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Invariant (mathematics)

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106: 163: 1225: 43: 1402:, and thus the lengths of all three sides form a complete set of invariants for triangles. The three angle measures of a triangle are also invariant under rigid motions, but do not form a complete set as incongruent triangles can share the same angle measures. However, if one allows scaling in addition to rigid motions, then the 1338:) are invariant. For example, rotation in the plane about a point leaves the point about which it rotates invariant, while translation in the plane does not leave any points invariant, but does leave all lines parallel to the direction of translation invariant as lines. Formally, define the set of lines in the plane 1442:
defined invariant. This is the case for the Euler characteristic, and a general method for defining and computing invariants is to define them for a given presentation, and then show that they are independent of the choice of presentation. Note that there is no notion of a group action in this sense.
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example, there is currently no general automated tool that can detect that a derivation from MI to MU is impossible using only the rules 1–4. However, once the abstraction from the string to the number of its "I"s has been made by hand, leading, for example, to the following C program, an abstract
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These are connected as follows: invariants are constant on coinvariants (for example, congruent triangles have the same perimeter), while two objects which agree in the value of one invariant may or may not be congruent (for example, two triangles with the same perimeter need not be congruent). In
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This is an invariant to the problem, if for each of the transformation rules the following holds: if the invariant held before applying the rule, it will also hold after applying it. Looking at the net effect of applying the rules on the number of I's and U's, one can see this actually is the case
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that is invariant to all rules (that is, not changed by any of them), and that demonstrates that getting to MU is impossible. By looking at the puzzle from a logical standpoint, one might realize that the only way to get rid of any I's is to have three consecutive I's in the string. This makes the
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The table above shows clearly that the invariant holds for each of the possible transformation rules, which means that whichever rule one picks, at whatever state, if the number of I's was not a multiple of three before applying the rule, then it will not be afterwards either.
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In light of this, one might wonder whether it is possible to convert MI into MU, using only these four transformation rules. One could spend many hours applying these transformation rules to strings. However, it might be quicker to find a
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Given that there is a single I in the starting string MI, and one that is not a multiple of three, one can then conclude that it is impossible to go from MI to MU (as the number of I's will never be a multiple of three).
341:. In contrast, angles and ratios are not invariant under non-uniform scaling (such as stretching). The sum of a triangle's interior angles (180°) is invariant under all the above operations. As another example, all 1181: 198:
of a certain type are applied to the objects. The particular class of objects and type of transformations are usually indicated by the context in which the term is used. For example, the
981: 604: 2033: 1595:, a loop invariant has to be provided manually for each loop in the program, which is one of the reasons that this approach is generally impractical for most programs. 659: 170:
is invariant under some transformations. This one is invariant under horizontal and vertical translation, as well as rotation by 180° (but not under reflection).
1201: 683: 624: 1489:, one may ask if the property is unchanged under perturbation (for example, if an object is constant on families or invariant under change of metric). 1422:
is defined as the alternating sum of the number of cells in each dimension. One may forget the cell complex structure and look only at the underlying
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of the plane takes lines to lines – the group of rigid motions acts on the set of lines – and one may ask which lines are unchanged by an action.
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on a set, such as "radius of a circle in the plane", and then ask if this function is invariant under a group action, such as rigid motions.
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tools can compute simple invariants of given imperative computer programs. The kind of properties that can be found depend on the
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More sophisticated invariants generally have to be provided manually. In particular, when verifying an imperative program using
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Secondly, a function may be defined in terms of some presentation or decomposition of a mathematical object; for instance, the
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of a triangle is an invariant, while the set of triangles congruent to a given triangle is a coinvariant.
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to distinguish between these cases.) For example, a circle is an invariant subset of the plane under a
249:. The discovery of invariants is an important step in the process of classifying mathematical objects. 1554: 1415: 1395:, such that if two objects have the same values for this set of invariants, then they are congruent. 555: 519: 497: 285: 238: 215: 1887: 1876: 1540: 1528: 1376: 1298: 1058: 704: 627: 572: 489: 377: 183: 2436:, S.D. Swierstra (1991). "Iteratie en invariatie", Programmeren en Correctheid. Academic Service. 1430:) – as different cell complexes give the same underlying manifold, one may ask if the function is 1398:
For example, triangles such that all three sides are equal are congruent under rigid motions, via
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that are invariant under the transformation. They may, depending on the application, be called
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is a condition that is true at the beginning and the end of every iteration of a loop.
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is a good example of a logical problem where determining an invariant is of use for an
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of objects of any kind, there is a number to which we always arrive, regardless of the
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does not have this same property, as distance is not invariant under multiplication.
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The notion of invariance is formalized in three different ways in mathematics: via
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is an equation that remains true for all values of its variables. There are also
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Thirdly, if one is studying an object which varies in a family, as is common in
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Douc, Randal; Moulines, Eric; Priouret, Pierre; Soulier, Philippe (2018).
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An example derivation (with superscripts indicating the applied rules) is
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are similar: they can be transformed into each other and the ratio of the
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used. Typical example properties are single integer variable ranges like
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that is always held to be true during a certain phase of execution of a
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are unchanged, "invariant" under the group action, or under an element
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MI → MII → MIIII → MUI → MUIUI → MUIUIU → MUIUIUUIUIU → MUIUIIUIU → ...
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in terms of coordinate charts – invariants must be unchanged under
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Number of I's is unchanged. If the invariant held, it still does.
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Number of I's is unchanged. If the invariant held, it still does.
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Any three consecutive I's (III) may be replaced with a single U (
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For other uses of the word "invariant" in computer science, see
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with respect to that transformation. For example, objects with
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cannot be 0, and hence the "while"-loop will never terminate.
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A simple example of invariance is expressed in our ability to
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that remain true when the values of their variables change.
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Invariants are used in diverse areas of mathematics such as
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Property that is not changed by mathematical transformations
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Invariants are especially useful when reasoning about the
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do not change with rotation of the coordinate system (see
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are defined as transformations of the plane that preserve
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of mathematical objects) which remains unchanged after
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The number of I's in the string is not a multiple of 3
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The string after the M may be completely duplicated (M
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the same quantity to both numbers. On the other hand,
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Automatic invariant detection in imperative programs
1326:, which leaves one to determine which objects in an 2150: 2094: 1195: 1175: 975: 677: 653: 618: 598: 2559:"Applet: Visual Invariants in Sorting Algorithms" 2254:Bouajjani, A.; Drǎgoi, C.; Enea, C.; Rezine, A.; 1406:shows that this is a complete set of invariants. 1322:Frequently one will have a group acting on a set 711:If a string ends with an I, a U may be appended ( 1603:interpretation tool will be able to detect that 1550:in their code to make invariants explicit. Some 1176:{\displaystyle x\in S\Leftrightarrow T(x)\in S.} 424:is invariant under many mathematical operations. 398:is invariant under a linear change of variables. 2415:Introduction To Modern Algebra, Revised Edition 522:are invariant under orthogonal transformations. 547:is unchanged after the addition of a constant. 2295:"An axiomatic basis for computer programming" 1307:on a mathematical object (or set of objects) 869:−3 is not either. The invariant still holds. 782:following invariant interesting to consider: 353:is invariant (denoted by the Greek letter π ( 8: 2125:Representations of Finite and Compact Groups 2097:Gödel, Escher, Bach: An Eternal Golden Braid 554:of a transformation are the elements in the 409:of a topological object are invariant under 68:. There might be a discussion about this on 2217: 1580:, relations between several variables like 1253:. Unsourced material may be challenged and 444:Equiareal map § Linear transformations 2533:Probability Theory: A comprehensive course 951: 947: 847:is not either. The invariant still holds. 2274: 2128:. American Mathematical Soc. p. 16. 2009:"Invariant – Encyclopedia of Mathematics" 1273:Learn how and when to remove this message 1188: 1138: 1091:, in which case the eigenvectors span an 976:{\displaystyle x\in S\implies T(x)\in S.} 936: 670: 634: 611: 589: 580: 574: 566:are invariant under certain translations. 150:Learn how and when to remove this message 88:Learn how and when to remove this message 2193: 2181: 2068: 1465:, as discussed for Euler characteristic. 798: 752:Any two consecutive U's may be removed ( 113:This article includes a list of general 1945: 539:is invariant under translations of the 218:is a property that is constant on each 2241: 1019:about the circle's center. Further, a 427:Euclidean distance is invariant under 2205: 1557:have a special syntax for specifying 1364:Dual to the notion of invariants are 1203:is measurable, invariant sets form a 500:is invariant under a change of basis. 269:in which we count the objects in the 7: 2003: 2001: 1975: 1973: 1913:Mathematical constants and functions 1251:adding citations to reliable sources 1114:is an invariant line, though if the 1007:. (Some authors use the terminology 2080: 2041:Knot Theory Week 2: Tricolorability 1357:More importantly, one may define a 2351:A First Course In Abstract Algebra 1543:, all rely heavily on invariants. 1289:, presentations, and deformation. 661:is invariant under changes of the 434:Euclidean area is invariant under 119:it lacks sufficient corresponding 25: 2032:Qiao, Xiaoyu (January 20, 2015). 1525:correctness of a computer program 1030:An invariant set of an operation 317:of distances are invariant under 2093:Hofstadter, Douglas R. (1999) , 1223: 528:is invariant under translations. 360:Some more complicated examples: 333:. These transformations produce 206:is an invariant with respect to 104: 41: 1872:Invariant differential operator 1584:, and modulus information like 1375:which formalizes the notion of 843:is not a multiple of 3, then 2× 1493:Invariants in computer science 1446:The most common examples are: 1311:then one may ask which points 1161: 1155: 1149: 1023:is invariant as a set under a 961: 955: 948: 648: 636: 599:{\textstyle \int _{M}K\,d\mu } 337:shapes, which is the basis of 1: 2488:Billingsley, Patrick (1995). 2153:A Course in Modern Geometries 2377:Blaisdell Publishing Company 1598:In the context of the above 1477:Unchanged under perturbation 1293:Unchanged under group action 503:The principal invariants of 2477:Encyclopedia of Mathematics 2276:10.1007/978-3-642-14295-6_8 1410:Independent of presentation 1391:, one might seek to find a 2598: 2568:by William Braynen in 1997 2399:Holt, Rinehart and Winston 2349:Fraleigh, John B. (1976), 2013:www.encyclopediaofmath.org 1499:invariant (disambiguation) 1496: 1452:presentation of a manifold 1393:complete set of invariants 1087:is an invariant set under 1053:that are stable under the 606:of the Gaussian curvature 543:. Hence the variance of a 451:projective transformations 429:orthogonal transformations 32:Invariant (disambiguation) 29: 2494:. John Wiley & Sons. 2353:(2nd ed.), Reading: 2303:Communications of the ACM 2149:Judith Cederberg (1989). 1933:Young–Deruyts development 1045:that are so important in 457:of three or more points, 2582:Mathematical terminology 2371:Herstein, I. N. (1964), 1609: 1404:AAA similarity criterion 1079:, then the line through 865:is not a multiple of 3, 537:probability distribution 461:of three or more lines, 295:between two points on a 2491:Probability and Measure 2413:McCoy, Neal H. (1968), 1923:Symmetry in mathematics 1693:// non-terminating loop 1570:Abstract interpretation 1470:presentation of a group 1463:manifold decompositions 1438:in which case it is an 1389:classification problems 1209:invariant sigma-algebra 931:under the mapping when 134:more precise citations. 2530:Klenke, Achim (2020). 2393:Kay, David C. (1969), 1546:Programmers often use 1297:Firstly, if one has a 1197: 1177: 1095:which is stable under 995:, even though the set 977: 679: 655: 620: 600: 564:translational symmetry 496:. In other words, the 492:are invariant under a 396:degree of a polynomial 171: 2316:10.1145/363235.363259 2034:"Tricolorability.pdf" 1986:mathworld.wolfram.com 1928:Topological invariant 1908:Mathematical constant 1893:Invariants of tensors 1555:programming languages 1531:, the methodology of 1487:differential geometry 1456:change of coordinates 1198: 1178: 1122:has no fixed points. 1067:linear transformation 978: 680: 656: 654:{\displaystyle (M,g)} 626:of a two-dimensional 621: 601: 509:Invariants of tensors 165: 2157:. Springer. p.  1529:optimizing compilers 1508:, an invariant is a 1416:Euler characteristic 1247:improve this section 1187: 1137: 1013:pointwise invariant, 935: 811:Effect on invariant 688:Gauss–Bonnet theorem 669: 633: 610: 573: 498:spectrum of a matrix 376:are invariant under 239:discrete mathematics 216:equivalence relation 54:confusing or unclear 30:For other uses, see 2071:, pp. 166–167) 1980:Weisstein, Eric W. 1888:Invariant (physics) 1877:Invariant estimator 1541:program correctness 1055:inner automorphisms 1041:. For example, the 1034:is also said to be 705:impossibility proof 628:Riemannian manifold 490:linear endomorphism 449:Some invariants of 378:complex conjugation 184:mathematical object 182:is a property of a 66:clarify the article 2564:2022-02-24 at the 2450:Weisstein, Eric W. 2230:Douc et al. (2018) 2220:, pp. 313–314 2218:Billingsley (1995) 1958:www.mathsisfun.com 1593:the Hoare calculus 1582:0<=i-j<2*n-1 1533:design by contract 1483:algebraic geometry 1193: 1173: 1127:probability theory 1108:screw displacement 1093:invariant subspace 1009:setwise invariant, 973: 675: 651: 616: 596: 299:is not changed by 172: 2543:978-3-030-56401-8 2522:978-3-319-97703-4 2373:Topics In Algebra 2244:, p. 494-495 2168:978-1-4757-3831-5 2135:978-0-8218-7196-6 1883:Invariant measure 1516:. For example, a 1510:logical assertion 1424:topological space 1283: 1282: 1275: 1196:{\displaystyle T} 887: 886: 678:{\displaystyle g} 663:Riemannian metric 619:{\displaystyle K} 273:. The quantity—a 220:equivalence class 160: 159: 152: 98: 97: 90: 16:(Redirected from 2589: 2547: 2526: 2505: 2484: 2463: 2462: 2429: 2409: 2395:College Geometry 2389: 2367: 2335: 2334: 2332: 2326:. Archived from 2299: 2293:(October 1969). 2287: 2281: 2280: 2278: 2264: 2251: 2245: 2239: 2233: 2227: 2221: 2215: 2209: 2203: 2197: 2191: 2185: 2179: 2173: 2172: 2156: 2146: 2140: 2139: 2119: 2113: 2112:Here: Chapter I. 2111: 2100: 2090: 2084: 2078: 2072: 2066: 2060: 2059: 2057: 2055: 2049: 2043:. Archived from 2038: 2029: 2023: 2022: 2020: 2019: 2005: 1996: 1995: 1993: 1992: 1977: 1968: 1967: 1965: 1964: 1950: 1918:Scale invariance 1898:Invariant theory 1862:Erlangen program 1850: 1847: 1844: 1841: 1838: 1835: 1832: 1829: 1826: 1823: 1820: 1817: 1814: 1811: 1808: 1805: 1802: 1799: 1796: 1793: 1790: 1787: 1784: 1781: 1778: 1775: 1772: 1769: 1766: 1763: 1760: 1757: 1754: 1751: 1748: 1745: 1742: 1739: 1736: 1733: 1730: 1727: 1724: 1721: 1718: 1715: 1712: 1709: 1706: 1703: 1700: 1697: 1694: 1691: 1688: 1685: 1682: 1679: 1676: 1673: 1670: 1667: 1664: 1661: 1658: 1655: 1652: 1649: 1646: 1643: 1640: 1637: 1634: 1631: 1628: 1625: 1622: 1619: 1616: 1613: 1606: 1587: 1583: 1579: 1574:abstract domains 1559:class invariants 1539:for determining 1527:. The theory of 1514:computer program 1506:computer science 1468:Invariants of a 1278: 1271: 1267: 1264: 1258: 1227: 1219: 1215:Formal statement 1202: 1200: 1199: 1194: 1182: 1180: 1179: 1174: 1043:normal subgroups 999:is fixed in the 982: 980: 979: 974: 799: 684: 682: 681: 676: 660: 658: 657: 652: 625: 623: 622: 617: 605: 603: 602: 597: 585: 584: 526:Lebesgue measure 422:dynamical system 155: 148: 144: 141: 135: 130:this article by 121:inline citations 108: 107: 100: 93: 86: 82: 79: 73: 45: 44: 37: 21: 2597: 2596: 2592: 2591: 2590: 2588: 2587: 2586: 2572: 2571: 2566:Wayback Machine 2555: 2550: 2544: 2529: 2523: 2508: 2502: 2487: 2466: 2448: 2447: 2419:Allyn and Bacon 2412: 2392: 2387: 2370: 2365: 2348: 2344: 2339: 2338: 2330: 2310:(10): 576–580. 2297: 2291:Hoare, C. A. R. 2289: 2288: 2284: 2262: 2253: 2252: 2248: 2240: 2236: 2228: 2224: 2216: 2212: 2204: 2200: 2192: 2188: 2180: 2176: 2169: 2148: 2147: 2143: 2136: 2121: 2120: 2116: 2109: 2101:, Basic Books, 2092: 2091: 2087: 2083:, pp. 219) 2079: 2075: 2067: 2063: 2053: 2051: 2050:on May 25, 2024 2047: 2036: 2031: 2030: 2026: 2017: 2015: 2007: 2006: 1999: 1990: 1988: 1979: 1978: 1971: 1962: 1960: 1952: 1951: 1947: 1942: 1937: 1867:Graph invariant 1857: 1852: 1851: 1848: 1845: 1842: 1839: 1836: 1833: 1830: 1827: 1824: 1821: 1818: 1815: 1812: 1809: 1806: 1803: 1800: 1797: 1794: 1791: 1788: 1785: 1782: 1779: 1776: 1773: 1770: 1767: 1764: 1761: 1758: 1755: 1752: 1749: 1746: 1743: 1740: 1737: 1734: 1731: 1728: 1725: 1722: 1719: 1716: 1713: 1710: 1707: 1704: 1701: 1698: 1695: 1692: 1689: 1686: 1683: 1680: 1677: 1674: 1671: 1668: 1665: 1662: 1659: 1656: 1653: 1650: 1647: 1644: 1641: 1638: 1635: 1632: 1629: 1626: 1623: 1620: 1617: 1614: 1611: 1604: 1585: 1581: 1578:0<=x<1024 1577: 1567: 1552:object oriented 1502: 1495: 1479: 1412: 1295: 1279: 1268: 1262: 1259: 1244: 1228: 1217: 1185: 1184: 1135: 1134: 1057:of the ambient 1021:conical surface 933: 932: 902: 794:for all rules: 697: 686:. This is the 667: 666: 631: 630: 608: 607: 576: 571: 570: 545:random variable 516:singular values 494:change of basis 407:homology groups 385:tricolorability 275:cardinal number 255: 212:Euclidean plane 196:transformations 156: 145: 139: 136: 126:Please help to 125: 109: 105: 94: 83: 77: 74: 63: 46: 42: 35: 28: 23: 22: 15: 12: 11: 5: 2595: 2593: 2585: 2584: 2574: 2573: 2570: 2569: 2554: 2553:External links 2551: 2549: 2548: 2542: 2527: 2521: 2506: 2500: 2485: 2464: 2445: 2430: 2410: 2390: 2386:978-1114541016 2385: 2368: 2363: 2355:Addison-Wesley 2345: 2343: 2340: 2337: 2336: 2333:on 2016-03-04. 2282: 2256:Sighireanu, M. 2246: 2234: 2222: 2210: 2208:, p. 183) 2198: 2194:Herstein (1964 2186: 2184:, p. 103) 2182:Fraleigh (1976 2174: 2167: 2141: 2134: 2114: 2107: 2085: 2073: 2069:Fraleigh (1976 2061: 2024: 1997: 1969: 1944: 1943: 1941: 1938: 1936: 1935: 1930: 1925: 1920: 1915: 1910: 1905: 1903:Knot invariant 1900: 1895: 1890: 1885: 1880: 1874: 1869: 1864: 1858: 1856: 1853: 1610: 1566: 1563: 1537:formal methods 1518:loop invariant 1494: 1491: 1478: 1475: 1474: 1473: 1466: 1459: 1411: 1408: 1400:SSS congruence 1371:also known as 1319:of the group. 1294: 1291: 1281: 1280: 1231: 1229: 1222: 1216: 1213: 1192: 1172: 1169: 1166: 1163: 1160: 1157: 1154: 1151: 1148: 1145: 1142: 1131:ergodic theory 1063:linear algebra 983:Note that the 972: 969: 966: 963: 960: 957: 954: 950: 946: 943: 940: 911:of the domain 901: 898: 889: 888: 885: 884: 881: 878: 875: 871: 870: 859: 856: 853: 849: 848: 837: 834: 831: 827: 826: 823: 820: 817: 813: 812: 809: 806: 803: 791: 790: 774: 773: 766: 765: 750: 731: 720: 696: 693: 692: 691: 674: 650: 647: 644: 641: 638: 615: 595: 592: 588: 583: 579: 567: 548: 529: 523: 512: 501: 470: 463:conic sections 447: 432: 425: 416:The number of 414: 399: 392: 381: 374:complex number 370:absolute value 305:multiplication 254: 251: 243:conformal maps 158: 157: 112: 110: 103: 96: 95: 49: 47: 40: 26: 24: 14: 13: 10: 9: 6: 4: 3: 2: 2594: 2583: 2580: 2579: 2577: 2567: 2563: 2560: 2557: 2556: 2552: 2545: 2539: 2535: 2534: 2528: 2524: 2518: 2514: 2513: 2512:Markov Chains 2507: 2503: 2501:0-471-00710-2 2497: 2493: 2492: 2486: 2483: 2479: 2478: 2473: 2469: 2465: 2460: 2459: 2454: 2451: 2446: 2443: 2442:90-6233-681-7 2439: 2435: 2432:J.D. Fokker, 2431: 2428: 2424: 2420: 2416: 2411: 2408: 2404: 2400: 2396: 2391: 2388: 2382: 2378: 2374: 2369: 2366: 2364:0-201-01984-1 2360: 2356: 2352: 2347: 2346: 2341: 2329: 2325: 2321: 2317: 2313: 2309: 2305: 2304: 2296: 2292: 2286: 2283: 2277: 2272: 2268: 2261: 2257: 2250: 2247: 2243: 2242:Klenke (2020) 2238: 2235: 2231: 2226: 2223: 2219: 2214: 2211: 2207: 2202: 2199: 2196:, p. 42) 2195: 2190: 2187: 2183: 2178: 2175: 2170: 2164: 2160: 2155: 2154: 2145: 2142: 2137: 2131: 2127: 2126: 2122:Barry Simon. 2118: 2115: 2110: 2108:0-465-02656-7 2104: 2099: 2098: 2089: 2086: 2082: 2077: 2074: 2070: 2065: 2062: 2046: 2042: 2035: 2028: 2025: 2014: 2010: 2004: 2002: 1998: 1987: 1983: 1976: 1974: 1970: 1959: 1955: 1949: 1946: 1939: 1934: 1931: 1929: 1926: 1924: 1921: 1919: 1916: 1914: 1911: 1909: 1906: 1904: 1901: 1899: 1896: 1894: 1891: 1889: 1886: 1884: 1881: 1879:in statistics 1878: 1875: 1873: 1870: 1868: 1865: 1863: 1860: 1859: 1854: 1608: 1601: 1596: 1594: 1589: 1575: 1571: 1564: 1562: 1560: 1556: 1553: 1549: 1544: 1542: 1538: 1534: 1530: 1526: 1521: 1519: 1515: 1511: 1507: 1500: 1492: 1490: 1488: 1484: 1476: 1471: 1467: 1464: 1460: 1457: 1453: 1449: 1448: 1447: 1444: 1441: 1440:intrinsically 1437: 1436:presentation, 1434:of choice of 1433: 1429: 1425: 1421: 1417: 1409: 1407: 1405: 1401: 1396: 1394: 1390: 1384: 1382: 1378: 1374: 1370: 1368: 1362: 1360: 1355: 1353: 1349: 1345: 1341: 1337: 1333: 1329: 1325: 1320: 1318: 1314: 1310: 1306: 1303: 1300: 1292: 1290: 1288: 1287:group actions 1277: 1274: 1266: 1263:February 2010 1256: 1252: 1248: 1242: 1241: 1237: 1232:This section 1230: 1226: 1221: 1220: 1214: 1212: 1210: 1206: 1205:sigma-algebra 1190: 1183:When the map 1170: 1167: 1164: 1158: 1152: 1146: 1143: 1140: 1132: 1128: 1123: 1121: 1118:is non-zero, 1117: 1113: 1109: 1105: 1100: 1098: 1094: 1090: 1086: 1082: 1078: 1075: 1071: 1068: 1064: 1060: 1056: 1052: 1048: 1044: 1040: 1037: 1033: 1028: 1026: 1022: 1018: 1014: 1010: 1006: 1002: 998: 994: 990: 986: 970: 967: 964: 958: 952: 944: 941: 938: 930: 929:invariant set 926: 922: 918: 915:of a mapping 914: 910: 907: 900:Invariant set 899: 897: 893: 882: 879: 876: 873: 872: 868: 864: 860: 857: 854: 851: 850: 846: 842: 838: 835: 832: 829: 828: 824: 821: 818: 815: 814: 810: 807: 804: 801: 800: 797: 796: 795: 788: 785: 784: 783: 780: 771: 770: 769: 763: 759: 755: 751: 748: 744: 740: 736: 732: 729: 725: 721: 718: 714: 710: 709: 708: 706: 702: 694: 689: 685: 672: 664: 645: 642: 639: 629: 613: 593: 590: 586: 581: 577: 569:The integral 568: 565: 561: 557: 553: 549: 546: 542: 538: 534: 530: 527: 524: 521: 517: 513: 510: 506: 502: 499: 495: 491: 487: 483: 479: 475: 471: 468: 464: 460: 456: 452: 448: 445: 441: 437: 433: 430: 426: 423: 419: 415: 412: 411:homeomorphism 408: 404: 400: 397: 393: 390: 386: 382: 379: 375: 371: 367: 363: 362: 361: 358: 356: 352: 348: 347:circumference 344: 340: 336: 332: 328: 324: 320: 316: 312: 308: 306: 302: 298: 294: 289: 287: 283: 278: 276: 272: 268: 264: 260: 252: 250: 248: 244: 240: 236: 232: 228: 223: 221: 217: 213: 209: 205: 201: 197: 193: 189: 185: 181: 177: 169: 164: 154: 151: 143: 133: 129: 123: 122: 116: 111: 102: 101: 92: 89: 81: 71: 70:the talk page 67: 61: 57: 55: 50:This article 48: 39: 38: 33: 19: 18:Invariant set 2536:. Springer. 2532: 2515:. Springer. 2511: 2490: 2475: 2456: 2414: 2397:, New York: 2394: 2372: 2350: 2328:the original 2307: 2301: 2285: 2266: 2249: 2237: 2232:, p. 99 2225: 2213: 2201: 2189: 2177: 2152: 2144: 2124: 2117: 2096: 2088: 2076: 2064: 2052:. Retrieved 2045:the original 2040: 2027: 2016:. Retrieved 2012: 1989:. Retrieved 1985: 1961:. Retrieved 1957: 1948: 1597: 1590: 1568: 1545: 1522: 1503: 1480: 1445: 1439: 1435: 1431: 1420:cell complex 1413: 1397: 1385: 1372: 1367:coinvariants 1365: 1363: 1358: 1356: 1352:rigid motion 1347: 1343: 1339: 1335: 1331: 1327: 1323: 1321: 1316: 1312: 1308: 1301: 1296: 1284: 1269: 1260: 1245:Please help 1233: 1124: 1119: 1103: 1101: 1096: 1088: 1084: 1080: 1076: 1069: 1047:group theory 1038: 1036:stable under 1035: 1031: 1029: 1012: 1008: 1004: 996: 988: 928: 924: 920: 916: 912: 908: 903: 894: 890: 866: 862: 844: 840: 792: 786: 775: 767: 761: 757: 753: 746: 742: 738: 734: 727: 723: 716: 712: 698: 665: 552:fixed points 482:eigenvectors 455:collinearity 418:fixed points 359: 339:trigonometry 327:translations 309: 290: 286:inequalities 279: 256: 224: 179: 173: 146: 137: 118: 84: 78:January 2024 75: 64:Please help 60:group action 51: 2472:"Invariant" 2468:Popov, V.L. 2453:"Invariant" 2375:, Waltham: 2206:McCoy (1968 1982:"Invariant" 1432:independent 1074:eigenvector 486:eigenvalues 474:determinant 467:cross-ratio 459:concurrency 440:determinant 438:which have 436:linear maps 331:reflections 297:number line 176:mathematics 132:introducing 2434:H. Zantema 2417:, Boston: 2342:References 2018:2019-12-05 1991:2019-12-05 1963:2019-12-05 1702:RandomRule 1636:RandomRule 1548:assertions 1377:congruence 1350:); then a 1328:associated 1112:screw axis 1049:are those 1027:of space. 465:, and the 263:finite set 208:isometries 192:operations 140:April 2015 115:references 56:to readers 2482:EMS Press 2470:(2001) , 2458:MathWorld 2324:207726175 2267:Proc. CAV 2081:Kay (1969 1600:MU puzzle 1381:perimeter 1234:does not 1165:∈ 1150:⇔ 1144:∈ 1051:subgroups 1025:homothety 1001:power set 965:∈ 949:⟹ 942:∈ 701:MU puzzle 695:MU puzzle 594:μ 578:∫ 560:symmetric 541:real line 403:dimension 366:real part 323:rotations 180:invariant 168:wallpaper 2576:Category 2562:Archived 2427:68-15225 2407:69-12075 2258:(2010). 1855:See also 1630:volatile 1615:MUPuzzle 1605:ICount%3 1461:Various 1428:manifold 1359:function 1017:rotation 991:are not 985:elements 779:property 533:variance 453:include 442:±1 (see 368:and the 351:diameter 319:scalings 293:distance 282:identity 261:. For a 253:Examples 231:topology 227:geometry 204:triangle 2054:May 25, 1373:orbits, 1255:removed 1240:sources 1072:has an 1065:, if a 505:tensors 349:to the 343:circles 335:similar 235:algebra 210:of the 128:improve 52:may be 2540:  2519:  2498:  2440:  2425:  2405:  2383:  2361:  2322:  2165:  2132:  2105:  1825:UCount 1798:UCount 1786:ICount 1759:UCount 1747:ICount 1720:UCount 1696:switch 1675:ICount 1657:UCount 1645:ICount 1586:y%4==0 1535:, and 1305:acting 1207:, the 1110:, the 927:is an 906:subset 556:domain 520:matrix 484:, and 315:ratios 311:Angles 301:adding 247:angles 186:(or a 117:, but 2331:(PDF) 2320:S2CID 2298:(PDF) 2263:(PDF) 2048:(PDF) 2037:(PDF) 1940:Notes 1837:break 1810:break 1771:break 1732:break 1669:while 1426:(the 1418:of a 1299:group 1116:pitch 1106:is a 1102:When 1061:. In 1059:group 993:fixed 535:of a 518:of a 488:of a 478:trace 420:of a 389:knots 372:of a 267:order 259:count 202:of a 188:class 178:, an 2538:ISBN 2517:ISBN 2496:ISBN 2438:ISBN 2423:LCCN 2403:LCCN 2381:ISBN 2359:ISBN 2163:ISBN 2130:ISBN 2103:ISBN 2056:2024 1816:case 1777:case 1738:case 1711:case 1621:void 1612:void 1485:and 1450:The 1330:set 1238:any 1236:cite 1129:and 1083:and 1011:vs. 808:#U's 805:#I's 802:Rule 715:I → 699:The 550:The 531:The 514:The 472:The 405:and 401:The 394:The 383:The 364:The 357:)). 329:and 313:and 291:The 237:and 200:area 2312:doi 2271:doi 2159:174 1642:int 1633:int 1504:In 1342:as 1249:by 1125:In 1003:of 987:of 861:If 839:If 737:III 726:→ M 719:IU) 387:of 280:An 271:set 194:or 174:In 2578:: 2480:, 2474:, 2455:. 2421:, 2401:, 2379:, 2357:, 2318:. 2308:12 2306:. 2300:. 2269:. 2265:. 2161:. 2039:. 2011:. 2000:^ 1984:. 1972:^ 1956:. 1828:-= 1801:+= 1789:-= 1762:*= 1750:*= 1723:+= 1684:!= 1561:. 1309:X, 1211:. 1099:. 923:→ 919:: 904:A 880:−2 877:+0 858:+1 855:−3 836:×2 833:×2 822:+1 819:+0 762:xy 760:→ 756:UU 741:→ 728:xx 511:). 480:, 476:, 446:). 355:pi 325:, 321:, 233:, 229:, 222:. 166:A 62:). 2546:. 2525:. 2504:. 2461:. 2444:. 2314:: 2279:. 2273:: 2171:. 2138:. 2058:. 2021:. 1994:. 1966:. 1849:} 1843:} 1840:; 1834:; 1831:2 1822:: 1819:4 1813:; 1807:; 1804:1 1795:; 1792:3 1783:: 1780:3 1774:; 1768:; 1765:2 1756:; 1753:2 1744:: 1741:2 1735:; 1729:; 1726:1 1717:: 1714:1 1708:{ 1705:) 1699:( 1690:) 1687:0 1681:3 1678:% 1672:( 1666:; 1663:0 1660:= 1654:, 1651:1 1648:= 1639:; 1627:{ 1624:) 1618:( 1501:. 1472:. 1458:. 1369:, 1348:P 1346:( 1344:L 1340:P 1336:X 1334:( 1332:F 1324:X 1317:g 1313:x 1302:G 1276:) 1270:( 1265:) 1261:( 1257:. 1243:. 1191:T 1171:. 1168:S 1162:) 1159:x 1156:( 1153:T 1147:S 1141:x 1120:T 1104:T 1097:T 1089:T 1085:v 1081:0 1077:v 1070:T 1039:T 1032:T 1005:U 997:S 989:S 971:. 968:S 962:) 959:x 956:( 953:T 945:S 939:x 925:U 921:U 917:T 913:U 909:S 874:4 867:n 863:n 852:3 845:n 841:n 830:2 816:1 789:. 764:) 758:y 754:x 749:) 747:y 745:U 743:x 739:y 735:x 730:) 724:x 717:x 713:x 690:. 673:g 649:) 646:g 643:, 640:M 637:( 614:K 591:d 587:K 582:M 469:. 431:. 413:. 391:. 380:. 153:) 147:( 142:) 138:( 124:. 91:) 85:( 80:) 76:( 72:. 34:. 20:)

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