Hyperarithmetical sets, in
*Martin Davis on computability, computational logic and
mathematical foundations*, edited by Eugenio G. Omodeo and Alberto
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On the Church-Turing Thesis and relative recursion, Proceedings of the 14th International Congress in Logic, Methodology and Philosophy of Science (Nancy 2011), published by College Publications in 2014, pp. 179 - 200.

Classical descriptive set theory as a refinement of effective descriptive set theory. Annals of Pure and Applied Logic, vol. 162 (2010), pp. 243 - 255.

Kleene's amazing second recursion theorem. The Bulletin of Symbolic Logic, vol. 16 (2010), pp. 189 - 239.

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Two aspects of situated meaning,
with Eleni Kalyvianaki, in *Logics for Linguistic Structures,*
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Elementary
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with Vasilis Paschalis, in *New
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Lower bounds for coprimeness and other decision problems in arithmetic, Extended abstract of a 2005 lecture, published in the Proceedings of the Seminaire: de Structures Algebriques Ordonnees, No 79, (8 pages). [The published version has some unfortunate typos, especially in the references to the bibliography which systematically point to the wrong papers; this version is the correct one.]

Arithmetic complexity, with Lou van den Dries, ACM Transactions on Computational Logic, vol. 10 (2009), pp. 1—49.

Recursion and complexity, in New Computational Paradigms: First Conference on Computability in Europe, CiE 2005, Amsterdam, The Netherlands, June 8-12, 2005. Proceedings. Springer Lecture Notes in CS. vol. 3526/2005. Editors: S. Barry Cooper, Benedikt Lowe, Leen Torenvliet.

Αλγοριθμική σημασιολογία: το νόημα ως προσδιορισμός αναφοράς (Algorithmic semantics: meaning as referential intension), with Eleni Kalyvianaki. In Greek. To appear in a volume of articles which will be published by the Greek Mathematical Society. Posted on August 31, 2004.

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The logic of recursive equations , with A. J. Hurkens, Monica McArthur, Lawrence Moss and Glen Whitney. The Journal of Symbolic Logic, vol. 63 (1998), pages 451 - 478.

A
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Συνέντευξη στο Quantum (Interview in the Greek edition of Quantum, published in the July-August issue of 1997). In Greek.

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Powerdomains,
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Sense and denotation as algorithm and value , Postscript file, 39 pages. In PDF format. Published in Lecture Notes in Logic, #2 (1994), Springer J. Oikkonen and J. Vaananen, eds. pages 210-249. Posted on February 15, 2007: There is a gap in the proof of the main Theorem 4.1 of this paper. Here is a correct (and more detailed) version of this proof, in PDF form.

A
mathematical modeling of pure, recursive algorithms ,
PDF file, 22 pages. Published in *Logic
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The formal
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