No Arabic abstract
For the moduli space of unmarked convex $mathbb{RP}^2$ structures on the surface $S_{g,m}$ with negative Euler characteristic, we investigate the subsets of the moduli space defined by the notions like boundedness of projective invariants, area, Gromov hyperbolicity constant, quasisymmetricity constant etc. These subsets are comparable to each other. We show that the Goldman symplectic volume of the subset with certain projective invariants bounded above by $t$ and fixed boundary simple root lengths $mathbf{L}$ is bounded above by a positive polynomial of $(t,mathbf{L})$ and thus the volume of all the other subsets are finite. We show that the analog of Mumfords compactness theorem holds for the area bounded subset.
We estimate the upper bound for the $ell^{infty}$-norm of the volume form on $mathbb{H}^2timesmathbb{H}^2timesmathbb{H}^2$ seen as a class in $H_{c}^{6}(mathrm{PSL}_{2}mathbb{R}timesmathrm{PSL}_{2}mathbb{R}timesmathrm{PSL}_{2}mathbb{R};mathbb{R})$. This gives the lower bound for the simplicial volume of closed Riemennian manifolds covered by $mathbb{H}^{2}timesmathbb{H}^{2}timesmathbb{H}^{2}$. The proof of these facts yields an algorithm to compute the lower bound of closed Riemannian manifolds covered by $big(mathbb{H}^2big)^n$.
We extend V. Arnolds theory of asymptotic linking for two volume preserving flows on a domain in ${mathbb R}^3$ and $S^3$ to volume preserving actions of ${mathbb R}^k$ and ${mathbb R}^ell$ on certain domains in ${mathbb R}^n$ and also to linking of a volume preserving action of ${mathbb R}^k$ with a closed oriented singular $ell$-dimensional submanifold in ${mathbb R}^n$, where $n=k+ell+1$. We also extend the Biot-Savart formula to higher dimensions.
We reinterpret the renormalized volume as the asymptotic difference of the isoperimetric profiles for convex co-compact hyperbolic 3-manifolds. By similar techniques we also prove a sharp Minkowski inequality for horospherically convex sets in $mathbb{H}^3$. Finally, we include the classification of stable constant mean curvature surfaces in regions bounded by two geodesic planes in $mathbb{H}^3$ or in cyclic quotients of $mathbb{H}^3$.
We use the symmetries of the tetrahedron, octahedron and icosahedron to construct local models for a $mathbb{Z}/2$ harmonic 1-form or spinor in 3-dimensions near a singular point in its zero loci. The local models are $mathbb{Z}/2$ harmonic 1-forms or spinors on $mathbb{R}^3$ that are homogeneous with respect to rescaling of $mathbb{R}^3$ with their zero locus consisting of four or more rays from the origin. The rays point from the origin to the vertices of a centered tetrahedron in one example; and they point from those of a centered octahedron and a centered icosahedron in two others.
We study the infimum of the renormalized volume for convex-cocompact hyperbolic manifolds, as well as describing how a sequence converging to such values behaves. In particular, we show that the renormalized volume is continuous under the appropriate notion of limit. This result generalizes previous work in the subject.