5576: 5573: 5570: 5567: 5564: 5561: 5558: 5555: 5552: 5532: 5529: 5526: 5517:is defined by 5501: 5479: 5476: 5450: 5447: 5437:, and various 5415:Main article: 5412: 5409: 5394: 5390: 5369: 5349: 5329: 5326: 5306: 5284: 5280: 5276: 5273: 5270: 5265: 5261: 5240: 5220: 5188: 5183: 5179: 5156: 5152: 5131: 5128: 5106: 5102: 5098: 5095: 5092: 5087: 5083: 5062: 5038: 5035: 5004: 4984: 4981: 4957: 4937: 4913: 4910: 4899:inverse images 4886: 4866: 4839: 4836: 4833: 4830: 4827: 4807: 4787: 4776:quotient space 4760:indexed family 4750: 4749: 4721: 4719: 4712: 4706: 4703: 4691: 4686: 4682: 4659: 4655: 4626: 4623: 4603: 4583: 4563: 4560: 4557: 4554: 4551: 4531: 4528: 4525: 4522: 4519: 4516: 4497: 4494: 4491: 4488: 4485: 4482: 4471:order topology 4458: 4455: 4452: 4449: 4446: 4443: 4440: 4429:ordinal number 4416: 4391: 4370: 4367: 4364: 4361: 4358: 4355: 4328: 4273:of systems of 4258: 4253: 4248: 4224: 4219: 4146: 4143: 4123: 4120: 4117: 4114: 4111: 4091: 4067: 4049: 4046: 4031: 4026: 4000: 3996: 3986:. Similarly, 3969: 3964: 3951:usual topology 3936: 3931: 3910:open intervals 3896: 3871: 3867: 3829:Main article: 3826: 3823: 3806: 3803: 3750: 3720: 3700: 3697: 3694: 3691: 3688: 3685: 3682: 3662: 3642: 3622: 3619: 3616: 3613: 3593: 3573: 3570: 3567: 3541: 3538: 3535: 3532: 3529: 3511:Main article: 3508: 3505: 3493: 3490: 3470: 3450: 3426: 3423: 3403: 3379: 3376: 3355: 3351: 3348: 3345: 3342: 3337: 3333: 3328: 3324: 3321: 3297: 3284: 3280: 3276: 3272: 3257: 3252: 3248: 3237: 3221: 3217: 3196: 3191: 3187: 3176: 3160: 3156: 3146:one says that 3135: 3130: 3126: 3103: 3099: 3083:Main article: 3080: 3077: 3075:is specified. 3060: 3030: 3027: 2995: 2992: 2979: 2959: 2939: 2936: 2916: 2896: 2885: 2884: 2881: 2878: 2866: 2840: 2837: 2836: 2835: 2824: 2821: 2801: 2797: 2785: 2770: 2749: 2729: 2725: 2721: 2718: 2707: 2703:discrete space 2689: 2686: 2683: 2680: 2677: 2657: 2654: 2634: 2631: 2628: 2625: 2622: 2619: 2599: 2596: 2572: 2548: 2545: 2542: 2539: 2536: 2533: 2530: 2527: 2524: 2521: 2518: 2515: 2504: 2493: 2490: 2470: 2450: 2447: 2444: 2441: 2438: 2435: 2432: 2429: 2426: 2423: 2420: 2417: 2414: 2411: 2408: 2405: 2402: 2399: 2396: 2393: 2390: 2387: 2384: 2381: 2378: 2375: 2372: 2369: 2366: 2363: 2360: 2340: 2337: 2334: 2331: 2328: 2325: 2322: 2319: 2316: 2313: 2310: 2307: 2296: 2285: 2282: 2262: 2242: 2239: 2236: 2233: 2230: 2227: 2224: 2221: 2218: 2215: 2212: 2209: 2206: 2203: 2200: 2197: 2194: 2191: 2188: 2185: 2182: 2179: 2156: 2146: 2128: 2125: 2122: 2119: 2116: 2113: 2110: 2107: 2104: 2101: 2098: 2095: 2081:], is missing. 2070: 2067: 2064: 2044: 2041: 2038: 2035: 2032: 2012: 2009: 2006: 2003: 2000: 1980: 1977: 1974: 1971: 1968: 1948: 1945: 1942: 1922: 1919: 1916: 1896: 1893: 1890: 1887: 1884: 1881: 1878: 1875: 1855: 1839: 1836: 1823: 1820: 1817: 1794: 1791: 1788: 1785: 1782: 1772: 1769:is said to be 1758: 1755: 1752: 1730: 1727: 1703: 1692: 1691: 1680: 1677: 1657: 1646: 1635: 1632: 1612: 1603:of members of 1597: 1586: 1583: 1563: 1523: 1500: 1497: 1485: 1482: 1479: 1476: 1456: 1436: 1416: 1396: 1375: 1372: 1352: 1328: 1308: 1286: 1283: 1263: 1253: 1238: 1217: 1197: 1193: 1170: 1167: 1155: 1154: 1143: 1140: 1120: 1100: 1080: 1060: 1040: 1029: 1018: 1015: 995: 980: 969: 966: 946: 943: 940: 916: 913: 893: 873: 870: 850: 830: 819: 805: 783: 763: 760: 757: 754: 734: 731: 728: 723: 718: 715: 695: 675: 645: 623: 593: 581: 570: 546: 524: 514: 513:neighbourhoods 500: 497: 494: 489: 467: 464: 455:of subsets of 444: 441: 438: 433: 411: 391: 365: 353: 339: 319: 303: 300: 297: 295:neighbourhoods 291: 284:axiomatization 268:Main article: 265: 262: 223:Henri PoincarĂ© 147: 144: 141: 138: 135: 132: 129: 115:Leonhard Euler 110: 107: 53:neighbourhoods 15: 13: 10: 9: 6: 4: 3: 2: 6819: 6808: 6805: 6803: 6800: 6799: 6797: 6782: 6774: 6770: 6767: 6765: 6762: 6760: 6757: 6756: 6755: 6747: 6745: 6741: 6737: 6735: 6731: 6727: 6725: 6720: 6715: 6713: 6705: 6704: 6701: 6695: 6692: 6690: 6687: 6685: 6682: 6680: 6677: 6675: 6672: 6670: 6667: 6666: 6664: 6662: 6658: 6652: 6651:Orientability 6649: 6647: 6644: 6642: 6639: 6637: 6634: 6632: 6629: 6628: 6626: 6622: 6616: 6613: 6611: 6608: 6606: 6603: 6601: 6598: 6596: 6593: 6591: 6588: 6586: 6583: 6579: 6576: 6574: 6571: 6570: 6569: 6566: 6562: 6559: 6557: 6554: 6552: 6549: 6547: 6544: 6542: 6539: 6538: 6537: 6534: 6532: 6529: 6527: 6524: 6522: 6518: 6515: 6514: 6512: 6508: 6503: 6493: 6490: 6488: 6487:Set-theoretic 6485: 6481: 6478: 6477: 6476: 6473: 6469: 6466: 6465: 6464: 6461: 6459: 6456: 6454: 6451: 6449: 6448:Combinatorial 6446: 6444: 6441: 6439: 6436: 6435: 6433: 6429: 6425: 6418: 6413: 6411: 6406: 6404: 6399: 6398: 6395: 6387: 6383: 6382: 6377: 6373: 6372: 6368: 6362: 6360:0-486-43479-6 6356: 6352: 6351: 6345: 6341: 6335: 6331: 6326: 6323: 6322:0-03-079485-4 6319: 6315: 6314: 6309: 6305: 6302: 6299: 6297:0-356-02077-0 6293: 6289: 6284: 6281: 6280:0-387-25790-X 6277: 6273: 6269: 6266: 6265:0-13-181629-2 6262: 6258: 6254: 6251: 6248: 6247:0-07-037988-2 6244: 6240: 6236: 6232: 6227: 6223: 6222: 6217: 6212: 6209: 6208:0-387-94327-7 6205: 6201: 6197: 6194: 6191: 6187: 6184: 6179: 6177:1-4196-2722-8 6173: 6170:. Booksurge. 6169: 6168: 6163: 6162:Brown, Ronald 6159: 6156: 6152: 6149: 6146: 6145:0-387-97926-3 6142: 6138: 6134: 6131: 6127: 6125:0-387-90839-0 6121: 6117: 6113: 6108: 6107: 6103: 6094: 6090: 6086: 6082: 6078: 6074: 6071:(1): 91–119. 6070: 6066: 6065: 6057: 6053: 6049: 6043: 6040: 6035: 6031: 6027: 6023: 6019: 6015: 6011: 6007: 6004:topologies". 5989: 5985: 5962: 5958: 5946: 5943: 5938: 5932: 5928: 5921: 5918: 5914: 5909: 5906: 5902: 5897: 5894: 5890: 5885: 5882: 5878: 5873: 5870: 5866: 5864: 5851: 5849:9783110989854 5845: 5841: 5840: 5835: 5829: 5826: 5821: 5813: 5809: 5808: 5802: 5795: 5792: 5786: 5783: 5779: 5774: 5772: 5768: 5764: 5759: 5756: 5751: 5747: 5743: 5741:0-19-853155-9 5737: 5733: 5732: 5724: 5721: 5717: 5716:Schubert 1968 5712: 5709: 5702: 5697: 5694: 5688: 5685: 5679: 5676: 5673: 5670: 5667: 5664: 5661: 5660:Hilbert space 5658: 5655: 5652: 5650: 5647: 5644: 5641: 5638: 5637:Compact space 5635: 5632: 5629: 5628: 5624: 5619: 5603: 5583: 5577: 5571: 5568: 5565: 5559: 5553: 5550: 5530: 5527: 5524: 5516: 5514: 5510: 5505: 5502: 5499: 5495: 5491: 5490: 5486:: A space is 5485: 5482: 5481: 5477: 5475: 5473: 5469: 5465: 5461: 5456: 5448: 5446: 5444: 5440: 5436: 5432: 5431:connectedness 5428: 5424: 5418: 5410: 5408: 5392: 5388: 5367: 5347: 5327: 5324: 5304: 5282: 5278: 5274: 5271: 5268: 5263: 5259: 5238: 5218: 5211: 5208: 5204: 5203:Fell topology 5199: 5186: 5181: 5177: 5154: 5150: 5129: 5126: 5104: 5100: 5096: 5093: 5090: 5085: 5081: 5060: 5052: 5036: 5033: 5025: 5020: 5018: 5002: 4982: 4979: 4971: 4955: 4935: 4927: 4911: 4908: 4900: 4884: 4864: 4856: 4853: 4837: 4831: 4828: 4825: 4805: 4785: 4777: 4772: 4769: 4765: 4761: 4757: 4746: 4741: 4737: 4736: 4735:Fell topology 4731: 4730: 4725: 4720: 4711: 4710: 4704: 4702: 4689: 4684: 4680: 4657: 4653: 4645: 4641: 4637: 4624: 4621: 4601: 4581: 4558: 4555: 4552: 4529: 4523: 4520: 4517: 4495: 4489: 4486: 4483: 4472: 4453: 4450: 4447: 4441: 4438: 4430: 4414: 4405: 4368: 4362: 4359: 4356: 4345: 4340: 4338: 4333: 4331: 4324: 4319: 4317: 4313: 4308: 4306: 4302: 4297: 4295: 4291: 4287: 4283: 4278: 4276: 4272: 4271:solution sets 4256: 4251: 4222: 4207: 4203: 4199: 4194: 4192: 4188: 4184: 4180: 4175: 4173: 4168: 4166: 4162: 4159:Many sets of 4157: 4144: 4141: 4118: 4089: 4081: 4055: 4047: 4045: 4029: 4014: 3998: 3985: 3967: 3952: 3934: 3920: 3915: 3911: 3885: 3869: 3855: 3853: 3849: 3845: 3840: 3838: 3832: 3825:Metric spaces 3824: 3822: 3820: 3816: 3812: 3804: 3802: 3800: 3796: 3792: 3788: 3784: 3783:homeomorphism 3781: 3777: 3773: 3769: 3765: 3761: 3757: 3752: 3748: 3746: 3742: 3738: 3737:homeomorphism 3734: 3733:inverse image 3718: 3698: 3695: 3692: 3686: 3680: 3660: 3640: 3617: 3611: 3591: 3571: 3568: 3565: 3558:if for every 3557: 3556: 3539: 3533: 3530: 3527: 3520: 3514: 3506: 3504: 3491: 3488: 3468: 3448: 3440: 3424: 3421: 3401: 3393: 3377: 3374: 3353: 3349: 3346: 3343: 3340: 3335: 3331: 3326: 3322: 3319: 3311: 3295: 3286: 3282: 3278: 3274: 3270: 3255: 3250: 3246: 3235: 3219: 3215: 3194: 3189: 3185: 3174: 3158: 3154: 3133: 3128: 3124: 3101: 3097: 3086: 3078: 3076: 3074: 3058: 3050: 3046: 3041: 3028: 3025: 3017: 3013: 3009: 3005: 3000: 2993: 2991: 2977: 2957: 2937: 2934: 2914: 2894: 2882: 2879: 2864: 2856: 2855: 2854: 2852: 2851: 2846: 2838: 2822: 2819: 2799: 2783: 2747: 2727: 2719: 2716: 2708: 2705: 2704: 2684: 2681: 2678: 2655: 2652: 2629: 2620: 2617: 2597: 2594: 2586: 2570: 2562: 2546: 2540: 2537: 2534: 2531: 2528: 2525: 2522: 2516: 2513: 2505: 2491: 2488: 2468: 2445: 2442: 2436: 2433: 2430: 2427: 2424: 2418: 2412: 2409: 2406: 2400: 2394: 2391: 2388: 2382: 2376: 2370: 2361: 2358: 2338: 2332: 2329: 2326: 2323: 2320: 2317: 2314: 2308: 2305: 2297: 2283: 2280: 2260: 2237: 2234: 2225: 2216: 2213: 2210: 2207: 2204: 2201: 2198: 2192: 2180: 2177: 2170: 2154: 2144: 2142: 2126: 2120: 2117: 2114: 2111: 2108: 2105: 2102: 2096: 2093: 2085: 2084: 2065: 2039: 2036: 2033: 2007: 2004: 2001: 1975: 1972: 1969: 1943: 1917: 1894: 1888: 1885: 1882: 1879: 1876: 1853: 1844: 1837: 1835: 1821: 1815: 1808: 1789: 1786: 1783: 1770: 1756: 1753: 1750: 1741: 1728: 1725: 1717: 1701: 1678: 1675: 1655: 1647: 1633: 1630: 1610: 1602: 1598: 1584: 1581: 1561: 1553: 1549: 1548: 1547: 1545: 1537: 1521: 1510: 1506: 1498: 1496: 1483: 1480: 1477: 1474: 1454: 1434: 1414: 1394: 1373: 1370: 1350: 1342: 1326: 1306: 1297: 1284: 1281: 1261: 1252:neighbourhood 1251: 1215: 1195: 1181: 1168: 1165: 1141: 1138: 1118: 1098: 1078: 1058: 1038: 1030: 1016: 1013: 993: 985: 981: 967: 964: 944: 941: 938: 930: 914: 911: 891: 871: 868: 848: 828: 820: 781: 761: 758: 755: 752: 729: 716: 713: 693: 673: 665: 664: 663: 661: 621: 613: 609: 568: 560: 559:(or, simply, 522: 512: 495: 465: 462: 439: 409: 389: 381: 351: 337: 317: 309: 301: 299: 296: 293: 290: 287: 285: 281: 277: 271: 263: 261: 259: 255: 251: 247: 246:Metric spaces 243: 238: 236: 232: 228: 224: 220: 216: 212: 207: 205: 200: 196: 192: 187: 185: 181: 177: 174:(1750–1840), 173: 169: 165: 161: 145: 142: 139: 136: 133: 130: 127: 120: 116: 113:Around 1735, 108: 106: 104: 100: 95: 93: 89: 88:metric spaces 85: 81: 80:connectedness 77: 73: 69: 64: 62: 58: 54: 50: 46: 42: 38: 34: 30: 26: 22: 6781:Publications 6646:Chern number 6636:Betti number 6535: 6519: / 6510:Key concepts 6458:Differential 6379: 6349: 6330:Set Topology 6329: 6311: 6287: 6271: 6256: 6238: 6230: 6220: 6199: 6189: 6186:ÄŚech, Eduard 6166: 6154: 6136: 6118:. Springer. 6111: 6104:Bibliography 6068: 6062: 6048:Culler, Marc 6042: 6009: 6005: 5945: 5926: 5920: 5908: 5896: 5884: 5872: 5862: 5860: 5853:. Retrieved 5838: 5828: 5805: 5794: 5785: 5758: 5730: 5723: 5711: 5512: 5508: 5503: 5487: 5483: 5472:local fields 5452: 5420: 5210:Polish space 5202: 5200: 5023: 5021: 4773: 4753: 4744: 4733: 4727: 4638: 4406: 4341: 4334: 4320: 4309: 4298: 4282:linear graph 4279: 4195: 4176: 4169: 4158: 4057: 4048:Other spaces 3950: 3884:real numbers 3856: 3852:vector space 3844:metric space 3841: 3834: 3831:Metric space 3808: 3763: 3753: 3749:homeomorphic 3553: 3516: 3287: 3088: 3042: 3008:fixed points 3001: 2997: 2886: 2848: 2842: 2701: 2700:is called a 2147:topology on 1742: 1715: 1693: 1543: 1504: 1502: 1340: 1298: 1182: 1156: 984:intersection 927:I.e., every 659: 658:is called a 606:is called a 305: 275: 273: 239: 208: 204:homeomorphic 189:Yet, "until 188: 183: 164:planar graph 112: 96: 65: 24: 18: 6744:Wikiversity 6661:Key results 6224:. Springer. 5435:compactness 4745:(June 2024) 4640:Outer space 4277:equations. 4172:local field 4011:the set of 3882:the set of 2877:are closed. 2850:closed sets 2351:the family 1668:belongs to 1623:belongs to 402:(point) in 264:Definitions 211:Felix Klein 21:mathematics 6796:Categories 6590:CW complex 6531:Continuity 6521:Closed set 6480:cohomology 6339:0486404560 6216:Xu, Dianna 6190:Point Sets 5889:Brown 2006 5877:Brown 2006 5822:required.) 5763:Gauss 1827 5049:named for 4948:for which 4852:surjective 4768:projection 4644:free group 4312:finite set 4275:polynomial 4189:and every 4052:See also: 3787:invariants 3760:categories 3673:such that 3555:continuous 2782:itself is 2145:indiscrete 1807:complement 1467:such that 1111:such that 182:published 76:continuity 6769:geometric 6764:algebraic 6615:Cobordism 6551:Hausdorff 6546:connected 6463:Geometric 6453:Continuum 6443:Algebraic 6386:EMS Press 6093:122869546 6012:: 77–81. 5855:20 August 5703:Citations 5572:⁡ 5566:⊆ 5554:⁡ 5528:≤ 5500:theorem). 5272:… 5094:… 4835:→ 4622:γ 4602:β 4582:α 4559:γ 4553:α 4524:β 4490:β 4484:α 4454:γ 4439:γ 4415:γ 4122:Γ 4119:∪ 4113:∅ 4082:on a set 4066:Γ 3776:morphisms 3741:bijection 3693:⊆ 3569:∈ 3537:→ 3390:then the 3347:∈ 3344:α 3336:α 3332:τ 3247:τ 3216:τ 3186:τ 3155:τ 3125:τ 3098:τ 3016:power set 2958:τ 2915:τ 2820:τ 2748:τ 2685:τ 2624:℘ 2618:τ 2585:power set 2368:∅ 2359:τ 2232:∅ 2178:τ 1854:τ 1819:∖ 1790:τ 1754:⊆ 1743:A subset 1702:τ 1676:τ 1656:τ 1631:τ 1611:τ 1582:τ 1552:empty set 1544:open sets 1542:, called 1522:τ 1478:∈ 942:∈ 756:∈ 717:∈ 289:open sets 206:or not." 172:L'Huilier 131:− 92:manifolds 61:open sets 33:closeness 31:in which 6734:Wikibook 6712:Category 6600:Manifold 6568:Homotopy 6526:Interior 6517:Open set 6475:Homology 6424:Topology 6288:Topology 6257:Topology 6218:(2013). 6164:(2006). 6054:(1986). 5927:Topology 5625:See also 5498:Hochster 5489:spectral 5484:Spectral 5453:For any 4995:The map 4855:function 4290:vertices 4179:manifold 3799:K-theory 3519:function 3437:and the 3308:forms a 3279:stronger 3049:sequence 3012:operator 1716:topology 1505:topology 929:superset 745:), then 380:function 276:topology 213:in his " 49:topology 37:distance 6759:general 6561:uniform 6541:compact 6492:Digital 6388:, 2001 6073:Bibcode 6034:0244927 6026:2037491 5750:1679102 5718:, p. 13 5251:-tuple 5073:-tuple 4740:Discuss 4187:simplex 3772:objects 3745:inverse 3275:smaller 3236:coarser 3014:on the 2583:is the 2167:is the 2141:trivial 1805:if its 1536:subsets 706:(i.e., 610:if the 191:Riemann 119:formula 109:History 6754:Topics 6556:metric 6431:Fields 6357:  6336:  6320:  6294:  6278:  6263:  6245:  6206:  6174:  6143:  6122:  6091:  6032:  6024:  5933:  5846:  5748:  5738:  5596:where 4901:under 4574:where 4427:is an 4286:graphs 4208:. 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Index

mathematics
geometrical space
closeness
distance
set
points
topology
neighbourhoods
axioms
open sets
mathematical space
limits
continuity
connectedness
Euclidean spaces
metric spaces
manifolds
point-set topology
general topology
Leonhard Euler
formula
convex polyhedron
planar graph
Cauchy
L'Huilier
boosted the study
Carl Friedrich Gauss
Riemann
Möbius
Jordan

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