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wClips-120321

Speaker: Zsuzsanna Dancso

width: 400 720 ogg/wClips-120321_400.ogg orig/wClips-120321.MOD

Videography by Karene Chu troubleshooting

Notes on wClips-120321: [edit, refresh]

Section 4 - Algebraic Structures.

[edit]

Announcements. small circle, UofT, LDT Blog (also here). Email Dror to join our mailing list!

Resources. How to use this site, Dror's notebook, blackboard shots.

The wClips

http://katlas.math.toronto.edu/drorbn/dbnvp/dbnvp.png

Date	Links
Jan 11, 2012	120111-1: Introduction. 120111-2: Section 2.1 - v-Braids.
Jan 18, 2012	120118-1: An introduction to this web site. 120118-2: Section 2.2 - w-Braids by generators and relations and as flying rings. 120118-3: Section 2.2 - w-Braids - other drawing conventions, "wens".
Jan 25, 2012	120125-1: Section 2.2.3 - basis conjugating automorphisms of $F_n$ . 120125-2: A very quick introduction to finite type invariants in the "u" case.
Feb 1, 2012	120201: Section 2.3 - finite type invariants of v- and w-braids, arrow diagrams, 6T, TC and 4T relations, expansions / universal finite type invariants.
Feb 8, 2012	120208: Review of u,v, and w braids and of Section 2.3.
Feb 15, 2012	120215: Section 2.5 - mostly compatibilities of $Z^w$ , also injectivity and uniqueness of $Z^w$ .
Feb 22, 2012	120222: Section 2.5.5, $\alpha:{\mathcal A}^u\to{\mathcal A}^v$ , and Section 3.1 (partially), the definition of v- and w-knots.
Feb 29, 2012	120229: Sections 3.1-3.4: v-Knots and w-Knots: Definitions, framings, finite type invariants, dimensions, and the expansion in the w case.
Mar 7, 2012	120307: Section 3.5: Jacobi diagrams and the bracket-rise theorem.
Mar 14, 2012	120314: Section 3.6 - the relation with Lie algebras.
Mar 21, 2012	120321: Section 4 - Algebraic Structures.
Mar 28, 2012	Out-of-sequence not-on-tape we watched the video of Talks: GWU-1203.
Apr 4, 2012	120404: Section 3.7 - The Alexander Theorem (statement).
Apr 18, 2012	120418: Aside on the Euler trick, the differential of $\exp$ , and the BCH formula.
Apr 25, 2012	120425: Section 3.8, a disorganized lecture towards the proof of the Alexander theorem.
May 2, 2012	120502: Section 4: Algebraic structures (review), circuit algebras, v- and w-tangles.
May 10, 2012	120510: Sections 5.1 and 5.2: tangles, their projectivization and its relationship with Alekseev-Torossian spaces.
May 23, 2012	120523: Section 5.2: Proof of the relationship with A-T spaces.
May 30, 2012	120530: Interpreting ${\mathcal A}^w(\uparrow_n)$ as a universal space of invariant tangential differential operators.
Group photo on January 11, 2012: DBN, ZD, Stephen Morgan, Lucy Zhang, Iva Halacheva, David Li-Bland, Sam Selmani, Oleg Chterental, Peter Lee.

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panel Managed by dbnvp: Tip: blackboard shots are taken when the discussion of their content has just ended. To see the beginning of the discussion on a certain blackboard, roll the video to the time of the preceeding blackboard.

0:00:00 [edit] Blackboard shots by Stephen Morgan.

0:03:41 [edit] "0-nary" operations (constants) are often called "nullary operation". --Drorbn 15:24, 25 March 2012 (EDT)

0:05:00 [add] Algebraic Structures.

0:07:54 [edit] "Objects" in our context are just "objects" in the literal sense of the word. Mathematically it is the same as saying "elements". They have nothing to do with "objects" in a category. --Drorbn 15:24, 25 March 2012 (EDT)

0:09:49 [add] Examples - groups and group homomorphisms.

0:10:50 [edit] See http://www.math.toronto.edu/zsuzsi/research/thesis/.

0:14:03 [add] Examples - Actions, Quandles, QTGs, fibered situations.

0:19:06 [add] The augmentation ideal.

0:22:35 [edit] "Addition" is never one of the operations in our structures - it is added later by allowing formal linear combinations of objects. I guess if you started with a structure that already has an addition operation - say, "connect sum" of knots - you'll have to rename it "original addition" so as to distinguish it from the "addition" we add later when we allow formal linear combinations.

When talking about powers of the augmentation ideal, we only use the original operations of our structure.

So in the example where the structure is a group $G$, its group-ring ${\mathbb Q}G$ is again a structure with just one binary operation (multiplication) plus an artificially-added auxiliary operation "addition" which does not participate in taking powers of the augmentation ideal.

An alternative to all that is to start with a structure whose ${\mathcal O}_\alpha$'s are linear spaces (or at least, ${\mathbb Z}$-modules) and all of whose operations are multi-linear. Here again "addition" will have a special role and will not participate in forming powers of the augmentation ideal. --Drorbn 15:46, 25 March 2012 (EDT)

0:28:45 [add] ${\mathcal I}^m$ and the projectivization.