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1. Kauffman bracket skein modules of small 3-manifolds

   https://doi.org/10.1016/j.aim.2025.110169  

   Detcherry, Renaud; Kalfagianni, Efstratia; Sikora, Adam S (May 2025, Advances in Mathematics)

   The proof of Witten's finiteness conjecture established that the Kauffman bracket skein modules of closed $$3$$-manifolds are finitely generated over $$\Q(A)$$. In this paper, we develop a novel method for computing these skein modules. We show that if the skein module $$S(M,\Q[A^\pmo])$$ of $$M$$ is tame (e.g. finitely generated over $$\Q[A^{\pm 1}]$$), and the $$SL(2, \C)$$-character scheme is reduced, then the dimension $$\dim_{\Q(A)}\, S(M, \Q(A))$$ is the number of closed points in this character scheme. This, in particular, verifies a conjecture in the literature relating $$\dim_{\Q(A)}\, S(M, \Q(A))$$ to the Abouzaid-Manolescu $$SL(2,\C)$$-Floer theoretic invariants, for infinite families of 3-manifolds. We prove a criterion for reducedness of character varieties of closed $$3$$-manifolds and use it to compute the skein modules of Dehn fillings of $(2,2n+1)$-torus knots and of the figure-eight knot. The later family gives the first instance of computations of skein modules for closed hyperbolic 3-manifolds. We also prove that the skein modules of rational homology spheres have dimension at least $$1$$ over $$\Q(A)$$. 

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2. Stated SL(n$$n$$)‐skein modules and algebras

   https://doi.org/10.1112/topo.12350  

   Lê, Thang_T Q; Sikora, Adam S (September 2024, Journal of Topology)

   Abstract We develop a theory of stated SL()‐skein modules, , of 3‐manifolds marked with intervals in their boundaries. These skein modules, generalizing stated SL(2)‐modules of the first author, stated SL(3)‐modules of Higgins', and SU(n)‐skein modules of the second author, consist of linear combinations of framed, oriented graphs, called ‐webs, with ends in , considered up to skein relations of the ‐Reshetikhin–Turaev functor on tangles, involving coupons representing the anti‐symmetrizer and its dual. We prove the Splitting Theorem asserting that cutting of a marked 3‐manifold along a disk resulting in a 3‐manifold yields a homomorphism for all . That result allows to analyze the skein modules of 3‐manifolds through the skein modules of their pieces. The theory of stated skein modules is particularly rich for thickened surfaces , in whose case, is an algebra, denoted by . One of the main results of this paper asserts that the skein algebra of the ideal bigon is isomorphic with and it provides simple geometric interpretations of the product, coproduct, counit, the antipode, and the cobraided structure on . (In particular, the coproduct is given by a splitting homomorphism.) We show that for surfaces with boundary every splitting homomorphism is injective and that is a free module with a basis induced from the Kashiwara–Lusztig canonical bases. Additionally, we show that a splitting of a thickened bigon near a marking defines a right ‐comodule structure on , or dually, a left ‐module structure. Furthermore, we show that the skein algebra of surfaces glued along two sides of a triangle is isomorphic with the braided tensor product of Majid. These results allow for geometric interpretation of further concepts in the theory of quantum groups, for example, of the braided products and of Majid's transmutation operation. Building upon the above results, we prove that the factorization homology with coefficients in the category of representations of is equivalent to the category of left modules over for surfaces with . We also establish isomorphisms of our skein algebras with the quantum moduli spaces of Alekseev–Schomerus and with the internal algebras of the skein categories for these surfaces and . 

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3. Skein lasagna modules for 2-handlebodies

   https://doi.org/10.1515/crelle-2022-0021  

   Manolescu, Ciprian; Neithalath, Ikshu (July 2022, Journal für die reine und angewandte Mathematik (Crelles Journal))

   Abstract Morrison, Walker, and Wedrich used the blob complex to construct a generalization of Khovanov–Rozansky homology to links in the boundary of a 4-manifold. The degree zero part of their theory, called the skein lasagna module, admits an elementary definition in terms of certain diagrams in the 4-manifold. We give a description of the skein lasagna module for 4-manifolds without 1- and 3-handles, and present some explicit calculations for disk bundles over $S^2${S^{2}}. 

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4. 3–Manifolds without any embedding insymplectic 4–manifolds

   https://doi.org/10.2140/gt.2024.28.3357  

   Daemi, Aliakbar; Lidman, Tye; Miller_Eismeier, Mike (November 2024, Geometry & Topology)

   We show that there exist infinitely many closed 3–manifolds that do not embed in closed symplectic 4–manifolds, disproving a conjecture of Etnyre–Min–Mukherjee. To do this, we construct L–spaces that cannot bound positive- or negative-definite manifolds. The arguments use Heegaard Floer correction terms and instanton moduli spaces. 

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5. A new Gram determinant from the Möbius band

   https://doi.org/10.1142/S0218216524500378  

   Ibarra, Dionne; Montoya-Vega, Gabriel (October 2024, Journal of Knot Theory and Its Ramifications)

   Gram determinants earned traction among knot theorists after Witten’s presumption about the existence of a 3-manifold invariant connected to the Jones polynomial. Triggered by the creation of such an invariant by Reshetikhin and Turaev, several mathematicians have explored this line of research ever since. Gram determinants came into play by Lickorish’s skein theoretic approach to the invariant. The construction of different bilinear forms is possible through changes in the ambient surface of the Kauffman bracket skein module. Hence, different types of Gram determinants have arisen in knot theory throughout the years; some of these determinants are discussed here. In this paper, we introduce a new version of such a determinant from the Möbius band and prove some important results about its structure. In particular, we explore its connection to the annulus case and factors of its closed formula. 

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