Quotients of decidable objects in a topos
1983 ◽
Vol 93
(3)
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pp. 409-419
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In (5), Peter Freyd recently raised the question of whether every Grothendieck topos could be obtained from the topos of sets by means of the two constructions of taking sheaves on a locale and of taking continuous actions of a topological group (i.e. the topos-theoretic analogues of the set-theorists' techniques of forcing extensions and permutation models). He showed that these two constructions do suffice to within epsilon; provided we allow ourselves the freedom to take exponential varieties (4) (which do not change the internal logic of the topos) we can obtain every Grothendieck topos in this way.
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2008 ◽
Vol 78
(1)
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pp. 171-176
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2015 ◽
Vol 54
(6)
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pp. 853-865
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1987 ◽
Vol 46
(1)
◽
pp. 49-58
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