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- Discussion Type
- discussion topicmoduli space of monopoles
- Category Latest Changes
- Started by Urs
- Comments 8
- Last comment by Urs
- Last Active 3 days ago

starting something, but nothing here yet. For the moment this is just a home for

- Michael Atiyah, Nigel Hitchin,
*The geometry and dynamics of magnetic monopoles*M. B. Porter Lectures. Princeton University Press, Princeton, NJ, 1988 (jstor:j.ctt7zv206)

- Michael Atiyah, Nigel Hitchin,

- Discussion Type
- discussion topicPauli exclusion principle
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 3 days ago

added these pointers:

An interpretation of the s-rule for D-brane intersections with NS5-branes (Dp-D(p+2) brane intersections and Dp-D(p+4) brane intersections) as a version of the Pauli exclusion principle is discussed in:

Constantin Bachas, Michael Green, Adam Schwimmer, Section 2.3 of:

*$(8,0)$ Quantum mechanics and symmetry enhancement in type I’ superstrings*, JHEP 9801 :006, 1998 (arXiv:hep-th/9712086)Constantin Bachas, Michael Green,

*A Classical Manifestation of the Pauli Exclusion Principle*, JHEP 9801 (1998) 015 (arXiv:hep-th/9712187)

- Discussion Type
- discussion topics-rule
- Category Latest Changes
- Started by Urs
- Comments 4
- Last comment by Urs
- Last Active 3 days ago

- Discussion Type
- discussion topiccohomology
- Category Latest Changes
- Started by Urs
- Comments 69
- Last comment by David_Corfield
- Last Active 3 days ago

added a cool reference by Brian Conrad to cohomology, which was mentioned at MathOverflow

- Discussion Type
- discussion topicall horizontal weight systems are partitioned Lie algebra weight systems
- Category Latest Changes
- Started by Urs
- Comments 9
- Last comment by Urs
- Last Active 3 days ago

to record the result of

- Dror Bar-Natan,
*Vassiliev and Quantum Invariants of Braids*, Geom. Topol. Monogr. 4 (2002) 143-160 (arxiv:q-alg/9607001)

- Dror Bar-Natan,

- Discussion Type
- discussion topicintensive and extensive
- Category Latest Changes
- Started by Urs
- Comments 4
- Last comment by Dean
- Last Active 3 days ago

finally created

*intensive and extensive*with the topos-theoretic formalization following the concise statement in the introduction of*Categories in Continuum Physics*

- Discussion Type
- discussion topicAmit Giveon
- Category Latest Changes
- Started by Urs
- Comments 1
- Last comment by Urs
- Last Active 3 days ago

- Discussion Type
- discussion topicRobinson arithmetic
- Category Latest Changes
- Started by TobyBartels
- Comments 2
- Last comment by TobyBartels
- Last Active 4 days ago

In Robinson arithmetic, I recorded the simplest nonstandard model (with a single nonstandard element $\infty$).

- Discussion Type
- discussion topicsecond-order arithmetic
- Category Latest Changes
- Started by atmacen
- Comments 6
- Last comment by TobyBartels
- Last Active 4 days ago

- Discussion Type
- discussion topicLie algebra weight system
- Category Latest Changes
- Started by Urs
- Comments 15
- Last comment by Urs
- Last Active 4 days ago

- Discussion Type
- discussion topicJoe Moeller
- Category Latest Changes
- Started by nLab edit announcer
- Comments 8
- Last comment by Urs
- Last Active 4 days ago

- Discussion Type
- discussion topicGrothendieck construction for monoidal categories
- Category Latest Changes
- Started by nLab edit announcer
- Comments 2
- Last comment by Joe Moeller
- Last Active 4 days ago

- Discussion Type
- discussion topiclinear chord diagram
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active 5 days ago

- Discussion Type
- discussion topiccommutative monoidal category
- Category Latest Changes
- Started by nLab edit announcer
- Comments 16
- Last comment by Joe Moeller
- Last Active 5 days ago

- Discussion Type
- discussion topichomotopy
- Category Latest Changes
- Started by nLab edit announcer
- Comments 1
- Last comment by nLab edit announcer
- Last Active 5 days ago

- Discussion Type
- discussion topicKate Ponto
- Category Latest Changes
- Started by Joe Moeller
- Comments 1
- Last comment by Joe Moeller
- Last Active 5 days ago

- Discussion Type
- discussion topictoo simple to be simple
- Category Latest Changes
- Started by Oscar_Cunningham
- Comments 37
- Last comment by TobyBartels
- Last Active 5 days ago

(Hi, I’m new)

I added some examples relating too simple to be simple to the idea of unbiased definitions. The point is that we often define things to be simple whenever they are not a non-trivial (co)product of two objects, and we can extend this definition to cover the “to simple to be simple case” by removing the word “two”. The trivial object is often the

*empty*(co)product. If we had been using an unbiased definition we would have automatically covered this case from the beginning.I also noticed that the page about the empty space referred to the naive definition of connectedness as being

“a space is connected if it cannot be partitioned into disjoint nonempty open subsets”

but this misses out the word “two” and so is accidentally giving the sophisticated definition! I’ve now corrected it to make it wrong (as it were).

- Discussion Type
- discussion topicsurreal number
- Category Latest Changes
- Started by Mike Shulman
- Comments 1
- Last comment by Mike Shulman
- Last Active 5 days ago

- Discussion Type
- discussion topicAbout
- Category Latest Changes
- Started by Andrew Stacey
- Comments 14
- Last comment by bdxbh
- Last Active 5 days ago

I've edited the About page a little. My initial intention was just to update the technical information but I ended up adding a load more, mainly to expand on the "lab book" view. Given that we've discussed this back-and-forth for quite some time, I felt it time someone started actually modifying the page itself. Of course, if you don't like what I've said then

**change it**!It

*is*a wiki, after all - even if it isn't an encyclopaedia.

- Discussion Type
- discussion topicweight systems on chord diagrams in physics
- Category Latest Changes
- Started by Urs
- Comments 4
- Last comment by Urs
- Last Active 5 days ago

- Discussion Type
- discussion topicLie algebra object
- Category Latest Changes
- Started by Urs
- Comments 2
- Last comment by Urs
- Last Active 5 days ago

am splitting this off from

*Lie algebra*, for ease of cross-linking.

- Discussion Type
- discussion topicThe Blind Spot
- Category Latest Changes
- Started by David_Corfield
- Comments 2
- Last comment by DavidRoberts
- Last Active 5 days ago

- Discussion Type
- discussion topicflavour anomaly
- Category Latest Changes
- Started by Urs
- Comments 97
- Last comment by Urs
- Last Active 5 days ago

- Discussion Type
- discussion topicfuzzy dark matter
- Category Latest Changes
- Started by Urs
- Comments 4
- Last comment by Urs
- Last Active 5 days ago

Added to the entry

*fuzzy dark matter*pointer to Lee 17 which appeared today on the preprint server. This is just a concise 2.5 page survey of all the available literature, but as such is very useful. For instance it points out this Nature-article:- Hsi-Yu Schive, Tzihong Chiueh, Tom Broadhurst,
*Cosmic structure as the quantum interference of a coherent dark wave*, Nature Physics 10, 496–499 (2014) (doi:10.1038/nphys2996)

which presents numerical simulation of the fuzzy dark matter model compared to experimental data.

- Hsi-Yu Schive, Tzihong Chiueh, Tom Broadhurst,

- Discussion Type
- discussion topicspectral triple
- Category Latest Changes
- Started by Urs
- Comments 16
- Last comment by Urs
- Last Active 5 days ago

created spectral triple, but so far a bit bizarre:

I give an unorthodox category-theoretic VAGUE definition, which I have reason to think is the

*right*oneand then I record an unusual reference on vonNeumann spectral triple (just because at MO somebody asked for this and I don't like to dig out a link just to throw it away after one reference use like a paper napkin )

- Discussion Type
- discussion topicAlbert algebra
- Category Latest Changes
- Started by Urs
- Comments 5
- Last comment by Urs
- Last Active 5 days ago

I have spelled out the proof (here) of the claim from

- Michel Dubois-Violette, Ivan Todorov,
*Exceptional quantum geometry and particle physics II*(arXiv:1808.08110)

that the stabilizer in the automorphism group $F_4$ of the octonionic Albert algebra “of a 4d Minkowski subspace” happens to be the

*exact*gauge group of the standard model of particle physics.- Michel Dubois-Violette, Ivan Todorov,

- Discussion Type
- discussion topicFeynman category
- Category Latest Changes
- Started by zskoda
- Comments 11
- Last comment by Mike Shulman
- Last Active 5 days ago

The definition and the annotated bibliography are given for Feynman category.

I wonder how useful this could be in related to elucidate the cohomological and motivic quantization via correspondences (Kan extensions in the setup of Feynman categories can help getting the pushforwards, Connes-Kreimer Hopf algebra, Feynman transform (which in some cases gives coefficients in the formal development of the Feynman integal, basically being partition functions, hence connection to graphs).

- Discussion Type
- discussion topicSakura Schäfer-Nameki
- Category Latest Changes
- Started by Urs
- Comments 4
- Last comment by Todd_Trimble
- Last Active 5 days ago

- Discussion Type
- discussion topicconvergence space
- Category Latest Changes
- Started by nLab edit announcer
- Comments 3
- Last comment by Todd_Trimble
- Last Active 5 days ago

- Discussion Type
- discussion topicsingle trace operator
- Category Latest Changes
- Started by Urs
- Comments 10
- Last comment by David_Corfield
- Last Active 5 days ago