HTTP/2 301 server: nginx date: Tue, 30 Dec 2025 10:27:52 GMT content-type: application/rss+xml; charset=UTF-8 location: https://lamington.wordpress.com/comments/feed/ x-hacker: Want root? Visit join.a8c.com/hacker and mention this header. host-header: WordPress.com vary: accept, content-type, cookie last-modified: Tue, 30 Dec 2025 10:27:52 GMT etag: "1a7cb4ac7abcbc47d3b5f3f8ac666413" x-redirect-by: WordPress x-ac: 3.bom _dca MISS alt-svc: h3=":443"; ma=86400 strict-transport-security: max-age=31536000 server-timing: a8c-cdn, dc;desc=bom, cache;desc=MISS;dur=340.0 HTTP/2 200 server: nginx date: Tue, 30 Dec 2025 10:27:52 GMT content-type: application/rss+xml; charset=UTF-8 vary: Accept-Encoding x-hacker: Want root? Visit join.a8c.com/hacker and mention this header. host-header: WordPress.com vary: accept, content-type, cookie last-modified: Tue, 30 Dec 2025 10:27:52 GMT etag: W/"1a7cb4ac7abcbc47d3b5f3f8ac666413" content-encoding: gzip x-ac: 1.bom _dca MISS alt-svc: h3=":443"; ma=86400 strict-transport-security: max-age=31536000 server-timing: a8c-cdn, dc;desc=bom, cache;desc=MISS;dur=348.0 https://lamington.wordpress.com Fri, 17 Oct 2025 02:54:04 +0000 hourly 1 https://wordpress.com/ https://lamington.wordpress.com/2009/09/07/the-goldman-bracket/#comment-31216 Fri, 17 Oct 2025 02:54:04 +0000 https://lamington.wordpress.com/?p=550#comment-31216 From the recent article, the Goldman bracket appears to be interpretable as the commutation relations in the Drinfeld–Jimbo quantum group: 

https://link.springer.com/article/10.1007/s00220-025-05456-6

]]> https://lamington.wordpress.com/2012/10/17/upper-curvature-bounds-and-catk/#comment-31215 Mon, 17 Mar 2025 16:56:29 +0000 https://lamington.wordpress.com/?p=1746#comment-31215 Great bloog post

]]> https://lamington.wordpress.com/2010/04/08/hyperbolic-geometry-157b-notes-1/#comment-31214 Sun, 08 Sep 2024 23:22:42 +0000 https://lamington.wordpress.com/?p=1160#comment-31214 This is a great posst

]]> https://lamington.wordpress.com/2017/04/08/bings-wild-involution/#comment-31054 Mon, 20 Feb 2023 03:29:41 +0000 https://lamington.wordpress.com/?p=2543#comment-31054 great blog
really informative and educative

]]> https://lamington.wordpress.com/2009/06/22/big-mapping-class-groups-and-dynamics/#comment-30606 Fri, 08 Apr 2022 15:24:34 +0000 https://lamington.wordpress.com/?p=263#comment-30606 […] (3) uniformly perfect groups (since they have trivial scl), which holds for many transformation groups, typically because of the suspension trick. This includes for example mathrm{Homeo}^+(S^1) (Section 2.3) and the mapping class group of the sphere minus a Cantor set (see this blog post) […]

]]> https://lamington.wordpress.com/2016/02/04/stiefel-whitney-cycles-as-intersections/#comment-30387 Tue, 06 Jul 2021 15:43:13 +0000 https://lamington.wordpress.com/?p=2516#comment-30387 (This was a comment from Dev Sinha.)

]]> https://lamington.wordpress.com/2016/02/04/stiefel-whitney-cycles-as-intersections/#comment-30386 Tue, 06 Jul 2021 15:42:34 +0000 https://lamington.wordpress.com/?p=2516#comment-30386 I think that the Chern case is essentially the top of Quillen’s paper “Elementary Proofs of Some Results of Cobordism Theory Using Steenrod Operations”. It seems needs cobordism to have a sharp connection between operations and Chern classes, but Quillen’s approach is geometric.

]]> https://lamington.wordpress.com/2017/04/08/bings-wild-involution/#comment-30069 Thu, 01 Oct 2020 06:06:11 +0000 https://lamington.wordpress.com/?p=2543#comment-30069 Geometry and the imagination: SRT spacetime (4D)
Minkowski Light cone and an antique sand watch ( hourglass )
—–
Minkowski explained the spacetime by using the ”Light cone” scheme.
   Minkowski light cone
”Light cone in 2D space plus a time dimension.. . , .
A light cone is the path that a flash of light, . . . through spacetime”
(light travel from an enormous  past light cone through a place
of the very tiny present to an enormous future light cone)
      / look the scheme /
https://en.wikipedia.org/wiki/Light_cone
#
Antique  sand watch ( hourglass )
Sand in hourglass flows from the upper vessel (place of a past)
 through very tiny hole (place of the short present life) to the lower vessel
( place of the future )    / look the picture /
#
We can turn over the hourglass and the time will flow vice versa.
Similar: . . .  the light in an absolute Minkowski  spacetime can travel
 backward in time, according to ”The law of conservation and
 transformation of energy-mass”  and  the entropy principle.
#
The Minkowski scheme of Light cone has three systems
of coordinate: past, present, future . . . for light traveling
with constant speed the time is ”frozen” . . . the present
state is the border between past and future . . . light takes
 an important place in the present system . . . .
(from photosynthesis . . . to atoms, cells, living creatures  . . .)
To go from past to future Light must change its parameters
in the present system according to ”The law of conservation
and transformation of energy-mass”. The concrete changes
of quantum of light in the present time were described
  by the ”Lorentz laws of transformation”
————-
Practically Minkowski ”cone” is a flat, homogeneous, isotropic.
Mathematically Minkowski ”cone” is an abstract construction.
 Practically, according to the WMAP (2013 measurement) the
 Cosmic Space is ”pretty flat” to within 0,4% – 0,5%
#
  Minkowski’s  kamuflage.
The ”time” in Einstein’s SRT was negative.
Minkoski saw that mathematically it is ”ugly” and he
changed negative time into positive time by the beautiful
mathematical construction ”an absolute spacetime-4D. 
 Minkowski did not create a new theory, he only masked the negative
 time problem, he only masked the reference frame for ”spacetime”.
Where can we see the negative time and spacetime in nature?
 The unity of space and time we can see in the cold cosmic vacuum.
The structure of the cold cosmic vacuum doesn’t have ”time”
My conclusion:
 Einstein’s SRT (1905) has only one absolute reference frame.
This absolute reference frame. is a cold , flat, homogeneous,
 isotropic cosmic vacuum.
All other reference frames are relative systems.
——–
Best wishes
Israel Sadovnik Socratus
=================
  P.S.
”You cannot be a physicist, if you don’t understand
the beauty of the Minkowski mathematical construction.”
    / a professor to the students /
======================

]]> https://lamington.wordpress.com/2010/04/10/hyperbolic-geometry-notes-2-triangles-and-gauss-bonnet/#comment-29792 Wed, 19 Feb 2020 22:28:36 +0000 https://lamington.wordpress.com/?p=1179#comment-29792 Reblogged this on hegelianblog.

]]> https://lamington.wordpress.com/2014/08/22/groups-quasi-isometric-to-planes/#comment-29780 Mon, 30 Dec 2019 10:01:44 +0000 https://lamington.wordpress.com/?p=2244#comment-29780 Hi Danny, Thanks for the wonderful note.
By the way, the link doesn’t work.

]]> https://lamington.wordpress.com/2011/10/22/zonohedra-and-the-sylvester-gallai-theorem/#comment-29756 Tue, 29 Oct 2019 18:29:06 +0000 https://lamington.wordpress.com/?p=1258#comment-29756 thanks

]]> https://lamington.wordpress.com/2013/10/18/scharlemann-on-schoenflies/#comment-29613 Tue, 09 Jul 2019 19:52:05 +0000 https://lamington.wordpress.com/?p=2044#comment-29613 In reply to Ian Agol.

Actually all you need for the last bit of your argument is that Diff^+(S^3) is path connected which Cerf proved in Springer Lecture Notes 53 in 1968.

]]> https://lamington.wordpress.com/2009/09/23/how-to-see-the-genus/#comment-12411 Fri, 19 Oct 2018 23:55:53 +0000 https://lamington.wordpress.com/?p=646#comment-12411 In reply to Adam Wood.

See Khovanskii, A. G., “Newton polyhedra and the genus of complete intersections.” Functional
Analysis and Its Applications 12, no. 1 (1978): 38–46.

]]> https://lamington.wordpress.com/2009/09/23/how-to-see-the-genus/#comment-12410 Fri, 19 Oct 2018 23:23:11 +0000 https://lamington.wordpress.com/?p=646#comment-12410 Do you have a reference for the following two statements in the second paragraph?

1. The number of interior points of the Newton polygon is the genus of the surface.

2. One can find a basis for the holomorphic 1-forms using the Newton polygon.

]]> https://lamington.wordpress.com/2009/06/16/measure-theory-topology-and-the-role-of-examples/#comment-12286 Sat, 08 Sep 2018 19:01:29 +0000 https://lamington.wordpress.com/?p=218#comment-12286 […] are irrelevant in topology. A discussion on the difference between measure theory and topology: https://lamington.wordpress.com/2009/06/16/measure-theory-topology-and-the-role-of-examples/ And an old thread here about it: […]

]]> https://lamington.wordpress.com/2012/08/07/circle-packing-theory-and-practice/#comment-12238 Sun, 05 Aug 2018 15:51:01 +0000 https://lamington.wordpress.com/?p=1672#comment-12238 Hi this is nice work,
I tried your algorithm for some simple examples, but it gave no out output, meaning it didn’t stop. Does it work only only for hexgonal circle configurations?

For example the following vertices-edge file produces no result:
21
4 1 2 3 4
7 0 3 4 5 6 7 8
7 0 3 4 17 18 19 20
7 0 1 2 5 9 13 17
7 0 1 2 8 12 16 20
4 1 3 6 9
4 1 5 7 10
4 1 6 8 11
4 1 4 7 12
4 3 5 10 13
4 6 9 11 14
4 7 10 12 15
4 4 8 11 16
4 3 9 14 17
4 10 13 15 18
4 11 14 16 19
4 4 12 15 20
4 2 3 13 18
4 2 14 17 19
4 2 15 18 20
4 2 4 16 19

]]> https://lamington.wordpress.com/2009/08/25/second-variation-formula-for-minimal-surfaces/#comment-10304 Fri, 27 Apr 2018 13:22:26 +0000 https://lamington.wordpress.com/?p=528#comment-10304 Perhaps it is a silly question. I want to understand how the area of a minimal surface changes as one changes the ambient metric. Mpre precisely, is there a way of formulating that change in area in terms of the expression for the second variation using a suitable function $f$ related to the perturbation of the metric $\delta g$.

Best :)

]]> https://lamington.wordpress.com/2009/09/23/how-to-see-the-genus/#comment-10038 Sat, 07 Apr 2018 04:22:02 +0000 https://lamington.wordpress.com/?p=646#comment-10038 Next time I read a blog, I hope that it does not disappoint me just as much as this one. I mean, Yes, it was my choice to read, but I genuinely believed you would probably have something interesting to talk about. All I hear is a bunch of crying about something you could fix if you were not too busy searching for attention.

]]> https://lamington.wordpress.com/2012/03/26/agols-virtual-haken-theorem-2/#comment-9403 Sat, 17 Feb 2018 11:56:16 +0000 https://lamington.wordpress.com/?p=1581#comment-9403 sure there exist an important relation of involution as say prof dr mircea orasanu and prof horia orasanu

]]> https://lamington.wordpress.com/2017/04/08/bings-wild-involution/#comment-9402 Sat, 17 Feb 2018 04:27:11 +0000 https://lamington.wordpress.com/?p=2543#comment-9402 here must most as say prof dr mircea orasanu

]]>