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Peter LeFanu Lumsdaine: Classifying subobject operations (jww Martin Brandenburg)

Time: Wed 2025-02-05 10.00 - 12.00

Location: Albano house 1, floor 3, Room U (Kovalevsky)

Participating: Peter LeFanu Lumsdaine (Stockholm University)

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Abstract

In various categories, one can ask: what are the “natural” operations on subobjects? — where “natural” is w.r.t. the *covariant* subobject functor. In Set, for example, “union” is a natural binary operation — but not the only one! I will discuss this and related questions in various naturally-occurring categories, giving complete classifications in some cases, and partial results in others.