Theo Johnson-Freyd

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Name	Theo Johnson-Freyd
Member for	5 months
Seen	2 hours ago
Website	theojf.blogspot.com
Location	Berkeley
Age	24

Graduate student at UC Berkeley, studying quantum field theory.

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787

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What does “quantization is not a functor” really mean?

qa.quantum-algebra ct.category-theory

feb 27 at 16:41 David Jordan 1,633●2●12

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answers

440

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Is “semisimple” a dense condition among Lie algebras?

dec 25 at 1:08 Theo Johnson-Freyd 6,110●4●32

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answers

269

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What is the classifying space of “G-bundles with connections”

ct.category-theory lie-groups smooth-manifolds at.algebraic-topology

feb 18 at 2:04 Konrad Waldorf 152●6

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answers

805

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What does the generating function $x/(1 - e^{-x})$ count?

co.combinatorics lie-algebras hopf-algebras

mar 9 at 9:06 Bruce Westbury 750●10

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answers

499

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Which is the correct ring of functions for a topological space?

gn.general-topology real-analysis

nov 30 at 9:04 Andrew Stacey 5,933●2●38

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answer

258

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What’s the status of the following relationship between Ramanujan’s $\tau$ function and the simple Lie algebras?

nt.number-theory lie-algebras

dec 28 at 20:36 mathphysicist 735●2●7

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answers

393

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How is tropicalization like taking the classical limit?

mp.mathematical-physics tropical-geometry

oct 16 at 19:58 Thomas Sauvaget 656●9

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answers

287

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Is there a “categorical” description of Grothendieck’s algebra of differential operators?

ra.rings-and-algebras rt.representation-theory universal-property sheaf-theory

mar 15 at 15:32 Theo Johnson-Freyd 6,110●4●32

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311

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How cavalier can I be when demanding a category have direct sums?

ct.category-theory abelian-categories

feb 15 at 21:07 Reid Barton 10.3k●15●63

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977

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What is the symbol of a differential operator?

dg.differential-geometry lie-groups ap.analysis-of-pdes lie-algebras mp.mathematical-physics

mar 5 at 16:25 Steve Huntsman 3,284●4●23

Answers

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What is to Quantize something?

“Philosophical” meaning of the Yoneda Lemma

Is there a Faa di Bruno-like formula for composition of three functions?

How to respond to “I was never much good at maths at school.”

Character table does not determine group Vs Tannaka duality

When and why did the postdoctoral position originate?

Do convolution and multiplication satisfy any nontrivial algebraic identities?

A single paper everyone should read?

Can a corollary follow a conjecture?

Examples of great mathematical writing

When does a subgroup H of a group G have a complement in G?

Cogroup Objects

Why forgetful functors usually have LEFT adjoint?

Groupoid structure on G/H?

Why is addition of observables in quantum mechanics commutative?

Equivalent Axiomatizations

What is the relation between characters of a group and its lie algebra?

Can the inner structure of an object be systematically deduced from its position in the category?

Taking lecture notes in lectures

Nimber multiplication

What is the comultiplication of a matrix frobenius algebra?

Which commutative rigs arise from a distributive category?

What is lambda calculus related to?

What is Chern-Simons theory?

A problem of infinite balls and a jug

Chances to win an election

Favorite popular math book

Outer automorphisms of simple Lie Algebras

Group-Adjoint and Hopf-Algebra-Adjoint Maps

Representation of Groupoids

340

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309

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Theo Johnson-Freyd

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Questions

What does “quantization is not a functor” really mean?

Is “semisimple” a dense condition among Lie algebras?

What is the classifying space of “G-bundles with connections”

What does the generating function $x/(1 - e^{-x})$ count?

Which is the correct ring of functions for a topological space?

What’s the status of the following relationship between Ramanujan’s $\tau$ function and the simple Lie algebras?

How is tropicalization like taking the classical limit?

Is there a “categorical” description of Grothendieck’s algebra of differential operators?

How cavalier can I be when demanding a category have direct sums?

What is the symbol of a differential operator?

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