Mathematically Structured but not Necessarily Functional Programming

These are the slides and the extended abstract from my MSFP 2008 talk. Apparently, I forgot to publish them online. There is a discussion on the Agda mailing list to which the talk is somewhat relevant, so I am publishing now.

Abstract: Realizability is an interpretation of intuitionistic logic which subsumes the Curry-Howard interpretation of propositions [...]

Efficient computation with Dedekind reals

Two versions of this talk were given at Computability and complexity in analysis 2008 and at Mathematics, Algorithms and Proofs 2008.

Joint work with Paul Taylor.

Abstract: Cauchy’s construction of reals as sequences of rational approximations is the theoretical basis for a number of implementations of exact real numbers, while Dedekind’s construction of reals as cuts has [...]

The Role of the Interval Domain in Modern Exact Real Arithmetic

With Iztok Kavkler.

Abstract: The interval domain was proposed by Dana Scott as a domain-theoretic model for real numbers. It is a successful theoretical idea which also inspired a number of computational models for real numbers. However, current state-of-the-art implementations of real numbers, e.g., Mueller’s iRRAM and Lambov’s RealLib, do not seem to be based on [...]

Synthetic Computability (MFPS XXIII Tutorial)

A tutorial presented at the Mathematical Foundations of Programming Semantics XXIII Tutorial Day.

Metric Spaces in Synthetic Topology

With Davorin Lešnik.

Abstract: We investigate the relationship between constructive theory of metric spaces and synthetic topology. Connections between these are established by requiring a relationship to exist between the intrinsic and the metric topology of a space. We propose a non-classical axiom which has several desirable consequences, e.g., that all maps between separable metric spaces [...]

Implementing real numbers with RZ

With Iztok Kavkler.

Abstract: RZ is a tool which translates axiomatizations of mathematical structures to program specifications using the realizability interpretation of logic. This helps programmers correctly implement data structures for computable mathematics. RZ does not prescribe a particular method of implementation, but allows programmers to write efficient code by hand, or to extract trusted code [...]

RZ: a tool for bringing constructive and computable mathematics closer to programming practice

With Chris Stone.

Abstract:
Realizability theory is not only a fundamental tool in logic and computability, but also has direct application to the design and implementation of programs: it can produce interfaces for the data structure corresponding to a mathematical theory. Our tool, called RZ, serves as a bridge between the worlds of constructive mathematics and programming. [...]

Continuity Begets Continuity (Frauenwörth slides)

With Alex Simpson.

Abstract: We present a constructive meta-theorem about sequential continuity which allows us to conclude from a constructive proof of existence of a function between complete metric spaces satisfying a given system of (functional) equations that there also exists a sequentially continuous function satisfying the system.

Presented at: Trends in Constructive mathematics, Frauenwörth am Chimsee, [...]

Specifications via Realizability (Dagstuhl)

With Chris Stone.

Presented at: Reliable Implementation of Real Number Algorithms: Theory and Practice, Dagstuhl Seminar 06021.

Abstract: see “Specifications via Realizability (CLASE)”.

Talk notes: rz-dagstuhl.pdf (handwritten notes of the talk with examples of how RZ works)

First Steps in Synthetic Computability Theory (Fischbachau)

At the EST training workshop in Fischbachau, Germany, I gave two lectures on syntehtic computability theory. This version of the talk contains material on recursive analysis which is not found in the MFPS XXI version of a similar talk.

Abstract:
Computability theory, which investigates computable functions and computable sets, lies at the foundation of logic and computer [...]