In this paper, we generalize examples of Lagrangian mean curvature flows constructed by Lee and Wang in $\mathbb{C}^m$ to toric almost Calabi–Yau manifolds. To be more precise, we construct examples of weighted Hamiltonian stationary Lagrangian submanifolds in toric almost Calabi–Yau manifolds and solutions of generalized Lagrangian mean curvature flows starting from these examples. We allow these flows to have some singularities and topological changes.

We show that the category of mixed Hodge complexes admits a Cartan-Eilenberg structure, a notion introduced by Guillén-Navarro-Pascual-Roig leading to a good calculation of the homotopy category in terms of (co) fibrant objects. Using Deligne’s décalage, we show that the homotopy categories associated with the two notions of mixed Hodge complex introduced by Deligne and Beilinson respectively, are equivalent. The results provide a conceptual framework from which Beilinson’s and Carlson’s results on mixed Hodge complexes and extensions of mixed Hodge structures follow easily.

We introduce the notion of $(G, \varGamma)$-crossed action on a tensor category, where $(G, \varGamma)$ is a matched pair of finite groups. A tensor category is called a $(G, \varGamma)$-crossed tensor category if it is endowed with a $(G, \varGamma)$-crossed action. We show that every $(G, \varGamma)$-crossed tensor category $\mathcal{C}$ gives rise to a tensor category $\mathcal{C}^{(G, \varGamma)}$ that fits into an exact sequence of tensor categories Rep $G \longrightarrow\mathcal{C}^{(G, \varGamma)} \longrightarrow \mathcal{C}$. We also define the notion of a $(G, \varGamma)$-braiding in a $(G, \varGamma)$-crossed tensor category, which is connected with certain set-theoretical solutions of the QYBE. This extends the notion of $G$-crossed braided tensor category due to Turaev. We show that if $\mathcal{C}$ is a $(G, \varGamma)$-crossed tensor category equipped with a $(G, \varGamma)$-braiding, then the tensor category $\mathcal{C}^{(G, \varGamma)}$ is a braided tensor category in a canonical way.

In this paper we study matrix valued orthogonal polynomials of one variable associated with a compact connected Gelfand pair $(G,K)$ of rank one, as a generalization of earlier work by Koornwinder [30] and subsequently by Koelink, van Pruijssen and Roman [28], [29] for the pair (SU (2)$\times$SU (2), SU (2)), and by Grünbaum, Pacharoni and Tirao [13] for the pair (SU (3), U (2)). Our method is based on representation theory using an explicit determination of the relevant branching rules. Our matrix valued orthogonal polynomials have the Sturm–Liouville property of being eigenfunctions of a second order matrix valued linear differential operator coming from the Casimir operator, and in fact are eigenfunctions of a commutative algebra of matrix valued linear differential operators coming from the $K$-invariant elements in the universal enveloping algebra of the Lie algebra of $G$.

In this article we give an extension of the Lê-Greuel formula to the general setting of function germs $(f,g)$ defined on a complex analytic variety $X$ with arbitrary singular set, where $f = (f_1,\ldots,f_k): (X,\underline{0}) \to (\mathbb{C}^k,\underline{0})$ is generically a submersion with respect to some Whitney stratification on $X$. We assume further that the dimension of the zero set $V (f)$ is larger than 0, that $f$ has the Thom $a_f$-property with respect to this stratification, and $g: (X,\underline{0}) \to (\mathbb{C},0)$ has an isolated critical point in the stratified sense, both on $X$ and on $V (f)$.

Let $G$ be a finite group not of prime power order. Two real $G$-modules $U$ and $V$ are $\mathcal{P}(G)$-connectively Smith equivalent if there exists a homotopy sphere with smooth $G$-action such that the fixed point set by $P$ is connected for all Sylow subgroups $P$ of $G$, it has just two fixed points, and $U$ and $V$ are isomorphic to the tangential representations as real $G$-modules respectively. We study the $\mathcal{P}(G)$-connective Smith set for a finite Oliver group $G$ of the real representation ring consisting of all differences of $\mathcal{P}(G)$-connectively Smith equivalent $G$-modules, and determine this set for certain nonsolvable groups $G$.

We give a complete classification of umbilical surfaces of arbitrary codimension of a product $\mathbb{Q}_{k_1}^n_1\times \mathbb{Q}_{k_2}^n_2$ of space forms whose curvatures satisfy $k_1+k_2\neq 0$.