Abstract
We introduce a method of extending arbitrary categories by a terminal object and apply this method in various type theoretic settings. In particular, we show that categories that are cartesian closed except for the lack of a terminal object have a universal full extension to a cartesian closed category, and we characterize categories for which the latter category is a topos. Both the basic construction and its correctness proof are extremely simple. This is quite surprising in view of the fact that the corresponding results for the simply typed λ-calculus with surjective pairing, in particular concerning the decision problem for equality of terms in the presence of a terminal type, are comparatively involved.
This is a preview of subscription content, log in via an institution.
Buying options
Tax calculation will be finalised at checkout
Purchases are for personal use only
Learn about institutional subscriptionsPreview
Unable to display preview. Download preview PDF.
References
J. Adámek, H. Herrlich, and G. E. Strecker, Abstract and concrete categories, Wiley, New York, 1990.
D. Aspinall, Subtyping with singleton types, Computer Science Logic, LNCS, vol. 933, Springer, 1995, pp. 1–15.
F. Borceux, Handbook of categorical algebra 1, Cambridge, 1994.
R. L. Crole, Categories for types, Cambridge, 1994.
P.-L. Curien, Categorical combinators, sequential algorithms, and functional programming. 2nd ed., Birkhäuser, Boston, 1993.
P.-L. Curien and R. Di Cosmo, A confluent reduction for the λ-calculus with surjective pairing and terminal object, J. Funct. Programming 6 (1996), 299–327.
R. Di Cosmo, On the power of simple diagrams, Rewriting Techniques and Applications, LNCS, vol. 1103, Springer, 1996, pp. 200–214.
R. Di Cosmo and D. Kesner, Rewriting with polymorphic extensional λ-calculus, Computer Science Logic, LNCS, vol. 1092, Springer, 1996, pp. 215–232.
N. Ghani, Eta-expansions in dependent type theory — the calculus of constructions, Typed Lambda Calculus and Applications, LNCS, vol. 1210, Springer, 1997, pp. 164–180.
T. Hardin, Confluence results for the pure strong categorical logic CCL; lambda-calculi as subsystems of CCL, Theoret. Comput. Sci. 65 (1989), 291–342.
B. Jacobs, Categorical logic and type theory, Elsevier, Amsterdam, 1999.
C. B. Jay and N. Ghani, The virtues of eta-expansion, J. Funct. Programming 5 (1995), 135–154.
C. P. J. Koymans, Models of the lambda calculus, CWI, Amsterdam, 1984.
J. Lambek and P. J. Scott, Introduction to higher order categorical logic, Cambridge, 1986.
S. Mac Lane, Categories for the working mathematician, Springer, 1997.
Adam Obtulowicz, Algebra of constructions I. The word problem for partial algebras, Inform. and Comput. 73 (1987), 129–173.
Axel Poigné, Cartesian closure-higher types in categories, Category Theory and Computer Programming, LNCS, vol. 240, Springer, 1985, pp. 58–75.
P. H. Rodenberg and F. J. van der Linden, Manufacturing a cartesian closed category with exactly two objects out of a C-monoid, Stud. Log. 48 (1989), 279–283.
D. S. Scott, Relating theories of the λ-calculus, To H.B. Curry: Essays in Combinatory Logic, Lambda Calculus and Formalisms, Academic Press, 1980, pp. 403–450.
R. A. G. Seely, Locally cartesian closed categories and type theory, Math. Proc. Cambridge Philos. Soc. 95 (1984), 33–48.
R. A. G. Seely, Categorical semantics for higher order polymorphic lambda calclus, J. Symbolic Logic 52 (1987), 969–989.
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2001 Springer-Verlag Berlin Heidelberg
About this paper
Cite this paper
Schröder, L. (2001). Life without the Terminal Type. In: Fribourg, L. (eds) Computer Science Logic. CSL 2001. Lecture Notes in Computer Science, vol 2142. Springer, Berlin, Heidelberg. https://doi.org/10.1007/3-540-44802-0_30
Download citation
DOI: https://doi.org/10.1007/3-540-44802-0_30
Published:
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-540-42554-0
Online ISBN: 978-3-540-44802-0
eBook Packages: Springer Book Archive