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This is the construction page for my paper Expansions and Quadraticity for Groups (PDF here).

Abstract. First year students learn that the Taylor expansion $Z_T$ carries functions into power series, and that it has some nice algebraic properties (e.g. multiplicativity, $Z_T(fg)=Z_T(f)Z_T(g)$). It is less well known that the same game can be played within arbitrary groups: there is a natural way to say "a Taylor expansion $Z$ for elements of an arbitrary group $G$", and a natural way to carry the algebraic properties of the Taylor expansion to this more general context. In the case of a general $G$ "Taylor expansions" (expansions with the same good properties as $Z_T$) may or may not exist, may or may not be unique, may or may not separate group elements, and a further good property which is hidden in the case of $Z_T$, "quadraticity", may or may not hold.

The purpose of this expository note is to properly define all the notions in the above paragraph, to enumerate some classes of groups whose theory of expansions we either understand or wish to understand, to indicate the relationship between these notions and the notions of "finite type invariants" and "unipotent" and "Mal'cev" completions, and to point out (with references) that our generalization of "expansions" to arbitrary groups is merely the tip of an iceberg, for almost everything we say can be generalized further to "expansions for arbitrary algebraic structures".

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 PageCreated (UT)Last Modified (UT)
1 The co-product on A(G) 2015-01-05 19:54:42 2015-01-07 14:47:02
2 --- Double Filtrations 2015-01-07 15:11:08 2015-01-07 15:23:07
3 Gr(PBn) from generators and relations 2015-01-25 19:27:57 2015-01-25 19:43:38
4 Random 2015-02-02 16:23:44 2015-02-02 16:26:16
5 Products and Semi-Direct Products 2015-04-17 16:38:28 2015-04-17 22:45:26
6 Quillen's Theorem 2015-05-08 18:28:24 2015-08-12 17:31:11
7 --- Quillen's theorem - degree 2 testing 2015-08-12 16:42:32 2015-08-17 14:02:42
8 --- Quillen's theorem - degree 2 testing, 2 2015-08-12 16:42:32 2015-08-17 14:40:43
9 The LCS expansion 2015-06-22 15:34:51 2015-08-12 13:59:39
10 scratch 150902 2015-09-02 16:00:31 2015-09-02 16:27:21
11 Scratch 150907 2015-09-07 15:58:20 2015-09-07 16:19:15
12 Degree by degree constructions 2015-10-14 13:36:38 2015-10-14 14:06:31
(.one source file for all pages above)

<< Mathematica Notebooks >>

 Notebook (.pdf)Source (.nb)CreatedLast ModifiedSummary
1 index source 2015-12-17 19:18:14 2016-02-05 09:34:32  
2 ProgressiveScanning source 2016-05-12 17:26:53 2016-05-12 17:53:14  

<< Links >>

  1. Studied 2015-02-01 11:36:58: Groupprops.
  2. Studied 2015-02-01 11:57:24: braid groups - Almost-direct product and 1-formality - MathOverflow.
  3. Studied 2015-02-01 12:13:57: Goetz-Conner_Talk.
  4. Studied 2015-02-23 14:12:24: [0705.4201v1] Bardakov, Bellingeri- On residual properties of pure braid groups of closed surfaces.
  5. Studied 2015-02-23 14:13:38: [math0512155v2] Bellingeri, Garvais, Guaschi- Lower central series for surface braid groups.
  6. Studied 2015-02-23 14:16:25: [1001.4471v2] Bellingeri, Gervais- Surface framed braids.
  7. Studied 2015-02-23 17:25:55: [1302.6536] Guaschi, Pineda- A survey of surface braid groups and the lower algebraic K-theory of their group rings.
  8. Studied 2015-10-09 10:52:14: Expositiones Mathematicae - Journal - Elsevier.
  9. Studied 2016-04-10 12:27:39: hopf algebras - The augmentation filtration on a group ring - MathOverflow.
  10. Studied 2016-05-18 16:25:28: The LaTeX Font Catalogue - Augie.
  11. Studied 2017-07-02 21:01:56: [1703.03448] Margalit, Winarski- The Birman-Hilden theory.

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DoubleFiltrations_1.jpg

DoubleFiltrations_2.jpg

DoubleFiltrations_3.jpg

DoubleFiltrations_4.jpg

DoubleFiltrations_5.jpg

SemiDirectProducts_1.jpg

WithMassuyeau-151110.jpg

WordCloud.png

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[0705.4201v1] Bardakov, Bellingeri- On residual properties of pure braid groups of closed surfaces.URL   [1001.4471v2] Bellingeri, Gervais- Surface framed braids.URL   [1302.6536] Guaschi, Pineda- A survey of surface braid groups and the lower algebraic K-theory of their group rings.URL   [1703.03448] Margalit, Winarski- The Birman-Hilden theory.URL   abstract.sed   abstract.tex   abstract.txt   beyond.tex   braid groups - Almost-direct product and 1-formality - MathOverflow.URL   dbd.tex   dbnsymb.56pk   dbnsymb.600pk   dbnsymb.mf   dbnsymb.sty   dbnsymb.tfm   defs.tex   DoubleFiltrations_1.jpg   DoubleFiltrations_2.jpg   DoubleFiltrations_3.jpg   DoubleFiltrations_4.jpg   DoubleFiltrations_5.jpg   Expositiones Mathematicae - Journal - Elsevier.URL   ExQu3up.pdf   ExQu.aux   ExQu.brf   ExQu.pdf   ExQuTagged.aux   ExQuTagged.brf   ExQuTagged.pdf   ExQu.tex   Goetz-Conner_Talk.URL   Groupprops.URL   harder.tex   HelpNeeded-1602.aux   HelpNeeded-1602.pdf   HelpNeeded-1602.tex   hopf algebras - The augmentation filtration on a group ring - MathOverflow.URL   index.html   index.m   index.nb   macros.tex   main.tex   makefile   [math0512155v2] Bellingeri, Garvais, Guaschi- Lower central series for surface braid groups.URL   new_aux   old_aux   picins.sty   ProgressiveScanning.nb   recycling.tex   recycling.txt   refs.tex   SemiDirectProducts_1.jpg   soft.tex   specific.tex   table.tex   The LaTeX Font Catalogue - Augie.URL   ToDo.tex   WithMassuyeau-151110.jpg   WordCloud.png