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Constructive analysis

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6938: 6792:) will equal 0, so that IVT is valid automatically. Thus in classical analysis, which uses classical logic, in order to prove the full IVT, it is sufficient to prove the constructive version. From this perspective, the full IVT fails in constructive analysis simply because constructive analysis does not accept classical logic. Conversely, one may argue that the true meaning of IVT, even in classical mathematics, is the constructive version involving the 1400: 1814: 47:, which in this context means analysis done according to the more common principles of classical mathematics. However, there are various schools of thought and many different formalizations of constructive analysis. Whether classical or constructive in some fashion, any such framework of analysis axiomatizes the 1244:
proves the non-contradiction claim for any proposition, and that the negation of excluded middle for any given proposition would be absurd. This also means there is no consistent theory (even if anti-classical) rejecting the excluded middle disjunction for any given proposition. Indeed, it holds that
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being provable would be absurd, and so the latter cannot also be provable in a consistent theory. The double-negated existence claim is a logically negative statement and implied by, but generally not equivalent to the existence claim itself. Much of the intricacies of constructive analysis can be
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even if these disjunction claims here do not carry any information. In the absence of further axioms breaking the meta-logical properties, constructive entailment instead generally reflects provability. Taboo statements that ought not be decidable (if the aim is to respect the provability
3777:. The constant sequences correspond to rational numbers. Algebraic operations such as addition and multiplication can be defined component-wise, together with a systematic reindexing for speedup. The definition in terms of sequences furthermore enables the definition of a strict order " 3170:
and zero are related, with respect to the ordering predicate on the reals, while a demonstration of the latter shows how negation of such conditions would imply to a contradiction. In turn, there is then also a strong and a looser notion of, e.g., being a third-order polynomial.
6876:.) Again, this is classically equivalent to the full least upper bound principle, since every set is located in classical mathematics. And again, while the definition of located set is complicated, nevertheless it is satisfied by many commonly studied sets, including all 5755:. An upshot is that the set theory will prove properties for the reals, i.e. for this class of sets, expressed using the logical equality. Constructive reals in the presence of appropriate choice axioms will be Cauchy-complete but not automatically order-complete. 6796:
condition, with the full IVT following by "pure logic" afterwards. Some logicians, while accepting that classical mathematics is correct, still believe that the constructive approach gives a better insight into the true meaning of theorems, in much this way.
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has better completeness properties as a collection, but a more intricate theory of its order-relation and, in turn, worse locatedness properties. While less commonly employed, also this construction simplifies to the classical real numbers when assuming
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are always uncountable also over a constructive framework. One variant of the diagonal construction relevant for the present context may be formulated as follows, proven using countable choice and for reals as sequences of rationals:
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to the non-existence claim of a sequence for which the excluded middle disjunction about equality-to-zero would be disprovable. No sequence with that disjunction being rejected can be exhibited. Assume the theories at hand are
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However, constructive analysis provides several alternative formulations of IVT, all of which are equivalent to the usual form in classical analysis, but not in constructive analysis. For example, under the same conditions on
4975:, and likewise for the equality of two such reals. And also the sequences of rationals may be required to carry a modulus of convergence. Positivity properties may defined as being eventually forever apart by some rational. 927: 2897: 5234: 4442: 1620: 6397:
Through the optional adoption of further consistent axioms, the negation of decidability may be provable. For example, equality-to-zero is rejected to be decidable when adopting Brouwerian continuity principles or
1109: 5389: 1558: 5321: 1044: 4201: 5751:. In that language, regular rational sequences are degraded to a mere representative of a Cauchy real. Equality of those reals is then given by the equality of sets, which is governed by the set theoretical 3553: 4519: 4354: 2749: 5152: 735: 6237: 5451: 2156: 790: 4356:, where the relation on the right hand side is in terms of rational numbers. Formally, a positive real in this language is a regular sequence together with a natural witnessing positivity. Further, 2946:. In words: A demonstration that a number is somehow apart from zero is also a demonstration that this number is non-zero. But constructively it does not follow that the doubly negative statement 2667: 2238: 5861: 4973: 3965: 560: 1455: 2414: 2310: 6891:
are constructively valid—or from another point of view, there are several different concepts that are classically equivalent but not constructively equivalent. Indeed, if the interval were
3863:, eventually has an index beyond which all its elements are invertible. Various implications between the relations, as well as between sequences with various properties, may then be proven. 2476: 5505: 498:
While a constructive theory proves fewer theorems than its classical counter-part in its classical presentation, it may exhibit attractive meta-logical properties. For example, if a theory
323: 6005: 5930: 5743: 5053: 5012: 3775: 2602: 661: 153: 5972: 4575: 4710: 1395:{\displaystyle {\mathsf {T}}\,\,\,\vdash \,\,\,\forall (x\in {\mathbb {Q} }^{\mathbb {N} }).\,\neg \neg {\big (}(x\cong _{\mathrm {ext} }0)\lor \neg (x\cong _{\mathrm {ext} }0){\big )}} 1661: 620: 590: 364: 6325: 6516:. Notably, there are two anti-classical schools as incompatible with one-another. This article discusses principles compatible with the classical theory and choice is made explicit. 6372: 3967:. Such a modulus may be considered for a sequence of reals, but it may also be considered for all the reals themselves, in which case one is really dealing with a sequence of pairs. 2944: 2808: 1997: 6510: 6472: 6434: 4577:
are deemed equivalent to the zero sequence. Such definitions are of course compatible with classical investigations and variations thereof were well studied also before. One has
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is adopted in the Russian school of recursive mathematics. This principle strengthens the impact of proven negation of strict equality. A so-called analytical form of it grants
3407: 3910: 3480: 1809:{\displaystyle {\mathsf {T}}+{\mathrm {PEM} }\,\,\,\vdash \,\,\,\forall (x\in {\mathbb {Q} }^{\mathbb {N} }).\,(x\cong _{\mathrm {ext} }0)\lor \neg (x\cong _{\mathrm {ext} }0)} 6039: 5819: 3717: 3682: 2345: 275: 5690: 5659: 4822: 4793: 4289: 4260: 2979: 391: 199: 6067: 5789: 5627: 5529: 5077: 1167: 226: 3317: 1945: 1479: 1234: 520: 3930: 1199: 6177: 4639: 5576: 4764: 3224: 109: 4665: 4022: 3620: 3369: 3343: 3278: 6098: 5710: 5600: 4892: 4601: 4231: 3244: 2690: 2525: 2091: 2053: 2027: 1910: 1884: 1838: 83: 6125: 5893: 4042: 3642: 3168: 3121: 411: 4086: 4066: 3861: 3795: 3198: 3005: 2839: 2176: 3727:
In the commutative ring of real numbers, a provably non-invertible element equals zero. This and the most basic locality structure is abstracted in the theory of
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As explained, various predicates will fail to be decidable in a constructive formulation, such as these formed from order-theoretical relations. This includes "
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apart and so one may compute natural numbers exceeding any real. For the regular sequences, one defines the logically positive loose positivity property as
416: 115:. While this term is thus overloaded in the subject, all the frameworks share a broad common core of results that are also theorems of classical analysis. 6749:
can be constructed. This is a complicated condition, but there are several other conditions that imply it and that are commonly met; for example, every
6250:, "a historical misrepresentation has been perpetuated that associates diagonalization with non-constructivity" and a constructive component of the 1131:" is used in several contexts here. For any theory capturing arithmetic, there are many yet undecided and even provenly independent such statements 6821:(or supremum), possibly infinite. However, as with the intermediate value theorem, an alternative version survives; in constructive analysis, any 835: 229: 2846: 5157: 4359: 1563: 7540: 7015: 1049: 1999:, which constitutes a strict total order in its constructive formulation (also called linear order or, to be explicit about the context, a 5334: 1504: 5239: 972: 4126: 622:. Already in classical arithmetic, this is violated for the most basic propositions about sequences of numbers - as demonstrated next. 3496: 4447: 3685: 7247: 7223: 7204: 6956: 5899:
existence. As a result, the constructive theory of cardinal order can diverge substantially from the classical one. Here, sets like
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theory is relevant as the structures discussed below are model thereof. However, this section thus does not concern aspects akin to
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in constructive analysis, then the classical IVT would follow from the first constructive version in the example; one could find
5764: 5747: 3448: 2316: 6182: 5394: 2108: 4262:, and in the latter case non-zero indices ought to be used. No two of the rational entries in a regular sequence are more than 3797:" fulfilling the desired axioms. Other relations discussed above may then be defined in terms of it. In particular, any number 1840:" in formalizations below as well. For implications of disjunctions of yet not proven or disproven propositions, one speaks of 740: 3007:. Consequently, many classically equivalent statements bifurcate into distinct statement. For example, for a fixed polynomial 7535: 3975:
Given such a model then enables the definition of more set theoretic notions. For any subset of reals, one may speak of an
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may be axiomatized such that all the non-logical axioms are in accordance with constructive principles. This concerns a
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is apart from zero is stronger than the mere statement that it is non-zero. A demonstration of former explicates how
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of constructive analysis, modeling the order properties described above, proves theorems for sequences of rationals
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to begin with, the encoding also means these objects are in scope of the quantifiers in second-order arithmetic.
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Another difference between classical and constructive analysis is that constructive analysis does not prove the
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is often employed in the constructive study of Cauchy sequences of reals, meaning the association of any
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definable from an asymmetric order structure. Center stage takes a positivity predicate, here denoted
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Demanding good order properties as above but strong completeness properties at the same time implies
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as well, or extension encoding tags or metadata. For an example using this encoding, the sequence
3915: 3226:. However, see the discussion of possible further axiomatic principles regarding the strength of " 2501:
The theory shall validate further axioms concerning the relation between the positivity predicate
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All these considerations may also be undertaken in a topos or appropriate dependent type theory.
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on a finite set of rationals is decidable, an absolute value map on the reals may be defined and
2609: 1841: 119: 56: 4606: 3622:, but the other direction is also not provable in general. In a constructive real closed field, 1820:
interpretation of constructive claims) can be designed for definitions of a custom equivalence "
7499: 7464: 7452: 7429: 7416: 7406: 7393: 7219: 7200: 7011: 6904: 6818: 6750: 5555: 5454: 4743: 3203: 2248: 2059: 1853: 1206: 969:. Here, for the sake of demonstration, defining an extensional equality to the zero sequence 664: 88: 4644: 4001: 3599: 3348: 3322: 3257: 7457: 7148: 7096: 6475: 6378: 6247: 6077: 6042: 5695: 5585: 5328: 4867: 4580: 4206: 3409:, which as noted will not be provable in general. But neither will the totality disjunction 3229: 2692:", rendering it a negation. All negations are stable in intuitionistic logic, and therefore 2675: 2504: 2416:. Likewise, the asymmetric order in the theory ought to fulfill the weak linearity property 2076: 2032: 2006: 1889: 1863: 1857: 1823: 62: 48: 7025: 6613:. In constructive analysis, this does not hold, because the constructive interpretation of 6103: 5878: 5629:
and validates the existence of even classically uncountable function spaces (and certainly
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hovers near zero during a stretch along its domain, then this cannot necessarily be done.
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A common strategy of formalization of real numbers is in terms of sequences or rationals,
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for polynomial. In this theory, between any two separated numbers, other numbers exist.
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and so we draw motivation and examples in terms of those. So to define terms, consider a
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In this context it may also be possible to model a theory or real numbers in terms of
3490:, the conjunction of such statements is also rendered a negation of apartness, and so 488:{\displaystyle {\big (}\exists x.\theta (x){\big )}\to \neg \forall x.\neg \theta (x)} 7529: 7192: 6961: 6900: 6888: 6537: 6386: 4096: 4048:
is an upper bound given through a sequence of reals, positively characterized using "
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can be coded rather compactly, as they each may be mapped to a unique subclass of
7042:, Mathematical Logic Quarterly, Volume 48, Issue 2, Pages: 163-320, February 2002 6887:
Closely related to this, in constructive mathematics, fewer characterisations of
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A common approach is to identify the real numbers with non-volatile sequences in
2348:. Other disjunctions are however implied based on other positivity results, e.g. 7383: 7309: 6881: 6869: 6689:
Alternatively, we can keep the same conclusion as in the classical IVT—a single
6678:. That is, we can get as close to zero as we like, even if we can't construct a 6595: 2527:
and the algebraic operations including multiplicative inversion, as well as the
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Formulations of the reals aided by explicit moduli permit separate treatments.
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framed in terms of the weakness of propositions of the logically negative form
7322: 6933: 6648:(no matter how large), there exists (that is, we can construct) a real number 6610: 5582:. Note, however, that there are properties which can distinguish between two 7476: 7327: 6564: 5552:
is given to such well-behaved sequences or rationals, and relations such as
4795:. Other formalizations directly take as definition that for any fixed bound 52: 4864:
must eventually be forever at least as close. Exponentially falling bounds
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again amounts to the proposition of universally quantified form. Trivially
922:{\displaystyle q_{n}\,:=\,{\textstyle \sum }_{k=0}^{n}\chi _{Q}(n)/2^{n+1}} 2892:{\displaystyle (\phi \to \neg \psi )\leftrightarrow (\psi \to \neg \phi )} 7055:; Studies in Logic and the Foundations of Mathematics; (2023) pp. 201-207 5863:, holding pairs representing inhabited, pairwise intersecting intervals. 5229:{\displaystyle \langle i,n_{i},d_{i},s_{i}\rangle \in {\mathbb {N} }^{4}} 4732:, but then shown to be equivalent of the logical negation of the former. 4437:{\displaystyle x\cong y\,:=\,\forall n.|x_{n}-y_{n}|\leq {\tfrac {2}{n}}} 4045: 2063: 1615:{\displaystyle {\mathsf {T}}\,\nvdash \,\neg (g\cong _{\mathrm {ext} }0)} 6625:(in the sense that it can be approximated to any desired precision by a 2243:
and indeed at most one of the three can hold at once. But the stronger,
7469: 7116: 3932:) is required in the form of an explicit, strictly increasing function 1104:{\displaystyle q\cong _{\mathrm {ext} }0\leftrightarrow \forall n.Q(n)} 7232: 6994:; Studies in Logic and the Foundations of Mathematics; Springer, 1988; 667:
predicate on the naturals, which in the constructive vernacular means
7151:, "The Mathematical Development of Set Theory from Cantor to Cohen", 6810: 6524:
Many classical theorems can only be proven in a formulation that is
5384:{\displaystyle i\mapsto {\textstyle \sum }_{k=0}^{i}{\tfrac {1}{k}}} 4068:". If a subset with an upper bound is well-behaved with respect to " 3912:
to an appropriate index (beyond which the sequences are closer than
1553:{\displaystyle {\mathsf {T}}\,\nvdash \,(g\cong _{\mathrm {ext} }0)} 7173: 6402:
in recursive mathematics. The weak continuity principle as well as
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Another approach is to define a real number as a certain subset of
3644:" is a negation and is not equivalent to the disjunction in general 7051:
Bridges D., Ishihara H., Rathjen M., Schwichtenberg H. (Editors),
5316:{\displaystyle 2^{i}\cdot 3^{n_{i}}\cdot 5^{d_{i}}\cdot 7^{s_{i}}} 1039:{\displaystyle (q\cong _{\mathrm {ext} }0)\,:=\,\forall n.q_{n}=0} 4196:{\displaystyle |x_{n}-x_{m}|\leq {\tfrac {1}{n}}+{\tfrac {1}{m}}} 2613:. With it, the substitute of the principles above give tightness 929:
is monotone, with values non-strictly growing between the bounds
7481: 3548:{\displaystyle (x\geq y\land y\geq x)\leftrightarrow (x\cong y)} 7236: 6772:
For another way to view this example, notice that according to
4514:{\displaystyle \neg \exists n.|x_{n}-y_{n}|>{\tfrac {2}{n}}} 4349:{\displaystyle x>0\,:=\,\exists n.x_{n}>{\tfrac {1}{n}}} 2744:{\displaystyle \neg \neg (x\cong y)\leftrightarrow (x\cong y)} 118:
Constructive frameworks for its formulation are extensions of
111:. The members of the collection are generally just called the 325:
is provable, this exactly means that the non-existence claim
7005: 5952: 5147:{\displaystyle i\mapsto {\tfrac {n_{i}}{d_{i}}}(-1)^{s_{i}}} 4667:
may be defined from a numerical non-negativity property, as
730:{\displaystyle \forall n.{\big (}Q(n)\lor \neg Q(n){\big )}} 7167:
Diener, Hannes (2020). "Constructive Reverse Mathematics".
7118:
On the Cauchy Completeness of the Constructive Cauchy Reals
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condition fails, then it must fail at some specific point
6552:(IVT). In classical analysis, IVT implies that, given any 6232:{\displaystyle \forall (n\in {\mathbb {N} }).x_{n}\,\#\,z} 5446:{\displaystyle 1,2,{\tfrac {5}{2}},{\tfrac {8}{3}},\dots } 3879:
and limits of sequences of reals can be defined as usual.
2151:{\displaystyle (\phi \lor \psi )\to (\neg \phi \to \psi )} 5531:. While this example, an explicit sequence of sums, is a 785:{\displaystyle \chi _{Q}\colon {\mathbb {N} }\to \{0,1\}} 6753:
is locally non-zero (assuming that it already satisfies
6701:) is exactly zero—while strengthening the conditions on 5745:
may be collected into a set and then this is called the
4525:. Via this predicate, the regular sequences in the band 6825:
subset of the real line has a supremum. (Here a subset
4024:. One may speak of least upper bounds with respect to " 1481:
proves the zero-sequence to be a good approximation to
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An Intuitionistic Axiomatisation of Real Closed Fields
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or dependent choice, these structures are isomorphic.
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In contrast, in a set theory that models the naturals
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Thus, apartness can also function as a definition of "
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The elusive trichotomy disjunction itself then reads
2701: 2678: 2662:{\displaystyle \neg (x\#0)\leftrightarrow (x\cong 0)} 2622: 2552: 2507: 2484: 2422: 2354: 2323: 2262: 2187: 2164: 2111: 2079: 2035: 2009: 1953: 1918: 1892: 1866: 1826: 1672: 1628: 1566: 1507: 1501:, but it can also meta-logically be established that 1487: 1463: 1424: 1254: 1218: 1175: 1137: 1117: 1052: 975: 955: 935: 838: 818: 798: 743: 673: 636: 598: 568: 532: 504: 419: 399: 373: 331: 287: 253: 207: 177: 128: 91: 65: 7130:
Bauer, A., Hanson, J. A. "The countable reals", 2022
2233:{\displaystyle \neg (x>0\lor 0>x)\to x\cong 0} 1886:, with a positive unit and non-positive zero, i.e., 7492: 7443: 7415: 7392: 7374: 7346: 7308: 7270: 6536:. Some theorems can only be formulated in terms of 5856:{\displaystyle {\mathbb {Q} }\times {\mathbb {Q} }} 4968:{\displaystyle \forall n.|x_{n}-x_{n+1}|<2^{-n}} 4894:are also used, also say in a real number condition 3960:{\displaystyle \varepsilon \mapsto N(\varepsilon )} 555:{\displaystyle {\mathsf {T}}\vdash \phi \lor \psi } 6504: 6466: 6428: 6366: 6319: 6231: 6171: 6139: 6119: 6092: 6061: 6033: 5999: 5966: 5924: 5887: 5855: 5813: 5783: 5737: 5704: 5684: 5653: 5621: 5594: 5570: 5523: 5499: 5457:and with the above coding it maps to the subclass 5445: 5383: 5315: 5236:. In turn, this can be encoded as unique naturals 5228: 5146: 5071: 5047: 5006: 4967: 4886: 4856: 4836: 4816: 4787: 4758: 4724: 4704: 4659: 4633: 4595: 4569: 4513: 4436: 4348: 4283: 4254: 4225: 4195: 4111: 4080: 4060: 4036: 4016: 3990: 3959: 3924: 3904: 3855: 3829: 3809: 3789: 3769: 3711: 3676: 3636: 3614: 3588: 3547: 3474: 3439: 3401: 3363: 3337: 3311: 3272: 3238: 3218: 3192: 3162: 3135: 3115: 3088: 3068: 3038: 2999: 2973: 2938: 2891: 2833: 2802: 2743: 2684: 2661: 2596: 2519: 2490: 2470: 2408: 2339: 2304: 2232: 2170: 2150: 2085: 2047: 2021: 1991: 1939: 1904: 1878: 1832: 1808: 1655: 1614: 1552: 1493: 1473: 1450:{\displaystyle g\in {\mathbb {Q} }^{\mathbb {N} }} 1449: 1394: 1228: 1193: 1161: 1123: 1103: 1038: 961: 941: 921: 824: 804: 784: 729: 655: 614: 584: 554: 514: 487: 405: 385: 358: 317: 269: 220: 193: 147: 103: 77: 6845:are real numbers, either there exists an element 5895:" in set theory is the primary notion defined as 2409:{\displaystyle (x+y>0)\to (x>0\lor y>0)} 6992:Constructivism in mathematics: an introduction 1 6801:The least-upper-bound principle and compact sets 6721:, there exists (we can construct) a real number 4444:, which is logically equivalent to the negation 2607:may be independently defined and constitutes an 2305:{\displaystyle (x>0\lor 0>x)\lor x\cong 0} 792:be the characteristic function defined to equal 7010:. Cambridge, U.K.: Cambridge University Press. 5932:or some models of the reals can be taken to be 2471:{\displaystyle (y>x)\to (y>t\lor t>x)} 5500:{\displaystyle \{15,90,24300,6561000,\dots \}} 3280:may be defined by or proven equivalent to the 2253:, i.e. it is not provable that for all reals, 2066:and relevant arithmetic substructures are not 318:{\displaystyle \neg \neg \exists x.\theta (x)} 7248: 6000:{\displaystyle {\mathbb {Q} }^{\mathbb {N} }} 5925:{\displaystyle {\mathbb {Q} }^{\mathbb {N} }} 5738:{\displaystyle {\mathbb {Q} }^{\mathbb {N} }} 5048:{\displaystyle {\mathbb {Q} }^{\mathbb {N} }} 5007:{\displaystyle {\mathbb {N} }^{\mathbb {N} }} 4521:. This is provably transitive and in turn an 3770:{\displaystyle {\mathbb {Q} }^{\mathbb {N} }} 2597:{\displaystyle x\#y\,:=\,(x>y\lor y>x)} 1387: 1314: 722: 685: 656:{\displaystyle {\mathbb {Q} }^{\mathbb {N} }} 450: 422: 148:{\displaystyle {\mathbb {N} }^{\mathbb {N} }} 8: 6967:Indecomposability (constructive mathematics) 6745:)| > 0. In this case, the desired number 6617:("there exists") requires one to be able to 5967:{\displaystyle {\mathcal {P}}{\mathbb {N} }} 5494: 5464: 5206: 5161: 5014:or stronger principles aid such frameworks. 779: 767: 7157:/ Volume 2 / Issue 01 / March 1996, pp 1-71 7139:See, e.g., Theorem 1 in Bishop, 1967, p. 25 4570:{\displaystyle |x_{n}|\leq {\tfrac {2}{n}}} 1860:with postulates for a positivity predicate 240:The base logic of constructive analysis is 7255: 7241: 7233: 5692:) the numbers equivalent with respect to " 4705:{\displaystyle x_{n}\geq -{\tfrac {1}{n}}} 2539:In the context of analysis, the auxiliary 51:by some means, a collection extending the 7172: 7100: 6495: 6487: 6485: 6483: 6441: 6419: 6411: 6409: 6407: 6332: 6285: 6225: 6221: 6215: 6200: 6199: 6198: 6184: 6152: 6132: 6111: 6105: 6079: 6054: 6053: 6052: 6050: 6019: 6018: 6016: 5991: 5990: 5989: 5984: 5983: 5982: 5979: 5959: 5958: 5957: 5951: 5950: 5948: 5943:proving uncountability of powersets like 5916: 5915: 5914: 5909: 5908: 5907: 5904: 5880: 5848: 5847: 5846: 5838: 5837: 5836: 5834: 5799: 5798: 5796: 5776: 5775: 5774: 5772: 5729: 5728: 5727: 5722: 5721: 5720: 5717: 5697: 5670: 5669: 5667: 5639: 5638: 5636: 5614: 5613: 5612: 5610: 5587: 5557: 5548:In some frameworks of analysis, the name 5516: 5515: 5514: 5512: 5462: 5425: 5410: 5396: 5369: 5363: 5352: 5345: 5336: 5305: 5300: 5285: 5280: 5265: 5260: 5247: 5241: 5220: 5215: 5214: 5213: 5200: 5187: 5174: 5159: 5136: 5131: 5109: 5099: 5092: 5084: 5064: 5063: 5062: 5060: 5039: 5038: 5037: 5032: 5031: 5030: 5027: 4998: 4997: 4996: 4991: 4990: 4989: 4986: 4956: 4944: 4932: 4919: 4910: 4899: 4875: 4869: 4849: 4829: 4802: 4800: 4773: 4771: 4745: 4717: 4690: 4678: 4672: 4646: 4608: 4582: 4555: 4547: 4541: 4532: 4530: 4499: 4491: 4485: 4472: 4463: 4449: 4422: 4414: 4408: 4395: 4386: 4376: 4372: 4361: 4334: 4325: 4311: 4307: 4296: 4269: 4267: 4240: 4238: 4214: 4208: 4181: 4166: 4158: 4152: 4139: 4130: 4128: 4104: 4073: 4053: 4029: 4003: 3983: 3937: 3917: 3891: 3842: 3822: 3802: 3782: 3761: 3760: 3759: 3754: 3753: 3752: 3749: 3697: 3696: 3694: 3662: 3661: 3659: 3629: 3601: 3563: 3498: 3457: 3456: 3454: 3414: 3376: 3350: 3324: 3289: 3259: 3231: 3205: 3179: 3154: 3148: 3128: 3107: 3101: 3081: 3061: 3060: 3059: 3051: 3022: 3021: 3020: 3012: 2986: 2951: 2904: 2848: 2820: 2762: 2700: 2677: 2621: 2566: 2562: 2551: 2506: 2483: 2421: 2353: 2325: 2324: 2322: 2261: 2186: 2163: 2110: 2078: 2034: 2008: 1967: 1963: 1952: 1917: 1891: 1865: 1825: 1787: 1786: 1751: 1750: 1739: 1727: 1726: 1725: 1720: 1719: 1718: 1704: 1703: 1702: 1698: 1697: 1696: 1684: 1683: 1674: 1673: 1671: 1656:{\displaystyle g\cong _{\mathrm {ext} }0} 1637: 1636: 1627: 1593: 1592: 1578: 1574: 1568: 1567: 1565: 1531: 1530: 1519: 1515: 1509: 1508: 1506: 1486: 1465: 1464: 1462: 1441: 1440: 1439: 1434: 1433: 1432: 1423: 1386: 1385: 1366: 1365: 1330: 1329: 1313: 1312: 1305: 1293: 1292: 1291: 1286: 1285: 1284: 1270: 1269: 1268: 1264: 1263: 1262: 1256: 1255: 1253: 1220: 1219: 1217: 1185: 1180: 1174: 1136: 1116: 1061: 1060: 1051: 1024: 1010: 1006: 987: 986: 974: 954: 934: 907: 898: 883: 873: 862: 855: 853: 849: 843: 837: 817: 797: 759: 758: 757: 748: 742: 721: 720: 684: 683: 672: 647: 646: 645: 640: 639: 638: 635: 615:{\displaystyle {\mathsf {T}}\vdash \psi } 600: 599: 597: 585:{\displaystyle {\mathsf {T}}\vdash \phi } 570: 569: 567: 534: 533: 531: 506: 505: 503: 449: 448: 421: 420: 418: 398: 372: 359:{\displaystyle \neg \exists x.\theta (x)} 330: 286: 255: 254: 252: 209: 208: 206: 179: 178: 176: 139: 138: 137: 132: 131: 130: 127: 90: 64: 6717:in the interval and any natural number 6320:{\displaystyle \neg (x\leq 0)\to x>0} 4088:" (discussed below), it has a supremum. 1418:mean that there is an explicit sequence 6983: 6641:as in the classical theorem, given any 6367:{\displaystyle \neg (x\cong 0)\to x\#0} 2939:{\displaystyle x\#0\to \neg (x\cong 0)} 2498:, related to locatedness of the reals. 2178:-direction. In a pseudo-order, one has 277:is not automatically assumed for every 43:The name of the subject contrasts with 7216:Real Analysis: A Constructive Approach 5677: 5674: 5671: 5646: 5643: 5640: 4203:. An alternative is using the tighter 2803:{\displaystyle (x\#0)\lor \neg (x\#0)} 1992:{\displaystyle y>x\,:=\,(y-x>0)} 1675: 1569: 1510: 1466: 1257: 1221: 601: 571: 535: 507: 213: 210: 186: 183: 180: 5022:It is worth noting that sequences in 1240:, rational-valued sequences. Already 31:done according to some principles of 7: 7197:Foundations of Constructive Analysis 7082:Foundations of Constructive Analysis 7066:Foundations of Constructive Analysis 7053:Handbook of Constructive Mathematics 5154:may be encoded as set of quadruples 2251:disjunction does not hold in general 1457:such that, for any fixed precision, 85:, which governs an equality-to-zero 7007:An introduction to Gödel's Theorems 6548:For a simple example, consider the 6505:{\displaystyle {\mathrm {CT} _{0}}} 6467:{\displaystyle x\geq 0\lor 0\geq x} 6429:{\displaystyle {\mathrm {CT} _{0}}} 6254:already appeared in Cantor's work. 3589:{\displaystyle x>y\lor x\cong y} 3440:{\displaystyle x\geq 0\lor 0\geq x} 3069:{\displaystyle k\in {\mathbb {N} }} 3039:{\displaystyle p\in {\mathbb {R} }} 1947:. In any such ring, one may define 6491: 6488: 6415: 6412: 6374:. Weaker forms may be formulated. 6358: 6334: 6287: 6222: 6186: 6026: 6023: 6020: 5806: 5803: 5800: 4901: 4454: 4451: 4377: 4312: 3847: 3704: 3701: 3698: 3669: 3666: 3663: 3467: 3464: 3461: 3458: 3402:{\displaystyle x>0\lor 0\geq x} 3291: 3200:is apriori stronger than that for 3184: 2991: 2953: 2918: 2909: 2880: 2859: 2843:, in both senses of the word. Via 2825: 2791: 2782: 2770: 2705: 2702: 2632: 2623: 2556: 2332: 2329: 2326: 2188: 2158:generally really only goes in the 2133: 1919: 1794: 1791: 1788: 1773: 1758: 1755: 1752: 1705: 1691: 1688: 1685: 1644: 1641: 1638: 1600: 1597: 1594: 1579: 1538: 1535: 1532: 1373: 1370: 1367: 1352: 1337: 1334: 1331: 1309: 1306: 1271: 1177: 1138: 1080: 1068: 1065: 1062: 1011: 994: 991: 988: 832:is true. The associated sequence 705: 674: 526:, then if it proves a disjunction 470: 461: 458: 427: 377: 374: 335: 332: 294: 291: 288: 262: 259: 256: 14: 6957:Constructive nonstandard analysis 6385:and adopts the classically valid 5325:fundamental theorem of arithmetic 3998:, negatively characterized using 3905:{\displaystyle \varepsilon >0} 3475:{\displaystyle {\mathrm {LLPO} }} 393:, which is generally weaker than 201:, a constructive counter-part of 6990:Troelstra, A. S., van Dalen D., 6936: 6034:{\displaystyle {\mathrm {PEM} }} 5814:{\displaystyle {\mathrm {PEM} }} 3712:{\displaystyle {\mathrm {PEM} }} 3677:{\displaystyle {\mathrm {PEM} }} 2340:{\displaystyle {\mathrm {LPO} }} 270:{\displaystyle {\mathrm {PEM} }} 7102:10.1090/s0002-9904-1970-12455-7 6713:, meaning that given any point 6512:. Such phenomena also occur in 6274:is adopted in various schools. 6270:For practical mathematics, the 5974:and plain function spaces like 5685:{\displaystyle {\mathsf {ZFC}}} 5654:{\displaystyle {\mathsf {CZF}}} 4817:{\displaystyle {\tfrac {2}{N}}} 4788:{\displaystyle {\tfrac {2}{n}}} 4284:{\displaystyle {\tfrac {3}{2}}} 4255:{\displaystyle {\tfrac {1}{n}}} 2974:{\displaystyle \neg (x\cong 0)} 1842:weak Brouwerian counterexamples 495:can generally be not reversed. 413:. In turn, also an implication 386:{\displaystyle \neg \neg \phi } 194:{\displaystyle {\mathsf {CZF}}} 6657:in the interval such that the 6544:The intermediate value theorem 6352: 6349: 6337: 6305: 6302: 6290: 6205: 6189: 6062:{\displaystyle {\mathbb {R} }} 5784:{\displaystyle {\mathbb {Q} }} 5622:{\displaystyle {\mathbb {N} }} 5524:{\displaystyle {\mathbb {N} }} 5341: 5128: 5118: 5089: 5072:{\displaystyle {\mathbb {N} }} 4945: 4911: 4622: 4610: 4548: 4533: 4492: 4464: 4415: 4387: 4159: 4131: 3954: 3948: 3942: 3542: 3530: 3527: 3524: 3500: 3306: 3294: 3033: 3027: 2968: 2956: 2933: 2921: 2915: 2886: 2877: 2871: 2868: 2865: 2856: 2850: 2797: 2785: 2776: 2764: 2738: 2726: 2723: 2720: 2708: 2656: 2644: 2641: 2638: 2626: 2591: 2567: 2465: 2441: 2438: 2435: 2423: 2403: 2379: 2376: 2373: 2355: 2287: 2263: 2218: 2215: 2191: 2165: 2145: 2139: 2130: 2127: 2124: 2112: 1986: 1968: 1934: 1922: 1803: 1776: 1767: 1740: 1733: 1708: 1609: 1582: 1547: 1520: 1414:and arithmetically sound. Now 1382: 1355: 1346: 1319: 1299: 1274: 1236:with quantifiers ranging over 1162:{\displaystyle \forall n.Q(n)} 1156: 1150: 1098: 1092: 1077: 1003: 976: 895: 889: 764: 717: 711: 699: 693: 482: 476: 455: 445: 439: 353: 347: 312: 306: 221:{\displaystyle {\mathsf {ZF}}} 1: 7078:Stolzenberg, Gabriel (1970). 5941:Cantors diagonal construction 4091: 3312:{\displaystyle \neg (x>0)} 1940:{\displaystyle \neg (0>0)} 1474:{\displaystyle {\mathsf {T}}} 1229:{\displaystyle {\mathsf {T}}} 515:{\displaystyle {\mathsf {T}}} 7541:Constructivism (mathematics) 5871:Recall that the preorder on 3925:{\displaystyle \varepsilon } 2841:carries positive information 2101:In intuitonistic logic, the 1194:{\displaystyle \Pi _{1}^{0}} 246:principle of excluded middle 7402:Ontology (computer science) 6807:least-upper-bound principle 6725:in the interval such that | 6381:school reasons in terms of 6172:{\displaystyle a<z<b} 3174:So the excluded middle for 7562: 7295:Intuitionistic type theory 7154:Bulletin of Symbolic Logic 6615:existential quantification 6601:in the interval such that 6550:intermediate value theorem 6100:and any sequence of reals 6074:For any two pair of reals 5327:. There are more economic 4634:{\displaystyle (y-x)>0} 2529:intermediate value theorem 6272:axiom of dependent choice 5791:. At least when assuming 5453:, may be used to compute 3076:, the statement that the 2815:proof of the disjunction 169:constructive set theories 7080:"Review: Errett Bishop, 6258:Category and type theory 5580:equality or real numbers 5571:{\displaystyle x\cong y} 5533:total recursive function 4759:{\displaystyle x\cong y} 4740:The above definition of 3250:Non-strict partial order 3219:{\displaystyle x\cong 0} 1622:. Here this proposition 1111:. Note that the symbol " 232:may be studied as well. 104:{\displaystyle x\cong 0} 33:constructive mathematics 7300:Constructive set theory 5753:axiom of extensionality 5079:. A sequence rationals 4660:{\displaystyle x\geq 0} 4017:{\displaystyle x\leq b} 3615:{\displaystyle x\geq y} 3364:{\displaystyle 0\geq x} 3338:{\displaystyle x\leq 0} 3273:{\displaystyle 0\geq x} 244:, which means that the 157:second-order arithmetic 7214:Bridger, Mark (2007). 7089:Bull. Amer. Math. Soc. 6594:, then there exists a 6506: 6468: 6430: 6393:Anti-classical schools 6368: 6321: 6233: 6173: 6141: 6127:, there exists a real 6121: 6094: 6093:{\displaystyle a<b} 6063: 6035: 6001: 5968: 5926: 5889: 5857: 5815: 5785: 5739: 5706: 5705:{\displaystyle \cong } 5686: 5655: 5623: 5596: 5595:{\displaystyle \cong } 5572: 5525: 5501: 5447: 5385: 5317: 5230: 5148: 5073: 5049: 5008: 4969: 4888: 4887:{\displaystyle 2^{-n}} 4858: 4838: 4818: 4789: 4760: 4726: 4706: 4661: 4635: 4597: 4596:{\displaystyle y>x} 4571: 4515: 4438: 4350: 4285: 4256: 4227: 4226:{\displaystyle 2^{-n}} 4197: 4113: 4092:Bishop's formalization 4082: 4062: 4038: 4018: 3992: 3961: 3926: 3906: 3884:modulus of convergence 3857: 3831: 3811: 3791: 3771: 3713: 3678: 3638: 3616: 3590: 3549: 3476: 3441: 3403: 3365: 3339: 3313: 3274: 3240: 3239:{\displaystyle \cong } 3220: 3194: 3164: 3137: 3117: 3090: 3070: 3040: 3001: 2975: 2940: 2893: 2835: 2804: 2745: 2686: 2685:{\displaystyle \cong } 2663: 2598: 2521: 2520:{\displaystyle x>0} 2492: 2472: 2410: 2341: 2306: 2234: 2172: 2152: 2087: 2086:{\displaystyle \cong } 2049: 2048:{\displaystyle 0>x} 2023: 2022:{\displaystyle x<0} 1993: 1941: 1906: 1905:{\displaystyle 1>0} 1880: 1879:{\displaystyle x>0} 1848:Order vs. disjunctions 1834: 1833:{\displaystyle \cong } 1810: 1657: 1616: 1554: 1495: 1475: 1451: 1396: 1230: 1195: 1163: 1125: 1105: 1040: 963: 943: 923: 826: 806: 786: 731: 657: 626:Undecidable predicates 616: 586: 556: 516: 489: 407: 387: 360: 319: 271: 222: 195: 149: 105: 79: 78:{\displaystyle x>0} 7536:Mathematical analysis 7285:Constructive analysis 7004:Smith, Peter (2007). 6507: 6474:. The existence of a 6469: 6431: 6369: 6322: 6234: 6174: 6142: 6122: 6120:{\displaystyle x_{n}} 6095: 6064: 6041:or alternatively the 6036: 6002: 5969: 5927: 5890: 5888:{\displaystyle \leq } 5858: 5816: 5786: 5740: 5707: 5687: 5656: 5624: 5597: 5573: 5526: 5502: 5448: 5386: 5318: 5231: 5149: 5074: 5050: 5009: 4970: 4889: 4859: 4839: 4819: 4790: 4761: 4727: 4707: 4662: 4636: 4598: 4572: 4516: 4439: 4351: 4286: 4257: 4228: 4198: 4114: 4083: 4063: 4039: 4037:{\displaystyle \leq } 4019: 3993: 3962: 3927: 3907: 3858: 3832: 3812: 3792: 3772: 3714: 3679: 3639: 3637:{\displaystyle \geq } 3617: 3591: 3550: 3477: 3442: 3404: 3366: 3340: 3314: 3275: 3254:Lastly, the relation 3241: 3221: 3195: 3165: 3163:{\displaystyle a_{k}} 3138: 3118: 3116:{\displaystyle a_{k}} 3091: 3071: 3041: 3002: 2976: 2941: 2899:it also follows that 2894: 2836: 2805: 2746: 2687: 2664: 2599: 2522: 2493: 2473: 2411: 2342: 2307: 2235: 2173: 2153: 2103:disjunctive syllogism 2088: 2050: 2024: 1994: 1942: 1907: 1881: 1835: 1811: 1658: 1617: 1555: 1496: 1476: 1452: 1397: 1231: 1196: 1164: 1126: 1106: 1041: 964: 944: 924: 827: 807: 787: 737:is provable, and let 732: 658: 617: 587: 557: 517: 490: 408: 406:{\displaystyle \phi } 388: 361: 320: 272: 236:Logical preliminaries 230:direct axiomatization 223: 196: 150: 106: 80: 29:mathematical analysis 25:constructive analysis 16:Mathematical analysis 7338:Fuzzy set operations 7333:Fuzzy finite element 7280:Intuitionistic logic 7115:Robert S. Lubarsky, 6893:sequentially compact 6526:logically equivalent 6482: 6440: 6406: 6331: 6284: 6183: 6151: 6131: 6104: 6078: 6049: 6015: 5978: 5947: 5903: 5879: 5833: 5795: 5771: 5716: 5696: 5666: 5635: 5609: 5586: 5556: 5511: 5461: 5395: 5335: 5240: 5158: 5083: 5059: 5026: 4985: 4898: 4868: 4848: 4828: 4799: 4770: 4766:uses a common bound 4744: 4716: 4671: 4645: 4607: 4581: 4529: 4523:equivalence relation 4448: 4360: 4295: 4266: 4237: 4207: 4127: 4103: 4081:{\displaystyle <} 4072: 4061:{\displaystyle <} 4052: 4028: 4002: 3982: 3936: 3916: 3890: 3856:{\displaystyle x\#0} 3841: 3821: 3801: 3790:{\displaystyle >} 3781: 3748: 3693: 3686:MacNeille completion 3658: 3628: 3600: 3562: 3497: 3453: 3413: 3375: 3349: 3323: 3288: 3258: 3230: 3204: 3193:{\displaystyle x\#0} 3178: 3147: 3127: 3100: 3080: 3050: 3011: 3000:{\displaystyle x\#0} 2985: 2950: 2903: 2847: 2834:{\displaystyle x\#y} 2819: 2761: 2699: 2676: 2620: 2550: 2505: 2482: 2420: 2352: 2321: 2260: 2185: 2171:{\displaystyle \to } 2162: 2109: 2077: 2033: 2007: 1951: 1916: 1890: 1864: 1824: 1670: 1626: 1564: 1505: 1485: 1461: 1422: 1407:logically equivalent 1252: 1216: 1212:Consider any theory 1173: 1135: 1115: 1050: 973: 953: 933: 836: 816: 796: 741: 671: 634: 596: 566: 530: 524:disjunction property 502: 417: 397: 371: 329: 285: 251: 242:intuitionistic logic 205: 175: 126: 89: 63: 7515:Non-monotonic logic 7264:Non-classical logic 6952:Computable analysis 6554:continuous function 6514:realizability topoi 5825:Interval arithmetic 5368: 1238:primitive recursive 1203:Goldbach conjecture 1190: 878: 281:. If a proposition 159:, or strong enough 122:by types including 7510:Intermediate logic 7290:Heyting arithmetic 7218:. Hoboken: Wiley. 6944:Mathematics portal 6705:. We require that 6502: 6464: 6426: 6364: 6317: 6278:Markov's principle 6229: 6169: 6137: 6117: 6090: 6059: 6031: 6009:intuitionistically 5997: 5964: 5922: 5885: 5853: 5811: 5781: 5748:Cauchy real number 5735: 5702: 5682: 5651: 5619: 5592: 5568: 5521: 5497: 5443: 5435: 5420: 5381: 5379: 5350: 5344: 5313: 5226: 5144: 5116: 5069: 5045: 5004: 4965: 4884: 4854: 4834: 4814: 4812: 4785: 4783: 4756: 4722: 4702: 4700: 4657: 4631: 4593: 4567: 4565: 4511: 4509: 4434: 4432: 4346: 4344: 4281: 4279: 4252: 4250: 4223: 4193: 4191: 4176: 4109: 4078: 4058: 4034: 4014: 3988: 3971:Bounds and suprema 3957: 3922: 3902: 3877:Cauchy convergence 3853: 3827: 3807: 3787: 3767: 3740:Rational sequences 3709: 3674: 3634: 3612: 3586: 3545: 3472: 3437: 3399: 3361: 3335: 3309: 3282:logically negative 3270: 3236: 3216: 3190: 3160: 3133: 3113: 3086: 3066: 3036: 2997: 2971: 2936: 2889: 2831: 2800: 2741: 2682: 2659: 2610:apartness relation 2594: 2541:logically positive 2517: 2488: 2468: 2406: 2337: 2302: 2245:logically positive 2230: 2168: 2148: 2083: 2045: 2019: 1989: 1937: 1902: 1876: 1852:The theory of the 1830: 1806: 1653: 1612: 1550: 1491: 1471: 1447: 1392: 1226: 1201:-examples are the 1191: 1176: 1159: 1121: 1101: 1046:, it follows that 1036: 959: 939: 919: 860: 854: 822: 802: 782: 727: 653: 612: 582: 552: 512: 485: 403: 383: 356: 315: 267: 218: 191: 145: 120:Heyting arithmetic 101: 75: 57:apartness relation 45:classical analysis 7523: 7522: 7505:Inquisitive logic 7500:Dynamic semantics 7453:Three-state logic 7407:Ontology language 7017:978-0-521-67453-9 6905:infinite sequence 6819:least upper bound 6813:of the real line 6751:analytic function 6674:) is less than 1/ 6252:diagonal argument 6140:{\displaystyle z} 6045:axiom, models of 5434: 5419: 5378: 5329:pairing functions 5115: 4857:{\displaystyle y} 4837:{\displaystyle x} 4811: 4782: 4725:{\displaystyle n} 4699: 4564: 4508: 4431: 4343: 4278: 4249: 4190: 4175: 4112:{\displaystyle x} 4097:One formalization 3991:{\displaystyle b} 3830:{\displaystyle 0} 3810:{\displaystyle x} 3136:{\displaystyle p} 3089:{\displaystyle k} 2491:{\displaystyle t} 2249:law of trichotomy 1854:real closed field 1494:{\displaystyle g} 1124:{\displaystyle 0} 962:{\displaystyle 1} 942:{\displaystyle 0} 825:{\displaystyle Q} 805:{\displaystyle 0} 7553: 7458:Tri-state buffer 7257: 7250: 7243: 7234: 7229: 7210: 7179: 7178: 7176: 7164: 7158: 7149:Akihiro Kanamori 7146: 7140: 7137: 7131: 7128: 7122: 7113: 7107: 7106: 7104: 7075: 7069: 7062: 7056: 7049: 7043: 7036: 7030: 7029: 7001: 6995: 6988: 6946: 6941: 6940: 6809:, i.e. that any 6794:locally non-zero 6778:locally non-zero 6711:locally non-zero 6621:the real number 6534:separable spaces 6511: 6509: 6508: 6503: 6501: 6500: 6499: 6494: 6476:Specker sequence 6473: 6471: 6470: 6465: 6435: 6433: 6432: 6427: 6425: 6424: 6423: 6418: 6373: 6371: 6370: 6365: 6326: 6324: 6323: 6318: 6238: 6236: 6235: 6230: 6220: 6219: 6204: 6203: 6178: 6176: 6175: 6170: 6146: 6144: 6143: 6138: 6126: 6124: 6123: 6118: 6116: 6115: 6099: 6097: 6096: 6091: 6068: 6066: 6065: 6060: 6058: 6057: 6043:countable choice 6040: 6038: 6037: 6032: 6030: 6029: 6011:valid. Assuming 6006: 6004: 6003: 5998: 5996: 5995: 5994: 5988: 5987: 5973: 5971: 5970: 5965: 5963: 5962: 5956: 5955: 5931: 5929: 5928: 5923: 5921: 5920: 5919: 5913: 5912: 5894: 5892: 5891: 5886: 5862: 5860: 5859: 5854: 5852: 5851: 5842: 5841: 5820: 5818: 5817: 5812: 5810: 5809: 5790: 5788: 5787: 5782: 5780: 5779: 5744: 5742: 5741: 5736: 5734: 5733: 5732: 5726: 5725: 5711: 5709: 5708: 5703: 5691: 5689: 5688: 5683: 5681: 5680: 5660: 5658: 5657: 5652: 5650: 5649: 5628: 5626: 5625: 5620: 5618: 5617: 5602:-related reals. 5601: 5599: 5598: 5593: 5577: 5575: 5574: 5569: 5530: 5528: 5527: 5522: 5520: 5519: 5506: 5504: 5503: 5498: 5452: 5450: 5449: 5444: 5436: 5427: 5421: 5412: 5390: 5388: 5387: 5382: 5380: 5371: 5367: 5362: 5351: 5322: 5320: 5319: 5314: 5312: 5311: 5310: 5309: 5292: 5291: 5290: 5289: 5272: 5271: 5270: 5269: 5252: 5251: 5235: 5233: 5232: 5227: 5225: 5224: 5219: 5218: 5205: 5204: 5192: 5191: 5179: 5178: 5153: 5151: 5150: 5145: 5143: 5142: 5141: 5140: 5117: 5114: 5113: 5104: 5103: 5094: 5078: 5076: 5075: 5070: 5068: 5067: 5054: 5052: 5051: 5046: 5044: 5043: 5042: 5036: 5035: 5013: 5011: 5010: 5005: 5003: 5002: 5001: 4995: 4994: 4974: 4972: 4971: 4966: 4964: 4963: 4948: 4943: 4942: 4924: 4923: 4914: 4893: 4891: 4890: 4885: 4883: 4882: 4863: 4861: 4860: 4855: 4843: 4841: 4840: 4835: 4823: 4821: 4820: 4815: 4813: 4804: 4794: 4792: 4791: 4786: 4784: 4775: 4765: 4763: 4762: 4757: 4731: 4729: 4728: 4723: 4711: 4709: 4708: 4703: 4701: 4692: 4683: 4682: 4666: 4664: 4663: 4658: 4640: 4638: 4637: 4632: 4602: 4600: 4599: 4594: 4576: 4574: 4573: 4568: 4566: 4557: 4551: 4546: 4545: 4536: 4520: 4518: 4517: 4512: 4510: 4501: 4495: 4490: 4489: 4477: 4476: 4467: 4443: 4441: 4440: 4435: 4433: 4424: 4418: 4413: 4412: 4400: 4399: 4390: 4355: 4353: 4352: 4347: 4345: 4336: 4330: 4329: 4290: 4288: 4287: 4282: 4280: 4271: 4261: 4259: 4258: 4253: 4251: 4242: 4232: 4230: 4229: 4224: 4222: 4221: 4202: 4200: 4199: 4194: 4192: 4183: 4177: 4168: 4162: 4157: 4156: 4144: 4143: 4134: 4118: 4116: 4115: 4110: 4087: 4085: 4084: 4079: 4067: 4065: 4064: 4059: 4043: 4041: 4040: 4035: 4023: 4021: 4020: 4015: 3997: 3995: 3994: 3989: 3966: 3964: 3963: 3958: 3931: 3929: 3928: 3923: 3911: 3909: 3908: 3903: 3862: 3860: 3859: 3854: 3836: 3834: 3833: 3828: 3816: 3814: 3813: 3808: 3796: 3794: 3793: 3788: 3776: 3774: 3773: 3768: 3766: 3765: 3764: 3758: 3757: 3718: 3716: 3715: 3710: 3708: 3707: 3683: 3681: 3680: 3675: 3673: 3672: 3643: 3641: 3640: 3635: 3621: 3619: 3618: 3613: 3595: 3593: 3592: 3587: 3558:The disjunction 3554: 3552: 3551: 3546: 3481: 3479: 3478: 3473: 3471: 3470: 3446: 3444: 3443: 3438: 3408: 3406: 3405: 3400: 3370: 3368: 3367: 3362: 3344: 3342: 3341: 3336: 3318: 3316: 3315: 3310: 3279: 3277: 3276: 3271: 3245: 3243: 3242: 3237: 3225: 3223: 3222: 3217: 3199: 3197: 3196: 3191: 3169: 3167: 3166: 3161: 3159: 3158: 3142: 3140: 3139: 3134: 3122: 3120: 3119: 3114: 3112: 3111: 3096:'th coefficient 3095: 3093: 3092: 3087: 3075: 3073: 3072: 3067: 3065: 3064: 3045: 3043: 3042: 3037: 3026: 3025: 3006: 3004: 3003: 2998: 2980: 2978: 2977: 2972: 2945: 2943: 2942: 2937: 2898: 2896: 2895: 2890: 2840: 2838: 2837: 2832: 2809: 2807: 2806: 2801: 2750: 2748: 2747: 2742: 2691: 2689: 2688: 2683: 2668: 2666: 2665: 2660: 2603: 2601: 2600: 2595: 2526: 2524: 2523: 2518: 2497: 2495: 2494: 2489: 2477: 2475: 2474: 2469: 2415: 2413: 2412: 2407: 2346: 2344: 2343: 2338: 2336: 2335: 2311: 2309: 2308: 2303: 2239: 2237: 2236: 2231: 2177: 2175: 2174: 2169: 2157: 2155: 2154: 2149: 2092: 2090: 2089: 2084: 2054: 2052: 2051: 2046: 2028: 2026: 2025: 2020: 2003:). As is usual, 1998: 1996: 1995: 1990: 1946: 1944: 1943: 1938: 1911: 1909: 1908: 1903: 1885: 1883: 1882: 1877: 1858:commutative ring 1839: 1837: 1836: 1831: 1815: 1813: 1812: 1807: 1799: 1798: 1797: 1763: 1762: 1761: 1732: 1731: 1730: 1724: 1723: 1695: 1694: 1679: 1678: 1662: 1660: 1659: 1654: 1649: 1648: 1647: 1621: 1619: 1618: 1613: 1605: 1604: 1603: 1573: 1572: 1559: 1557: 1556: 1551: 1543: 1542: 1541: 1514: 1513: 1500: 1498: 1497: 1492: 1480: 1478: 1477: 1472: 1470: 1469: 1456: 1454: 1453: 1448: 1446: 1445: 1444: 1438: 1437: 1416:Gödel's theorems 1405:This theorem is 1401: 1399: 1398: 1393: 1391: 1390: 1378: 1377: 1376: 1342: 1341: 1340: 1318: 1317: 1298: 1297: 1296: 1290: 1289: 1261: 1260: 1235: 1233: 1232: 1227: 1225: 1224: 1200: 1198: 1197: 1192: 1189: 1184: 1168: 1166: 1165: 1160: 1130: 1128: 1127: 1122: 1110: 1108: 1107: 1102: 1073: 1072: 1071: 1045: 1043: 1042: 1037: 1029: 1028: 999: 998: 997: 968: 966: 965: 960: 948: 946: 945: 940: 928: 926: 925: 920: 918: 917: 902: 888: 887: 877: 872: 861: 848: 847: 831: 829: 828: 823: 811: 809: 808: 803: 791: 789: 788: 783: 763: 762: 753: 752: 736: 734: 733: 728: 726: 725: 689: 688: 662: 660: 659: 654: 652: 651: 650: 644: 643: 621: 619: 618: 613: 605: 604: 591: 589: 588: 583: 575: 574: 561: 559: 558: 553: 539: 538: 521: 519: 518: 513: 511: 510: 494: 492: 491: 486: 454: 453: 426: 425: 412: 410: 409: 404: 392: 390: 389: 384: 365: 363: 362: 357: 324: 322: 321: 316: 276: 274: 273: 268: 266: 265: 227: 225: 224: 219: 217: 216: 200: 198: 197: 192: 190: 189: 154: 152: 151: 146: 144: 143: 142: 136: 135: 110: 108: 107: 102: 84: 82: 81: 76: 49:real number line 7561: 7560: 7556: 7555: 7554: 7552: 7551: 7550: 7526: 7525: 7524: 7519: 7488: 7439: 7411: 7388: 7370: 7361:Relevance logic 7356:Structural rule 7342: 7318:Degree of truth 7304: 7266: 7261: 7226: 7213: 7207: 7191: 7188: 7186:Further reading 7183: 7182: 7166: 7165: 7161: 7147: 7143: 7138: 7134: 7129: 7125: 7114: 7110: 7077: 7076: 7072: 7064:Errett Bishop, 7063: 7059: 7050: 7046: 7038:Erik Palmgren, 7037: 7033: 7018: 7003: 7002: 6998: 6989: 6985: 6980: 6942: 6935: 6932: 6925: 6915: 6803: 6774:classical logic 6673: 6656: 6627:rational number 6561:closed interval 6546: 6530:classical logic 6522: 6486: 6480: 6479: 6478:is proven from 6438: 6437: 6410: 6404: 6403: 6400:Church's thesis 6395: 6329: 6328: 6282: 6281: 6268: 6260: 6211: 6181: 6180: 6149: 6148: 6129: 6128: 6107: 6102: 6101: 6076: 6075: 6047: 6046: 6013: 6012: 5981: 5976: 5975: 5945: 5944: 5906: 5901: 5900: 5877: 5876: 5869: 5831: 5830: 5827: 5793: 5792: 5769: 5768: 5761: 5719: 5714: 5713: 5694: 5693: 5664: 5663: 5633: 5632: 5607: 5606: 5584: 5583: 5578:are called the 5554: 5553: 5546: 5541: 5509: 5508: 5459: 5458: 5393: 5392: 5333: 5332: 5301: 5296: 5281: 5276: 5261: 5256: 5243: 5238: 5237: 5212: 5196: 5183: 5170: 5156: 5155: 5132: 5127: 5105: 5095: 5081: 5080: 5057: 5056: 5029: 5024: 5023: 5020: 4988: 4983: 4982: 4979:Function choice 4952: 4928: 4915: 4896: 4895: 4871: 4866: 4865: 4846: 4845: 4826: 4825: 4797: 4796: 4768: 4767: 4742: 4741: 4738: 4714: 4713: 4674: 4669: 4668: 4643: 4642: 4605: 4604: 4579: 4578: 4537: 4527: 4526: 4481: 4468: 4446: 4445: 4404: 4391: 4358: 4357: 4321: 4293: 4292: 4264: 4263: 4235: 4234: 4210: 4205: 4204: 4148: 4135: 4125: 4124: 4119:fulfilling the 4101: 4100: 4094: 4070: 4069: 4050: 4049: 4026: 4025: 4000: 3999: 3980: 3979: 3973: 3934: 3933: 3914: 3913: 3888: 3887: 3869: 3839: 3838: 3819: 3818: 3799: 3798: 3779: 3778: 3751: 3746: 3745: 3742: 3737: 3725: 3691: 3690: 3684:. Notably, the 3656: 3655: 3652: 3626: 3625: 3598: 3597: 3560: 3559: 3495: 3494: 3488:De Morgan's law 3451: 3450: 3411: 3410: 3373: 3372: 3347: 3346: 3321: 3320: 3286: 3285: 3256: 3255: 3252: 3228: 3227: 3202: 3201: 3176: 3175: 3150: 3145: 3144: 3125: 3124: 3103: 3098: 3097: 3078: 3077: 3048: 3047: 3009: 3008: 2983: 2982: 2948: 2947: 2901: 2900: 2845: 2844: 2817: 2816: 2813:Importantly, a 2759: 2758: 2697: 2696: 2674: 2673: 2618: 2617: 2548: 2547: 2537: 2503: 2502: 2480: 2479: 2418: 2417: 2350: 2349: 2319: 2318: 2258: 2257: 2183: 2182: 2160: 2159: 2107: 2106: 2099: 2075: 2074: 2031: 2030: 2005: 2004: 1949: 1948: 1914: 1913: 1888: 1887: 1862: 1861: 1850: 1822: 1821: 1782: 1746: 1717: 1668: 1667: 1632: 1624: 1623: 1588: 1562: 1561: 1526: 1503: 1502: 1483: 1482: 1459: 1458: 1431: 1420: 1419: 1361: 1325: 1283: 1250: 1249: 1214: 1213: 1207:Rosser sentence 1171: 1170: 1133: 1132: 1113: 1112: 1056: 1048: 1047: 1020: 982: 971: 970: 951: 950: 931: 930: 903: 879: 839: 834: 833: 814: 813: 794: 793: 744: 739: 738: 669: 668: 637: 632: 631: 628: 594: 593: 564: 563: 528: 527: 500: 499: 415: 414: 395: 394: 369: 368: 327: 326: 283: 282: 249: 248: 238: 228:. Of course, a 203: 202: 173: 172: 155:, constructive 129: 124: 123: 87: 86: 61: 60: 41: 17: 12: 11: 5: 7559: 7557: 7549: 7548: 7543: 7538: 7528: 7527: 7521: 7520: 7518: 7517: 7512: 7507: 7502: 7496: 7494: 7490: 7489: 7487: 7486: 7485: 7484: 7474: 7473: 7472: 7462: 7461: 7460: 7449: 7447: 7441: 7440: 7438: 7437: 7432: 7427: 7421: 7419: 7413: 7412: 7410: 7409: 7404: 7398: 7396: 7390: 7389: 7387: 7386: 7380: 7378: 7376:Paraconsistent 7372: 7371: 7369: 7368: 7363: 7358: 7352: 7350: 7344: 7343: 7341: 7340: 7335: 7330: 7325: 7320: 7314: 7312: 7306: 7305: 7303: 7302: 7297: 7292: 7287: 7282: 7276: 7274: 7272:Intuitionistic 7268: 7267: 7262: 7260: 7259: 7252: 7245: 7237: 7231: 7230: 7224: 7211: 7205: 7193:Bishop, Errett 7187: 7184: 7181: 7180: 7159: 7141: 7132: 7123: 7108: 7095:(2): 301–323. 7070: 7057: 7044: 7031: 7016: 6996: 6982: 6981: 6979: 6976: 6975: 6974: 6969: 6964: 6959: 6954: 6948: 6947: 6931: 6928: 6917: 6911: 6889:compact spaces 6802: 6799: 6682:that gives us 6669: 6659:absolute value 6652: 6643:natural number 6545: 6542: 6538:approximations 6521: 6518: 6498: 6493: 6490: 6463: 6460: 6457: 6454: 6451: 6448: 6445: 6422: 6417: 6414: 6394: 6391: 6363: 6360: 6357: 6354: 6351: 6348: 6345: 6342: 6339: 6336: 6316: 6313: 6310: 6307: 6304: 6301: 6298: 6295: 6292: 6289: 6267: 6264: 6259: 6256: 6241: 6240: 6228: 6224: 6218: 6214: 6210: 6207: 6202: 6197: 6194: 6191: 6188: 6168: 6165: 6162: 6159: 6156: 6136: 6114: 6110: 6089: 6086: 6083: 6056: 6028: 6025: 6022: 5993: 5986: 5961: 5954: 5918: 5911: 5884: 5868: 5867:Uncountability 5865: 5850: 5845: 5840: 5826: 5823: 5808: 5805: 5802: 5778: 5760: 5759:Dedekind reals 5757: 5731: 5724: 5701: 5679: 5676: 5673: 5648: 5645: 5642: 5616: 5591: 5567: 5564: 5561: 5545: 5542: 5540: 5537: 5518: 5496: 5493: 5490: 5487: 5484: 5481: 5478: 5475: 5472: 5469: 5466: 5455:Euler's number 5442: 5439: 5433: 5430: 5424: 5418: 5415: 5409: 5406: 5403: 5400: 5377: 5374: 5366: 5361: 5358: 5355: 5349: 5343: 5340: 5308: 5304: 5299: 5295: 5288: 5284: 5279: 5275: 5268: 5264: 5259: 5255: 5250: 5246: 5223: 5217: 5211: 5208: 5203: 5199: 5195: 5190: 5186: 5182: 5177: 5173: 5169: 5166: 5163: 5139: 5135: 5130: 5126: 5123: 5120: 5112: 5108: 5102: 5098: 5091: 5088: 5066: 5041: 5034: 5019: 5016: 5000: 4993: 4962: 4959: 4955: 4951: 4947: 4941: 4938: 4935: 4931: 4927: 4922: 4918: 4913: 4909: 4906: 4903: 4881: 4878: 4874: 4853: 4833: 4824:, the numbers 4810: 4807: 4781: 4778: 4755: 4752: 4749: 4737: 4734: 4721: 4698: 4695: 4689: 4686: 4681: 4677: 4656: 4653: 4650: 4630: 4627: 4624: 4621: 4618: 4615: 4612: 4592: 4589: 4586: 4563: 4560: 4554: 4550: 4544: 4540: 4535: 4507: 4504: 4498: 4494: 4488: 4484: 4480: 4475: 4471: 4466: 4462: 4459: 4456: 4453: 4430: 4427: 4421: 4417: 4411: 4407: 4403: 4398: 4394: 4389: 4385: 4382: 4379: 4375: 4371: 4368: 4365: 4342: 4339: 4333: 4328: 4324: 4320: 4317: 4314: 4310: 4306: 4303: 4300: 4277: 4274: 4248: 4245: 4220: 4217: 4213: 4189: 4186: 4180: 4174: 4171: 4165: 4161: 4155: 4151: 4147: 4142: 4138: 4133: 4108: 4093: 4090: 4077: 4057: 4033: 4013: 4010: 4007: 3987: 3972: 3969: 3956: 3953: 3950: 3947: 3944: 3941: 3921: 3901: 3898: 3895: 3868: 3865: 3852: 3849: 3846: 3826: 3806: 3786: 3763: 3756: 3741: 3738: 3736: 3733: 3729:Heyting fields 3724: 3721: 3706: 3703: 3700: 3671: 3668: 3665: 3651: 3648: 3633: 3624:the relation " 3611: 3608: 3605: 3585: 3582: 3579: 3576: 3573: 3570: 3567: 3556: 3555: 3544: 3541: 3538: 3535: 3532: 3529: 3526: 3523: 3520: 3517: 3514: 3511: 3508: 3505: 3502: 3469: 3466: 3463: 3460: 3436: 3433: 3430: 3427: 3424: 3421: 3418: 3398: 3395: 3392: 3389: 3386: 3383: 3380: 3360: 3357: 3354: 3345:is defined as 3334: 3331: 3328: 3308: 3305: 3302: 3299: 3296: 3293: 3269: 3266: 3263: 3251: 3248: 3235: 3215: 3212: 3209: 3189: 3186: 3183: 3157: 3153: 3132: 3110: 3106: 3085: 3063: 3058: 3055: 3035: 3032: 3029: 3024: 3019: 3016: 2996: 2993: 2990: 2970: 2967: 2964: 2961: 2958: 2955: 2935: 2932: 2929: 2926: 2923: 2920: 2917: 2914: 2911: 2908: 2888: 2885: 2882: 2879: 2876: 2873: 2870: 2867: 2864: 2861: 2858: 2855: 2852: 2830: 2827: 2824: 2811: 2810: 2799: 2796: 2793: 2790: 2787: 2784: 2781: 2778: 2775: 2772: 2769: 2766: 2752: 2751: 2740: 2737: 2734: 2731: 2728: 2725: 2722: 2719: 2716: 2713: 2710: 2707: 2704: 2681: 2670: 2669: 2658: 2655: 2652: 2649: 2646: 2643: 2640: 2637: 2634: 2631: 2628: 2625: 2605: 2604: 2593: 2590: 2587: 2584: 2581: 2578: 2575: 2572: 2569: 2565: 2561: 2558: 2555: 2536: 2533: 2516: 2513: 2510: 2487: 2467: 2464: 2461: 2458: 2455: 2452: 2449: 2446: 2443: 2440: 2437: 2434: 2431: 2428: 2425: 2405: 2402: 2399: 2396: 2393: 2390: 2387: 2384: 2381: 2378: 2375: 2372: 2369: 2366: 2363: 2360: 2357: 2334: 2331: 2328: 2313: 2312: 2301: 2298: 2295: 2292: 2289: 2286: 2283: 2280: 2277: 2274: 2271: 2268: 2265: 2241: 2240: 2229: 2226: 2223: 2220: 2217: 2214: 2211: 2208: 2205: 2202: 2199: 2196: 2193: 2190: 2167: 2147: 2144: 2141: 2138: 2135: 2132: 2129: 2126: 2123: 2120: 2117: 2114: 2098: 2095: 2082: 2044: 2041: 2038: 2029:is defined as 2018: 2015: 2012: 1988: 1985: 1982: 1979: 1976: 1973: 1970: 1966: 1962: 1959: 1956: 1936: 1933: 1930: 1927: 1924: 1921: 1901: 1898: 1895: 1875: 1872: 1869: 1849: 1846: 1829: 1817: 1816: 1805: 1802: 1796: 1793: 1790: 1785: 1781: 1778: 1775: 1772: 1769: 1766: 1760: 1757: 1754: 1749: 1745: 1742: 1738: 1735: 1729: 1722: 1716: 1713: 1710: 1707: 1701: 1693: 1690: 1687: 1682: 1677: 1652: 1646: 1643: 1640: 1635: 1631: 1611: 1608: 1602: 1599: 1596: 1591: 1587: 1584: 1581: 1577: 1571: 1549: 1546: 1540: 1537: 1534: 1529: 1525: 1522: 1518: 1512: 1490: 1468: 1443: 1436: 1430: 1427: 1403: 1402: 1389: 1384: 1381: 1375: 1372: 1369: 1364: 1360: 1357: 1354: 1351: 1348: 1345: 1339: 1336: 1333: 1328: 1324: 1321: 1316: 1311: 1308: 1304: 1301: 1295: 1288: 1282: 1279: 1276: 1273: 1267: 1259: 1223: 1209:of a theory. 1188: 1183: 1179: 1158: 1155: 1152: 1149: 1146: 1143: 1140: 1120: 1100: 1097: 1094: 1091: 1088: 1085: 1082: 1079: 1076: 1070: 1067: 1064: 1059: 1055: 1035: 1032: 1027: 1023: 1019: 1016: 1013: 1009: 1005: 1002: 996: 993: 990: 985: 981: 978: 958: 938: 916: 913: 910: 906: 901: 897: 894: 891: 886: 882: 876: 871: 868: 865: 859: 852: 846: 842: 821: 812:exactly where 801: 781: 778: 775: 772: 769: 766: 761: 756: 751: 747: 724: 719: 716: 713: 710: 707: 704: 701: 698: 695: 692: 687: 682: 679: 676: 649: 642: 627: 624: 611: 608: 603: 581: 578: 573: 551: 548: 545: 542: 537: 509: 484: 481: 478: 475: 472: 469: 466: 463: 460: 457: 452: 447: 444: 441: 438: 435: 432: 429: 424: 402: 382: 379: 376: 355: 352: 349: 346: 343: 340: 337: 334: 314: 311: 308: 305: 302: 299: 296: 293: 290: 264: 261: 258: 237: 234: 215: 212: 188: 185: 182: 141: 134: 100: 97: 94: 74: 71: 68: 40: 37: 15: 13: 10: 9: 6: 4: 3: 2: 7558: 7547: 7544: 7542: 7539: 7537: 7534: 7533: 7531: 7516: 7513: 7511: 7508: 7506: 7503: 7501: 7498: 7497: 7495: 7491: 7483: 7480: 7479: 7478: 7475: 7471: 7468: 7467: 7466: 7463: 7459: 7456: 7455: 7454: 7451: 7450: 7448: 7446: 7445:Digital logic 7442: 7436: 7433: 7431: 7428: 7426: 7423: 7422: 7420: 7418: 7414: 7408: 7405: 7403: 7400: 7399: 7397: 7395: 7391: 7385: 7382: 7381: 7379: 7377: 7373: 7367: 7364: 7362: 7359: 7357: 7354: 7353: 7351: 7349: 7348:Substructural 7345: 7339: 7336: 7334: 7331: 7329: 7326: 7324: 7321: 7319: 7316: 7315: 7313: 7311: 7307: 7301: 7298: 7296: 7293: 7291: 7288: 7286: 7283: 7281: 7278: 7277: 7275: 7273: 7269: 7265: 7258: 7253: 7251: 7246: 7244: 7239: 7238: 7235: 7227: 7225:0-471-79230-6 7221: 7217: 7212: 7208: 7206:4-87187-714-0 7202: 7198: 7194: 7190: 7189: 7185: 7175: 7170: 7163: 7160: 7156: 7155: 7150: 7145: 7142: 7136: 7133: 7127: 7124: 7120: 7119: 7112: 7109: 7103: 7098: 7094: 7091: 7090: 7085: 7083: 7074: 7071: 7067: 7061: 7058: 7054: 7048: 7045: 7041: 7035: 7032: 7027: 7023: 7019: 7013: 7009: 7008: 7000: 6997: 6993: 6987: 6984: 6977: 6973: 6970: 6968: 6965: 6963: 6962:Heyting field 6960: 6958: 6955: 6953: 6950: 6949: 6945: 6939: 6934: 6929: 6927: 6924: 6920: 6914: 6910: 6906: 6902: 6901:cluster point 6898: 6894: 6890: 6885: 6883: 6879: 6875: 6871: 6867: 6864: 6860: 6856: 6852: 6848: 6844: 6840: 6837:if, whenever 6836: 6832: 6828: 6824: 6820: 6817:would have a 6816: 6812: 6808: 6800: 6798: 6795: 6791: 6787: 6783: 6779: 6775: 6770: 6768: 6764: 6761:) < 0 and 6760: 6756: 6752: 6748: 6744: 6740: 6736: 6732: 6728: 6724: 6720: 6716: 6712: 6708: 6704: 6700: 6696: 6692: 6687: 6685: 6681: 6677: 6672: 6668: 6664: 6660: 6655: 6651: 6647: 6644: 6640: 6634: 6632: 6628: 6624: 6620: 6616: 6612: 6609:) is exactly 6608: 6604: 6600: 6597: 6593: 6589: 6585: 6581: 6577: 6573: 6569: 6566: 6562: 6558: 6555: 6551: 6543: 6541: 6539: 6535: 6531: 6527: 6519: 6517: 6515: 6496: 6477: 6461: 6458: 6455: 6452: 6449: 6446: 6443: 6420: 6401: 6392: 6390: 6388: 6387:bar induction 6384: 6380: 6375: 6361: 6355: 6346: 6343: 6340: 6314: 6311: 6308: 6299: 6296: 6293: 6279: 6275: 6273: 6265: 6263: 6257: 6255: 6253: 6249: 6246:According to 6244: 6226: 6216: 6212: 6208: 6195: 6192: 6166: 6163: 6160: 6157: 6154: 6134: 6112: 6108: 6087: 6084: 6081: 6073: 6072: 6071: 6044: 6010: 5942: 5937: 5935: 5898: 5882: 5874: 5866: 5864: 5843: 5824: 5822: 5766: 5765:Dedekind cuts 5758: 5756: 5754: 5750: 5749: 5699: 5661: 5603: 5589: 5581: 5565: 5562: 5559: 5551: 5543: 5538: 5536: 5534: 5491: 5488: 5485: 5482: 5479: 5476: 5473: 5470: 5467: 5456: 5440: 5437: 5431: 5428: 5422: 5416: 5413: 5407: 5404: 5401: 5398: 5375: 5372: 5364: 5359: 5356: 5353: 5347: 5338: 5330: 5326: 5306: 5302: 5297: 5293: 5286: 5282: 5277: 5273: 5266: 5262: 5257: 5253: 5248: 5244: 5221: 5209: 5201: 5197: 5193: 5188: 5184: 5180: 5175: 5171: 5167: 5164: 5137: 5133: 5124: 5121: 5110: 5106: 5100: 5096: 5086: 5017: 5015: 4980: 4976: 4960: 4957: 4953: 4949: 4939: 4936: 4933: 4929: 4925: 4920: 4916: 4907: 4904: 4879: 4876: 4872: 4851: 4831: 4808: 4805: 4779: 4776: 4753: 4750: 4747: 4735: 4733: 4719: 4696: 4693: 4687: 4684: 4679: 4675: 4654: 4651: 4648: 4628: 4625: 4619: 4616: 4613: 4590: 4587: 4584: 4561: 4558: 4552: 4542: 4538: 4524: 4505: 4502: 4496: 4486: 4482: 4478: 4473: 4469: 4460: 4457: 4428: 4425: 4419: 4409: 4405: 4401: 4396: 4392: 4383: 4380: 4373: 4369: 4366: 4363: 4340: 4337: 4331: 4326: 4322: 4318: 4315: 4308: 4304: 4301: 4298: 4275: 4272: 4246: 4243: 4218: 4215: 4211: 4187: 4184: 4178: 4172: 4169: 4163: 4153: 4149: 4145: 4140: 4136: 4122: 4106: 4098: 4089: 4075: 4055: 4047: 4031: 4011: 4008: 4005: 3985: 3978: 3970: 3968: 3951: 3945: 3939: 3919: 3899: 3896: 3893: 3885: 3880: 3878: 3874: 3866: 3864: 3850: 3844: 3824: 3804: 3784: 3739: 3735:Formalization 3734: 3732: 3730: 3723:Invertibility 3722: 3720: 3687: 3649: 3647: 3645: 3631: 3609: 3606: 3603: 3583: 3580: 3577: 3574: 3571: 3568: 3565: 3539: 3536: 3533: 3521: 3518: 3515: 3512: 3509: 3506: 3503: 3493: 3492: 3491: 3489: 3484: 3482: 3434: 3431: 3428: 3425: 3422: 3419: 3416: 3396: 3393: 3390: 3387: 3384: 3381: 3378: 3358: 3355: 3352: 3332: 3329: 3326: 3303: 3300: 3297: 3283: 3267: 3264: 3261: 3249: 3247: 3233: 3213: 3210: 3207: 3187: 3181: 3172: 3155: 3151: 3130: 3108: 3104: 3083: 3056: 3053: 3030: 3017: 3014: 2994: 2988: 2965: 2962: 2959: 2930: 2927: 2924: 2912: 2906: 2883: 2874: 2862: 2853: 2842: 2828: 2822: 2794: 2788: 2779: 2773: 2767: 2757: 2756: 2755: 2735: 2732: 2729: 2717: 2714: 2711: 2695: 2694: 2693: 2679: 2653: 2650: 2647: 2635: 2629: 2616: 2615: 2614: 2612: 2611: 2588: 2585: 2582: 2579: 2576: 2573: 2570: 2563: 2559: 2553: 2546: 2545: 2544: 2542: 2534: 2532: 2530: 2514: 2511: 2508: 2499: 2485: 2462: 2459: 2456: 2453: 2450: 2447: 2444: 2432: 2429: 2426: 2400: 2397: 2394: 2391: 2388: 2385: 2382: 2370: 2367: 2364: 2361: 2358: 2347: 2299: 2296: 2293: 2290: 2284: 2281: 2278: 2275: 2272: 2269: 2266: 2256: 2255: 2254: 2252: 2250: 2246: 2227: 2224: 2221: 2212: 2209: 2206: 2203: 2200: 2197: 2194: 2181: 2180: 2179: 2142: 2136: 2121: 2118: 2115: 2104: 2096: 2094: 2080: 2071: 2069: 2065: 2061: 2056: 2042: 2039: 2036: 2016: 2013: 2010: 2002: 1983: 1980: 1977: 1974: 1971: 1964: 1960: 1957: 1954: 1931: 1928: 1925: 1899: 1896: 1893: 1873: 1870: 1867: 1859: 1855: 1847: 1845: 1843: 1827: 1800: 1783: 1779: 1770: 1764: 1747: 1743: 1736: 1714: 1711: 1699: 1680: 1666: 1665: 1664: 1650: 1633: 1629: 1606: 1589: 1585: 1575: 1544: 1527: 1523: 1516: 1488: 1428: 1425: 1417: 1413: 1408: 1379: 1362: 1358: 1349: 1343: 1326: 1322: 1302: 1280: 1277: 1265: 1248: 1247: 1246: 1243: 1242:minimal logic 1239: 1210: 1208: 1204: 1186: 1181: 1153: 1147: 1144: 1141: 1118: 1095: 1089: 1086: 1083: 1074: 1057: 1053: 1033: 1030: 1025: 1021: 1017: 1014: 1007: 1000: 983: 979: 956: 936: 914: 911: 908: 904: 899: 892: 884: 880: 874: 869: 866: 863: 857: 850: 844: 840: 819: 799: 776: 773: 770: 754: 749: 745: 714: 708: 702: 696: 690: 680: 677: 666: 625: 623: 609: 606: 579: 576: 549: 546: 543: 540: 525: 522:exhibits the 496: 479: 473: 467: 464: 442: 436: 433: 430: 400: 380: 350: 344: 341: 338: 309: 303: 300: 297: 280: 247: 243: 235: 233: 231: 170: 166: 162: 158: 121: 116: 114: 98: 95: 92: 72: 69: 66: 58: 54: 50: 46: 38: 36: 34: 30: 26: 22: 7546:Intuitionism 7425:Three-valued 7366:Linear logic 7284: 7215: 7196: 7162: 7152: 7144: 7135: 7126: 7117: 7111: 7092: 7087: 7081: 7073: 7065: 7060: 7052: 7047: 7039: 7034: 7006: 6999: 6991: 6986: 6972:Pseudo-order 6922: 6918: 6912: 6908: 6896: 6886: 6882:compact sets 6873: 6865: 6858: 6854: 6850: 6846: 6842: 6838: 6834: 6830: 6826: 6822: 6814: 6804: 6793: 6789: 6785: 6781: 6777: 6771: 6766: 6762: 6758: 6754: 6746: 6742: 6738: 6734: 6730: 6726: 6722: 6718: 6714: 6710: 6706: 6702: 6698: 6694: 6690: 6688: 6683: 6679: 6675: 6670: 6666: 6662: 6653: 6649: 6645: 6638: 6635: 6630: 6622: 6618: 6606: 6602: 6598: 6587: 6583: 6575: 6571: 6567: 6556: 6547: 6523: 6436:even refute 6396: 6376: 6276: 6269: 6261: 6245: 6242: 5938: 5934:subcountable 5870: 5828: 5762: 5746: 5604: 5579: 5550:real numbers 5549: 5547: 5544:Cauchy reals 5021: 4977: 4739: 4120: 4095: 3974: 3881: 3870: 3743: 3726: 3653: 3623: 3557: 3485: 3281: 3253: 3173: 2981:would imply 2814: 2812: 2753: 2671: 2608: 2606: 2540: 2538: 2500: 2314: 2247: 2244: 2242: 2105:in the form 2100: 2072: 2057: 2001:pseudo-order 1851: 1818: 1404: 1211: 629: 497: 239: 117: 113:real numbers 112: 55:and with an 44: 42: 39:Introduction 24: 18: 7465:Four-valued 7435:Ɓukasiewicz 7430:Four-valued 7417:Many-valued 7394:Description 7384:Dialetheism 7121:, July 2015 7068:, July 1967 6870:upper bound 6784:; and then 6769:) > 0). 6596:real number 5939:That said, 4233:instead of 3977:upper bound 3817:apart from 3486:By a valid 3449:analytical 3447:, see also 3319:, and then 2317:analytical 2060:first-order 1560:as well as 279:proposition 21:mathematics 7530:Categories 7323:Fuzzy rule 7174:1804.05495 6978:References 6853:such that 6693:such that 6629:). But if 6379:Brouwerian 6266:Principles 5539:Set theory 5323:using the 4736:Variations 4123:condition 4121:regularity 3650:Variations 3284:statement 3046:and fixed 2543:predicate 2097:Trichotomy 1412:consistent 562:then also 7477:IEEE 1164 7328:Fuzzy set 6878:intervals 6776:, if the 6733:| < 1/ 6619:construct 6565:real line 6459:≥ 6453:∨ 6447:≥ 6359:# 6353:→ 6344:≅ 6335:¬ 6306:→ 6297:≤ 6288:¬ 6223:# 6196:∈ 6187:∀ 5897:injection 5883:≤ 5873:cardinals 5844:× 5700:≅ 5590:≅ 5563:≅ 5492:… 5441:… 5348:∑ 5342:↦ 5294:⋅ 5274:⋅ 5254:⋅ 5210:∈ 5207:⟩ 5162:⟨ 5122:− 5090:↦ 4958:− 4926:− 4902:∀ 4877:− 4751:≅ 4688:− 4685:≥ 4652:≥ 4617:− 4553:≤ 4479:− 4455:∃ 4452:¬ 4420:≤ 4402:− 4378:∀ 4367:≅ 4313:∃ 4216:− 4164:≤ 4146:− 4032:≤ 4009:≤ 3952:ε 3943:↦ 3940:ε 3920:ε 3894:ε 3848:# 3632:≥ 3607:≥ 3581:≅ 3575:∨ 3537:≅ 3528:↔ 3519:≥ 3513:∧ 3507:≥ 3432:≥ 3426:∨ 3420:≥ 3394:≥ 3388:∨ 3356:≥ 3330:≤ 3292:¬ 3265:≥ 3246:" below. 3234:≅ 3211:≅ 3185:# 3057:∈ 3018:∈ 2992:# 2963:≅ 2954:¬ 2928:≅ 2919:¬ 2916:→ 2910:# 2884:ϕ 2881:¬ 2878:→ 2875:ψ 2869:↔ 2863:ψ 2860:¬ 2857:→ 2854:ϕ 2826:# 2792:# 2783:¬ 2780:∨ 2771:# 2733:≅ 2724:↔ 2715:≅ 2706:¬ 2703:¬ 2680:≅ 2651:≅ 2642:↔ 2633:# 2624:¬ 2580:∨ 2557:# 2535:Apartness 2454:∨ 2439:→ 2392:∨ 2377:→ 2297:≅ 2291:∨ 2276:∨ 2225:≅ 2219:→ 2204:∨ 2189:¬ 2166:→ 2143:ψ 2140:→ 2137:ϕ 2134:¬ 2128:→ 2122:ψ 2119:∨ 2116:ϕ 2081:≅ 2070:therein. 2068:definable 1975:− 1920:¬ 1828:≅ 1784:≅ 1774:¬ 1771:∨ 1748:≅ 1715:∈ 1706:∀ 1700:⊢ 1634:≅ 1590:≅ 1580:¬ 1576:⊬ 1528:≅ 1517:⊬ 1429:∈ 1363:≅ 1353:¬ 1350:∨ 1327:≅ 1310:¬ 1307:¬ 1281:∈ 1272:∀ 1266:⊢ 1178:Π 1139:∀ 1081:∀ 1078:↔ 1058:≅ 1012:∀ 984:≅ 881:χ 858:∑ 765:→ 755:: 746:χ 706:¬ 703:∨ 675:∀ 665:decidable 610:ψ 607:⊢ 580:ϕ 577:⊢ 550:ψ 547:∨ 544:ϕ 541:⊢ 474:θ 471:¬ 462:∀ 459:¬ 456:→ 437:θ 428:∃ 401:ϕ 381:ϕ 378:¬ 375:¬ 345:θ 336:∃ 333:¬ 304:θ 295:∃ 292:¬ 289:¬ 96:≅ 53:rationals 7195:(1967). 6930:See also 6880:and all 6592:positive 6580:negative 6520:Theorems 6248:Kanamori 5662:or even 4712:for all 4641:. Also, 4046:supremum 3596:implies 2478:for all 2064:topology 1205:and the 171:such as 7470:Verilog 7026:2384958 6903:of the 6835:located 6823:located 6684:exactly 6563:to the 6559:from a 6528:, over 6383:spreads 5486:6561000 3873:maximum 3871:As the 3837:, i.e. 7493:Others 7222:  7203:  7024:  7014:  6868:is an 6811:subset 6686:zero. 6582:while 5018:Coding 3867:Moduli 1169:. Two 7310:Fuzzy 7169:arXiv 6899:as a 6857:< 6841:< 6737:and | 6590:) is 6578:) is 6570:, if 6147:with 5712:" in 5480:24300 5391:, or 4044:". A 2058:This 167:- or 161:topos 7482:VHDL 7220:ISBN 7201:ISBN 7012:ISBN 6611:zero 6377:The 6312:> 6179:and 6164:< 6158:< 6085:< 5631:say 4950:< 4844:and 4626:> 4588:> 4497:> 4332:> 4302:> 4076:< 4056:< 3897:> 3785:> 3569:> 3382:> 3301:> 2586:> 2574:> 2512:> 2460:> 2448:> 2430:> 2398:> 2386:> 2368:> 2315:See 2282:> 2270:> 2210:> 2198:> 2040:> 2014:< 1981:> 1958:> 1929:> 1912:and 1897:> 1871:> 949:and 165:type 70:> 7097:doi 6872:of 6849:of 6833:is 6829:of 6709:be 6661:of 6327:or 6007:is 5767:of 5507:of 4981:in 4603:as 3123:of 592:or 163:-, 27:is 19:In 7532:: 7199:. 7093:76 7086:. 7022:MR 7020:. 6926:. 6884:. 6863:or 6861:, 6729:- 6540:. 6389:. 5936:. 5474:90 5468:15 4374::= 4309::= 3882:A 3731:. 3719:. 3646:. 3483:. 2564::= 2055:. 1965::= 1844:. 1008::= 851::= 35:. 23:, 7256:e 7249:t 7242:v 7228:. 7209:. 7177:. 7171:: 7105:. 7099:: 7084:" 7028:. 6923:N 6921:∈ 6919:n 6916:) 6913:n 6909:c 6907:( 6897:c 6874:S 6866:y 6859:s 6855:x 6851:S 6847:s 6843:y 6839:x 6831:R 6827:S 6815:R 6790:x 6788:( 6786:f 6782:x 6767:b 6765:( 6763:f 6759:a 6757:( 6755:f 6747:c 6743:y 6741:( 6739:f 6735:m 6731:x 6727:y 6723:y 6719:m 6715:x 6707:f 6703:f 6699:c 6697:( 6695:f 6691:c 6680:c 6676:n 6671:n 6667:c 6665:( 6663:f 6654:n 6650:c 6646:n 6639:f 6631:f 6623:c 6607:c 6605:( 6603:f 6599:c 6588:b 6586:( 6584:f 6576:a 6574:( 6572:f 6568:R 6557:f 6497:0 6492:T 6489:C 6462:x 6456:0 6450:0 6444:x 6421:0 6416:T 6413:C 6362:0 6356:x 6350:) 6347:0 6341:x 6338:( 6315:0 6309:x 6303:) 6300:0 6294:x 6291:( 6239:. 6227:z 6217:n 6213:x 6209:. 6206:) 6201:N 6193:n 6190:( 6167:b 6161:z 6155:a 6135:z 6113:n 6109:x 6088:b 6082:a 6055:R 6027:M 6024:E 6021:P 5992:N 5985:Q 5960:N 5953:P 5917:N 5910:Q 5875:" 5849:Q 5839:Q 5807:M 5804:E 5801:P 5777:Q 5730:N 5723:Q 5678:C 5675:F 5672:Z 5647:F 5644:Z 5641:C 5615:N 5566:y 5560:x 5517:N 5495:} 5489:, 5483:, 5477:, 5471:, 5465:{ 5438:, 5432:3 5429:8 5423:, 5417:2 5414:5 5408:, 5405:2 5402:, 5399:1 5376:k 5373:1 5365:i 5360:0 5357:= 5354:k 5339:i 5307:i 5303:s 5298:7 5287:i 5283:d 5278:5 5267:i 5263:n 5258:3 5249:i 5245:2 5222:4 5216:N 5202:i 5198:s 5194:, 5189:i 5185:d 5181:, 5176:i 5172:n 5168:, 5165:i 5138:i 5134:s 5129:) 5125:1 5119:( 5111:i 5107:d 5101:i 5097:n 5087:i 5065:N 5040:N 5033:Q 4999:N 4992:N 4961:n 4954:2 4946:| 4940:1 4937:+ 4934:n 4930:x 4921:n 4917:x 4912:| 4908:. 4905:n 4880:n 4873:2 4852:y 4832:x 4809:N 4806:2 4780:n 4777:2 4754:y 4748:x 4720:n 4697:n 4694:1 4680:n 4676:x 4655:0 4649:x 4629:0 4623:) 4620:x 4614:y 4611:( 4591:x 4585:y 4562:n 4559:2 4549:| 4543:n 4539:x 4534:| 4506:n 4503:2 4493:| 4487:n 4483:y 4474:n 4470:x 4465:| 4461:. 4458:n 4429:n 4426:2 4416:| 4410:n 4406:y 4397:n 4393:x 4388:| 4384:. 4381:n 4370:y 4364:x 4341:n 4338:1 4327:n 4323:x 4319:. 4316:n 4305:0 4299:x 4276:2 4273:3 4247:n 4244:1 4219:n 4212:2 4188:m 4185:1 4179:+ 4173:n 4170:1 4160:| 4154:m 4150:x 4141:n 4137:x 4132:| 4107:x 4012:b 4006:x 3986:b 3955:) 3949:( 3946:N 3900:0 3851:0 3845:x 3825:0 3805:x 3762:N 3755:Q 3705:M 3702:E 3699:P 3670:M 3667:E 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900:/ 896:) 893:n 890:( 885:Q 875:n 870:0 867:= 864:k 845:n 841:q 820:Q 800:0 780:} 777:1 774:, 771:0 768:{ 760:N 750:Q 723:) 718:) 715:n 712:( 709:Q 700:) 697:n 694:( 691:Q 686:( 681:. 678:n 648:N 641:Q 602:T 572:T 536:T 508:T 483:) 480:x 477:( 468:. 465:x 451:) 446:) 443:x 440:( 434:. 431:x 423:( 354:) 351:x 348:( 342:. 339:x 313:) 310:x 307:( 301:. 298:x 263:M 260:E 257:P 214:F 211:Z 187:F 184:Z 181:C 140:N 133:N 99:0 93:x 73:0 67:x

Index

mathematics
mathematical analysis
constructive mathematics
real number line
rationals
apartness relation
Heyting arithmetic
second-order arithmetic
topos
type
constructive set theories
direct axiomatization
intuitionistic logic
principle of excluded middle
proposition
disjunction property
decidable
Goldbach conjecture
Rosser sentence
primitive recursive
minimal logic
logically equivalent
consistent
Gödel's theorems
weak Brouwerian counterexamples
real closed field
commutative ring
pseudo-order
first-order
topology

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