Pub Date : 1980-12-01DOI: 10.1016/0003-4843(80)90012-1
Bill Jacob
Let K be a field, and let W(K) denote its Witt ring of Quadratic Forms. It is well-known in the theory of Quadratic Forms that the orders of K correpond in a one to one way with all ring surjections . In particular, a field L is formally real over an ordered field K if and only if there is a homomorphism which extends the given ‘signature’ . (E.g. is the functinal map.)
Using the above, one may discuss the usual theory of formally real and real closed fields in terms of Witt rings, Knebusch in [6] has, in the above setting, given a remarkable new proof of the uniqueness of real closures. One might ask what happens when the above is replaced by some other ring R? That is the subject of this present note. In particular, we shall prove some algebraic and model theoretic analogues of well-known results for real closed fields, where the above is replaced by some finitely generated reduced Witt ring.
设K是一个域,设W(K)表示它的二次型威特环。众所周知,在二次型理论中,K的阶与所有的环上射W(K)→Z以一对一的方式对应。特别地,域L在有序域K上是形式实的,当且仅当存在一个扩展给定的“签名”的同态态(): W(L)→Z。(例如:K = 1, i *,其中i *: W(K)1→W(L)是函数映射。)在此基础上,我们可以讨论Witt环的形式实域和实闭域的一般理论,在此背景下,Knebusch在[6]中给出了实闭域唯一性的新证明。有人可能会问,当上面的Z被另一个环R取代时会发生什么?这就是本文的主题。特别地,我们将证明实闭场的一些已知结果的代数和模型理论类似,其中上面的Z被一些有限生成的约简Witt环所取代。
{"title":"The model theory of ‘R-formal’ fields","authors":"Bill Jacob","doi":"10.1016/0003-4843(80)90012-1","DOIUrl":"https://doi.org/10.1016/0003-4843(80)90012-1","url":null,"abstract":"<div><p>Let <em>K</em> be a field, and let <em>W</em>(<em>K</em>) denote its Witt ring of Quadratic Forms. It is well-known in the theory of Quadratic Forms that the orders of <em>K</em> correpond in a one to one way with all ring surjections <span><math><mtext>W(K) → </mtext><mtext>Z</mtext></math></span>. In particular, a field <em>L</em> is formally real over an ordered field <em>K</em> if and only if there is a homomorphism <span><math><mtext>ϕ</mtext><msub><mi></mi><mn>1</mn></msub><mtext>: W(L)→</mtext><mtext>Z</mtext></math></span> which extends the given ‘signature’ <span><math><mtext>ϕ</mtext><msub><mi></mi><mn>K</mn></msub><mtext>: W(K)→</mtext><mtext>Z</mtext></math></span>. (E.g. <span><math><mtext>ϕ</mtext><msub><mi></mi><mn>K</mn></msub><mtext> = ϕ</mtext><msub><mi></mi><mn>1</mn></msub><mtext>, i</mtext><msub><mi></mi><mn>∗</mn></msub><mtext>, </mtext><mtext>where</mtext><mtext> i</mtext><msub><mi></mi><mn>∗</mn></msub><mtext>: W(K)1 → W(L)</mtext></math></span> is the functinal map.)</p><p>Using the above, one may discuss the usual theory of formally real and real closed fields in terms of Witt rings, Knebusch in [6] has, in the above setting, given a remarkable new proof of the uniqueness of real closures. One might ask what happens when the <span><math><mtext>Z</mtext></math></span> above is replaced by some other ring <em>R</em>? That is the subject of this present note. In particular, we shall prove some algebraic and model theoretic analogues of well-known results for real closed fields, where the above <span><math><mtext>Z</mtext></math></span> is replaced by some finitely generated reduced Witt ring.</p></div>","PeriodicalId":100093,"journal":{"name":"Annals of Mathematical Logic","volume":"19 3","pages":"Pages 263-282"},"PeriodicalIF":0.0,"publicationDate":"1980-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0003-4843(80)90012-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91721875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1980-12-01DOI: 10.1016/0003-4843(80)90010-8
Howard Becker
{"title":"Thin collections of sets of projective ordinals and analogs of L","authors":"Howard Becker","doi":"10.1016/0003-4843(80)90010-8","DOIUrl":"https://doi.org/10.1016/0003-4843(80)90010-8","url":null,"abstract":"","PeriodicalId":100093,"journal":{"name":"Annals of Mathematical Logic","volume":"19 3","pages":"Pages 205-241"},"PeriodicalIF":0.0,"publicationDate":"1980-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0003-4843(80)90010-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91721878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1980-12-01DOI: 10.1016/0003-4843(80)90012-1
B. Jacob
{"title":"The model theory of ‘R-formal’ fields","authors":"B. Jacob","doi":"10.1016/0003-4843(80)90012-1","DOIUrl":"https://doi.org/10.1016/0003-4843(80)90012-1","url":null,"abstract":"","PeriodicalId":100093,"journal":{"name":"Annals of Mathematical Logic","volume":"15 1","pages":"263-282"},"PeriodicalIF":0.0,"publicationDate":"1980-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81834189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1980-12-01DOI: 10.1016/0003-4843(80)90011-X
Walter Baur
{"title":"On the elementary theory of quadruples of vector spaces","authors":"Walter Baur","doi":"10.1016/0003-4843(80)90011-X","DOIUrl":"https://doi.org/10.1016/0003-4843(80)90011-X","url":null,"abstract":"","PeriodicalId":100093,"journal":{"name":"Annals of Mathematical Logic","volume":"19 3","pages":"Pages 243-262"},"PeriodicalIF":0.0,"publicationDate":"1980-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0003-4843(80)90011-X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91721877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1980-11-01DOI: 10.1016/0003-4843(80)90023-6
Henry A. Kierstead
{"title":"Countable models of ω1-categorical theories in admissible languages","authors":"Henry A. Kierstead","doi":"10.1016/0003-4843(80)90023-6","DOIUrl":"10.1016/0003-4843(80)90023-6","url":null,"abstract":"","PeriodicalId":100093,"journal":{"name":"Annals of Mathematical Logic","volume":"19 1","pages":"Pages 127-175"},"PeriodicalIF":0.0,"publicationDate":"1980-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0003-4843(80)90023-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88605392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1980-11-01DOI: 10.1016/0003-4843(80)90018-2
Martin Stein
Well-known interpretations of Heyting's arithmetic of all finite types are the Diller-Nahm λ-interpretation [1] and Kreisel's modified realizability, subsequently called mr-interpretation [4]. For both interpretations one can define hybrids λ q resp. mq.
In Section 4 a chain of interpretations—called M-interpretations—is defined (it was introduced in [6], filling the “gap” between λ-interpretation and mr-interpretation.
In this paper it is shwon that it is possible to prove in one stroke the soundness resp. characterization theorems for all interpretations of HAω 〈〉 (Heyting's arithmetic of all finite types with functionals for coding finite sequences). This is done by means of interpretations of systems which contain set-symbols. For these so called M-interpretations, soundness-resp. characterization theorems can be proved simultaneously (Theorem 2.51. Special translations of set symbols and of the formula (λωϵW)A — this means, special decisions about the size of the set W; see Sections 3 and 4 — yield the corresponding results for all interpretations of HAω〈〉 mentioned.
The terminology of set theoretical language — we consider an extension of HAω〈〉 by an extensively weak fragment only, which leads to a conservative extension of HAω〈〉 — is of good use for studying realizing terms of different interpretations: if HAω<>⊢A, AM∃υ ∀wAM, and ⊢AM[tM, w] by soundness theorem for M-interpretations, there exists a simple operation which maps , the realizing term for modified realizability. For interpretations of Heyting's arithmetic — λ-interpretation. M-interpretations and mr-interpretation — this leads to the following stability result for existence theorems: if is the term computed by λ-interpretation. resp. M-interpretation, with , then — using extensional equality and ω-rule for equations — we can prove that (Section 5).
{"title":"Interpretations of Heyting's arithmetic—An analysis by means of a language with set symbols","authors":"Martin Stein","doi":"10.1016/0003-4843(80)90018-2","DOIUrl":"10.1016/0003-4843(80)90018-2","url":null,"abstract":"<div><p>Well-known interpretations of Heyting's arithmetic of all finite types are the Diller-Nahm λ-interpretation [1] and Kreisel's modified realizability, subsequently called mr-interpretation [4]. For both interpretations one can define hybrids λ q resp. mq.</p><p>In Section 4 a chain of interpretations—called <strong>M</strong>-interpretations—is defined (it was introduced in [6], filling the “gap” between λ-interpretation and mr-interpretation.</p><p>In this paper it is shwon that it is possible to prove <em>in one stroke</em> the soundness resp. characterization theorems for <em>all</em> interpretations of HA<sub>ω 〈〉</sub> (Heyting's arithmetic of all finite types with functionals for coding finite sequences). This is done by means of interpretations of systems which contain set-symbols. For these so called <em>M</em>-interpretations, soundness-resp. characterization theorems can be proved simultaneously (Theorem 2.51. Special translations of set symbols and of the formula (<em>λωϵW</em>)<em>A</em> — this means, special decisions about the size of the set <em>W</em>; see Sections 3 and 4 — yield the corresponding results for all interpretations of HA<sub>ω〈〉</sub> mentioned.</p><p>The terminology of set theoretical language — we consider an extension of HA<sub>ω〈〉</sub> by an extensively weak fragment only, which leads to a conservative extension of HA<sub>ω〈〉</sub> — is of good use for studying realizing terms of different interpretations: if HA<sub><em>ω</em></sub><>⊢<em>A</em>, <em>A</em><sup><em>M</em></sup>∃<em>υ</em> ∀<em>w</em> <em>A</em><sub><em>M</em></sub>, and ⊢<em>A</em><sub><em>M</em></sub>[<em>t</em><sub><em>M</em></sub>, <em>w</em>] by soundness theorem for <em>M</em>-interpretations, there exists a simple operation which maps <span><math><mtext>v</mtext><mtext>̄</mtext><mtext> </mtext><mtext>to</mtext><mtext> </mtext><mtext>t</mtext><mtext>̄</mtext><msub><mi></mi><mn><mtext>mr</mtext></mn></msub></math></span>, the realizing term for modified realizability. For interpretations of Heyting's arithmetic — λ-interpretation. <strong>M</strong>-interpretations and mr-interpretation — this leads to the following stability result for existence theorems: if <span><math><mtext>∃λ A </mtext><mtext>and</mtext><mtext> t</mtext><msub><mi></mi><mn>^</mn></msub><mtext> </mtext><mtext>resp.</mtext><mtext> t</mtext><msub><mi></mi><mn><mtext>M</mtext><mtext>M</mtext></mn></msub></math></span> is the term computed by λ-interpretation. resp. <strong>M</strong>-interpretation, with <span><math><mtext>∃A[t</mtext><msub><mi></mi><mn><mtext>M</mtext></mn></msub><mtext>]</mtext></math></span>, then — using extensional equality and ω-rule for equations — we can prove that <span><math><mtext>t</mtext><msub><mi></mi><mn>λ</mn></msub><mtext> = t</mtext><msub><mi></mi><mn><mtext>M</mtext></mn></msub><mtext> = t</mtext><msub><mi></mi><mn><mtext>mr</mtext></mn></msub></math></span> (Section 5).</p></div>","PeriodicalId":100093,"journal":{"name":"Annals of Mathematical Logic","volume":"19 1","pages":"Pages 1-31"},"PeriodicalIF":0.0,"publicationDate":"1980-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0003-4843(80)90018-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87664539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1980-11-01DOI: 10.1016/0003-4843(80)90019-4
Susumu Hayashi
{"title":"Derived rules related to a constructive theory of metric spaces in intuitionistic higher order arithmetic without countable choice","authors":"Susumu Hayashi","doi":"10.1016/0003-4843(80)90019-4","DOIUrl":"10.1016/0003-4843(80)90019-4","url":null,"abstract":"","PeriodicalId":100093,"journal":{"name":"Annals of Mathematical Logic","volume":"19 1","pages":"Pages 33-65"},"PeriodicalIF":0.0,"publicationDate":"1980-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0003-4843(80)90019-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73273096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1980-11-01DOI: 10.1016/0003-4843(80)90022-4
Keith J. Devlin
{"title":"Concerning the consistency of the Souslin hypothesis with the continuum hypothesis","authors":"Keith J. Devlin","doi":"10.1016/0003-4843(80)90022-4","DOIUrl":"10.1016/0003-4843(80)90022-4","url":null,"abstract":"","PeriodicalId":100093,"journal":{"name":"Annals of Mathematical Logic","volume":"19 1","pages":"Pages 115-125"},"PeriodicalIF":0.0,"publicationDate":"1980-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0003-4843(80)90022-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77387719","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}