Some Recent Papers

Realizability: a historical Essay. Mathematical Structures in Computer Science (2002),12,pp.239-263.

Relative and Modified Relative Realizability, with Lars Birkedal.Annals of Pure and Applied Logic 118 (2002),pp.115-132.

Ordered PCA's, with Pieter Hofstra. Mathematical Proceedings of the Cambridge Philosophical Society, 2003,134,pp.445-463.

Erratum to "Ordered PCA's".

A Partial Analysis of Modified Realizability. Journal of Symbolic Logic 69 (2004),2,pp.421-429.

Well-foundedness in Realizability. With Martin Hoffman and Thomas Streicher.Archive for Mathematical Logic 45 (2006), 795-805.

A Coinductive Definition of Repletion.Note.

Review of "Sheaves, Games and Model Completions" by S. Ghilardi and M. Zawadowski. Bulletin of Symbolic Logic,10 (2004),2,216-217.

Note on the Independence of Premiss principle.

Filtered Colimits in the Effective Topos. Journal of Pure and Applied Algebra 205 (2006), 446-451.

Algebraic Set Theory and the Effective Topos. With Claire Kouwenhoven. Journal of Symbolic Logic 70 (2005),3, pp.879--890.

A general form of relative recursion, October 2005. Notre Dame Journal of Formal Logic 47 (2006), no.3, 311-318

Review of "From Sets and Types...", July 2006. Bulletin of Symbolic Logic 12 (2006),no.4,611-612

Review of Ponstein's "Nonstandard Analysis" (in Dutch; Nieuw Archief voor Wiskunde ser.5,vol.7,nr.3, september 2006, p.218)


Slides of invited tutorial What is Synthetic Domain Theory?, FMCS 2006, Kananaskis (Canada)

Partial Combinatory Algebras of Functions, May 2009. Notre Dame Journal of Formal Logic 52 (2011),4,431-448.

A Notion of Homotopy for the Effective Topos, March 2010

Review of Simpson's "Subsystems of Second Order Arithmetic" (in Dutch, for Nieuw Archief voor Wiskunde), May 2011

Arithmetic is Categorical, May 2011. With Benno van den Berg.

Basic Subtoposes of the Effective Topos, with Sori Lee. Annals of Pure and Applied Logic 164 (2013), 866-883.

Realizability with a Local Operator of A.M. Pitts, Theoretical Computer Science 546 (2014), 237-243.

Review of Schwichtenberg and Wainer's "Proofs and Computations" (in Dutch), Nieuw Archief voor Wiskunde, december 2013, 290--291.

Effective Operations of Type 2 in PCAs, with Eric Faber. Computability 5 (2016), pp.127-146.

More on Geometric Morphisms between Realizability Toposes, with Eric Faber.
Theory and Applications of Categories vol. 29, no. 30 (2014), pp. 874-895.

Review of "Homotopy Type Theory", Bulletin of Symbolic Logic 20 (4) (December 2014), pp. 497-500.

Defining Functors by Well-founded Recursion, note.

Classical and Relative Realizability, with Tingxiang Zou. Theory and Applications of Categories 31 (2016), 22, pp.571--593.

Extensions of Scott's Graph Model and Kleene's Second Algebra, with Niels Voorneveld. Indagationes Mathematicae 29 (2018), pp.5--22.

The Sierpinski Object in the Scott Realizability Topos, with Tom de Jong. Logical Methods in Computer Science16 (2020),3, pp.12:1--12:16.

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