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Field extension

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2129: 2442: 1867: 2200: 2124:{\displaystyle {\begin{aligned}\mathbb {Q} \left({\sqrt {2}},{\sqrt {3}}\right)&=\mathbb {Q} \left({\sqrt {2}}\right)\left({\sqrt {3}}\right)\\&=\left\{a+b{\sqrt {3}}\mid a,b\in \mathbb {Q} \left({\sqrt {2}}\right)\right\}\\&=\left\{a+b{\sqrt {2}}+c{\sqrt {3}}+d{\sqrt {6}}\mid a,b,c,d\in \mathbb {Q} \right\},\end{aligned}}} 2437:{\displaystyle {\begin{aligned}\mathbb {Q} ({\sqrt {2}},{\sqrt {3}})&=\mathbb {Q} ({\sqrt {2}}+{\sqrt {3}})\\&=\left\{a+b({\sqrt {2}}+{\sqrt {3}})+c({\sqrt {2}}+{\sqrt {3}})^{2}+d({\sqrt {2}}+{\sqrt {3}})^{3}\mid a,b,c,d\in \mathbb {Q} \right\}.\end{aligned}}} 5156:. Extension of scalars of polynomials is often used implicitly, by just considering the coefficients as being elements of a larger field, but may also be considered more formally. Extension of scalars has numerous applications, as discussed in 1788: 1342:
It is often desirable to talk about field extensions in situations where the small field is not actually contained in the larger one, but is naturally embedded. For this purpose, one abstractly defines a field extension as an
2853: 5109:
is exactly the field. For example, the only finite field extension of the real numbers is the complex numbers, while the quaternions are a central simple algebra over the reals, and all CSAs over the reals are
4298: 4039:). On the opposite, even when one knows a transcendence basis, it may be difficult to decide whether the extension is purely separable, and if it is so, it may be difficult to find a transcendence basis 3550: 2205: 1872: 4571: 4489: 4106: 2778: 1646: 1856: 1175: 3302: 2167: 1604: 1498: 1056: 1111: 4973: 2972: 2507: 1691: 4221: 4151: 3645: 2664: 2192: 1816: 4433: 3788: 3762: 3740: 3718: 3696: 3572: 2994: 2467: 1466: 1444: 1422: 1397: 256: 99: 3620: 3596: 3122: 4703: 3155: 873: 4667: 2586: 1706: 1572: 4634: 3653:
it is finite. This implies that an extension is algebraic if and only if it is the union of its finite subextensions, and that every finite extension is algebraic.
4597: 4515: 4411: 5051: 4931: 4869: 4838: 4774: 3970: 3930: 3830: 3497: 3082: 904: 799: 771: 743: 715: 687: 578: 547: 480: 70: 4385: 1540: 4723: 4362: 4338: 4318: 4171: 4126: 409: 371: 351: 324: 296: 276: 227: 204: 633: 2790: 4729: 3016: 5367: 5065:). The significance of Galois extensions and Galois groups is that they allow a complete description of the intermediate fields: there is a 5074: 4599:
is a transcendence basis that does not generates the whole extension. However the extension is purely transcendental since, if one set
2477:. Another extension field of the rationals, which is also important in number theory, although not a finite extension, is the field of 5342: 3996:, but, however, there are extensions with this property which are not purely transcendental—a class of such extensions take the form 5320: 3178: 4226: 1226: 3222:
is a finite extension. In this case the degree of the extension equals the degree of the minimal polynomial, and a basis of the
3510: 5413: 5359: 4740:
of a rational variety is equivalent with the problem of finding a transcendence basis that generates the whole extension.
1694: 4520: 4438: 5408: 5140:" on associated algebraic objects. For example, given a real vector space, one can produce a complex vector space via 3904:. All transcendence bases have the same cardinality, equal to the transcendence degree of the extension. An extension 597: 4061: 2722: 5169: 1609: 5334: 1821: 5430: 4899: 3841: 1267: 1116: 109: 3240: 5174: 4737: 3799: 2137: 1577: 1471: 1263: 1003: 593: 415: 389: 1369:
Henceforth, we will suppress the injective homomorphism and assume that we are dealing with actual subfields.
3507:. Equivalently, an algebraic extension is an extension that is generated by algebraic elements. For example, 384:, which is itself a subfield of the complex numbers. More generally, the field of rational numbers is (or is 1331:
or any other kind of division. Instead the slash expresses the word "over". In some literature the notation
1061: 160: 5403: 5098: 4781: 3186: 2589: 2470: 638:
The degree of an extension is 1 if and only if the two fields are equal. In this case, the extension is a
303: 299: 4939: 1354:
non-zero ring homomorphism between fields is injective because fields do not possess nontrivial proper
2943: 2483: 1650: 5157: 5153: 5137: 5131: 5106: 4884: 3857: 2933: 4180: 5145: 4872: 4131: 3893: 3625: 3043: 2607: 2597: 2172: 1796: 1355: 207: 73: 4416: 3771: 3745: 3723: 3701: 3679: 3555: 2977: 2450: 1449: 1427: 1405: 1380: 235: 78: 5090: 4733: 3601: 3577: 3103: 3089: 2911: 2675: 2532: 1363: 1344: 172: 5362:, vol. 211 (Corrected fourth printing, revised third ed.), New York: Springer-Verlag, 1783:{\displaystyle \mathbb {Q} ({\sqrt {2}})=\left\{a+b{\sqrt {2}}\mid a,b\in \mathbb {Q} \right\},} 5385: 5363: 5338: 5316: 5189: 5184: 5111: 5019: 4672: 4341: 3320: 3127: 3047: 3005: 2997: 2875: 1347: 1296: 807: 4639: 2558: 1545: 5141: 4892: 4777: 4602: 3170: 1218: 164: 4576: 4494: 4390: 5381: 5179: 5115: 5086: 4174: 2926: 2686: 2525: 377: 5028: 4908: 4846: 4815: 4751: 3947: 3907: 3807: 3474: 3059: 881: 776: 748: 720: 692: 664: 555: 524: 457: 47: 4367: 3672:, and also the smallest extension field such that every polynomial with coefficients in 1503: 5312: 5102: 4902:
states that every finite separable extension has a primitive element (i.e. is simple).
4708: 4347: 4323: 4303: 4156: 4111: 3650: 1328: 985: 394: 356: 336: 309: 281: 261: 212: 189: 149: 145: 606: 5424: 5015: 2601: 2521: 2478: 2474: 2194:
of degree 2 and 4 respectively. It is also a simple extension, as one can show that
1324: 168: 17: 5011: 4976: 3227: 2717: 2709: 589: 2848:{\displaystyle \operatorname {GF} (p)=\mathbb {F} _{p}=\mathbb {Z} /p\mathbb {Z} } 2785: 1400: 385: 381: 153: 33: 29:
Construction of a larger algebraic field by "adding elements" to a smaller field
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is a transcendence basis of the extension, it doesn't necessarily follow that
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under the operations of addition, subtraction, multiplication, and taking the
5066: 3856:. The largest cardinality of an algebraically independent set is called the 4728:
Purely transcendental extensions of an algebraically closed field occur as
5144:. In addition to vector spaces, one can perform extension of scalars for 5070: 1359: 141: 5094: 2701:
in which the given polynomial splits into a product of linear factors.
37: 5010:. When the extension is Galois this automorphism group is called the 418:
of a subfield is the same as the characteristic of the larger field.
230: 5114:
to the reals or the quaternions. CSAs can be further generalized to
258:
that is a field with respect to the field operations inherited from
5105:(no non-trivial 2-sided ideals, just as for a field) and where the 3661: 1270:, which does not hold true for fields of non-zero characteristic. 5389: 3124:
is algebraic over the rational numbers, because it is a root of
4517:
is a transcendence basis that does not generates the extension
1446:
in turn is an extension field of the field of rational numbers
2516:
It is common to construct an extension field of a given field
2716:
is a positive integer, there is a unique (up to isomorphism)
1266:
0, every finite extension is a simple extension. This is the
4293:{\displaystyle \mathbb {Q} (X)/\langle Y^{2}-X^{3}\rangle ,} 2918:. This field of rational functions is an extension field of 4887:, i.e., has no repeated roots in an algebraic closure over 3984:). Such an extension has the property that all elements of 3848:
if no non-trivial polynomial relation with coefficients in
2996:
if we identify every complex number with the corresponding
156:; the real numbers are a subfield of the complex numbers. 2685:
By iterating the above construction, one can construct a
1818:
also clearly a simple extension. The degree is 2 because
4895:
is a field extension that is both normal and separable.
3331:. This results from the preceding characterization: if 1323:
is purely formal and does not imply the formation of a
5053:, one is often interested in the intermediate fields 5031: 4942: 4911: 4849: 4818: 4754: 4711: 4675: 4642: 4605: 4579: 4523: 4497: 4441: 4419: 4393: 4370: 4350: 4326: 4306: 4229: 4183: 4159: 4134: 4114: 4064: 3950: 3910: 3810: 3774: 3748: 3726: 3704: 3682: 3628: 3604: 3580: 3558: 3545:{\displaystyle \mathbb {Q} ({\sqrt {2}},{\sqrt {3}})} 3513: 3477: 3243: 3130: 3106: 3062: 2980: 2946: 2793: 2725: 2610: 2561: 2486: 2453: 2203: 2175: 2140: 1870: 1824: 1799: 1709: 1653: 1612: 1580: 1548: 1506: 1474: 1452: 1430: 1408: 1383: 1119: 1064: 1006: 884: 810: 779: 751: 723: 695: 667: 609: 558: 527: 460: 397: 359: 339: 312: 284: 278:. Equivalently, a subfield is a subset that contains 264: 238: 215: 192: 81: 50: 5118:, where the base field is replaced by a commutative 5014:of the extension. Extensions whose Galois group is 4840:is normal and which is minimal with this property. 3026:), consisting of the rational functions defined on 5045: 4967: 4925: 4863: 4832: 4768: 4717: 4697: 4661: 4628: 4591: 4565: 4509: 4483: 4427: 4405: 4379: 4356: 4332: 4312: 4292: 4215: 4165: 4145: 4120: 4100: 3964: 3940:if and only if there exists a transcendence basis 3924: 3824: 3782: 3756: 3734: 3712: 3690: 3639: 3614: 3590: 3566: 3544: 3491: 3296: 3149: 3116: 3076: 2988: 2966: 2847: 2772: 2674:contain an element whose square is −1 (namely the 2658: 2580: 2501: 2461: 2436: 2186: 2161: 2123: 1850: 1810: 1782: 1685: 1640: 1598: 1566: 1534: 1492: 1460: 1438: 1416: 1391: 1169: 1105: 1050: 898: 867: 793: 765: 737: 709: 681: 627: 572: 541: 474: 403: 365: 345: 318: 290: 270: 250: 221: 198: 93: 64: 5101:(CSAs) – ring extensions over a field, which are 4566:{\displaystyle \mathbb {Q} (x,y)/\mathbb {Q} (x)} 4484:{\displaystyle \mathbb {Q} (x,y)/\mathbb {Q} (x)} 5378:Introduction To Modern Algebra, Revised Edition 5148:defined over the field, such as polynomials or 4101:{\displaystyle \mathbb {Q} (x,y)/\mathbb {Q} ,} 4875:if the minimal polynomial of every element of 3664:an isomorphism the largest extension field of 3394:is also finite, as well as the sub extensions 2773:{\displaystyle GF(p^{n})=\mathbb {F} _{p^{n}}} 1606:is finite. This is a simple extension because 1641:{\displaystyle \mathbb {C} =\mathbb {R} (i).} 926:. It is the intersection of all subfields of 8: 4792:completely factors into linear factors over 4586: 4580: 4504: 4498: 4400: 4394: 4284: 4258: 2784:elements; this is an extension field of the 1851:{\displaystyle \left\{1,{\sqrt {2}}\right\}} 1561: 1549: 1158: 1126: 1045: 1013: 3499:is an extension such that every element of 1170:{\displaystyle K(\{x_{1},\ldots ,x_{n}\}),} 3297:{\displaystyle 1,s,s^{2},\ldots ,s^{d-1},} 2974:It is a transcendental extension field of 658:is an extension that has a finite degree. 646:. Extensions of degree 2 and 3 are called 140:. For example, under the usual notions of 5035: 5030: 4954: 4943: 4941: 4915: 4910: 4853: 4848: 4822: 4817: 4758: 4753: 4710: 4686: 4674: 4653: 4641: 4615: 4604: 4578: 4550: 4549: 4544: 4525: 4524: 4522: 4496: 4468: 4467: 4462: 4443: 4442: 4440: 4421: 4420: 4418: 4392: 4369: 4349: 4325: 4305: 4278: 4265: 4253: 4231: 4230: 4228: 4201: 4188: 4182: 4158: 4136: 4135: 4133: 4113: 4091: 4090: 4085: 4066: 4065: 4063: 3954: 3949: 3914: 3909: 3814: 3809: 3776: 3775: 3773: 3750: 3749: 3747: 3728: 3727: 3725: 3706: 3705: 3703: 3684: 3683: 3681: 3630: 3629: 3627: 3605: 3603: 3581: 3579: 3560: 3559: 3557: 3532: 3522: 3515: 3514: 3512: 3481: 3476: 3319:form a subextension, which is called the 3308:is the degree of the minimal polynomial. 3279: 3260: 3242: 3135: 3129: 3107: 3105: 3066: 3061: 2982: 2981: 2979: 2948: 2947: 2945: 2841: 2840: 2832: 2828: 2827: 2818: 2814: 2813: 2792: 2762: 2757: 2753: 2752: 2739: 2724: 2641: 2629: 2609: 2566: 2560: 2493: 2489: 2488: 2485: 2455: 2454: 2452: 2418: 2417: 2384: 2373: 2363: 2348: 2337: 2327: 2308: 2298: 2261: 2251: 2244: 2243: 2226: 2216: 2209: 2208: 2204: 2202: 2177: 2176: 2174: 2162:{\displaystyle \mathbb {Q} ({\sqrt {2}})} 2149: 2142: 2141: 2139: 2105: 2104: 2070: 2057: 2044: 2004: 1996: 1995: 1973: 1938: 1923: 1915: 1914: 1895: 1885: 1876: 1875: 1871: 1869: 1836: 1823: 1801: 1800: 1798: 1768: 1767: 1745: 1718: 1711: 1710: 1708: 1677: 1676: 1666: 1665: 1658: 1657: 1652: 1622: 1621: 1614: 1613: 1611: 1599:{\displaystyle \mathbb {C} /\mathbb {R} } 1592: 1591: 1586: 1582: 1581: 1579: 1547: 1519: 1518: 1511: 1510: 1505: 1493:{\displaystyle \mathbb {C} /\mathbb {Q} } 1486: 1485: 1480: 1476: 1475: 1473: 1454: 1453: 1451: 1432: 1431: 1429: 1410: 1409: 1407: 1385: 1384: 1382: 1152: 1133: 1118: 1094: 1075: 1063: 1051:{\displaystyle S=\{x_{1},\ldots ,x_{n}\}} 1039: 1020: 1005: 888: 883: 809: 783: 778: 755: 750: 727: 722: 699: 694: 671: 666: 608: 562: 557: 531: 526: 464: 459: 396: 358: 338: 311: 283: 263: 237: 214: 191: 80: 54: 49: 5291: 5279: 5267: 5255: 5243: 5219: 5207: 5069:between the intermediate fields and the 1358:, so field extensions are precisely the 5200: 5085:Field extensions can be generalized to 4744:Normal, separable and Galois extensions 5097:. A closer non-commutative analog are 5073:of the Galois group, described by the 3868:. It is always possible to find a set 1399:is an extension field of the field of 1106:{\displaystyle K(x_{1},\ldots ,x_{n})} 5231: 7: 5075:fundamental theorem of Galois theory 4223:Such an extension can be defined as 4058:For example, consider the extension 3208:if and only if the simple extension 454:. Such a field extension is denoted 159:Field extensions are fundamental in 3660:has an algebraic closure, which is 1678: 1500:is also a field extension. We have 596:of this vector space is called the 501:, which is in turn an extension of 5309:A First Course In Abstract Algebra 5158:extension of scalars: applications 5136:Given a field extension, one can " 3720:, but not an algebraic closure of 1697:), so this extension is infinite. 914:, there is a smallest subfield of 801:are finite. In this case, one has 25: 4968:{\displaystyle {\text{Aut}}(L/K)} 4808:, which is an extension field of 3872:, algebraically independent over 1243:is often said to result from the 4725:generates the whole extension. 3649:A simple extension is algebraic 2967:{\displaystyle \mathbb {C} (M).} 2600:generated by this polynomial is 2502:{\displaystyle \mathbb {Q} _{p}} 1686:{\displaystyle ={\mathfrak {c}}} 1295:) is isomorphic to the field of 333:, the latter definition implies 3676:has a root in it. For example, 1232:An extension field of the form 450:, and this pair of fields is a 388:to) a subfield of any field of 4962: 4948: 4560: 4554: 4541: 4529: 4478: 4472: 4459: 4447: 4250: 4244: 4241: 4235: 4216:{\displaystyle y^{2}-x^{3}=0.} 4082: 4070: 3742:, as it is not algebraic over 3539: 3519: 3339:are algebraic, the extensions 2958: 2952: 2922:. This extension is infinite. 2806: 2800: 2745: 2732: 2653: 2634: 2626: 2620: 2381: 2360: 2345: 2324: 2315: 2295: 2268: 2248: 2233: 2213: 2156: 2146: 2134:is an extension field of both 1725: 1715: 1670: 1654: 1632: 1626: 1523: 1507: 1161: 1123: 1100: 1068: 859: 847: 841: 829: 823: 811: 745:is finite if and only if both 622: 610: 152:are an extension field of the 101:, such that the operations of 1: 5360:Graduate Texts in Mathematics 4387:Obviously, the singleton set 4146:{\displaystyle \mathbb {Q} ,} 4023:is purely transcendental and 3852:exists among the elements of 3640:{\displaystyle \mathbb {Q} .} 3552:is an algebraic extension of 3185:. This minimal polynomial is 2693:. This is an extension field 2659:{\displaystyle L=K/(X^{2}+1)} 2547:does not contain any element 2543:). Suppose for instance that 2187:{\displaystyle \mathbb {Q} ,} 1811:{\displaystyle \mathbb {Q} ,} 1574:is a basis, so the extension 1377:The field of complex numbers 1199:consists of a single element 5335:Blaisdell Publishing Company 5025:For a given field extension 4796:. Every algebraic extension 4428:{\displaystyle \mathbb {Q} } 3783:{\displaystyle \mathbb {Q} } 3757:{\displaystyle \mathbb {Q} } 3735:{\displaystyle \mathbb {Q} } 3713:{\displaystyle \mathbb {R} } 3691:{\displaystyle \mathbb {C} } 3567:{\displaystyle \mathbb {Q} } 2989:{\displaystyle \mathbb {C} } 2866:, we can consider the field 2462:{\displaystyle \mathbb {Q} } 1695:cardinality of the continuum 1461:{\displaystyle \mathbb {Q} } 1439:{\displaystyle \mathbb {R} } 1417:{\displaystyle \mathbb {R} } 1392:{\displaystyle \mathbb {C} } 373:have the same zero element. 251:{\displaystyle K\subseteq L} 94:{\displaystyle K\subseteq L} 5409:Encyclopedia of Mathematics 4736:. The problem of finding a 4012:are algebraically closed. 3888:) is algebraic. Such a set 3698:is an algebraic closure of 3615:{\displaystyle {\sqrt {3}}} 3591:{\displaystyle {\sqrt {2}}} 3311:The set of the elements of 3117:{\displaystyle {\sqrt {2}}} 3030:, is an extension field of 3004:. More generally, given an 5447: 5307:Fraleigh, John B. (1976), 5129: 4975:, consisting of all field 4905:Given any field extension 3797: 3173:of lowest degree that has 3041: 2555:= −1. Then the polynomial 376:For example, the field of 5311:(2nd ed.), Reading: 4900:primitive element theorem 3842:algebraically independent 2666:is an extension field of 1793:is an extension field of 1287:is not finite, the field 1268:primitive element theorem 171:, and are widely used in 5329:Herstein, I. N. (1964), 5175:Glossary of field theory 4804:admits a normal closure 4738:rational parametrization 4698:{\displaystyle y=t^{3},} 3992:are transcendental over 3804:Given a field extension 3800:Transcendental extension 3794:Transcendental extension 3668:which is algebraic over 3315:that are algebraic over 3177:as a root is called the 3150:{\displaystyle x^{2}-2.} 878:Given a field extension 868:{\displaystyle =\cdot .} 552:Given a field extension 306:of a nonzero element of 5376:McCoy, Neal H. (1968), 5099:central simple algebras 4843:An algebraic extension 4748:An algebraic extension 4662:{\displaystyle x=t^{2}} 4413:is transcendental over 4128:is transcendental over 2940:is a field, denoted by 2914:of the polynomial ring 2894:) are fractions of two 2689:of any polynomial from 2581:{\displaystyle X^{2}+1} 2535:for a given polynomial 2531:in order to "create" a 2471:algebraic number fields 1858:can serve as a basis. 1567:{\displaystyle \{1,i\}} 161:algebraic number theory 5404:"Extension of a field" 5047: 4969: 4933:, we can consider its 4927: 4865: 4834: 4782:irreducible polynomial 4770: 4719: 4699: 4663: 4630: 4629:{\displaystyle t=y/x,} 4593: 4567: 4511: 4485: 4429: 4407: 4381: 4358: 4334: 4314: 4294: 4217: 4167: 4147: 4122: 4102: 3966: 3926: 3826: 3784: 3768:is not algebraic over 3758: 3736: 3714: 3692: 3641: 3616: 3592: 3568: 3546: 3493: 3298: 3151: 3118: 3078: 2990: 2968: 2849: 2774: 2660: 2582: 2503: 2463: 2438: 2188: 2163: 2125: 1852: 1812: 1784: 1687: 1642: 1600: 1568: 1536: 1494: 1462: 1440: 1418: 1393: 1273:If a simple extension 1171: 1107: 1058:is finite, one writes 1052: 900: 869: 795: 767: 739: 711: 683: 629: 574: 543: 515:intermediate extension 476: 405: 367: 347: 320: 292: 272: 252: 223: 200: 163:, and in the study of 95: 66: 5154:group representations 5048: 4970: 4928: 4898:A consequence of the 4866: 4835: 4771: 4720: 4700: 4664: 4631: 4594: 4592:{\displaystyle \{y\}} 4568: 4512: 4510:{\displaystyle \{x\}} 4486: 4430: 4408: 4406:{\displaystyle \{x\}} 4382: 4359: 4335: 4315: 4295: 4218: 4168: 4148: 4123: 4103: 3967: 3936:purely transcendental 3927: 3827: 3785: 3759: 3737: 3715: 3693: 3642: 3617: 3593: 3569: 3547: 3494: 3299: 3152: 3119: 3096:with coefficients in 3079: 3056:of a field extension 2991: 2969: 2934:meromorphic functions 2882:with coefficients in 2850: 2775: 2661: 2583: 2504: 2473:and are important in 2464: 2447:Finite extensions of 2439: 2189: 2164: 2126: 1853: 1813: 1785: 1688: 1643: 1601: 1569: 1537: 1495: 1463: 1441: 1419: 1394: 1172: 1108: 1053: 901: 870: 796: 768: 740: 712: 684: 661:Given two extensions 630: 575: 544: 477: 406: 380:is a subfield of the 368: 348: 321: 293: 273: 253: 224: 201: 96: 67: 18:Purely transcendental 5146:associative algebras 5132:Extension of scalars 5126:Extension of scalars 5029: 4940: 4909: 4847: 4816: 4752: 4709: 4673: 4640: 4603: 4577: 4521: 4495: 4491:is algebraic; hence 4439: 4417: 4391: 4368: 4348: 4324: 4304: 4227: 4181: 4157: 4132: 4112: 4062: 3948: 3908: 3858:transcendence degree 3808: 3772: 3746: 3724: 3702: 3680: 3626: 3602: 3578: 3556: 3511: 3475: 3241: 3128: 3104: 3060: 2978: 2944: 2791: 2723: 2608: 2559: 2484: 2451: 2201: 2173: 2138: 1868: 1822: 1797: 1707: 1651: 1610: 1578: 1546: 1504: 1472: 1450: 1428: 1406: 1381: 1350:between two fields. 1117: 1062: 1004: 938:, and is denoted by 882: 808: 777: 749: 721: 693: 665: 648:quadratic extensions 607: 556: 525: 458: 395: 357: 337: 310: 282: 262: 236: 213: 190: 79: 48: 5152:and the associated 5089:which consist of a 5046:{\displaystyle L/K} 4926:{\displaystyle L/K} 4864:{\displaystyle L/K} 4833:{\displaystyle L/K} 4788:that has a root in 4769:{\displaystyle L/K} 4342:equivalence classes 3965:{\displaystyle L/K} 3925:{\displaystyle L/K} 3894:transcendence basis 3825:{\displaystyle L/K} 3622:are algebraic over 3492:{\displaystyle L/K} 3470:algebraic extension 3465:are all algebraic. 3447:). It follows that 3077:{\displaystyle L/K} 3044:Algebraic extension 3038:Algebraic extension 2596:, consequently the 2509:for a prime number 899:{\displaystyle L/K} 794:{\displaystyle M/L} 766:{\displaystyle L/K} 738:{\displaystyle M/K} 710:{\displaystyle M/L} 682:{\displaystyle L/K} 580:, the larger field 573:{\displaystyle L/K} 542:{\displaystyle L/K} 497:is an extension of 475:{\displaystyle L/K} 65:{\displaystyle L/K} 5107:center of the ring 5043: 5020:abelian extensions 4965: 4935:automorphism group 4923: 4861: 4830: 4766: 4734:rational varieties 4715: 4695: 4659: 4626: 4589: 4563: 4507: 4481: 4435:and the extension 4425: 4403: 4380:{\displaystyle Y.} 4377: 4354: 4330: 4310: 4290: 4213: 4163: 4143: 4118: 4098: 3962: 3922: 3822: 3780: 3754: 3732: 3710: 3688: 3637: 3612: 3588: 3564: 3542: 3503:is algebraic over 3489: 3294: 3204:is algebraic over 3179:minimal polynomial 3165:is algebraic over 3147: 3114: 3084:is algebraic over 3074: 2986: 2964: 2912:field of fractions 2886:; the elements of 2876:rational functions 2845: 2770: 2656: 2578: 2499: 2459: 2434: 2432: 2184: 2159: 2121: 2119: 1848: 1808: 1780: 1683: 1638: 1596: 1564: 1535:{\displaystyle =2} 1532: 1490: 1458: 1436: 1414: 1389: 1364:category of fields 1297:rational fractions 1229:of the extension. 1188:finitely generated 1177:and one says that 1167: 1103: 1048: 960:"). One says that 896: 865: 791: 763: 735: 707: 679: 654:, respectively. A 625: 603:and is denoted by 570: 539: 511:intermediate field 472: 401: 363: 343: 316: 288: 268: 248: 219: 196: 173:algebraic geometry 91: 62: 36:, particularly in 5369:978-0-387-95385-4 5331:Topics In Algebra 5190:Regular extension 5185:Primary extension 5112:Brauer equivalent 4946: 4718:{\displaystyle t} 4357:{\displaystyle X} 4333:{\displaystyle y} 4313:{\displaystyle x} 4166:{\displaystyle y} 4121:{\displaystyle x} 3610: 3586: 3537: 3527: 3376:are finite. Thus 3321:algebraic closure 3112: 3048:Algebraic element 3006:algebraic variety 2998:constant function 2932:, the set of all 2378: 2368: 2342: 2332: 2313: 2303: 2266: 2256: 2231: 2221: 2154: 2075: 2062: 2049: 2009: 1978: 1943: 1928: 1900: 1890: 1841: 1750: 1723: 1348:ring homomorphism 1227:primitive element 642:trivial extension 509:is said to be an 430:is a subfield of 404:{\displaystyle 0} 366:{\displaystyle L} 346:{\displaystyle K} 319:{\displaystyle K} 291:{\displaystyle 1} 271:{\displaystyle L} 222:{\displaystyle L} 199:{\displaystyle K} 16:(Redirected from 5438: 5431:Field extensions 5417: 5392: 5372: 5347: 5325: 5295: 5289: 5283: 5277: 5271: 5265: 5259: 5253: 5247: 5241: 5235: 5229: 5223: 5217: 5211: 5205: 5142:complexification 5116:Azumaya algebras 5052: 5050: 5049: 5044: 5039: 4974: 4972: 4971: 4966: 4958: 4947: 4944: 4932: 4930: 4929: 4924: 4919: 4893:Galois extension 4870: 4868: 4867: 4862: 4857: 4839: 4837: 4836: 4831: 4826: 4775: 4773: 4772: 4767: 4762: 4724: 4722: 4721: 4716: 4704: 4702: 4701: 4696: 4691: 4690: 4668: 4666: 4665: 4660: 4658: 4657: 4635: 4633: 4632: 4627: 4619: 4598: 4596: 4595: 4590: 4572: 4570: 4569: 4564: 4553: 4548: 4528: 4516: 4514: 4513: 4508: 4490: 4488: 4487: 4482: 4471: 4466: 4446: 4434: 4432: 4431: 4426: 4424: 4412: 4410: 4409: 4404: 4386: 4384: 4383: 4378: 4363: 4361: 4360: 4355: 4339: 4337: 4336: 4331: 4319: 4317: 4316: 4311: 4299: 4297: 4296: 4291: 4283: 4282: 4270: 4269: 4257: 4234: 4222: 4220: 4219: 4214: 4206: 4205: 4193: 4192: 4177:of the equation 4172: 4170: 4169: 4164: 4152: 4150: 4149: 4144: 4139: 4127: 4125: 4124: 4119: 4107: 4105: 4104: 4099: 4094: 4089: 4069: 3988:except those of 3971: 3969: 3968: 3963: 3958: 3938: 3937: 3931: 3929: 3928: 3923: 3918: 3831: 3829: 3828: 3823: 3818: 3789: 3787: 3786: 3781: 3779: 3767: 3763: 3761: 3760: 3755: 3753: 3741: 3739: 3738: 3733: 3731: 3719: 3717: 3716: 3711: 3709: 3697: 3695: 3694: 3689: 3687: 3646: 3644: 3643: 3638: 3633: 3621: 3619: 3618: 3613: 3611: 3606: 3597: 3595: 3594: 3589: 3587: 3582: 3573: 3571: 3570: 3565: 3563: 3551: 3549: 3548: 3543: 3538: 3533: 3528: 3523: 3518: 3498: 3496: 3495: 3490: 3485: 3456: 3446: 3439: 3425: 3411: 3393: 3375: 3352: 3303: 3301: 3300: 3295: 3290: 3289: 3265: 3264: 3221: 3171:monic polynomial 3156: 3154: 3153: 3148: 3140: 3139: 3123: 3121: 3120: 3115: 3113: 3108: 3083: 3081: 3080: 3075: 3070: 3011:over some field 2995: 2993: 2992: 2987: 2985: 2973: 2971: 2970: 2965: 2951: 2878:in the variable 2854: 2852: 2851: 2846: 2844: 2836: 2831: 2823: 2822: 2817: 2779: 2777: 2776: 2771: 2769: 2768: 2767: 2766: 2756: 2744: 2743: 2665: 2663: 2662: 2657: 2646: 2645: 2633: 2587: 2585: 2584: 2579: 2571: 2570: 2508: 2506: 2505: 2500: 2498: 2497: 2492: 2469:are also called 2468: 2466: 2465: 2460: 2458: 2443: 2441: 2440: 2435: 2433: 2426: 2422: 2421: 2389: 2388: 2379: 2374: 2369: 2364: 2353: 2352: 2343: 2338: 2333: 2328: 2314: 2309: 2304: 2299: 2274: 2267: 2262: 2257: 2252: 2247: 2232: 2227: 2222: 2217: 2212: 2193: 2191: 2190: 2185: 2180: 2168: 2166: 2165: 2160: 2155: 2150: 2145: 2130: 2128: 2127: 2122: 2120: 2113: 2109: 2108: 2076: 2071: 2063: 2058: 2050: 2045: 2023: 2019: 2015: 2014: 2010: 2005: 1999: 1979: 1974: 1952: 1948: 1944: 1939: 1933: 1929: 1924: 1918: 1906: 1902: 1901: 1896: 1891: 1886: 1879: 1857: 1855: 1854: 1849: 1847: 1843: 1842: 1837: 1817: 1815: 1814: 1809: 1804: 1789: 1787: 1786: 1781: 1776: 1772: 1771: 1751: 1746: 1724: 1719: 1714: 1692: 1690: 1689: 1684: 1682: 1681: 1669: 1661: 1647: 1645: 1644: 1639: 1625: 1617: 1605: 1603: 1602: 1597: 1595: 1590: 1585: 1573: 1571: 1570: 1565: 1541: 1539: 1538: 1533: 1522: 1514: 1499: 1497: 1496: 1491: 1489: 1484: 1479: 1468:. Clearly then, 1467: 1465: 1464: 1459: 1457: 1445: 1443: 1442: 1437: 1435: 1423: 1421: 1420: 1415: 1413: 1398: 1396: 1395: 1390: 1388: 1286: 1249: 1248: 1242: 1219:simple extension 1216: 1203:, the extension 1190: 1189: 1176: 1174: 1173: 1168: 1157: 1156: 1138: 1137: 1112: 1110: 1109: 1104: 1099: 1098: 1080: 1079: 1057: 1055: 1054: 1049: 1044: 1043: 1025: 1024: 955: 954: 905: 903: 902: 897: 892: 874: 872: 871: 866: 800: 798: 797: 792: 787: 772: 770: 769: 764: 759: 744: 742: 741: 736: 731: 717:, the extension 716: 714: 713: 708: 703: 688: 686: 685: 680: 675: 656:finite extension 652:cubic extensions 644: 643: 634: 632: 631: 628:{\displaystyle } 626: 601:of the extension 579: 577: 576: 571: 566: 548: 546: 545: 540: 535: 481: 479: 478: 473: 468: 410: 408: 407: 402: 378:rational numbers 372: 370: 369: 364: 352: 350: 349: 344: 332: 325: 323: 322: 317: 297: 295: 294: 289: 277: 275: 274: 269: 257: 255: 254: 249: 228: 226: 225: 220: 205: 203: 202: 197: 165:polynomial roots 116:. In this case, 100: 98: 97: 92: 71: 69: 68: 63: 58: 21: 5446: 5445: 5441: 5440: 5439: 5437: 5436: 5435: 5421: 5420: 5402: 5399: 5382:Allyn and Bacon 5375: 5370: 5350: 5345: 5328: 5323: 5306: 5303: 5298: 5290: 5286: 5278: 5274: 5266: 5262: 5254: 5250: 5242: 5238: 5230: 5226: 5218: 5214: 5206: 5202: 5198: 5180:Tower of fields 5166: 5134: 5128: 5093:and one of its 5087:ring extensions 5083: 5081:Generalizations 5027: 5026: 4938: 4937: 4907: 4906: 4845: 4844: 4814: 4813: 4750: 4749: 4746: 4730:function fields 4707: 4706: 4682: 4671: 4670: 4649: 4638: 4637: 4601: 4600: 4575: 4574: 4519: 4518: 4493: 4492: 4437: 4436: 4415: 4414: 4389: 4388: 4366: 4365: 4346: 4345: 4322: 4321: 4302: 4301: 4274: 4261: 4225: 4224: 4197: 4184: 4179: 4178: 4155: 4154: 4130: 4129: 4110: 4109: 4060: 4059: 3946: 3945: 3935: 3934: 3906: 3905: 3806: 3805: 3802: 3796: 3770: 3769: 3765: 3744: 3743: 3722: 3721: 3700: 3699: 3678: 3677: 3624: 3623: 3600: 3599: 3576: 3575: 3554: 3553: 3509: 3508: 3473: 3472: 3448: 3441: 3427: 3413: 3395: 3377: 3354: 3340: 3275: 3256: 3239: 3238: 3209: 3131: 3126: 3125: 3102: 3101: 3100:. For example, 3058: 3057: 3050: 3042:Main articles: 3040: 2976: 2975: 2942: 2941: 2927:Riemann surface 2812: 2789: 2788: 2758: 2751: 2735: 2721: 2720: 2687:splitting field 2637: 2606: 2605: 2562: 2557: 2556: 2526:polynomial ring 2487: 2482: 2481: 2449: 2448: 2431: 2430: 2380: 2344: 2285: 2281: 2272: 2271: 2236: 2199: 2198: 2171: 2170: 2136: 2135: 2118: 2117: 2034: 2030: 2021: 2020: 2000: 1963: 1959: 1950: 1949: 1934: 1919: 1907: 1884: 1880: 1866: 1865: 1829: 1825: 1820: 1819: 1795: 1794: 1735: 1731: 1705: 1704: 1649: 1648: 1608: 1607: 1576: 1575: 1544: 1543: 1502: 1501: 1470: 1469: 1448: 1447: 1426: 1425: 1404: 1403: 1379: 1378: 1375: 1313: 1274: 1246: 1245: 1233: 1204: 1187: 1186: 1148: 1129: 1115: 1114: 1090: 1071: 1060: 1059: 1035: 1016: 1002: 1001: 968:) is the field 952: 951: 880: 879: 806: 805: 775: 774: 747: 746: 719: 718: 691: 690: 663: 662: 641: 640: 605: 604: 554: 553: 523: 522: 456: 455: 452:field extension 440:extension field 424: 422:Extension field 393: 392: 355: 354: 335: 334: 330: 308: 307: 280: 279: 260: 259: 234: 233: 211: 210: 188: 187: 181: 150:complex numbers 122:extension field 77: 76: 72:) is a pair of 46: 45: 42:field extension 30: 23: 22: 15: 12: 11: 5: 5444: 5442: 5434: 5433: 5423: 5422: 5419: 5418: 5398: 5397:External links 5395: 5394: 5393: 5373: 5368: 5348: 5344:978-1114541016 5343: 5326: 5321: 5313:Addison-Wesley 5302: 5299: 5297: 5296: 5294:, p. 169) 5292:Herstein (1964 5284: 5282:, p. 319) 5280:Fraleigh (1976 5272: 5270:, p. 363) 5268:Fraleigh (1976 5260: 5258:, p. 193) 5256:Herstein (1964 5248: 5246:, p. 298) 5244:Fraleigh (1976 5236: 5234:, p. 116) 5224: 5222:, p. 167) 5220:Herstein (1964 5212: 5210:, p. 293) 5208:Fraleigh (1976 5199: 5197: 5194: 5193: 5192: 5187: 5182: 5177: 5172: 5165: 5162: 5150:group algebras 5138:extend scalars 5130:Main article: 5127: 5124: 5103:simple algebra 5082: 5079: 5057:(subfields of 5042: 5038: 5034: 4964: 4961: 4957: 4953: 4950: 4922: 4918: 4914: 4860: 4856: 4852: 4829: 4825: 4821: 4765: 4761: 4757: 4745: 4742: 4714: 4694: 4689: 4685: 4681: 4678: 4656: 4652: 4648: 4645: 4625: 4622: 4618: 4614: 4611: 4608: 4588: 4585: 4582: 4562: 4559: 4556: 4552: 4547: 4543: 4540: 4537: 4534: 4531: 4527: 4506: 4503: 4500: 4480: 4477: 4474: 4470: 4465: 4461: 4458: 4455: 4452: 4449: 4445: 4423: 4402: 4399: 4396: 4376: 4373: 4353: 4329: 4309: 4289: 4286: 4281: 4277: 4273: 4268: 4264: 4260: 4256: 4252: 4249: 4246: 4243: 4240: 4237: 4233: 4212: 4209: 4204: 4200: 4196: 4191: 4187: 4162: 4142: 4138: 4117: 4097: 4093: 4088: 4084: 4081: 4078: 4075: 4072: 4068: 3961: 3957: 3953: 3932:is said to be 3921: 3917: 3913: 3821: 3817: 3813: 3798:Main article: 3795: 3792: 3778: 3752: 3730: 3708: 3686: 3651:if and only if 3636: 3632: 3609: 3585: 3562: 3541: 3536: 3531: 3526: 3521: 3517: 3488: 3484: 3480: 3293: 3288: 3285: 3282: 3278: 3274: 3271: 3268: 3263: 3259: 3255: 3252: 3249: 3246: 3237:) consists of 3157:If an element 3146: 3143: 3138: 3134: 3111: 3073: 3069: 3065: 3039: 3036: 3017:function field 2984: 2963: 2960: 2957: 2954: 2950: 2862:Given a field 2843: 2839: 2835: 2830: 2826: 2821: 2816: 2811: 2808: 2805: 2802: 2799: 2796: 2765: 2761: 2755: 2750: 2747: 2742: 2738: 2734: 2731: 2728: 2655: 2652: 2649: 2644: 2640: 2636: 2632: 2628: 2625: 2622: 2619: 2616: 2613: 2577: 2574: 2569: 2565: 2496: 2491: 2479:p-adic numbers 2457: 2445: 2444: 2429: 2425: 2420: 2416: 2413: 2410: 2407: 2404: 2401: 2398: 2395: 2392: 2387: 2383: 2377: 2372: 2367: 2362: 2359: 2356: 2351: 2347: 2341: 2336: 2331: 2326: 2323: 2320: 2317: 2312: 2307: 2302: 2297: 2294: 2291: 2288: 2284: 2280: 2277: 2275: 2273: 2270: 2265: 2260: 2255: 2250: 2246: 2242: 2239: 2237: 2235: 2230: 2225: 2220: 2215: 2211: 2207: 2206: 2183: 2179: 2158: 2153: 2148: 2144: 2132: 2131: 2116: 2112: 2107: 2103: 2100: 2097: 2094: 2091: 2088: 2085: 2082: 2079: 2074: 2069: 2066: 2061: 2056: 2053: 2048: 2043: 2040: 2037: 2033: 2029: 2026: 2024: 2022: 2018: 2013: 2008: 2003: 1998: 1994: 1991: 1988: 1985: 1982: 1977: 1972: 1969: 1966: 1962: 1958: 1955: 1953: 1951: 1947: 1942: 1937: 1932: 1927: 1922: 1917: 1913: 1910: 1908: 1905: 1899: 1894: 1889: 1883: 1878: 1874: 1873: 1846: 1840: 1835: 1832: 1828: 1807: 1803: 1791: 1790: 1779: 1775: 1770: 1766: 1763: 1760: 1757: 1754: 1749: 1744: 1741: 1738: 1734: 1730: 1727: 1722: 1717: 1713: 1680: 1675: 1672: 1668: 1664: 1660: 1656: 1637: 1634: 1631: 1628: 1624: 1620: 1616: 1594: 1589: 1584: 1563: 1560: 1557: 1554: 1551: 1531: 1528: 1525: 1521: 1517: 1513: 1509: 1488: 1483: 1478: 1456: 1434: 1412: 1387: 1374: 1371: 1329:quotient group 1312: 1309: 1264:characteristic 1166: 1163: 1160: 1155: 1151: 1147: 1144: 1141: 1136: 1132: 1128: 1125: 1122: 1102: 1097: 1093: 1089: 1086: 1083: 1078: 1074: 1070: 1067: 1047: 1042: 1038: 1034: 1031: 1028: 1023: 1019: 1015: 1012: 1009: 986:generating set 918:that contains 895: 891: 887: 876: 875: 864: 861: 858: 855: 852: 849: 846: 843: 840: 837: 834: 831: 828: 825: 822: 819: 816: 813: 790: 786: 782: 762: 758: 754: 734: 730: 726: 706: 702: 698: 678: 674: 670: 624: 621: 618: 615: 612: 569: 565: 561: 538: 534: 530: 471: 467: 463: 423: 420: 416:characteristic 400: 390:characteristic 362: 342: 315: 287: 267: 247: 244: 241: 218: 195: 180: 177: 146:multiplication 90: 87: 84: 61: 57: 53: 28: 24: 14: 13: 10: 9: 6: 4: 3: 2: 5443: 5432: 5429: 5428: 5426: 5415: 5411: 5410: 5405: 5401: 5400: 5396: 5391: 5387: 5383: 5379: 5374: 5371: 5365: 5361: 5357: 5353: 5349: 5346: 5340: 5336: 5332: 5327: 5324: 5322:0-201-01984-1 5318: 5314: 5310: 5305: 5304: 5300: 5293: 5288: 5285: 5281: 5276: 5273: 5269: 5264: 5261: 5257: 5252: 5249: 5245: 5240: 5237: 5233: 5228: 5225: 5221: 5216: 5213: 5209: 5204: 5201: 5195: 5191: 5188: 5186: 5183: 5181: 5178: 5176: 5173: 5171: 5168: 5167: 5163: 5161: 5159: 5155: 5151: 5147: 5143: 5139: 5133: 5125: 5123: 5121: 5117: 5113: 5108: 5104: 5100: 5096: 5092: 5088: 5080: 5078: 5076: 5072: 5068: 5064: 5061:that contain 5060: 5056: 5040: 5036: 5032: 5023: 5021: 5017: 5013: 5009: 5005: 5001: 4997: 4993: 4989: 4985: 4981: 4978: 4977:automorphisms 4959: 4955: 4951: 4936: 4920: 4916: 4912: 4903: 4901: 4896: 4894: 4890: 4886: 4882: 4878: 4874: 4858: 4854: 4850: 4841: 4827: 4823: 4819: 4811: 4807: 4803: 4799: 4795: 4791: 4787: 4783: 4779: 4763: 4759: 4755: 4743: 4741: 4739: 4735: 4731: 4726: 4712: 4692: 4687: 4683: 4679: 4676: 4654: 4650: 4646: 4643: 4623: 4620: 4616: 4612: 4609: 4606: 4583: 4573:. Similarly, 4557: 4545: 4538: 4535: 4532: 4501: 4475: 4463: 4456: 4453: 4450: 4397: 4374: 4371: 4351: 4343: 4327: 4307: 4287: 4279: 4275: 4271: 4266: 4262: 4254: 4247: 4238: 4210: 4207: 4202: 4198: 4194: 4189: 4185: 4176: 4160: 4140: 4115: 4095: 4086: 4079: 4076: 4073: 4056: 4054: 4050: 4046: 4042: 4038: 4034: 4030: 4026: 4022: 4018: 4013: 4011: 4007: 4003: 3999: 3995: 3991: 3987: 3983: 3979: 3975: 3959: 3955: 3951: 3943: 3939: 3919: 3915: 3911: 3903: 3899: 3895: 3891: 3887: 3883: 3879: 3875: 3871: 3867: 3863: 3859: 3855: 3851: 3847: 3843: 3839: 3835: 3819: 3815: 3811: 3801: 3793: 3791: 3764:(for example 3675: 3671: 3667: 3663: 3659: 3654: 3652: 3647: 3634: 3607: 3583: 3534: 3529: 3524: 3506: 3502: 3486: 3482: 3478: 3471: 3466: 3464: 3460: 3455: 3451: 3444: 3438: 3434: 3430: 3424: 3420: 3416: 3410: 3406: 3402: 3398: 3392: 3388: 3384: 3380: 3373: 3369: 3365: 3361: 3357: 3351: 3347: 3343: 3338: 3334: 3330: 3326: 3322: 3318: 3314: 3309: 3307: 3291: 3286: 3283: 3280: 3276: 3272: 3269: 3266: 3261: 3257: 3253: 3250: 3247: 3244: 3236: 3232: 3229: 3225: 3220: 3216: 3212: 3207: 3203: 3199: 3194: 3192: 3188: 3184: 3180: 3176: 3172: 3168: 3164: 3160: 3144: 3141: 3136: 3132: 3109: 3099: 3095: 3092:of a nonzero 3091: 3087: 3071: 3067: 3063: 3055: 3049: 3045: 3037: 3035: 3033: 3029: 3025: 3021: 3018: 3014: 3010: 3007: 3003: 2999: 2961: 2955: 2939: 2935: 2931: 2928: 2923: 2921: 2917: 2913: 2909: 2905: 2902:, and indeed 2901: 2897: 2893: 2889: 2885: 2881: 2877: 2873: 2869: 2865: 2860: 2858: 2837: 2833: 2824: 2819: 2809: 2803: 2797: 2794: 2787: 2783: 2763: 2759: 2748: 2740: 2736: 2729: 2726: 2719: 2715: 2711: 2707: 2702: 2700: 2696: 2692: 2688: 2683: 2681: 2677: 2676:residue class 2673: 2669: 2650: 2647: 2642: 2638: 2630: 2623: 2617: 2614: 2611: 2603: 2599: 2595: 2591: 2575: 2572: 2567: 2563: 2554: 2550: 2546: 2542: 2538: 2534: 2530: 2527: 2523: 2522:quotient ring 2519: 2514: 2512: 2494: 2480: 2476: 2475:number theory 2472: 2427: 2423: 2414: 2411: 2408: 2405: 2402: 2399: 2396: 2393: 2390: 2385: 2375: 2370: 2365: 2357: 2354: 2349: 2339: 2334: 2329: 2321: 2318: 2310: 2305: 2300: 2292: 2289: 2286: 2282: 2278: 2276: 2263: 2258: 2253: 2240: 2238: 2228: 2223: 2218: 2197: 2196: 2195: 2181: 2151: 2114: 2110: 2101: 2098: 2095: 2092: 2089: 2086: 2083: 2080: 2077: 2072: 2067: 2064: 2059: 2054: 2051: 2046: 2041: 2038: 2035: 2031: 2027: 2025: 2016: 2011: 2006: 2001: 1992: 1989: 1986: 1983: 1980: 1975: 1970: 1967: 1964: 1960: 1956: 1954: 1945: 1940: 1935: 1930: 1925: 1920: 1911: 1909: 1903: 1897: 1892: 1887: 1881: 1864: 1863: 1862: 1859: 1844: 1838: 1833: 1830: 1826: 1805: 1777: 1773: 1764: 1761: 1758: 1755: 1752: 1747: 1742: 1739: 1736: 1732: 1728: 1720: 1703: 1702: 1701: 1698: 1696: 1673: 1662: 1635: 1629: 1618: 1587: 1558: 1555: 1552: 1529: 1526: 1515: 1481: 1402: 1372: 1370: 1367: 1365: 1361: 1357: 1353: 1349: 1346: 1340: 1338: 1334: 1330: 1326: 1325:quotient ring 1322: 1318: 1315:The notation 1310: 1308: 1306: 1302: 1298: 1294: 1290: 1285: 1281: 1277: 1271: 1269: 1265: 1260: 1258: 1254: 1250: 1240: 1236: 1230: 1228: 1224: 1220: 1215: 1211: 1207: 1202: 1198: 1194: 1184: 1180: 1164: 1153: 1149: 1145: 1142: 1139: 1134: 1130: 1120: 1095: 1091: 1087: 1084: 1081: 1076: 1072: 1065: 1040: 1036: 1032: 1029: 1026: 1021: 1017: 1010: 1007: 999: 995: 991: 987: 983: 979: 975: 971: 967: 963: 959: 956: 949: 945: 941: 937: 933: 930:that contain 929: 925: 921: 917: 913: 909: 906:and a subset 893: 889: 885: 862: 856: 853: 850: 844: 838: 835: 832: 826: 820: 817: 814: 804: 803: 802: 788: 784: 780: 760: 756: 752: 732: 728: 724: 704: 700: 696: 676: 672: 668: 659: 657: 653: 649: 645: 636: 619: 616: 613: 602: 600: 595: 591: 587: 583: 567: 563: 559: 550: 536: 532: 528: 520: 516: 512: 508: 504: 500: 496: 491: 489: 485: 469: 465: 461: 453: 449: 445: 441: 437: 433: 429: 421: 419: 417: 412: 398: 391: 387: 383: 379: 374: 360: 340: 327: 313: 305: 301: 285: 265: 245: 242: 239: 232: 216: 209: 193: 186: 178: 176: 174: 170: 169:Galois theory 166: 162: 157: 155: 151: 147: 143: 139: 135: 131: 127: 123: 119: 115: 111: 108: 105:are those of 104: 88: 85: 82: 75: 59: 55: 51: 43: 39: 35: 27: 19: 5407: 5377: 5355: 5330: 5308: 5287: 5275: 5263: 5251: 5239: 5227: 5215: 5203: 5170:Field theory 5135: 5084: 5062: 5058: 5054: 5024: 5012:Galois group 5007: 5003: 4999: 4995: 4991: 4987: 4983: 4979: 4934: 4904: 4897: 4888: 4880: 4876: 4842: 4809: 4805: 4801: 4797: 4793: 4789: 4785: 4747: 4727: 4057: 4052: 4048: 4044: 4040: 4036: 4032: 4028: 4024: 4020: 4016: 4014: 4009: 4005: 4001: 3997: 3993: 3989: 3985: 3981: 3977: 3973: 3941: 3933: 3901: 3897: 3892:is called a 3889: 3885: 3881: 3877: 3876:, such that 3873: 3869: 3865: 3861: 3853: 3849: 3845: 3837: 3833: 3803: 3673: 3669: 3665: 3657: 3656:Every field 3655: 3648: 3504: 3500: 3469: 3467: 3462: 3458: 3453: 3449: 3442: 3436: 3432: 3428: 3422: 3418: 3414: 3408: 3404: 3400: 3396: 3390: 3386: 3382: 3378: 3371: 3367: 3363: 3359: 3355: 3349: 3345: 3341: 3336: 3332: 3328: 3324: 3316: 3312: 3310: 3305: 3234: 3230: 3228:vector space 3223: 3218: 3214: 3210: 3205: 3201: 3197: 3195: 3190: 3182: 3174: 3166: 3162: 3158: 3097: 3085: 3053: 3051: 3031: 3027: 3023: 3019: 3012: 3008: 3001: 2937: 2929: 2924: 2919: 2915: 2907: 2903: 2899: 2891: 2887: 2883: 2879: 2871: 2867: 2863: 2861: 2856: 2781: 2718:finite field 2713: 2710:prime number 2705: 2703: 2698: 2694: 2690: 2684: 2679: 2671: 2667: 2593: 2552: 2548: 2544: 2540: 2536: 2528: 2517: 2515: 2510: 2446: 2133: 1860: 1792: 1699: 1401:real numbers 1376: 1368: 1351: 1341: 1336: 1332: 1320: 1316: 1314: 1304: 1300: 1292: 1288: 1283: 1279: 1275: 1272: 1261: 1256: 1252: 1244: 1238: 1234: 1231: 1225:is called a 1222: 1217:is called a 1213: 1209: 1205: 1200: 1196: 1192: 1182: 1178: 997: 993: 989: 981: 977: 973: 969: 965: 961: 957: 950: 947: 946:) (read as " 943: 939: 935: 931: 927: 923: 919: 915: 911: 907: 877: 660: 655: 651: 647: 639: 637: 598: 590:vector space 585: 581: 551: 519:subextension 518: 514: 510: 506: 502: 498: 494: 492: 487: 483: 451: 447: 443: 439: 435: 431: 427: 425: 413: 382:real numbers 375: 328: 184: 182: 158: 154:real numbers 137: 133: 129: 125: 121: 117: 113: 106: 102: 41: 31: 26: 5352:Lang, Serge 5333:, Waltham: 5232:McCoy (1968 5018:are called 4004:where both 3832:, a subset 3196:An element 3187:irreducible 3088:if it is a 3052:An element 3000:defined on 2936:defined on 2896:polynomials 2786:prime field 2590:irreducible 1700:The field 1113:instead of 980:, and that 34:mathematics 5380:, Boston: 5301:References 5120:local ring 4871:is called 4812:such that 4776:is called 4043:such that 3972:such that 3840:is called 3574:, because 3094:polynomial 2859:elements. 1861:The field 1247:adjunction 482:(read as " 442:or simply 386:isomorphic 110:restricted 5414:EMS Press 5071:subgroups 5067:bijection 4885:separable 4873:separable 4780:if every 4705:and thus 4300:in which 4285:⟩ 4272:− 4259:⟨ 4195:− 3284:− 3270:… 3142:− 2910:) is the 2874:) of all 2798:⁡ 2415:∈ 2391:∣ 2102:∈ 2078:∣ 1993:∈ 1981:∣ 1765:∈ 1753:∣ 1360:morphisms 1345:injective 1339:is used. 1143:… 1085:… 1030:… 970:generated 845:⋅ 594:dimension 444:extension 331:1 – 1 = 0 298:, and is 243:⊆ 86:⊆ 44:(denoted 5425:Category 5390:68015225 5354:(2004), 5164:See also 5095:subrings 5002:for all 4636:one has 4340:are the 2925:Given a 1542:because 1373:Examples 185:subfield 179:Subfield 167:through 142:addition 134:subfield 5416:, 2001 5356:Algebra 5016:abelian 2708:is any 2602:maximal 2524:of the 1362:in the 1311:Caveats 1000:. When 996:) over 505:, then 434:, then 304:inverse 38:algebra 5388:  5366:  5341:  5319:  4778:normal 4108:where 3461:and 1/ 3304:where 3169:, the 3015:, the 2670:which 2604:, and 1424:, and 1356:ideals 953:adjoin 599:degree 592:. The 438:is an 300:closed 231:subset 148:, the 120:is an 74:fields 5196:Notes 4990:with 4879:over 4173:is a 3844:over 3662:up to 3189:over 2898:over 2855:with 2780:with 2598:ideal 2551:with 2520:as a 1693:(the 1352:Every 1303:over 1195:. If 1191:over 1185:) is 984:is a 976:over 584:is a 521:) of 486:over 229:is a 208:field 206:of a 132:is a 5386:LCCN 5364:ISBN 5339:ISBN 5317:ISBN 5091:ring 4998:) = 4891:. A 4669:and 4364:and 4320:and 4175:root 4153:and 4008:and 3598:and 3440:(if 3426:and 3353:and 3335:and 3090:root 3046:and 2712:and 2672:does 2533:root 2169:and 1282:) / 1221:and 1212:) / 934:and 922:and 773:and 689:and 650:and 513:(or 490:"). 414:The 353:and 144:and 128:and 40:, a 5006:in 4945:Aut 4883:is 4784:in 4732:of 4344:of 4055:). 4015:If 3944:of 3896:of 3860:of 3836:of 3790:). 3468:An 3445:≠ 0 3435:) / 3431:(1/ 3421:) / 3407:) / 3389:) / 3366:) / 3348:) / 3327:in 3323:of 3217:) / 3200:of 3181:of 3161:of 2704:If 2697:of 2682:). 2678:of 2592:in 2588:is 1327:or 1299:in 1262:In 1255:to 1251:of 988:of 972:by 910:of 635:. 517:or 493:If 446:of 426:If 329:As 136:of 124:of 112:to 32:In 5427:: 5412:, 5406:, 5384:, 5358:, 5337:, 5315:, 5160:. 5122:. 5077:. 5022:. 4986:→ 4982:: 4211:0. 4047:= 4031:= 3976:= 3459:st 3457:, 3452:± 3419:st 3412:, 3403:± 3385:, 3362:)( 3193:. 3145:2. 3034:. 2795:GF 2513:. 1366:. 1319:/ 1307:. 1259:. 549:. 411:. 326:. 183:A 175:. 5063:K 5059:L 5055:F 5041:K 5037:/ 5033:L 5008:K 5004:x 5000:x 4996:x 4994:( 4992:α 4988:L 4984:L 4980:α 4963:) 4960:K 4956:/ 4952:L 4949:( 4921:K 4917:/ 4913:L 4889:K 4881:K 4877:L 4859:K 4855:/ 4851:L 4828:K 4824:/ 4820:L 4810:F 4806:L 4802:K 4800:/ 4798:F 4794:L 4790:L 4786:K 4764:K 4760:/ 4756:L 4713:t 4693:, 4688:3 4684:t 4680:= 4677:y 4655:2 4651:t 4647:= 4644:x 4624:, 4621:x 4617:/ 4613:y 4610:= 4607:t 4587:} 4584:y 4581:{ 4561:) 4558:x 4555:( 4551:Q 4546:/ 4542:) 4539:y 4536:, 4533:x 4530:( 4526:Q 4505:} 4502:x 4499:{ 4479:) 4476:x 4473:( 4469:Q 4464:/ 4460:) 4457:y 4454:, 4451:x 4448:( 4444:Q 4422:Q 4401:} 4398:x 4395:{ 4375:. 4372:Y 4352:X 4328:y 4308:x 4288:, 4280:3 4276:X 4267:2 4263:Y 4255:/ 4251:] 4248:Y 4245:[ 4242:) 4239:X 4236:( 4232:Q 4208:= 4203:3 4199:x 4190:2 4186:y 4161:y 4141:, 4137:Q 4116:x 4096:, 4092:Q 4087:/ 4083:) 4080:y 4077:, 4074:x 4071:( 4067:Q 4053:S 4051:( 4049:K 4045:L 4041:S 4037:S 4035:( 4033:K 4029:L 4025:S 4021:K 4019:/ 4017:L 4010:K 4006:L 4002:K 4000:/ 3998:L 3994:K 3990:K 3986:L 3982:S 3980:( 3978:K 3974:L 3960:K 3956:/ 3952:L 3942:S 3920:K 3916:/ 3912:L 3902:K 3900:/ 3898:L 3890:S 3886:S 3884:( 3882:K 3880:/ 3878:L 3874:K 3870:S 3866:K 3864:/ 3862:L 3854:S 3850:K 3846:K 3838:L 3834:S 3820:K 3816:/ 3812:L 3777:Q 3766:π 3751:Q 3729:Q 3707:R 3685:C 3674:K 3670:K 3666:K 3658:K 3635:. 3631:Q 3608:3 3584:2 3561:Q 3540:) 3535:3 3530:, 3525:2 3520:( 3516:Q 3505:K 3501:L 3487:K 3483:/ 3479:L 3463:s 3454:t 3450:s 3443:s 3437:K 3433:s 3429:K 3423:K 3417:( 3415:K 3409:K 3405:t 3401:s 3399:( 3397:K 3391:K 3387:t 3383:s 3381:( 3379:K 3374:) 3372:s 3370:( 3368:K 3364:t 3360:s 3358:( 3356:K 3350:K 3346:s 3344:( 3342:K 3337:t 3333:s 3329:L 3325:K 3317:K 3313:L 3306:d 3292:, 3287:1 3281:d 3277:s 3273:, 3267:, 3262:2 3258:s 3254:, 3251:s 3248:, 3245:1 3235:s 3233:( 3231:K 3226:- 3224:K 3219:K 3215:s 3213:( 3211:K 3206:K 3202:L 3198:s 3191:K 3183:x 3175:x 3167:K 3163:L 3159:x 3137:2 3133:x 3110:2 3098:K 3086:K 3072:K 3068:/ 3064:L 3054:x 3032:K 3028:V 3024:V 3022:( 3020:K 3013:K 3009:V 3002:M 2983:C 2962:. 2959:) 2956:M 2953:( 2949:C 2938:M 2930:M 2920:K 2916:K 2908:X 2906:( 2904:K 2900:K 2892:X 2890:( 2888:K 2884:K 2880:X 2872:X 2870:( 2868:K 2864:K 2857:p 2842:Z 2838:p 2834:/ 2829:Z 2825:= 2820:p 2815:F 2810:= 2807:) 2804:p 2801:( 2782:p 2764:n 2760:p 2754:F 2749:= 2746:) 2741:n 2737:p 2733:( 2730:F 2727:G 2714:n 2706:p 2699:K 2695:L 2691:K 2680:X 2668:K 2654:) 2651:1 2648:+ 2643:2 2639:X 2635:( 2631:/ 2627:] 2624:X 2621:[ 2618:K 2615:= 2612:L 2594:K 2576:1 2573:+ 2568:2 2564:X 2553:x 2549:x 2545:K 2541:X 2539:( 2537:f 2529:K 2518:K 2511:p 2495:p 2490:Q 2456:Q 2428:. 2424:} 2419:Q 2412:d 2409:, 2406:c 2403:, 2400:b 2397:, 2394:a 2386:3 2382:) 2376:3 2371:+ 2366:2 2361:( 2358:d 2355:+ 2350:2 2346:) 2340:3 2335:+ 2330:2 2325:( 2322:c 2319:+ 2316:) 2311:3 2306:+ 2301:2 2296:( 2293:b 2290:+ 2287:a 2283:{ 2279:= 2269:) 2264:3 2259:+ 2254:2 2249:( 2245:Q 2241:= 2234:) 2229:3 2224:, 2219:2 2214:( 2210:Q 2182:, 2178:Q 2157:) 2152:2 2147:( 2143:Q 2115:, 2111:} 2106:Q 2099:d 2096:, 2093:c 2090:, 2087:b 2084:, 2081:a 2073:6 2068:d 2065:+ 2060:3 2055:c 2052:+ 2047:2 2042:b 2039:+ 2036:a 2032:{ 2028:= 2017:} 2012:) 2007:2 2002:( 1997:Q 1990:b 1987:, 1984:a 1976:3 1971:b 1968:+ 1965:a 1961:{ 1957:= 1946:) 1941:3 1936:( 1931:) 1926:2 1921:( 1916:Q 1912:= 1904:) 1898:3 1893:, 1888:2 1882:( 1877:Q 1845:} 1839:2 1834:, 1831:1 1827:{ 1806:, 1802:Q 1778:, 1774:} 1769:Q 1762:b 1759:, 1756:a 1748:2 1743:b 1740:+ 1737:a 1733:{ 1729:= 1726:) 1721:2 1716:( 1712:Q 1679:c 1674:= 1671:] 1667:Q 1663:: 1659:R 1655:[ 1636:. 1633:) 1630:i 1627:( 1623:R 1619:= 1615:C 1593:R 1588:/ 1583:C 1562:} 1559:i 1556:, 1553:1 1550:{ 1530:2 1527:= 1524:] 1520:R 1516:: 1512:C 1508:[ 1487:Q 1482:/ 1477:C 1455:Q 1433:R 1411:R 1386:C 1337:K 1335:: 1333:L 1321:K 1317:L 1305:K 1301:s 1293:s 1291:( 1289:K 1284:K 1280:s 1278:( 1276:K 1257:K 1253:S 1241:) 1239:S 1237:( 1235:K 1223:s 1214:K 1210:s 1208:( 1206:K 1201:s 1197:S 1193:K 1183:S 1181:( 1179:K 1165:, 1162:) 1159:} 1154:n 1150:x 1146:, 1140:, 1135:1 1131:x 1127:{ 1124:( 1121:K 1101:) 1096:n 1092:x 1088:, 1082:, 1077:1 1073:x 1069:( 1066:K 1046:} 1041:n 1037:x 1033:, 1027:, 1022:1 1018:x 1014:{ 1011:= 1008:S 998:K 994:S 992:( 990:K 982:S 978:K 974:S 966:S 964:( 962:K 958:S 948:K 944:S 942:( 940:K 936:S 932:K 928:L 924:S 920:K 916:L 912:L 908:S 894:K 890:/ 886:L 863:. 860:] 857:K 854:: 851:L 848:[ 842:] 839:L 836:: 833:M 830:[ 827:= 824:] 821:K 818:: 815:M 812:[ 789:L 785:/ 781:M 761:K 757:/ 753:L 733:K 729:/ 725:M 705:L 701:/ 697:M 677:K 673:/ 669:L 623:] 620:K 617:: 614:L 611:[ 588:- 586:K 582:L 568:K 564:/ 560:L 537:K 533:/ 529:L 507:F 503:K 499:F 495:L 488:K 484:L 470:K 466:/ 462:L 448:K 436:L 432:L 428:K 399:0 361:L 341:K 314:K 286:1 266:L 246:L 240:K 217:L 194:K 138:L 130:K 126:K 118:L 114:K 107:L 103:K 89:L 83:K 60:K 56:/ 52:L 20:)

Index

Purely transcendental
mathematics
algebra
fields
restricted
addition
multiplication
complex numbers
real numbers
algebraic number theory
polynomial roots
Galois theory
algebraic geometry
field
subset
closed
inverse
rational numbers
real numbers
isomorphic
characteristic
characteristic
vector space
dimension
degree of the extension
generating set
simple extension
primitive element
characteristic
primitive element theorem

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