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Models of non-well-founded sets via an indexed final coalgebra theorem

  • Benno van den Berg (a1) and Federico de Marchi (a2)

The paper uses the formalism of indexed categories to recover the proof of a standard final coalgebra theorem, thus showing existence of final coalgebras for a special class of functors on finitely complete and cocomplete categories. As an instance of this result, we build the final coalgebra for the powerclass functor, in the context of a Heyting pretopos with a class of small maps. This is then proved to provide models for various non-well-founded set theories, depending on the chosen axiomatisation for the class of small maps.

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[1] Aczel, P., Non-well-founded sets, CSLI Lecture Notes, vol. 14, CSLI Publications, Stanford, CA, 1988.
[2] Aczel, P. and Mendler, N., A final coalgebra theorem. Category theory and computer science (Manchester, 1989), Lecture Notes in Computer Science, vol. 389, Springer-Verlag, Berlin, 1989, pp. 357–365.
[3] Aczel, P. and Rathjen, M., Notes on constructive set theory, Technical Report No. 40, Institut Mittag-Leffler, 2000/2001.
[4] Adámek, J., Milius, S., and Velebil, J., On coalgebra based on classes, Theoretical Computer Science, vol. 316 (2004), no. 1-3, pp. 3–23.
[5] Awodey, S., Butz, C., Simpson, A.K., and Streicher, T., Relating topos theory and set theory via categories of classes, available from, 06 2003.
[6] Awodey, S. and Warren, M.A., Predicative algebraic set theory, Theory and Applications of Categories, vol. 15 (2005), no. 1, pp. 1–39.
[7] van den Berg, B., Predicative topos theory and models for constructive set theory, Ph.D. thesis, University of Utrecht, 2006.
[8] van den Berg, B. and de Marchi, F., Non-well-founded trees in categories, Annals of Pure and Applied Logic, vol. 146 (2007), pp. 40–59.
[9] van den Berg, B. and Moerdijk, I., A unified approach to algebraic set theory, Submitted, 10 2006.
[10] Borceux, Francis, Handbook of categorical algebra. volume 2: Categories and structures, Encyclopedia of Mathematics and its Applications, vol. 51, Cambridge University Press, Cambridge, 1994.
[11] Butz, C., Bernays-Gödel type theory, Journal of Pure and Applied Algebra, vol. 178 (2003), no. 1, pp. 1–23.
[12] Hyland, J.M.E., The effective topos, The L.E.J. Brouwer Centenary Symposium (Noordwijker-hout, 1981) (Troelstra, A.S. and van Dalen, D., editors), Studies for Logic Foundations of Mathematics, vol. 110, North-Holland Publishing Co., Amsterdam, 1982, pp. 165–216.
[13] Johnstone, P.T., Sketches of an elephant: a topos theory compendium. Volume 1, Oxford Logic Guides, vol. 43, Oxford University Press, New York, 2002.
[14] Johnstone, P.T., Power, A.J., Tsujishita, T., Watanabe, H., and Worrell, J., On the structure of categories of coalgebras. Theoretical Computer Science, vol. 260 (2001), no. 1-2, pp. 87–117.
[15] Joyal, A. and Moerdijk, I., Algebraic set theory, London Mathematical Society Lecture Note Series, vol. 220, Cambridge University Press, Cambridge, 1995.
[16] Lambek, J., Subequalizers, Canadian Mathematical Bulletin, vol. 13 (1970), pp. 337–349.
[17] Lindström, I., A construction of non-well-founded sets within Martin-Löf's type theory, this Journal, vol. 54 (1989), no. 1, pp. 57–64.
[18] Moerdijk, I. and Palmgren, E., Wellfounded trees in categories, Annals of Pure and Applied Logic, vol. 104 (2000), pp. 189–218.
[19] Myhill, J., Constructive set theory, this Journal, vol. 40 (1975), no. 3, pp. 347–382.
[20] Pedicchio, M.C. and Tholen, W. (editors), Categorical foundations: Special topics in order, topology, algebra, and sheaf theory, Encyclopedia of Mathematics and Its Applications, vol. 97, Cambridge University Press, Cambridge, 2004.
[21] Rathjen, M., Kripke-Platek set theory and the anti-foundation axiom, Mathematical Logic Quarterly, vol. 47 (2001), no. 4, pp. 435–440.
[22] Rathjen, M., The anti-foundation axiom in constructive set theories, Games, logic, and constructive sets (Stanford, CA, 2000), CSLI Lecture Notes, vol. 161, CSLI Publications, Stanford, CA, 2003, pp. 87–108.
[23] Rathjen, M., Predicativity, circularity, and anti-foundation, One hundred years of Russell's paradox, de Gruyter Series in Logic and its Applications, vol. 6, De Gruyter, Berlin, 2004, pp. 191–219.
[24] Rieger, L., A contribution to Gödel's axiomatic set theory. I, Czechoslovak Mathematical Journal, vol. 7(82) (1957), pp. 323–357.
[25] Simpson, A.K., Elementary axioms for categories of classes (extended abstract), 14th Symposium on Logic in Computer Science (Trento, 1999), IEEE Computer Society, Los Alamitos, CA, 1999, pp. 77–85.
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