论文标题

Planar Heyting儿童代数2:当地运营商,J-Operators和Shashings

Planar Heyting Algebras for Children 2: Local Operators, J-Operators, and Slashings

论文作者

Ochs, Eduardo

论文摘要

选择topos $ e $。 $ e $上有几种不同的“断层概念”。我们如何可视化它们? 让我们将$ e $的分类器对象称为$ω$,并将其truth-sub-sub(1_e)$的Heyting代数,$ h $;有时,我们将$ h $称为TOPOS的“逻辑”。有一种众所周知的方式来代表层状的概念为形态$ j:ω\ toω$,但是当我们明确地绘制它们时,这些“ $ j $”的收益大图。在这里,我们将看到一种将这些“ $ j $”表示为Maps $ j:h \ to H $的方法,以更容易管理。 在本系列的上一篇论文中,我们展示了如何使用Heyting代数的某些玩具模型(称为“ Zhas”)来开发视觉直觉,以欣赏兴高采烈的代数和直觉命题逻辑工作;在这里,我们将将其扩展到滑轮。完整的想法是:融化的概念对应于本地运营商,反之亦然;本地运营商对应于J-操作员,反之亦然;如果我们的Heyting代数$ h $是ZHA,则J-Operators对应于$ H $的SHASHINGS,反之亦然; $ h $上的削减对应于“问号集”和反之亦然,并且每组问号都会引起擦除和重建的概念,从而引起链条。另外,每个Zha $ h $都对应于(acyclic)2个列图,反之亦然,对于任何两列图$(p,a)$,topos $ \ mathbf {set}^{(p,a)}的逻辑与$(p,p,a)$相关。

Choose a topos $E$. There are several different "notions of sheafness" on $E$. How do we visualize them? Let's refer to the classifier object of $E$ as $Ω$, and to its Heyting Algebra of truth-values, $Sub(1_E)$, as $H$; we will sometimes call $H$ the "logic" of the topos. There is a well-known way of representing notions of sheafness as morphisms $j:Ω\to Ω$, but these `$j$'s yield big diagrams when we draw them explicitly; here we will see a way to represent these `$j$'s as maps $J:H\to H$ in a way that is much more manageable. In the previous paper of this series we showed how certain toy models of Heyting Algebras, called "ZHAs", can be used to develop visual intuition for how Heyting Algebras and Intuitionistic Propositional Logic work; here we will extend that to sheaves. The full idea is this: notions of sheafness correspond to local operators and vice-versa; local operators correspond to J-operators and vice-versa; if our Heyting Algebra $H$ is a ZHA then J-operators correspond to slashings on $H$, and vice-versa; slashings on $H$ correspond to "sets of question marks" and vice-versa, and each set of question marks induces a notion of erasing and reconstructing, which induces a sheaf. Also, every ZHA $H$ corresponds to an (acyclic) 2-column graph, and vice-versa, and for any two-column graph $(P,A)$ the logic of the topos $\mathbf{Set}^{(P,A)}$ is exactly the ZHA $H$ associated to $(P,A)$.

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