This paper answers a basic question about the Birman exact sequence in the theory of mapping class groups. We prove that the Birman exact sequence does not admit a section over any subgroup contained in the Torelli group with finite index. A fortiori this proves that there is no section of the Birman exact sequence…
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We develop an analogue of the Birman exact sequence for the Torelli subgroup of Aut(F_n). This builds on earlier work of the authors who studied an analogue of the Birman exact sequence for the entire group Aut(F_n). These results play an important role in the authors' recent work on the second homology group of the To…
We study the Birman exact sequence for compact --manifolds, obtaining a complete picture of the relationship between the mapping class group of the manifold and the mapping class group of the submanifold obtained by deleting an interior point. This covers both orientable manifolds and non-orientable ones.
The Birman exact sequence describes the effect on the mapping class group of a surface with boundary of gluing discs to the boundary components. We construct an analogous exact sequence for the automorphism group of a free group. For the mapping class group, the kernel of the Birman exact sequence is a surface braid gr…
The paper studies mapping class groups of 3-manifolds fibered over surfaces.
problem Understanding the structure of mapping class groups of 3-manifolds.
method Examines an exact sequence involving the mapping class groups and relates it to the Birman exact sequence.
result Determines conditions under which the exact sequence splits.
Study of orbifold mapping class groups via arc and curve actions.
problem Understanding the structure of orbifold mapping class groups.
method Defined orbifold mapping class groups and studied their actions on arcs and curves. Established a Birman exact sequence and derived finite presentations.
result Finite presentations of orbifold mapping class groups established.
Point-pushing in 3-manifoldsmath.GT
We study the Birman exact sequence for compact 3-manifolds.
Study of Torelli subgroups of automorphism groups of free groups.
problem Understanding the structure of Torelli subgroups of Out().
method Adapting techniques from 3-manifolds and surface mapping class groups.
result These groups are finitely generated and satisfy a Birman exact sequence.
Pseudo-Anosov subgroups in surface bundles over tori are convex cocompact.
problem Understanding the structure of pseudo-Anosov subgroups in surface bundles over tori.
method Using the Birman exact sequence to show convex cocompactness.
result Finitely generated, purely pseudo-Anosov subgroups are convex cocompact in surface bundles over tori.
Study shows certain subgroups of fibered 3-manifolds are convex cocompact.
problem Understanding subgroups of fibered 3-manifolds in mapping class groups.
method Used the Birman exact sequence to show convex cocompactness.
result Finitely generated pseudo-Anosov subgroups are convex cocompact.
This paper provides an infinite presentation for a subgroup of mapping class groups of non-orientable surfaces.
problem Finite presentations for mapping class groups of non-orientable surfaces.
method Using Stukow's finite presentation and Birman exact sequences.
result An infinite presentation for the twist subgroup of the mapping class group of a compact non-orientable surface.
The hyperelliptic Torelli group is the subgroup of the mapping class group consisting of elements that act trivially on the homology of the surface and that also commute with some fixed hyperelliptic involution. We prove a Birman exact sequence for hyperelliptic Torelli groups, and we show that this sequence splits. As…
Study the relationship between orbit braid group and equivariant mapping class group on surfaces.
problem Understanding the relationship between mapping class groups and braid groups with group actions.
method Using the fibration and exact sequence.
result The conclusion is closely connected with the braid group of the quotient space.
The mapping class group of a non-orientable surface with punctures is studied via classical homotopy theory of configuration spaces. In particular, we obtain a non-orientable version of the Birman exact sequence. In the case of , we analize the Serre spectral sequence of a fiber bundle $…
We introduce machinery to allow ``cut-and-paste''-style inductive arguments in the Torelli subgroup of the mapping class group. In the past these arguments have been problematic because restricting the Torelli group to subsurfaces gives different groups depending on how the subsurfaces are embedded. We define a categor…
Let X be a hyperbolic surface and H the fundamental group of a hyperbolic 3-manifold that fibers over the circle with fiber X. Using the Birman exact sequence, H embeds in the mapping class group Mod(Y) of the surface Y obtained by removing a point from X. We prove that a subgroup G in H is convex cocompact in Mod(Y) i…
For , we give two proofs of the fact that the \emph{Birman exact sequence} for the Torelli group \[ 1\to π_1(S_g)\to {\cal I}_{g,1}\to {\cal I}_g\to 1 \] does not split. This result was claimed by G. Mess in \cite{mess1990unit}, but his proof has a critical and unrepairable error which will be discussed in the int…
Study braid group actions on exceptional sequences using branched coverings.
problem Transitivity of braid group action on full exceptional sequences.
method Relate exceptional sequences to branched coverings, apply Birman--Hilden theory.
result Counterexamples to Bondal--Polishchuk conjecture on braid group transitivity.
Linear progress in fibresmath.GT
Linear progress observed in fibered 3-manifold embeddings.
problem Understanding the geometric distortion of fibered embeddings.
method Verification of linear progress along typical rays using geometry and ergodic theory.
result A typical ray in the fiber makes linear progress in the ambient metric.
A knot type is exchange reducible if an arbitrary closed n-braid representative can be changed to a closed braid of minimum braid index by a finite sequence of braid isotopies, exchange moves and +/- destabilizations. In the manuscript [J Birman and NC Wrinkle, On transversally simple knots, preprint (1999)] a transver…
Quantifies the crossing number of knots based on genus and braid index.
problem Estimating the crossing number of knots given their genus and braid index.
method Quantitative Birman-Menasco finiteness theorem applied to crossing numbers.
result Estimates the crossing number of knots in terms of genus and braid index.
The study examines power quotients of surface groups and mapping class groups, proving structural properties and isomorphisms.
problem Structural properties and isomorphisms of power quotients of surface groups and mapping class groups.
method Analyzes the outer automorphism and automorphism groups of power quotients, proving isomorphisms and structural properties.
result The outer automorphism group of is isomorphic to the quotient of the extended mapping class group of by th powers of Dehn twists.
Study of point-pushing actions on manifolds with boundary.
problem Analyzing point-pushing actions on manifolds with boundary.
method Examining the homomorphism from braid groups to homotopy classes of homotopy equivalences.
result Injectivity of the map from the k-th braid group to homotopy classes of homotopy equivalences.
The paper proves a smooth Birman-Hilden theorem for hyperkähler manifolds.
problem Understanding the smooth mapping class groups of certain 4-manifolds.
method Geometric and Teichmüller-theoretic methods.
result Proves a global Torelli theorem for generalized Enriques manifolds.
Given a hyperbolic surface , a classic result of Birman and Series states that for each , all complete geodesics with at most self-intersections can only pass through a certain nowhere dense, Hausdorff dimension 1 subset of . We define a self-intersection function for each complete geodesic, which bounds t…
An explicit section of the Laudenbach exact sequence of the mapping class group of connect sums of math.GT
We provide an explicit section for a mapping class group sequence.
problem Mapping class group of connect sums of .
method Provided an explicit section for the split exact sequence.
result Explicit section for the exact sequence.
The paper studies splitting maps in link Floer homology using skein exact sequences.
problem Understanding splitting maps for links using link Floer homology.
method Link Floer homology and skein exact sequences.
result Splitting maps for torus links are associated with integer points in permutahedra.
Paper presents new cobordism sequences for singular maps.
problem Understanding cobordism groups of singular maps.
method Develops analogous exact sequences to classical ones.
result Positive answer to Szűcs' question on cobordisms of immersions.
Characterizes braid types and estimates twist coefficients.
problem Understanding braid types and their properties.
method Birman-Ko-Lee left canonical form of braids.
result Characterization of almost strongly quasipositive braids and estimates of fractional Dehn twist coefficient.
The Birman-Hilden theorymath.GT
In the 1970s Joan Birman and Hugh Hilden wrote several papers on the problem of relating the mapping class group of a surface to that of a cover. We survey their work, give an overview of the subsequent developments, and discuss open questions and new directions.
Corrects earlier work on surface orbifold pure braid groups.
problem Proving a four-term exact sequence for surface orbifold pure braid groups.
method Analyzes surface orbifold pure braid groups for all genus ≥ 1, 2D orientable orbifolds with cone points.
result Proves a four-term exact sequence for surface orbifold pure braid groups.
We give a definition of symplectic homology for pairs of filled Liouville cobordisms, and show that it satisfies analogues of the Eilenberg-Steenrod axioms except for the dimension axiom. The resulting long exact sequence of a pair generalizes various earlier long exact sequences such as the handle attaching sequence, …
Grid homology theory for spatial graphs extends skein sequence.
problem No specific problem stated; focuses on extending a sequence.
method Defined grid homology theory for spatial graphs and extended skein sequence.
result Skein exact sequence extended to grid homology for spatial graphs.
The Birman-Hilden theory is extended to infinite type surfaces and branched covers.
problem Extending Birman-Hilden theory to surfaces of infinite type and branched covers of infinite degree.
method Proving the Birman-Hilden property for fully ramified branched covering maps.
result The mapping class group of a non-orientable surface of infinite type can be realized as a subgroup of the mapping class group of its orientable double cover.
New exact sequence links cohomology, automorphisms, and extensions of symmetric quandles.
problem Understanding the structure of extensions and automorphisms in symmetric quandles.
method Derived a four-term exact sequence relating 1-cocycles, second cohomology, and automorphisms.
result Obstruction to automorphisms lies in the second cohomology of symmetric quandles.
Introduces a reduction system for Artin-Tits groups, improving algorithms and proving periodicity results.
problem Computing reduction systems in Artin-Tits groups of spherical type.
method Introduces a canonical reduction system, proves periodicity of centralizers, and provides algorithms.
result Improved algorithms for computing reduction systems in braid groups and Artin-Tits groups.
A 2-manifold's group structure is deduced from orbit configuration spaces.
problem Understanding the fundamental groups of orbit configuration spaces.
method Relating the four-term exact sequence of orbifold pure braid groups to the fundamental groups of the orbit configuration spaces.
result Fundamental groups of orbit configuration spaces form a four-term exact sequence.
Study cohomology of surfaces with punctures and boundaries, proving bounds on rational cohomology.
problem Understanding cohomology of surfaces with punctures and boundaries.
method Two proofs showing congruence subgroups have enormous rational cohomology.
result Bounds on cohomology are super-exponential in number of punctures and boundary components.
On Double Vector Bundlesmath.DG
In this paper, we construct a category of short exact sequences of vector bundles and prove that it is equivalent to the category of double vector bundles. Moreover, operations on double vector bundles can be transferred to operations on the corresponding short exact sequences. In particular, we study the duality theor…
This paper defines a spectral sequence connecting knot homologies.
problem Link Floer homology and its connections to knot homologies.
method Iterating a modified skein exact triangle to create a spectral sequence.
result A spectral sequence from reduced Khovanov homology of the mirror of a knot to knot Floer homology of the knot.
On the negative band numbermath.GT
Study negative band numbers in braids and links.
problem Characterizing braids with negative band numbers.
method Using Birman, Ko, and Lee's left-canonical form.
result Characterize strongly and almost strongly quasipositive braids.
We establish a long exact sequence for Legendrian submanifolds L in P x R, where P is an exact symplectic manifold, which admit a Hamiltonian isotopy that displaces the projection of L off of itself. In this sequence, the singular homology H_* maps to linearized contact cohomology CH^* which maps to linearized contact …
Birman-Lubotzky-McCarthy proved that any abelian subgroup of the mapping class groups for orientable surfaces is finitely generated. We apply Birman-Lubotzky-McCarthy's arguments to the mapping class groups for non-orientable surfaces. We especially find a finitely generated group isomorphic to a given torsion-free sub…
Simplified plat diagrams for unlink without stabilization.
problem Equivalence of plats without stabilization for unlink.
method Introducing pocket and flip moves to simplify plats.
result Simplified plat diagrams for unlink using pocket and flip moves.
In paper "A new twist on Lorenz links" (Journal of Topology 2(2009), 227-248) Joan Birman and Ilya Kofman prove the coincidence of the class of Lorenz links and the class of twisted links. The proof in that work is algebraic. We will identify this class in terms of grid diagrams and provide a transparent geometric argu…
This is the third part of the work on the exact triangles. We construct chain homomorphisms and show exactness of the resulting sequence.
We show a connection between a surgery exact sequence in knot Floer homology and the sequence derived in [18]. As a consequence of this relationship we see that the exact sequence in [18] also works with coherent orientations and admits refinements with respect to spinc-structures. As an application of this discussion,…
A transverse knot is a knot that is transverse to the planes of the standard contact structure on real 3-space. In this paper we prove the Markov Theorem for transverse braids, which states that two transverse closed braids that are isotopic as transverse knots are also isotopic as transverse braids. The methods of the…