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The study of manifolds equipped with special linear connections has become an important topic in contemporary Riemannian geometry. In this work, we investigate Kenmotsu manifolds endowed with a class of semi-symmetric non-metric connections that generalize several previously known connections in the literature. Particular attention is devoted to the geometric behavior of symmetric and skew-symmetric parallel tensor fields associated with such connections. We further examine the conditions under which these manifolds satisfy Ricci-symmetric, weakly symmetric, and weakly Ricci-symmetric properties. In addition, the existence and structure of Ricci solitons related to these non-metric connections are studied within the setting of Kenmotsu geometry.
The main objective of this paper is to characterize a class of lattices, called splittable lattices, in the nilpotent semidirect product Lie group $$$G=\mathbb R^n\rtimes_\eta\mathbb R^m$$$. Here, $$$\eta$$$ denotes the representation of the abelian Lie group $$$\mathbb R^m$$$ in $$$GL_n(\mathbb R)$$$ defined by $$$\eta(t_{1},\dots,t_{m})=\exp{(\sum_{i=1}^mt_iN_i)}$$$ with $$$(N_i)_{1\leq i\leq m}$$$ is a set of pairwise commuting nilpotent matrices in $$$\mathbb Q^{n\times n}$$$. As an application we study the case of the nilpotent Lie group $$$F_{n,m}=\mathbb R^n\rtimes_\eta\mathbb R^m$$$ where $$$N_i=J^i$$$ with $$$J=\sum_{k=1}^{n-1}E_{k+1,k}$$$ where $$$E_{k+1,k}\in\mathbb R^{n\times n}$$$ denotes the matrix given by the Kronecker delta, namely, $$$\big(E_{k+1,k}\big)_{i,j}=\delta_{i,k+1}\delta_{j,k}$$$.
We consider a compact Riemannian manifold $$$(M, g)$$$ of dimension $$$N \geq 3$$$ and $$$\Sigma$$$ a closed totally geodesic submanifold of dimension $$$1 \leq k \leq N-2$$$, and $$$h: M \to ℝ$$$ is a continuous function such that the linear operator $$$-Δ_g+h$$$ is coercive. We study existence of positive solutions $$$u \in H^1\left(M\right)$$$ to the following nonlinear PDE with two Hardy-Sobolev critical exponents :
(0.1) $$$ -\Delta_g u+h u=\lambda \rho_{\Sigma}^{-s_1} u^{2^*_{s_1}-1}+\rho_{\Sigma}^{-s_2} u^{2^*_{s_2}-1} \qquad \textrm{ in } (M, g)$$$
where $$$\lambda$$$ is a positive parameter, $$$0 < s_2 < s_1 < 2$$$, the $$$2^*_{s_i}:=\frac{2(N-s_i)}{N-2}$$$ $$$(i=1, 2)$$$ are two critical Hardy-Sobolev exponents and $$$\rho_\Sigma: \mathcal{M} \to ℝ$$$ is the distance function to $$$\Sigma$$$. In this paper, we give sufficient condition depending on the local geometries of the submanifold $$$\Sigma$$$ and the manifold $$$M$$$, for the existence of mountain pass solution to (0.1).
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