Regensburg low-dimensional geometry and topology seminar - Revision history

Brv60445 at 10:19, 12 December 2023

2023-12-12T10:19:25Z

← Older revision		Revision as of 11:19, 12 December 2023
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	\|- style="vertical-align:top;"		\|- style="vertical-align:top;"
	\| style="width:120px;" \| April 27		\| style="width:120px;" \| April 27
	\| style="width:300px;" \| ~~[https://www.maths.ox.ac.uk/people/guillem.cazassus~~ Guillem Cazassus] (Oxford)		\| style="width:300px;" \| Guillem Cazassus (Oxford)
	\| style="width:400px;" \| The earring correspondence of the pillowcase		\| style="width:400px;" \| The earring correspondence of the pillowcase
	[https://mediathek2.uni-regensburg.de/playthis/6088610d13d905.94167507 Video] [[Media:SS21-01-Cazassus.pdf\| <b>Slides<b>]]		[https://mediathek2.uni-regensburg.de/playthis/6088610d13d905.94167507 Video] [[Media:SS21-01-Cazassus.pdf\| <b>Slides<b>]]
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	\|- style="vertical-align:top;"		\|- style="vertical-align:top;"
	\| May 18		\| May 18
	\| ~~[https://math.virginia.edu/people/ra5aq/~~ Rostislav Akhmechet] (Virginia)		\| Rostislav Akhmechet (Virginia)
	\| Anchored foams and annular homology		\| Anchored foams and annular homology
	[https://mediathek2.uni-regensburg.de/playthis/60a4b821c1f1a5.35673801 Video] [[Media:SS21-04-Akhmechet.pdf\| <b>Slides<b>]]		[https://mediathek2.uni-regensburg.de/playthis/60a4b821c1f1a5.35673801 Video] [[Media:SS21-04-Akhmechet.pdf\| <b>Slides<b>]]
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	\| June 8		\| June 8
	\| ~~[https://cns.utexas.edu/directory/item/353-gordon-cameron-m?Itemid=349~~ Cameron Gordon] (UT Austin)		\| Cameron Gordon (UT Austin)
	\| Toroidal 3-manifolds and the properties in the L-space Conjecture		\| Toroidal 3-manifolds and the properties in the L-space Conjecture
	[https://mediathek2.uni-regensburg.de/playthis/60c21183e28952.80232532 Video] [[Media:SS21-06-Gordon.pdf\| <b>Slides<b>]]		[https://mediathek2.uni-regensburg.de/playthis/60c21183e28952.80232532 Video] [[Media:SS21-06-Gordon.pdf\| <b>Slides<b>]]
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	\|- style="vertical-align:top;"		\|- style="vertical-align:top;"
	\| <b>Monday</b> July 5 (note date change)		\| <b>Monday</b> July 5 (note date change)
	\| ~~[https://www.math.princeton.edu/people/jonathan-zung~~ Jonathan Zung] (Princeton)		\| Jonathan Zung (Princeton)
	\| Reeb flows transverse to foliations		\| Reeb flows transverse to foliations
	[https://mediathek2.uni-regensburg.de/playthis/60e355b66a0410.09286145 Video]		[https://mediathek2.uni-regensburg.de/playthis/60e355b66a0410.09286145 Video]
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	[https://sites.google.com/view/jpbowden/ Jonathan Bowden,]		[https://sites.google.com/view/jpbowden/ Jonathan Bowden,]
	[http://lewark.de/lukas/ Lukas Lewark],		[http://lewark.de/lukas/ Lukas Lewark],
	~~[http://www.mathematik.uni-regensburg.de/zentner/~~ Raphael Zentner].		<b>Raphael Zentner</b>.

Brv60445 at 08:28, 6 December 2023

2023-12-06T08:28:32Z

← Older revision		Revision as of 09:28, 6 December 2023
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	\| style="width:300px;" \| [https://www.maths.ox.ac.uk/people/guillem.cazassus Guillem Cazassus] (Oxford)		\| style="width:300px;" \| [https://www.maths.ox.ac.uk/people/guillem.cazassus Guillem Cazassus] (Oxford)
	\| style="width:400px;" \| The earring correspondence of the pillowcase		\| style="width:400px;" \| The earring correspondence of the pillowcase
	[https://mediathek2.uni-regensburg.de/playthis/6088610d13d905.94167507 Video]		[https://mediathek2.uni-regensburg.de/playthis/6088610d13d905.94167507 Video] [[Media:SS21-01-Cazassus.pdf\| <b>Slides<b>]]
	\| style="width:600px;" \| Singular instanton homology is a knot invariant introduced by Kronheimer and Mrowka. It is deeply tied to Khovanov homology, and among other things, permits to show that the latter detects the unknot.		\| style="width:600px;" \| Singular instanton homology is a knot invariant introduced by Kronheimer and Mrowka. It is deeply tied to Khovanov homology, and among other things, permits to show that the latter detects the unknot.

Brv60445 at 10:17, 29 November 2023

2023-11-29T10:17:02Z

← Older revision		Revision as of 11:17, 29 November 2023
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	\| style="width:120px;" \| April 27		\| style="width:120px;" \| April 27
	\| style="width:300px;" \| [https://www.maths.ox.ac.uk/people/guillem.cazassus Guillem Cazassus] (Oxford)		\| style="width:300px;" \| [https://www.maths.ox.ac.uk/people/guillem.cazassus Guillem Cazassus] (Oxford)
	\| style="width:400px;" \| The earring correspondence of the pillowcase [https://mediathek2.uni-regensburg.de/playthis/6088610d13d905.94167507 Video]		\| style="width:400px;" \| The earring correspondence of the pillowcase
			[https://mediathek2.uni-regensburg.de/playthis/6088610d13d905.94167507 Video]
	\| style="width:600px;" \| Singular instanton homology is a knot invariant introduced by Kronheimer and Mrowka. It is deeply tied to Khovanov homology, and among other things, permits to show that the latter detects the unknot.		\| style="width:600px;" \| Singular instanton homology is a knot invariant introduced by Kronheimer and Mrowka. It is deeply tied to Khovanov homology, and among other things, permits to show that the latter detects the unknot.

Brv60445 at 10:16, 29 November 2023

2023-11-29T10:16:44Z

← Older revision		Revision as of 11:16, 29 November 2023
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	\| style="width:120px;" \| April 27		\| style="width:120px;" \| April 27
	\| style="width:300px;" \| [https://www.maths.ox.ac.uk/people/guillem.cazassus Guillem Cazassus] (Oxford)		\| style="width:300px;" \| [https://www.maths.ox.ac.uk/people/guillem.cazassus Guillem Cazassus] (Oxford)
	\| style="width:400px;" \| The earring correspondence of the pillowcase[https://mediathek2.uni-regensburg.de/playthis/6088610d13d905.94167507 Video]		\| style="width:400px;" \| The earring correspondence of the pillowcase [https://mediathek2.uni-regensburg.de/playthis/6088610d13d905.94167507 Video]
	\| style="width:600px;" \| Singular instanton homology is a knot invariant introduced by Kronheimer and Mrowka. It is deeply tied to Khovanov homology, and among other things, permits to show that the latter detects the unknot.		\| style="width:600px;" \| Singular instanton homology is a knot invariant introduced by Kronheimer and Mrowka. It is deeply tied to Khovanov homology, and among other things, permits to show that the latter detects the unknot.

Brv60445 at 10:16, 29 November 2023

2023-11-29T10:16:00Z

← Older revision		Revision as of 11:16, 29 November 2023
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	\| [https://web.math.princeton.edu/~szabo/ Zoltán Szabó] (Princeton)		\| [https://web.math.princeton.edu/~szabo/ Zoltán Szabó] (Princeton)
	\| Knot Floer homology constructions and the Pong Algebra		\| Knot Floer homology constructions and the Pong Algebra
	[https://mediathek2.uni-regensburg.de/playthis/6092843f3ac1f2.55974595 Video]		[https://mediathek2.uni-regensburg.de/playthis/6092843f3ac1f2.55974595 Video] [[Media:SS21-02-Szabo.pdf\| <b>Slides<b>]]
	\| In a joint work with Peter Ozsvath we have developed algebraic invariants for knots using a family of bordered knot algebras. The goal of this lecture is to review these constructions and discuss some of the latest developments		\| In a joint work with Peter Ozsvath we have developed algebraic invariants for knots using a family of bordered knot algebras. The goal of this lecture is to review these constructions and discuss some of the latest developments
	\|- style="vertical-align:top;"		\|- style="vertical-align:top;"

Brv60445 at 10:14, 29 November 2023

2023-11-29T10:14:13Z

← Older revision		Revision as of 11:14, 29 November 2023
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	\| [https://sites.google.com/bc.edu/john-baldwin/home John Baldwin] (Boston College)		\| [https://sites.google.com/bc.edu/john-baldwin/home John Baldwin] (Boston College)
	\| Instanton L-spaces and splicing		\| Instanton L-spaces and splicing
	[https://mediathek2.uni-regensburg.de/playthis/609b80d9ef1517.27795704 Video]		[https://mediathek2.uni-regensburg.de/playthis/609b80d9ef1517.27795704 Video] [[Media:SS21-03-Baldwin.pdf\| <b>Slides<b>]]
	\| We prove that the 3-manifold obtained by gluing the complements of two nontrivial knots in homology 3-sphere instanton L-spaces, by a map which identifies meridians with Seifert longitudes, cannot be an instanton L-space. This recovers the recent theorem of Lidman–Pinzon-Caicedo–Zentner that the fundamental group of every closed, oriented, toroidal 3-manifold admits a nontrivial SU(2)-representation, and consequently Zentner’s earlier result that the fundamental group of every closed, oriented 3-manifold besides the 3-sphere admits a nontrivial SL(2, C)-representation. This is joint work with Steven Sivek.		\| We prove that the 3-manifold obtained by gluing the complements of two nontrivial knots in homology 3-sphere instanton L-spaces, by a map which identifies meridians with Seifert longitudes, cannot be an instanton L-space. This recovers the recent theorem of Lidman–Pinzon-Caicedo–Zentner that the fundamental group of every closed, oriented, toroidal 3-manifold admits a nontrivial SU(2)-representation, and consequently Zentner’s earlier result that the fundamental group of every closed, oriented 3-manifold besides the 3-sphere admits a nontrivial SL(2, C)-representation. This is joint work with Steven Sivek.
	\|- style="vertical-align:top;"		\|- style="vertical-align:top;"

Brv60445 at 10:00, 29 November 2023

2023-11-29T10:00:30Z

← Older revision		Revision as of 11:00, 29 November 2023
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	\|[https://people.mpim-bonn.mpg.de/aruray/ Arunima Ray] (MPIM Bonn)		\|[https://people.mpim-bonn.mpg.de/aruray/ Arunima Ray] (MPIM Bonn)
	\| A surface embedding theorem		\| A surface embedding theorem
	[https://mediathek2.uni-regensburg.de/playthis/60b73387b2e8b4.23924882 Video] [[Media:SS21-06-Ray.pdf\| <b>Slides<b>]]		[https://mediathek2.uni-regensburg.de/playthis/60b73387b2e8b4.23924882 Video] [[Media:SS21-05-Ray.pdf\| <b>Slides<b>]]
	\| Generalising work of Freedman-Quinn and Stong from 30-40 years ago, we prove a surface embedding theorem for 4-manifolds with good fundamental group, in the presence of potentially unframed dual spheres. The essential obstruction is the Kervaire-Milnor invariant, and I will describe how to compute it and present some useful corollaries of the theorem. The goal of the talk is to be reasonably self-contained, and no prior expert knowledge of 4-manifold topology should be required. This is joint work with Daniel Kasprowski, Mark Powell, and Peter Teichner.		\| Generalising work of Freedman-Quinn and Stong from 30-40 years ago, we prove a surface embedding theorem for 4-manifolds with good fundamental group, in the presence of potentially unframed dual spheres. The essential obstruction is the Kervaire-Milnor invariant, and I will describe how to compute it and present some useful corollaries of the theorem. The goal of the talk is to be reasonably self-contained, and no prior expert knowledge of 4-manifold topology should be required. This is joint work with Daniel Kasprowski, Mark Powell, and Peter Teichner.
	\|- style="vertical-align:top;"		\|- style="vertical-align:top;"

Brv60445 at 10:00, 29 November 2023

2023-11-29T10:00:00Z

← Older revision		Revision as of 11:00, 29 November 2023
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	\| [https://cns.utexas.edu/directory/item/353-gordon-cameron-m?Itemid=349 Cameron Gordon] (UT Austin)		\| [https://cns.utexas.edu/directory/item/353-gordon-cameron-m?Itemid=349 Cameron Gordon] (UT Austin)
	\| Toroidal 3-manifolds and the properties in the L-space Conjecture		\| Toroidal 3-manifolds and the properties in the L-space Conjecture
	[https://mediathek2.uni-regensburg.de/playthis/60c21183e28952.80232532 Video]		[https://mediathek2.uni-regensburg.de/playthis/60c21183e28952.80232532 Video] [[Media:SS21-06-Gordon.pdf\| <b>Slides<b>]]
	\| The L-space Conjecture asserts the equivalence, for prime 3-manifolds, of three properties: not being an L-space (NLS), having left-orderable fundamental group (LO), and supporting a co-orientable taut foliation (CTF). We study these properties for toroidal 3-manifolds. For example, Eftekhary and Hanselman-Rasmussen-Watson have shown that toroidal homology spheres are NLS; we show that they are LO. We also show that the cyclic branched covers of a prime satellite knot are NLS and LO, and CTF if the companion is fibered. A partial extension to links allows us to show that a prime quasi-alternating link is either a (2,q) torus link or hyperbolic, generalizing Menasco's classical result for non-split alternating links. This is joint work with Steve Boyer and Ying Hu.		\| The L-space Conjecture asserts the equivalence, for prime 3-manifolds, of three properties: not being an L-space (NLS), having left-orderable fundamental group (LO), and supporting a co-orientable taut foliation (CTF). We study these properties for toroidal 3-manifolds. For example, Eftekhary and Hanselman-Rasmussen-Watson have shown that toroidal homology spheres are NLS; we show that they are LO. We also show that the cyclic branched covers of a prime satellite knot are NLS and LO, and CTF if the companion is fibered. A partial extension to links allows us to show that a prime quasi-alternating link is either a (2,q) torus link or hyperbolic, generalizing Menasco's classical result for non-split alternating links. This is joint work with Steve Boyer and Ying Hu.
	\|- style="vertical-align:top;"		\|- style="vertical-align:top;"

Brv60445 at 09:58, 29 November 2023

2023-11-29T09:58:59Z

← Older revision		Revision as of 10:58, 29 November 2023
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	\|[https://people.mpim-bonn.mpg.de/aruray/ Arunima Ray] (MPIM Bonn)		\|[https://people.mpim-bonn.mpg.de/aruray/ Arunima Ray] (MPIM Bonn)
	\| A surface embedding theorem		\| A surface embedding theorem
	[https://mediathek2.uni-regensburg.de/playthis/60b73387b2e8b4.23924882 Video]		[https://mediathek2.uni-regensburg.de/playthis/60b73387b2e8b4.23924882 Video] [[Media:SS21-06-Ray.pdf\| <b>Slides<b>]]
	\| Generalising work of Freedman-Quinn and Stong from 30-40 years ago, we prove a surface embedding theorem for 4-manifolds with good fundamental group, in the presence of potentially unframed dual spheres. The essential obstruction is the Kervaire-Milnor invariant, and I will describe how to compute it and present some useful corollaries of the theorem. The goal of the talk is to be reasonably self-contained, and no prior expert knowledge of 4-manifold topology should be required. This is joint work with Daniel Kasprowski, Mark Powell, and Peter Teichner.		\| Generalising work of Freedman-Quinn and Stong from 30-40 years ago, we prove a surface embedding theorem for 4-manifolds with good fundamental group, in the presence of potentially unframed dual spheres. The essential obstruction is the Kervaire-Milnor invariant, and I will describe how to compute it and present some useful corollaries of the theorem. The goal of the talk is to be reasonably self-contained, and no prior expert knowledge of 4-manifold topology should be required. This is joint work with Daniel Kasprowski, Mark Powell, and Peter Teichner.
	\|- style="vertical-align:top;"		\|- style="vertical-align:top;"

Brv60445 at 09:56, 29 November 2023

2023-11-29T09:56:53Z

← Older revision		Revision as of 10:56, 29 November 2023
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	\| [https://math.virginia.edu/people/ra5aq/ Rostislav Akhmechet] (Virginia)		\| [https://math.virginia.edu/people/ra5aq/ Rostislav Akhmechet] (Virginia)
	\| Anchored foams and annular homology		\| Anchored foams and annular homology
	[https://mediathek2.uni-regensburg.de/playthis/60a4b821c1f1a5.35673801 Video]		[https://mediathek2.uni-regensburg.de/playthis/60a4b821c1f1a5.35673801 Video] [[Media:SS21-04-Akhmechet.pdf\| <b>Slides<b>]]
	\| We describe equivariant sl(2) and sl(3) homology for links in the solid torus, identified with the thickened annulus, via foam evaluation and universal construction. The solid torus is replaced by 3-space with a distinguished line in it. Generators of state spaces for annular webs are represented by foams that may intersect the distinguished line. Intersection points, called anchor points, contribute additional terms to the foam evaluation. State spaces and link homology carry additional gradings coming from anchor points. I will describe our evaluation formula and the resulting annular homology theories, as well as relations to other constructions. This is joint work with Mikhail Khovanov.		\| We describe equivariant sl(2) and sl(3) homology for links in the solid torus, identified with the thickened annulus, via foam evaluation and universal construction. The solid torus is replaced by 3-space with a distinguished line in it. Generators of state spaces for annular webs are represented by foams that may intersect the distinguished line. Intersection points, called anchor points, contribute additional terms to the foam evaluation. State spaces and link homology carry additional gradings coming from anchor points. I will describe our evaluation formula and the resulting annular homology theories, as well as relations to other constructions. This is joint work with Mikhail Khovanov.
	\|- style="vertical-align:top;"		\|- style="vertical-align:top;"

← Older revision		Revision as of 09:28, 6 December 2023
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	\| style="width:300px;" \| [https://www.maths.ox.ac.uk/people/guillem.cazassus Guillem Cazassus] (Oxford)		\| style="width:300px;" \| [https://www.maths.ox.ac.uk/people/guillem.cazassus Guillem Cazassus] (Oxford)
	\| style="width:400px;" \| The earring correspondence of the pillowcase		\| style="width:400px;" \| The earring correspondence of the pillowcase
	[https://mediathek2.uni-regensburg.de/playthis/6088610d13d905.94167507 Video]		[https://mediathek2.uni-regensburg.de/playthis/6088610d13d905.94167507 Video] [[Media:SS21-01-Cazassus.pdf\| <b>Slides<b>]]
	\| style="width:600px;" \| Singular instanton homology is a knot invariant introduced by Kronheimer and Mrowka. It is deeply tied to Khovanov homology, and among other things, permits to show that the latter detects the unknot.		\| style="width:600px;" \| Singular instanton homology is a knot invariant introduced by Kronheimer and Mrowka. It is deeply tied to Khovanov homology, and among other things, permits to show that the latter detects the unknot.

← Older revision		Revision as of 11:17, 29 November 2023
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	\| style="width:120px;" \| April 27		\| style="width:120px;" \| April 27
	\| style="width:300px;" \| [https://www.maths.ox.ac.uk/people/guillem.cazassus Guillem Cazassus] (Oxford)		\| style="width:300px;" \| [https://www.maths.ox.ac.uk/people/guillem.cazassus Guillem Cazassus] (Oxford)
	\| style="width:400px;" \| The earring correspondence of the pillowcase [https://mediathek2.uni-regensburg.de/playthis/6088610d13d905.94167507 Video]		\| style="width:400px;" \| The earring correspondence of the pillowcase
			[https://mediathek2.uni-regensburg.de/playthis/6088610d13d905.94167507 Video]
	\| style="width:600px;" \| Singular instanton homology is a knot invariant introduced by Kronheimer and Mrowka. It is deeply tied to Khovanov homology, and among other things, permits to show that the latter detects the unknot.		\| style="width:600px;" \| Singular instanton homology is a knot invariant introduced by Kronheimer and Mrowka. It is deeply tied to Khovanov homology, and among other things, permits to show that the latter detects the unknot.

← Older revision		Revision as of 11:16, 29 November 2023
Line 20:		Line 20:
	\| style="width:120px;" \| April 27		\| style="width:120px;" \| April 27
	\| style="width:300px;" \| [https://www.maths.ox.ac.uk/people/guillem.cazassus Guillem Cazassus] (Oxford)		\| style="width:300px;" \| [https://www.maths.ox.ac.uk/people/guillem.cazassus Guillem Cazassus] (Oxford)
	\| style="width:400px;" \| The earring correspondence of the pillowcase[https://mediathek2.uni-regensburg.de/playthis/6088610d13d905.94167507 Video]		\| style="width:400px;" \| The earring correspondence of the pillowcase [https://mediathek2.uni-regensburg.de/playthis/6088610d13d905.94167507 Video]
	\| style="width:600px;" \| Singular instanton homology is a knot invariant introduced by Kronheimer and Mrowka. It is deeply tied to Khovanov homology, and among other things, permits to show that the latter detects the unknot.		\| style="width:600px;" \| Singular instanton homology is a knot invariant introduced by Kronheimer and Mrowka. It is deeply tied to Khovanov homology, and among other things, permits to show that the latter detects the unknot.