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Definable completeness. (English) Zbl 1067.18001

In a series of joint papers with J. Funk, the first author has developed the topos-theoretic analogue of R. H. Fox’s topological notion of complete spread. The goal of the present paper is to separate out the spread property from the completeness: the authors introduce a notion of ‘definable completeness’ for geometric morphisms, and prove that a geometric morphism with locally connected domain and bounded codomain is definably complete (resp.a spread) iff the pure part of its comprehensive factorization is a surjection (resp.an inclusion).

MSC:

18B25 Topoi
54C10 Special maps on topological spaces (open, closed, perfect, etc.)

References:

[1] M. Barr and R. Paré . Molecular toposes . J. Pure Appl. Alg. , 17 : 127 - 152 , 1980 . MR 567064 | Zbl 0436.18002 · Zbl 0436.18002 · doi:10.1016/0022-4049(80)90080-8
[2] M. Bunge and J. Funk . Spreads and the symmetric topos . J. Pure Appl. Alg. , 113 : 1 - 38 , 1996 . MR 1411644 | Zbl 0861.18004 · Zbl 0861.18004 · doi:10.1016/0022-4049(95)00150-6
[3] M. Bunge , J. Funk , M. Jibladze , and T. Streicher . Distribution algebras and duality . Advances in Mathematics , 156 : 133 - 155 , 2000 . MR 1800256 | Zbl 0971.18002 · Zbl 0971.18002 · doi:10.1006/aima.2000.1947
[4] R.H. Fox . Covering spaces with singularities . In R. H. Fox et al., editors, Algebraic Geometry and Topology: A Symposium in Honor of S. Lefschetz , pages 243 257 . Princeton University Press , Princeton , 1957 . MR 123298 | Zbl 0079.16505 · Zbl 0079.16505
[5] J. Funk . The display locale of a cosheaf . Cahiers de Top. et Géom. Diff. Catégoriques , 36 ( 1 ): 53 - 93 , 1995 . Numdam | MR 1322801 | Zbl 0824.18005 · Zbl 0824.18005
[6] P.T. Johnstone . Topos Theory . Academic Press, Inc. , London , 1977 . MR 470019 | Zbl 0368.18001 · Zbl 0368.18001
[7] P.T. Johnstone . Sketches of an Elephant: A Topos Theory Compendium . Clarendon Press , Oxford , 2002 . Zbl 1071.18001 · Zbl 1071.18001
[8] F.W. Lawvere . Intensive and extensive quantities . Notes for the lectures given at the workshop on Categorical Methods in Geometry , Aarhus , 1983 .
[9] J.-L. Moens . Caracterisation des topos de faisceaux sur un site interne à un topos . PhD thesis, Univ. Louvain-la-Neuve , 1982 .
[10] Thomas Streicher . Fibered categories à la Jean Benabou . Unpublished notes, 2003 .
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