{"title":"Pregeometry over locally o-minimal structures and dimension","authors":"Masato Fujita","doi":"10.1002/malq.202200069","DOIUrl":"10.1002/malq.202200069","url":null,"abstract":"<p>We define a discrete closure operator for definably complete locally o-minimal structures <math>\u0000 <semantics>\u0000 <mi>M</mi>\u0000 <annotation>$mathcal {M}$</annotation>\u0000 </semantics></math>. The pair of the underlying set of <math>\u0000 <semantics>\u0000 <mi>M</mi>\u0000 <annotation>$mathcal {M}$</annotation>\u0000 </semantics></math> and the discrete closure operator forms a pregeometry. We define the rank of a definable set over a set of parameters using this fact and call it <math>\u0000 <semantics>\u0000 <mo>discl</mo>\u0000 <annotation>$operatorname{discl}$</annotation>\u0000 </semantics></math>-dimension. A definable set <i>X</i> is of dimension equal to the <math>\u0000 <semantics>\u0000 <mo>discl</mo>\u0000 <annotation>$operatorname{discl}$</annotation>\u0000 </semantics></math>-dimension of <i>X</i>. The structure <math>\u0000 <semantics>\u0000 <mi>M</mi>\u0000 <annotation>$mathcal {M}$</annotation>\u0000 </semantics></math> is simultaneously a first-order topological structure. The dimension rank of a set definable in the first-order topological structure <math>\u0000 <semantics>\u0000 <mi>M</mi>\u0000 <annotation>$mathcal {M}$</annotation>\u0000 </semantics></math> also coincides with its dimension.</p>","PeriodicalId":49864,"journal":{"name":"Mathematical Logic Quarterly","volume":"69 4","pages":"472-481"},"PeriodicalIF":0.3,"publicationDate":"2023-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76113023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Bisimulations and bisimulation games between Verbrugge models","authors":"Sebastijan Horvat, Tin Perkov, Mladen Vuković","doi":"10.1002/malq.202200042","DOIUrl":"https://doi.org/10.1002/malq.202200042","url":null,"abstract":"<p>Interpretability logic is a modal formalization of relative interpretability between first-order arithmetical theories. Verbrugge semantics is a generalization of Veltman semantics, the basic semantics for interpretability logic. Bisimulation is the basic equivalence between models for modal logic. We study various notions of bisimulation between Verbrugge models and develop a new one, which we call w-bisimulation. We show that the new notion, while keeping the basic property that bisimilarity implies modal equivalence, is weak enough to allow the converse to hold in the finitary case. To do this, we develop and use an appropriate notion of bisimulation games between Verbrugge models.</p>","PeriodicalId":49864,"journal":{"name":"Mathematical Logic Quarterly","volume":"69 2","pages":"231-243"},"PeriodicalIF":0.3,"publicationDate":"2023-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50126665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The permutations with n non-fixed points and the subsets with n elements of a set","authors":"Supakun Panasawatwong, Pimpen Vejjajiva","doi":"10.1002/malq.202300005","DOIUrl":"https://doi.org/10.1002/malq.202300005","url":null,"abstract":"<p>We write <math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>S</mi>\u0000 <mi>n</mi>\u0000 </msub>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mi>a</mi>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation>$mathcal {S}_n(mathfrak {a})$</annotation>\u0000 </semantics></math> and <math>\u0000 <semantics>\u0000 <msup>\u0000 <mrow>\u0000 <mo>[</mo>\u0000 <mi>a</mi>\u0000 <mo>]</mo>\u0000 </mrow>\u0000 <mi>n</mi>\u0000 </msup>\u0000 <annotation>$[mathfrak {a}]^n$</annotation>\u0000 </semantics></math> for the cardinalities of the set of permutations with <i>n</i> non-fixed points and the set of subsets with <i>n</i> elements, respectively, of a set which is of cardinality <math>\u0000 <semantics>\u0000 <mi>a</mi>\u0000 <annotation>$mathfrak {a}$</annotation>\u0000 </semantics></math>, where <i>n</i> is a natural number greater than 1. With the Axiom of Choice, <math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>S</mi>\u0000 <mi>n</mi>\u0000 </msub>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mi>a</mi>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation>$mathcal {S}_n(mathfrak {a})$</annotation>\u0000 </semantics></math> and <math>\u0000 <semantics>\u0000 <msup>\u0000 <mrow>\u0000 <mo>[</mo>\u0000 <mi>a</mi>\u0000 <mo>]</mo>\u0000 </mrow>\u0000 <mi>n</mi>\u0000 </msup>\u0000 <annotation>$[mathfrak {a}]^n$</annotation>\u0000 </semantics></math> are equal for all infinite cardinals <math>\u0000 <semantics>\u0000 <mi>a</mi>\u0000 <annotation>$mathfrak {a}$</annotation>\u0000 </semantics></math>. We show, in <span>ZF</span>, that if <math>\u0000 <semantics>\u0000 <msub>\u0000 <mtext>AC</mtext>\u0000 <mrow>\u0000 <mo>≤</mo>\u0000 <mi>n</mi>\u0000 </mrow>\u0000 </msub>\u0000 <annotation>$mbox{textsf {AC}}_{le n}$</annotation>\u0000 </semantics></math> is assumed, then <math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mrow>\u0000 <mo>[</mo>\u0000 <mi>a</mi>\u0000 <mo>]</mo>\u0000 </mrow>\u0000 <mi>n</mi>\u0000 </msup>\u0000 <mo>≤</mo>\u0000 <msub>\u0000 <mi>S</mi>\u0000 <mi>n</mi>\u0000 </msub>\u0000 ","PeriodicalId":49864,"journal":{"name":"Mathematical Logic Quarterly","volume":"69 3","pages":"341-346"},"PeriodicalIF":0.3,"publicationDate":"2023-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50126677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}