Peter LeFanu Lumsdaine

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Name Peter LeFanu Lumsdaine
Member for 3 years
Seen 15 hours ago
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Location Halifax, Canada
Age 30
math.LO/math.CT, currently of Dalhousie University, Nova Scotia, lately of Carnegie Mellon University, Pittsburgh.
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Why are matrices ubiquitous but hypermatrices rare?
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Sexy vacuity …
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Is there a “disjoint union” sigma algebra?
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Abstract Thought vs Calculation
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Can we have A={A} ?
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Is it possible to construct (without choice, even?) a non-finitely-generated group with no proper non-finitely-generated subgroup?
12
Simple adjective for “of the size of a proper class”?
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compact-open topology
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Locally a topos
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Indecomposable objects in a category
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Geometric intuition for limits
7
Non-examples of model structures, that fail for subtle/surprising reasons?
6
Characterization of Kleisli adjunctions
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Axiom of Replacement in Category Theory
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Can we define geometric morphisms (between ETCS categories) elementarily?
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“classes” with no cardinality; “classes” with no equality notion
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Are the axioms for higher category-theory effectively computable?
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Joins of simplicial sets
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Decomposing a large colimit as a pushout of smaller colimits
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Probably easy: Why is f*:A^C'->A^C continuous and cocontinuous for any functor f:C->C'?
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Describing global sections of sheafifications
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Deformations and the dual numbers
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Can we prove set theory is consistent?
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Is it true that a set is countable if and only if there exists a Turing machine to enumerate all the elements in the set?
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Game involving ‘asking questions about a real’
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Left/right exact functor “in nature” which is not a right/left adjoint
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Does this concept have a name, and what are some of its applications?
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What happens when we print the digits of a real number?
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An elementary question about adjunctions between presheaf categories preserving pullbacks.
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A functor that comes from a morphism in a bigger category
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