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arXiv 1609.05079cs.LO
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显式计算路径

Explicit Computational Paths

Arthur Freitas Ramos, Ruy J. G. B. de Queiroz, Anjolina G. de Oliveira

摘要:

在类型论中,将相等作为一种类型的处理,产生了一种有趣的类型论结构,称为“同一类型”。其思想是,给定类型$A$的项$a,b$,可以形成类型$Id_{A}(a,b)$,其元素是$a$和$b$是类型$A$的相等元素的证明。这种类型的术语$p : Id_{A}(a,b)$弥补了建立$a$确实等于$b$的理由(或证明)。在此基础上,一个相等的证明可以被看作是一个替换和重写的序列,也被称为“计算路径”。一个有趣的事实是,它是可能的重写计算路径使用一组减少规则所产生的冗余路径的分析。1994年,De Oliveira将这些规则映射到一个名为$LND_{EQ}-TRS$的术语重写系统中。在这里,我们使用计算路径和这个术语重写系统来发展同伦类型论的主要基础,即,我们发展引理和定理连接到这个理论的主要类型,类型如产品,余产品,单位类型,运输和许多其他。我们还表明,它是可能的,直接通过计算路径构造路径空间。为了证明这一点,我们构造了自然数和圆的基本群,并展示了与这些结构相关的结果。

英文摘要:

The treatment of equality as a type in type theory gives rise to an interesting type-theoretic structure known as `identity type'. The idea is that, given terms $a,b$ of a type $A$, one may form the type $Id_{A}(a,b)$, whose elements are proofs that $a$ and $b$ are equal elements of type $A$. A term of this type, $p : Id_{A}(a,b)$, makes up for the grounds (or proof) that establishes that $a$ is indeed equal to $b$. Based on that, a proof of equality can be seen as a sequence of substitutions and rewrites, also known as a `computational path'. One interesting fact is that it is possible to rewrite computational paths using a set of reduction rules arising from an analysis of redundancies in paths. These rules were mapped by De Oliveira in 1994 in a term rewrite system known as $LND_{EQ}-TRS$. Here we use computational paths and this term rewrite system to develop the main foundations of homotopy type theory, i.e., we develop the lemmas and theorems connected to the main types of this theory, types such as products, coproducts, identity type, transport and many others. We also show that it is possible to directly construct path spaces through computational paths. To show this, we construct the natural numbers and the fundamental group of the circle, showing results connected to these structures.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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