In this paper we propose a new approach to realizability interpretations for nonstandard arithmetic. We deal with nonstandard analysis in the context of (semi)intuitionistic realizability, focusing on the Lightstone-Robinson construction of a model for nonstandard analysis through an ultrapower. In particular, we consider an extension of the $\lambda$-calculus with a memory cell, that contains an integer (the state), in order to indicate in which slice of the ultrapower $\cal{M}^{\mathbb{N}}$ the computation is being done. We pay attention to the nonstandard principles (and their computational content) obtainable in this setting. In particular, we give non-trivial realizers to Idealization and a non-standard version of the LLPO principle. We then discuss how to quotient this product to mimic the Lightstone-Robinson construction.
翻译:本文提出了一种实现非标准算术可实现性解释的新方法。我们在(半)直觉主义可实现性的框架下处理非标准分析,重点关注通过超幂构造非标准分析模型的Lightstone-Robinson方法。具体而言,我们考虑对$\lambda$-演算扩展一个包含整数(状态)的存储单元,以指示计算正在超幂$\cal{M}^{\mathbb{N}}$中的哪个切片上进行。我们关注在此设置下可获得的非标准原理(及其计算内容),特别给出了理想化原理和非标准版本LLPO原理的非平凡实现者。最后讨论了如何对此乘积进行商化以模拟Lightstone-Robinson构造。