Knowledge

Real closed field

Source 📝

2865:. Using those axioms, one can show that the points on a line form a real closed field R, and one can introduce coordinates so that the Euclidean plane is identified with R . Employing the decidability of the theory of real closed fields, Tarski then proved that the elementary theory of Euclidean geometry is complete and decidable. 1326:-tuple of the components corresponding to the subset of variables. The projection theorem asserts that a projection of a semialgebraic set is a semialgebraic set, and that there is an algorithm that, given a quantifier-free formula defining a semialgebraic set, produces a quantifier-free formula for its projection. 1411:
The decidability of a first-order theory of the real numbers depends dramatically on the primitive operations and functions that are considered (here addition and multiplication). Adding other functions symbols, for example, the
784: 3208:"On the computational complexity and geometry of the first-order theory of the reals. Part I: Introduction. Preliminaries. The geometry of semi-algebraic sets. The decision problem for the existential theory of the reals" 2386: 2090:
These three cardinal numbers tell us much about the order properties of any real closed field, though it may be difficult to discover what they are, especially if we are not willing to invoke the
1552: 1439:'s results about the incompleteness and undecidability of the first-order theory of the natural numbers (using addition and multiplication). There is no contradiction, since the statement " 913: 520: 1472: 1238: 1195: 1164: 1129: 1092: 991: 956: 1425: 854: 819: 720: 1958:
is real closed and non-Archimedean. These fields contain infinitely large (larger than any integer) and infinitesimal (positive but smaller than any positive rational) elements.
1768: 2674:
a hyperreal field, and hence a suitable field for the usages of nonstandard analysis. It can be seen to be the higher-dimensional analogue of the real numbers; with cardinality
1722: 1395: 2309: 2276: 2207: 268: 2486: 2447: 2534: 2412: 1613: 876: 2834: 2807: 2780: 2753: 2726: 2699: 2664: 2633: 2588: 2046: 1822:, and therefore in double exponential time, but their argument (in the case of more than one variable) is generally held as flawed; see Renegar (1992) for a discussion. 1797: 1256:. Since the truth of quantifier-free formulas without free variables can be easily checked, this yields the desired decision procedure. These results were obtained 1947:. Note that this statement is not expressible in the first-order language of ordered fields, since it is not possible to quantify over integers in that language. 1049: 1029: 2422:, and its uniqueness is equivalent to the continuum hypothesis. (Even without the continuum hypothesis we have that if the cardinality of the continuum is 728: 1431:
Furthermore, the completeness and decidability of the first-order theory of the real numbers (using addition and multiplication) contrasts sharply with
1329:
In fact, the projection theorem is equivalent to quantifier elimination, as the projection of a semialgebraic set defined by the formula
1562: 295:
is formally real. (In other words, the field is maximal in an algebraic closure with respect to the property of being formally real.)
962:(as well as equality, if this is not considered a logical symbol). In this language, the (first-order) theory of real closed fields, 3188: 3169: 3132: 3042: 3014: 2917: 3344: 2350: 2017:
of the smallest cofinal set, which is to say, the size of the smallest cardinality giving an unbounded sequence. For example,
3265: 1267: 1252:
means that the two formulas are true for exactly the same values of the variables. Tarski's proof uses a generalization of
3124: 1951: 1502: 92: 3339: 2329: 3334: 3180: 881: 488: 321: 303: 958:
includes symbols for the operations of addition and multiplication, the constants 0 and 1, and the order relation
31: 1446: 1212: 1169: 1138: 1103: 1066: 965: 930: 1914:(1996) provided a well-behaved algorithm to decide the truth of such an existential formula with complexity of 1803:. This shows that both the time complexity and the space complexity of quantifier elimination are intrinsically 1672:
quantifiers, and involving polynomials of constant degree, such that any quantifier-free formula equivalent to
1493: 824: 789: 690: 3246: 1804: 1421: 88: 3002: 1911: 1486: 1315: 1206: 137: 1727: 3051: 3018: 2541: 1684: 1645: 1490: 1350: 3317: 2287: 2254: 2185: 236: 2464: 2425: 2419: 2325: 2091: 1417: 1198: 213: 134: 2537: 2502: 2139: 1241: 278: 163: 46: 2395: 1575: 859: 3285: 3077: 3073: 2998: 2862: 2812: 2785: 2758: 2731: 2704: 2677: 2642: 2611: 2566: 2496: 2024: 1800: 1060: 723: 535: 149: 2858: 1773: 1253: 675:
is a field (no ordering compatible with the field operations is assumed, nor is it assumed that
3184: 3165: 3128: 3038: 3010: 2324:
The characteristics of real closed fields become much simpler if we are willing to assume the
1936: 1566: 1291: 1056: 454: 450: 394: 366: 341: 335: 217: 91:
to the real numbers. In other words, it has the same first-order properties as the reals: any
53: 17: 3277: 3219: 3194: 3138: 3103: 3093: 3047: 2977: 2936: 2415: 2312: 1955: 1094:
is just the set of all first-order sentences that are true about the field of real numbers.
684: 554: 379: 372: 347: 221: 65: 61: 3297: 3157: 2991: 3293: 3237: 3198: 3142: 3107: 3026: 2987: 2547: 2242: 2238: 2131: 1132: 924: 578: 482: 231: 562: 3062: 2164: 2018: 1944: 1638: 1408:
represent respectively the set of eliminated variables, and the set of kept variables.
1034: 1014: 386: 359: 99: 3224: 3207: 3098: 3081: 2982: 2051:
We have therefore the following invariants defining the nature of a real closed field
3328: 3253: 2544: 1432: 1245: 1097: 1002: 531: 114: 2941: 1818:(1986) claimed to have proved that the theory of real closed fields is decidable in 2600:
however is not a complete field; if we take its completion, we end up with a field
2344: 1811: 1248:, produces an equivalent quantifier-free formula in the same free variables, where 779:{\displaystyle \mathbb {R} _{\mathrm {alg} }\!\times \mathbb {R} _{\mathrm {alg} }} 390: 27:
Non algebraically closed field whose extension by sqrt(–1) is algebraically closed
1205:
to determine the truth or falsity of any such sentence. This was done by showing
1166:-sentence can be proven either true or false from the above axioms. Furthermore, 3233: 2850:
property (which merely means between any two real numbers we can find another).
2014: 1939:, meaning it has the Archimedean property that for any real number, there is an 1436: 442: 353: 141: 122: 106: 57: 38: 1626:
is the product of the degrees of the polynomials occurring in the formula, and
433:
is a real closed field whose ordering is an extension of the given ordering on
30:"Artin–Schreier theorem" redirects here. For the branch of Galois theory, see 3030:, Journal of Computer and Systems Sciences 32 (1986), no. 2, pp. 251–264. 1962: 527: 130: 1443:
is an integer" cannot be formulated as a first-order formula in the language
2960:
Alling, Norman L. (1962), "On the existence of real-closed fields that are η
1815: 1290:, the set of the points that satisfy the formula. Such a subset is called a 1202: 3310: 2495:, we can do so much more constructively as the subfield of series with a 1819: 3239:
Combined Decision Procedures for Nonlinear Arithmetics, Real and Complex
3289: 2554: 2450: 2154: 2021:
are cofinal in the reals, and the cofinality of the reals is therefore
1940: 683:
still has a real closure, which may not be a field anymore, but just a
523: 3123:. Mathematical Surveys and Monographs. Vol. 124. Providence, RI: 1924: 3281: 1935:
A crucially important property of the real numbers is that it is an
291:
is a formally real field such that no proper algebraic extension of
1825:
For purely existential formulas, that is for formulas of the form
1648:
is nearly optimal for quantifier elimination by producing a family
993:, consists of all sentences that follow from the following axioms: 3179:. London Mathematical Society Lecture Note Series. Vol. 171. 2861:
are an axiom system for the first-order ("elementary") portion of
998: 438: 2328:. If the continuum hypothesis holds, all real closed fields with 2094:. There are also particular properties that may or may not hold: 1008:
the axiom asserting that every positive number has a square root;
60:. Some examples are the field of real numbers, the field of real 1413: 3035:
Quantifier elimination and cylindrical algebraic decomposition
2392:
is a maximal ideal not leading to a field order-isomorphic to
166:
such that every polynomial of odd degree with coefficients in
2608:
has the cardinality of the continuum, which by hypothesis is
80:
in which any of the following equivalent conditions is true:
3153:, Trans. of the American Math. Soc., Vol. 352, No. 12, 1998. 1569:, provides a much more practicable algorithm of complexity 1453: 1219: 1176: 1145: 1110: 1073: 972: 937: 302:
making it an ordered field such that, in this ordering, the
481:). For example, the real closure of the ordered field of 2381:{\displaystyle \mathbb {R} ^{\mathbb {N} }/\mathbf {M} } 1426:
Decidability of first-order theories of the real numbers
117:
such that, in this ordering, every positive element of
1961:
The Archimedean property is related to the concept of
3258:
A Decision Method for Elementary Algebra and Geometry
2920:
A decision method for elementary algebra and geometry
2815: 2788: 2761: 2734: 2707: 2680: 2645: 2614: 2569: 2505: 2467: 2428: 2398: 2353: 2290: 2257: 2188: 2027: 1776: 1730: 1687: 1578: 1505: 1449: 1353: 1215: 1172: 1141: 1106: 1069: 1037: 1031:, the axiom asserting that all polynomials of degree 1017: 968: 933: 884: 862: 827: 792: 731: 693: 491: 239: 3312:
Real Algebraic and Analytic Geometry Preprint Server
2670:
as a dense subfield. It is not an ultrapower but it
1547:{\displaystyle 2^{2^{\cdot ^{\cdot ^{\cdot ^{n}}}}}} 3082:"Real quantifier elimination is doubly exponential" 1622:is the total number of variables (free and bound), 1063:ranges only over elements of the field). Note that 786:(the two copies correspond to the two orderings of 3151:Weakly o-minimal structures and real closed fields 3033:Caviness, B F, and Jeremy R. Johnson, eds. (1998) 3005:(2003) "Algorithms in real algebraic geometry" in 2828: 2801: 2774: 2747: 2720: 2693: 2658: 2627: 2582: 2528: 2491:Moreover, we do not need ultrapowers to construct 2480: 2441: 2406: 2380: 2303: 2270: 2201: 2040: 1791: 1762: 1716: 1607: 1546: 1466: 1389: 1232: 1189: 1158: 1123: 1086: 1043: 1023: 985: 950: 907: 870: 848: 813: 778: 714: 514: 277:that does not extend to an ordering on any proper 262: 3027:The complexity of elementary algebra and geometry 2339:property are order isomorphic. This unique field 2082:, which is the minimum size of a dense subset of 1557:can bound the execution time of the algorithm if 752: 95:in the first-order language of fields is true in 3266:"An isomorphism theorem for real-closed fields" 3162:Handbook of Discrete and Computational Geometry 3264:Erdös, P.; Gillman, L.; Henriksen, M. (1955), 3149:Macpherson, D., Marker, D. and Steinhorn, C., 3024:Michael Ben-Or, Dexter Kozen, and John Reif, 1644:Davenport and Heintz (1988) proved that this 908:{\displaystyle \mathbb {R} _{\mathrm {alg} }} 687:. For example, the real closure of the field 515:{\displaystyle \mathbb {R} _{\mathrm {alg} }} 8: 565:there is a maximal ordered field extension ( 453:between real closed fields automatically is 1467:{\displaystyle {\mathcal {L}}_{\text{rcf}}} 1233:{\displaystyle {\mathcal {L}}_{\text{rcf}}} 1190:{\displaystyle {\mathcal {T}}_{\text{rcf}}} 1159:{\displaystyle {\mathcal {L}}_{\text{rcf}}} 1124:{\displaystyle {\mathcal {T}}_{\text{rcf}}} 1087:{\displaystyle {\mathcal {T}}_{\text{rcf}}} 986:{\displaystyle {\mathcal {T}}_{\text{rcf}}} 951:{\displaystyle {\mathcal {L}}_{\text{rcf}}} 3223: 3097: 3007:Algorithms and computation in mathematics 2981: 2940: 2820: 2814: 2793: 2787: 2766: 2760: 2739: 2733: 2712: 2706: 2685: 2679: 2650: 2644: 2619: 2613: 2574: 2568: 2507: 2506: 2504: 2472: 2466: 2433: 2427: 2400: 2399: 2397: 2373: 2368: 2362: 2361: 2360: 2356: 2355: 2352: 2295: 2289: 2262: 2256: 2193: 2187: 2032: 2026: 1775: 1740: 1735: 1729: 1697: 1692: 1686: 1588: 1583: 1577: 1530: 1525: 1520: 1515: 1510: 1504: 1458: 1452: 1451: 1448: 1352: 1224: 1218: 1217: 1214: 1181: 1175: 1174: 1171: 1150: 1144: 1143: 1140: 1115: 1109: 1108: 1105: 1078: 1072: 1071: 1068: 1036: 1016: 977: 971: 970: 967: 942: 936: 935: 932: 892: 891: 887: 886: 883: 864: 863: 861: 856:is considered as an ordered subfield of 849:{\displaystyle \mathbb {Q} ({\sqrt {2}})} 836: 829: 828: 826: 814:{\displaystyle \mathbb {Q} ({\sqrt {2}})} 801: 794: 793: 791: 763: 762: 758: 757: 739: 738: 734: 733: 730: 715:{\displaystyle \mathbb {Q} ({\sqrt {2}})} 702: 695: 694: 692: 499: 498: 494: 493: 490: 256: 246: 238: 3164:. CRC Press. 2004 edition, p. 743. 1420:, can provide undecidable theories; see 1209:: there is an algorithm that, given any 1055:All of these axioms can be expressed in 2874: 2284:real closed fields both of cardinality 1280:is a real closed field, a formula with 919:Decidability and quantifier elimination 418:has an algebraic extension, called the 2591: 1950:There are real-closed fields that are 1561:is the size of the input formula. The 878:, its real closure is again the field 3158:Computational Real Algebraic Geometry 2499:number of nonzero terms of the field 1270:extends this result to the following 7: 2911: 2909: 2320:The generalized continuum hypothesis 1910:, the complexity is lower. Basu and 230:is not algebraically closed but the 1763:{\displaystyle 2^{2^{\Omega (n)}},} 1681:must involve polynomials of degree 1563:cylindrical algebraic decomposition 1284:free variables defines a subset of 3117:Valuations, orderings, and Milnor 2817: 2790: 2763: 2736: 2709: 2682: 2647: 2616: 2571: 2469: 2430: 2292: 2259: 2245:; any two real closed fields are η 2233:and smaller than every element of 2190: 2029: 1810:For the decision problem, Ben-Or, 1777: 1741: 1717:{\displaystyle 2^{2^{\Omega (n)}}} 1698: 1390:{\displaystyle (\exists x)P(x,y),} 1357: 899: 896: 893: 770: 767: 764: 746: 743: 740: 506: 503: 500: 25: 2983:10.1090/S0002-9947-1962-0146089-X 2414:. This is the most commonly used 2304:{\displaystyle \aleph _{\alpha }} 2271:{\displaystyle \aleph _{\alpha }} 2237:. This is closely related to the 2202:{\displaystyle \aleph _{\alpha }} 263:{\displaystyle F({\sqrt {-1}}\,)} 2481:{\displaystyle \aleph _{\beta }} 2442:{\displaystyle \aleph _{\beta }} 2374: 2326:generalized continuum hypothesis 2092:generalized continuum hypothesis 1485:Tarski's original algorithm for 3212:Journal of Symbolic Computation 2942:10.1090/s0002-9904-1953-09664-1 2894:Rajwade (1993) pp. 222–223 2130:, this is equivalent to saying 522:of real algebraic numbers. The 306:holds for all polynomials over 76:A real closed field is a field 2523: 2520: 2514: 2511: 2343:can be defined by means of an 2278:-saturated, and moreover two η 2213:is less than every element of 1786: 1780: 1750: 1744: 1707: 1701: 1598: 1592: 1381: 1369: 1363: 1354: 843: 833: 808: 798: 709: 699: 329:Examples of real closed fields 257: 243: 18:Elementary theory of the reals 1: 3225:10.1016/S0747-7171(10)80003-3 3125:American Mathematical Society 3099:10.1016/s0747-7171(88)80004-x 2854:Elementary Euclidean geometry 2529:{\displaystyle \mathbb {R} ]} 2229:larger than every element of 2106:if there is no ordered field 1257: 652:the relative real closure of 601:, together with its ordering 3319:Model Theory preprint server 3260:. Univ. of California Press. 3156:Mishra, Bhubaneswar (1997) " 2407:{\displaystyle \mathbb {R} } 2330:cardinality of the continuum 2005:is an unbounded sequence in 1969:contained in an ordered set 1954:; for example, any field of 1608:{\displaystyle d^{2^{O(n)}}} 871:{\displaystyle \mathbb {R} } 648:is the algebraic closure of 2916:McNaughton, Robert (1953). 2829:{\displaystyle \aleph _{0}} 2802:{\displaystyle \aleph _{1}} 2775:{\displaystyle \aleph _{0}} 2748:{\displaystyle \aleph _{1}} 2721:{\displaystyle \aleph _{1}} 2694:{\displaystyle \aleph _{2}} 2659:{\displaystyle \aleph _{2}} 2628:{\displaystyle \aleph _{1}} 2583:{\displaystyle \aleph _{1}} 2209:such that every element of 2041:{\displaystyle \aleph _{0}} 1201:, meaning that there is an 549:) is an ordered field, and 56:properties as the field of 3361: 3181:Cambridge University Press 1923:arithmetic operations and 1792:{\displaystyle \Omega (n)} 304:intermediate value theorem 29: 2843:property in place of the 2182:of cardinality less than 2170:, if for any two subsets 1478:Complexity of deciding 𝘛 1268:Tarski–Seidenberg theorem 821:). On the other hand, if 410:is an ordered field, the 170:has at least one root in 2903:Efrat (2006) p. 177 2251:if and only if they are 1496:, meaning that no tower 1494:computational complexity 298:There is an ordering on 273:There is an ordering on 270:is algebraically closed. 174:, and for every element 102:it is true in the reals. 3345:Real algebraic geometry 3247:University of Edinburgh 3206:Renegar, James (1992). 3175:Rajwade, A. R. (1993). 2970:Trans. Amer. Math. Soc. 2604:of larger cardinality. 2122:. If the cofinality of 1263:and published in 1948. 1051:have at least one root. 631:real closed relative to 445:of fields identical on 89:elementarily equivalent 2830: 2803: 2776: 2749: 2722: 2695: 2660: 2629: 2584: 2530: 2482: 2449:then we have a unique 2443: 2416:hyperreal number field 2408: 2382: 2305: 2272: 2217:, there is an element 2203: 2042: 1793: 1764: 1718: 1657:of formulas of length 1609: 1548: 1487:quantifier elimination 1468: 1391: 1234: 1207:quantifier elimination 1191: 1160: 1125: 1088: 1045: 1025: 987: 952: 927:of real closed fields 909: 872: 850: 815: 780: 716: 516: 412:Artin–Schreier theorem 362:with real coefficients 264: 3069:. Oxford Univ. Press. 3052:Howard Jerome Keisler 2929:Bull. Amer. Math. Soc 2831: 2804: 2777: 2750: 2723: 2696: 2661: 2630: 2585: 2531: 2483: 2444: 2409: 2383: 2306: 2273: 2204: 2043: 1794: 1765: 1719: 1646:worst-case complexity 1610: 1549: 1469: 1392: 1235: 1192: 1161: 1126: 1089: 1046: 1026: 1011:for every odd number 988: 953: 910: 873: 851: 816: 781: 717: 607:relative real closure 517: 265: 32:Artin–Schreier theory 2813: 2786: 2759: 2732: 2705: 2678: 2643: 2612: 2567: 2503: 2465: 2426: 2420:nonstandard analysis 2396: 2351: 2288: 2255: 2241:property of being a 2186: 2110:properly containing 2025: 2009:. The cofinality of 1774: 1728: 1685: 1576: 1503: 1447: 1422:Richardson's theorem 1418:exponential function 1351: 1294:. Given a subset of 1244:, which may contain 1213: 1170: 1139: 1104: 1067: 1035: 1015: 966: 931: 882: 860: 825: 790: 729: 691: 489: 237: 214:algebraically closed 3340:Field (mathematics) 3115:Efrat, Ido (2006). 3074:Davenport, James H. 3003:Marie-Françoise Roy 2538:formal power series 2074:To this we may add 2059:The cardinality of 1135:, meaning that any 679:is orderable) then 668:described earlier. 279:algebraic extension 164:formally real field 64:, and the field of 3061:Dales, H. G., and 2863:Euclidean geometry 2826: 2799: 2772: 2745: 2718: 2691: 2656: 2625: 2580: 2526: 2478: 2439: 2404: 2378: 2301: 2268: 2199: 2066:The cofinality of 2038: 2001:. In other words, 1943:larger than it in 1902:stands for either 1805:double exponential 1801:big Omega notation 1789: 1760: 1714: 1605: 1544: 1464: 1387: 1272:projection theorem 1230: 1187: 1156: 1121: 1084: 1041: 1021: 983: 948: 905: 868: 846: 811: 776: 712: 512: 342:computable numbers 334:the field of real 260: 52:that has the same 3335:Real closed field 3067:Super-Real Fields 2149:An ordered field 1956:hyperreal numbers 1937:Archimedean field 1820:exponential space 1567:George E. Collins 1461: 1292:semialgebraic set 1227: 1184: 1153: 1118: 1081: 1057:first-order logic 1044:{\displaystyle d} 1024:{\displaystyle d} 980: 945: 841: 806: 707: 589:and the order on 451:ring homomorphism 449:(note that every 367:Levi-Civita field 348:definable numbers 336:algebraic numbers 254: 218:algebraic closure 148:has at least one 66:hyperreal numbers 62:algebraic numbers 43:real closed field 16:(Redirected from 3352: 3300: 3250: 3244: 3229: 3227: 3202: 3146: 3111: 3101: 3058:. North-Holland. 3048:Chen Chung Chang 2994: 2985: 2964:-sets of power â„” 2947: 2946: 2944: 2926: 2913: 2904: 2901: 2895: 2892: 2886: 2879: 2835: 2833: 2832: 2827: 2825: 2824: 2808: 2806: 2805: 2800: 2798: 2797: 2781: 2779: 2778: 2773: 2771: 2770: 2754: 2752: 2751: 2746: 2744: 2743: 2727: 2725: 2724: 2719: 2717: 2716: 2700: 2698: 2697: 2692: 2690: 2689: 2665: 2663: 2662: 2657: 2655: 2654: 2639:has cardinality 2634: 2632: 2631: 2626: 2624: 2623: 2589: 2587: 2586: 2581: 2579: 2578: 2535: 2533: 2532: 2527: 2510: 2487: 2485: 2484: 2479: 2477: 2476: 2448: 2446: 2445: 2440: 2438: 2437: 2413: 2411: 2410: 2405: 2403: 2387: 2385: 2384: 2379: 2377: 2372: 2367: 2366: 2365: 2359: 2313:order isomorphic 2310: 2308: 2307: 2302: 2300: 2299: 2277: 2275: 2274: 2269: 2267: 2266: 2208: 2206: 2205: 2200: 2198: 2197: 2132:Cauchy sequences 2047: 2045: 2044: 2039: 2037: 2036: 1931:Order properties 1925:polynomial space 1922: 1909: 1905: 1901: 1894: 1798: 1796: 1795: 1790: 1769: 1767: 1766: 1761: 1756: 1755: 1754: 1753: 1723: 1721: 1720: 1715: 1713: 1712: 1711: 1710: 1680: 1671: 1667: 1656: 1636: 1625: 1621: 1614: 1612: 1611: 1606: 1604: 1603: 1602: 1601: 1565:, introduced by 1560: 1553: 1551: 1550: 1545: 1543: 1542: 1541: 1540: 1539: 1538: 1537: 1536: 1535: 1534: 1473: 1471: 1470: 1465: 1463: 1462: 1459: 1457: 1456: 1407: 1403: 1396: 1394: 1393: 1388: 1343: 1325: 1321: 1318:that maps every 1313: 1307: 1297: 1289: 1283: 1279: 1262: 1259: 1239: 1237: 1236: 1231: 1229: 1228: 1225: 1223: 1222: 1196: 1194: 1193: 1188: 1186: 1185: 1182: 1180: 1179: 1165: 1163: 1162: 1157: 1155: 1154: 1151: 1149: 1148: 1130: 1128: 1127: 1122: 1120: 1119: 1116: 1114: 1113: 1093: 1091: 1090: 1085: 1083: 1082: 1079: 1077: 1076: 1050: 1048: 1047: 1042: 1030: 1028: 1027: 1022: 992: 990: 989: 984: 982: 981: 978: 976: 975: 961: 957: 955: 954: 949: 947: 946: 943: 941: 940: 914: 912: 911: 906: 904: 903: 902: 890: 877: 875: 874: 869: 867: 855: 853: 852: 847: 842: 837: 832: 820: 818: 817: 812: 807: 802: 797: 785: 783: 782: 777: 775: 774: 773: 761: 751: 750: 749: 737: 721: 719: 718: 713: 708: 703: 698: 685:real closed ring 660:is actually the 605:, is called the 555:Galois extension 521: 519: 518: 513: 511: 510: 509: 497: 483:rational numbers 465:if and only if ∃ 455:order preserving 437:, and is unique 380:superreal number 373:hyperreal number 322:weakly o-minimal 269: 267: 266: 261: 255: 247: 222:finite extension 21: 3360: 3359: 3355: 3354: 3353: 3351: 3350: 3349: 3325: 3324: 3307: 3282:10.2307/1969812 3263: 3242: 3234:Passmore, Grant 3232: 3205: 3191: 3174: 3135: 3114: 3086:J. Symb. Comput 3072: 2999:Richard Pollack 2997:Basu, Saugata, 2967: 2963: 2959: 2956: 2951: 2950: 2924: 2915: 2914: 2907: 2902: 2898: 2893: 2889: 2880: 2876: 2871: 2859:Tarski's axioms 2856: 2849: 2842: 2836:, and with the 2816: 2811: 2810: 2789: 2784: 2783: 2762: 2757: 2756: 2735: 2730: 2729: 2708: 2703: 2702: 2681: 2676: 2675: 2666:, and contains 2646: 2641: 2640: 2615: 2610: 2609: 2570: 2565: 2564: 2563:of cardinality 2560: 2548:divisible group 2542:totally ordered 2501: 2500: 2468: 2463: 2462: 2458: 2429: 2424: 2423: 2394: 2393: 2354: 2349: 2348: 2338: 2332:and having the 2322: 2291: 2286: 2285: 2283: 2258: 2253: 2252: 2250: 2243:saturated model 2239:model-theoretic 2189: 2184: 2183: 2162: 2028: 2023: 2022: 2019:natural numbers 1952:non-Archimedean 1933: 1915: 1907: 1903: 1899: 1892: 1883: 1876: 1867: 1858: 1851: 1845: 1836: 1829: 1772: 1771: 1736: 1731: 1726: 1725: 1693: 1688: 1683: 1682: 1679: 1673: 1669: 1658: 1655: 1649: 1627: 1623: 1619: 1584: 1579: 1574: 1573: 1558: 1526: 1521: 1516: 1511: 1506: 1501: 1500: 1483: 1481: 1450: 1445: 1444: 1405: 1401: 1349: 1348: 1330: 1323: 1319: 1309: 1303: 1298:variables, the 1295: 1285: 1281: 1275: 1260: 1254:Sturm's theorem 1216: 1211: 1210: 1173: 1168: 1167: 1142: 1137: 1136: 1107: 1102: 1101: 1070: 1065: 1064: 1033: 1032: 1013: 1012: 969: 964: 963: 959: 934: 929: 928: 921: 885: 880: 879: 858: 857: 823: 822: 788: 787: 756: 732: 727: 726: 689: 688: 492: 487: 486: 404: 387:surreal numbers 331: 235: 234: 232:field extension 74: 35: 28: 23: 22: 15: 12: 11: 5: 3358: 3356: 3348: 3347: 3342: 3337: 3327: 3326: 3323: 3322: 3315: 3306: 3305:External links 3303: 3302: 3301: 3276:(3): 542–554, 3261: 3251: 3230: 3218:(3): 255–299. 3203: 3189: 3172: 3154: 3147: 3133: 3112: 3092:(1–2): 29–35. 3070: 3063:W. Hugh Woodin 3059: 3045: 3031: 3022: 3019:online version 2995: 2965: 2961: 2955: 2952: 2949: 2948: 2905: 2896: 2887: 2881:D. Macpherson 2873: 2872: 2870: 2867: 2855: 2852: 2847: 2840: 2823: 2819: 2796: 2792: 2769: 2765: 2742: 2738: 2715: 2711: 2688: 2684: 2653: 2649: 2622: 2618: 2577: 2573: 2558: 2525: 2522: 2519: 2516: 2513: 2509: 2475: 2471: 2454: 2436: 2432: 2402: 2376: 2371: 2364: 2358: 2336: 2321: 2318: 2317: 2316: 2298: 2294: 2279: 2265: 2261: 2246: 2196: 2192: 2165:ordinal number 2158: 2147: 2088: 2087: 2078:The weight of 2072: 2071: 2064: 2035: 2031: 1973:is cofinal in 1945:absolute value 1932: 1929: 1896: 1895: 1888: 1881: 1872: 1868:) ⋈ 0 ∧ ... ∧ 1863: 1856: 1849: 1841: 1834: 1788: 1785: 1782: 1779: 1759: 1752: 1749: 1746: 1743: 1739: 1734: 1709: 1706: 1703: 1700: 1696: 1691: 1675: 1651: 1639:big O notation 1616: 1615: 1600: 1597: 1594: 1591: 1587: 1582: 1555: 1554: 1533: 1529: 1524: 1519: 1514: 1509: 1482: 1479: 1476: 1455: 1398: 1397: 1386: 1383: 1380: 1377: 1374: 1371: 1368: 1365: 1362: 1359: 1356: 1344:is defined by 1322:-tuple to the 1246:free variables 1221: 1178: 1147: 1112: 1075: 1061:quantification 1053: 1052: 1040: 1020: 1009: 1006: 1003:ordered fields 974: 939: 920: 917: 901: 898: 895: 889: 866: 845: 840: 835: 831: 810: 805: 800: 796: 772: 769: 766: 760: 755: 748: 745: 742: 736: 711: 706: 701: 697: 508: 505: 502: 496: 403: 400: 399: 398: 383: 376: 369: 363: 360:Puiseux series 356: 350: 344: 338: 330: 327: 326: 325: 324:ordered field. 315: 296: 286: 271: 259: 253: 250: 245: 242: 225: 207: 202: = âˆ’ 157: 103: 100:if and only if 73: 70: 26: 24: 14: 13: 10: 9: 6: 4: 3: 2: 3357: 3346: 3343: 3341: 3338: 3336: 3333: 3332: 3330: 3321: 3320: 3316: 3314: 3313: 3309: 3308: 3304: 3299: 3295: 3291: 3287: 3283: 3279: 3275: 3271: 3270:Ann. of Math. 3267: 3262: 3259: 3255: 3254:Alfred Tarski 3252: 3248: 3241: 3240: 3235: 3231: 3226: 3221: 3217: 3213: 3209: 3204: 3200: 3196: 3192: 3190:0-521-42668-5 3186: 3182: 3178: 3173: 3171: 3170:1-58488-301-4 3167: 3163: 3159: 3155: 3152: 3148: 3144: 3140: 3136: 3134:0-8218-4041-X 3130: 3126: 3122: 3118: 3113: 3109: 3105: 3100: 3095: 3091: 3087: 3083: 3079: 3075: 3071: 3068: 3064: 3060: 3057: 3053: 3049: 3046: 3044: 3043:3-211-82794-3 3040: 3036: 3032: 3029: 3028: 3023: 3020: 3016: 3015:3-540-33098-4 3012: 3008: 3004: 3000: 2996: 2993: 2989: 2984: 2979: 2975: 2971: 2958: 2957: 2953: 2943: 2938: 2934: 2930: 2923: 2922:by A. Tarski" 2921: 2912: 2910: 2906: 2900: 2897: 2891: 2888: 2884: 2878: 2875: 2868: 2866: 2864: 2860: 2853: 2851: 2846: 2839: 2821: 2794: 2782:, and weight 2767: 2740: 2728:, cofinality 2713: 2686: 2673: 2669: 2651: 2638: 2620: 2607: 2603: 2599: 2595: 2593: 2575: 2562: 2557: 2552: 2549: 2546: 2543: 2539: 2517: 2498: 2494: 2489: 2473: 2460: 2457: 2453: 2434: 2421: 2417: 2391: 2369: 2346: 2342: 2335: 2331: 2327: 2319: 2314: 2296: 2282: 2263: 2249: 2244: 2240: 2236: 2232: 2228: 2224: 2220: 2216: 2212: 2194: 2181: 2177: 2173: 2169: 2166: 2161: 2156: 2152: 2148: 2145: 2141: 2137: 2133: 2129: 2125: 2121: 2117: 2113: 2109: 2105: 2101: 2097: 2096: 2095: 2093: 2085: 2081: 2077: 2076: 2075: 2069: 2065: 2062: 2058: 2057: 2056: 2054: 2049: 2033: 2020: 2016: 2012: 2008: 2004: 2000: 1996: 1992: 1988: 1984: 1980: 1977:if for every 1976: 1972: 1968: 1964: 1959: 1957: 1953: 1948: 1946: 1942: 1938: 1930: 1928: 1926: 1921: 1918: 1913: 1891: 1887: 1880: 1875: 1871: 1866: 1862: 1855: 1848: 1844: 1840: 1833: 1828: 1827: 1826: 1823: 1821: 1817: 1813: 1808: 1806: 1802: 1783: 1757: 1747: 1737: 1732: 1704: 1694: 1689: 1678: 1665: 1661: 1654: 1647: 1642: 1640: 1634: 1630: 1595: 1589: 1585: 1580: 1572: 1571: 1570: 1568: 1564: 1531: 1527: 1522: 1517: 1512: 1507: 1499: 1498: 1497: 1495: 1492: 1491:nonelementary 1488: 1477: 1475: 1442: 1438: 1434: 1429: 1427: 1423: 1419: 1415: 1409: 1384: 1378: 1375: 1372: 1366: 1360: 1347: 1346: 1345: 1341: 1337: 1333: 1327: 1317: 1312: 1306: 1301: 1293: 1288: 1278: 1273: 1269: 1264: 1255: 1251: 1247: 1243: 1208: 1204: 1200: 1134: 1099: 1095: 1062: 1058: 1038: 1018: 1010: 1007: 1004: 1000: 996: 995: 994: 926: 918: 916: 838: 803: 753: 725: 704: 686: 682: 678: 674: 669: 667: 663: 659: 655: 651: 647: 643: 639: 635: 632: 628: 624: 620: 616: 612: 608: 604: 600: 596: 592: 588: 584: 580: 576: 572: 568: 564: 560: 556: 552: 548: 544: 539: 537: 533: 532:Otto Schreier 529: 526:is named for 525: 485:is the field 484: 480: 477: +  476: 473: =  472: 468: 464: 461: â‰€  460: 456: 452: 448: 444: 440: 436: 432: 428: 424: 421: 417: 413: 409: 401: 396: 392: 388: 385:the field of 384: 381: 377: 374: 370: 368: 364: 361: 358:the field of 357: 355: 352:the field of 351: 349: 346:the field of 345: 343: 340:the field of 339: 337: 333: 332: 328: 323: 319: 316: 313: 309: 305: 301: 297: 294: 290: 287: 284: 280: 276: 272: 251: 248: 240: 233: 229: 226: 223: 219: 215: 211: 208: 205: 201: 197: 194: =  193: 189: 185: 181: 177: 173: 169: 165: 161: 158: 155: 151: 147: 143: 139: 136: 132: 128: 124: 120: 116: 115:ordered field 113:making it an 112: 108: 104: 101: 98: 94: 90: 86: 83: 82: 81: 79: 71: 69: 67: 63: 59: 55: 51: 48: 44: 40: 33: 19: 3318: 3311: 3273: 3269: 3257: 3238: 3215: 3211: 3176: 3161: 3150: 3120: 3116: 3089: 3085: 3078:Heintz, Joos 3066: 3056:Model Theory 3055: 3037:. Springer. 3034: 3025: 3009:. Springer. 3006: 2973: 2969: 2935:(1): 91–93. 2932: 2928: 2919: 2899: 2890: 2882: 2877: 2857: 2844: 2837: 2671: 2667: 2636: 2605: 2601: 2597: 2596: 2555: 2550: 2492: 2490: 2455: 2451: 2389: 2340: 2333: 2323: 2280: 2247: 2234: 2230: 2226: 2222: 2218: 2214: 2210: 2179: 2175: 2171: 2167: 2159: 2150: 2143: 2135: 2127: 2123: 2119: 2118:is dense in 2115: 2111: 2107: 2103: 2099: 2089: 2083: 2079: 2073: 2067: 2060: 2052: 2050: 2010: 2006: 2002: 1998: 1994: 1990: 1986: 1985:there is an 1982: 1978: 1974: 1970: 1966: 1960: 1949: 1934: 1919: 1916: 1897: 1889: 1885: 1878: 1873: 1869: 1864: 1860: 1853: 1846: 1842: 1838: 1831: 1824: 1809: 1676: 1663: 1659: 1652: 1643: 1632: 1628: 1617: 1556: 1484: 1440: 1430: 1410: 1399: 1339: 1335: 1331: 1328: 1310: 1304: 1299: 1286: 1276: 1271: 1265: 1249: 1100:showed that 1096: 1054: 922: 680: 676: 672: 670: 665: 662:real closure 661: 657: 653: 649: 645: 641: 637: 633: 630: 626: 622: 621:. We call ( 618: 614: 610: 606: 602: 598: 594: 590: 586: 582: 574: 570: 566: 563:Zorn's lemma 558: 550: 546: 542: 540: 538:it in 1926. 478: 474: 470: 466: 462: 458: 446: 434: 430: 429:, such that 426: 422: 420:real closure 419: 415: 414:states that 411: 407: 405: 402:Real closure 391:proper class 354:real numbers 317: 311: 310:with degree 307: 299: 292: 288: 282: 274: 227: 209: 203: 199: 195: 191: 187: 183: 179: 175: 171: 167: 159: 153: 145: 142:coefficients 126: 118: 110: 96: 84: 77: 75: 58:real numbers 49: 42: 36: 2976:: 341–352, 2809:instead of 2755:instead of 2701:instead of 2592:Alling 1962 2553:that is an 2134:indexed by 2015:cardinality 1724:and length 1261: 1930 585:containing 443:isomorphism 389:(this is a 123:square root 107:total order 105:There is a 54:first-order 39:mathematics 3329:Categories 3199:0785.11022 3143:1103.12002 3108:0663.03015 2954:References 2345:ultrapower 2163:, for the 2157:property η 2140:convergent 2114:such that 1993:such that 1963:cofinality 1904:<, > 1300:projection 1250:equivalent 593:extending 561:, then by 528:Emil Artin 457:, because 216:, but its 190:such that 131:polynomial 72:Definition 2918:"Review: 2818:ℵ 2791:ℵ 2764:ℵ 2737:ℵ 2710:ℵ 2683:ℵ 2648:ℵ 2617:ℵ 2572:ℵ 2497:countable 2474:β 2470:ℵ 2435:β 2431:ℵ 2297:α 2293:ℵ 2264:α 2260:ℵ 2195:α 2191:ℵ 2030:ℵ 1778:Ω 1742:Ω 1699:Ω 1528:⋅ 1523:⋅ 1518:⋅ 1358:∃ 1203:algorithm 1199:decidable 754:× 441:a unique 249:− 182:there is 3236:(2011). 3080:(1988). 2461:of size 2388:, where 2153:has the 2104:complete 2098:A field 1965:. A set 1906:or  1837:, ..., ∃ 1316:function 1133:complete 925:language 644:. When 640:is just 579:subfield 469: : 393:, not a 129:and any 93:sentence 3298:0069161 3290:1969812 3256:(1951) 3245:(PhD). 3177:Squares 3121:-theory 3065:(1996) 3054:(1989) 2992:0146089 2545:abelian 2155:eta set 2013:is the 1941:integer 1884:, ..., 1859:, ..., 1668:, with 1435:'s and 1416:or the 1314:is the 1242:formula 722:is the 597:. This 573:) with 524:theorem 212:is not 3296:  3288:  3197:  3187:  3168:  3160:," in 3141:  3131:  3106:  3041:  3013:  3001:, and 2990:  2885:(1998) 2883:et al. 1898:where 1893:) ⋈ 0, 1814:, and 1770:where 1618:where 1437:Turing 1400:where 1098:Tarski 1059:(i.e. 999:axioms 536:proved 534:, who 382:fields 375:fields 138:degree 121:has a 3286:JSTOR 3272:, 2, 3243:(PDF) 2925:(PDF) 2869:Notes 2561:group 2540:on a 2459:field 2347:, as 2225:with 1997:< 1812:Kozen 1433:Gödel 1302:from 1274:. If 617:) in 553:is a 439:up to 320:is a 220:is a 162:is a 140:with 47:field 45:is a 3185:ISBN 3166:ISBN 3129:ISBN 3050:and 3039:ISBN 3011:ISBN 2968:.", 2311:are 2174:and 2138:are 1816:Reif 1489:has 1424:and 1414:sine 1404:and 1266:The 997:the 923:The 724:ring 609:of ( 541:If ( 530:and 378:the 371:the 365:the 150:root 41:, a 3278:doi 3220:doi 3195:Zbl 3139:Zbl 3104:Zbl 3094:doi 2978:doi 2974:103 2937:doi 2594:). 2536:of 2488:.) 2418:in 2221:in 2178:of 2142:in 2126:is 2102:is 1989:in 1981:in 1912:Roy 1799:is 1637:is 1480:rcf 1460:rcf 1308:to 1226:rcf 1197:is 1183:rcf 1152:rcf 1131:is 1117:rcf 1080:rcf 1001:of 979:rcf 944:rcf 671:If 664:of 656:in 636:if 581:of 557:of 425:of 406:If 395:set 281:of 198:or 186:in 178:of 152:in 144:in 135:odd 133:of 125:in 109:on 87:is 37:In 3331:: 3294:MR 3292:, 3284:, 3274:61 3268:, 3216:13 3214:. 3210:. 3193:. 3183:. 3137:. 3127:. 3102:. 3088:. 3084:. 3076:; 2988:MR 2986:, 2972:, 2933:59 2931:. 2927:. 2908:^ 2672:is 2635:, 2055:: 2048:. 1927:. 1807:. 1641:. 1474:. 1428:. 1338:, 1258:c. 915:. 629:) 625:, 613:, 577:a 569:, 545:, 314:0. 68:. 3280:: 3249:. 3228:. 3222:: 3201:. 3145:. 3119:K 3110:. 3096:: 3090:5 3021:) 3017:( 2980:: 2966:α 2962:α 2945:. 2939:: 2848:0 2845:η 2841:1 2838:η 2822:0 2795:1 2768:0 2741:1 2714:1 2687:2 2668:Ϝ 2652:2 2637:Κ 2621:1 2606:Ϝ 2602:Κ 2598:Ϝ 2590:( 2576:1 2559:1 2556:η 2551:G 2524:] 2521:] 2518:G 2515:[ 2512:[ 2508:R 2493:Ϝ 2456:ÎČ 2452:η 2401:R 2390:M 2375:M 2370:/ 2363:N 2357:R 2341:Ϝ 2337:1 2334:η 2315:. 2281:α 2248:α 2235:U 2231:L 2227:x 2223:F 2219:x 2215:U 2211:L 2180:F 2176:U 2172:L 2168:α 2160:α 2151:F 2146:. 2144:F 2136:Îș 2128:Îș 2124:F 2120:K 2116:F 2112:F 2108:K 2100:F 2086:. 2084:F 2080:F 2070:. 2068:F 2063:. 2061:F 2053:F 2034:0 2011:F 2007:F 2003:X 1999:x 1995:y 1991:X 1987:x 1983:F 1979:y 1975:F 1971:F 1967:X 1920:d 1917:s 1908:= 1900:⋈ 1890:k 1886:x 1882:1 1879:x 1877:( 1874:s 1870:P 1865:k 1861:x 1857:1 1854:x 1852:( 1850:1 1847:P 1843:k 1839:x 1835:1 1832:x 1830:∃ 1787:) 1784:n 1781:( 1758:, 1751:) 1748:n 1745:( 1738:2 1733:2 1708:) 1705:n 1702:( 1695:2 1690:2 1677:n 1674:Ί 1670:n 1666:) 1664:n 1662:( 1660:O 1653:n 1650:Ί 1635:) 1633:n 1631:( 1629:O 1624:d 1620:n 1599:) 1596:n 1593:( 1590:O 1586:2 1581:d 1559:n 1532:n 1513:2 1508:2 1454:L 1441:x 1406:y 1402:x 1385:, 1382:) 1379:y 1376:, 1373:x 1370:( 1367:P 1364:) 1361:x 1355:( 1342:) 1340:y 1336:x 1334:( 1332:p 1324:k 1320:n 1311:R 1305:R 1296:k 1287:R 1282:n 1277:R 1240:- 1220:L 1177:T 1146:L 1111:T 1074:T 1039:d 1019:d 1005:; 973:T 960:≀ 938:L 900:g 897:l 894:a 888:R 865:R 844:) 839:2 834:( 830:Q 809:) 804:2 799:( 795:Q 771:g 768:l 765:a 759:R 747:g 744:l 741:a 735:R 710:) 705:2 700:( 696:Q 681:F 677:F 673:F 666:F 658:E 654:F 650:F 646:E 642:F 638:M 634:E 627:P 623:F 619:E 615:P 611:F 603:Q 599:M 595:P 591:M 587:F 583:E 575:M 571:Q 567:M 559:F 551:E 547:P 543:F 507:g 504:l 501:a 495:R 479:z 475:x 471:y 467:z 463:y 459:x 447:F 435:F 431:K 427:F 423:K 416:F 408:F 397:) 318:F 312:≄ 308:F 300:F 293:F 289:F 285:. 283:F 275:F 258:) 252:1 244:( 241:F 228:F 224:. 210:F 206:. 204:b 200:a 196:b 192:a 188:F 184:b 180:F 176:a 172:F 168:F 160:F 156:. 154:F 146:F 127:F 119:F 111:F 97:F 85:F 78:F 50:F 34:. 20:)

Index

Elementary theory of the reals
Artin–Schreier theory
mathematics
field
first-order
real numbers
algebraic numbers
hyperreal numbers
elementarily equivalent
sentence
if and only if
total order
ordered field
square root
polynomial
odd
degree
coefficients
root
formally real field
algebraically closed
algebraic closure
finite extension
field extension
algebraic extension
intermediate value theorem
weakly o-minimal
algebraic numbers
computable numbers
definable numbers

Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.

↑