This paper deals with the stabilization of the contribution of elliptic elements to the geometric side of the general twisted trace formula. We extend the results of Langlands, Kottwitz and Shelstad to all elliptic elements for the general twisted trace formula.

AMS 2000 Mathematics subject classification: Primary 11F72; 11R39; 11R34

We present a general framework for automatic continuity results for groups of isometries of metric spaces. In particular, we prove automatic continuity property for the groups of isometries of the Urysohn space and the Urysohn sphere, i.e. that any homomorphism from either of these groups into a separable group is continuous. This answers a question of Ben Yaacov, Berenstein and Melleray. As a consequence, we get that the group of isometries of the Urysohn space has unique Polish group topology and the group of isometries of the Urysohn sphere has unique separable group topology. Moreover, as an application of our framework we obtain new proofs of the automatic continuity property for the group $\text{Aut}([0,1],\unicode[STIX]{x1D706})$, due to Ben Yaacov, Berenstein and Melleray and for the unitary group of the infinite-dimensional separable Hilbert space, due to Tsankov.

We prove that the Calabi–Yau equation can be solved on the Kodaira–Thurston manifold for all given T2-invariant volume forms. This provides support for Donaldson's conjecture that Yau's theorem has an extension to symplectic 4-manifolds with compatible but non-integrable almost complex structures.

The trace (or zeroth Hochschild homology) of Khovanov’s Heisenberg category is identified with a quotient of the algebra $W_{1+\infty }$. This induces an action of $W_{1+\infty }$ on the center of the categorified Fock space representation, which can be identified with the action of $W_{1+\infty }$ on symmetric functions.

We prove the connectedness of the Prym eigenforms loci in genus four (for real multiplication by some order of discriminant $D$), for any $D$. These loci were discovered by McMullen in 2006.

For a characteristic-$p\gt 0$ variety $X$ with controlled $F$-singularities, we state conditions which imply that a divisorial sheaf is Cohen–Macaulay or at least has depth $\geq $3 at certain points. This mirrors results of Kollár for varieties in characteristic 0. As an application, we show that relative canonical sheaves are compatible with arbitrary base change for certain families with sharply $F$-pure fibers.

This work is devoted to the study of uncertainty principles for finite combinations of Hermite functions. We establish some spectral inequalities for control subsets that are thick with respect to some unbounded densities growing almost linearly at infinity, and provide quantitative estimates, with respect to the energy level of the Hermite functions seen as eigenfunctions of the harmonic oscillator, for the constants appearing in these spectral estimates. These spectral inequalities allow us to derive the null-controllability in any positive time for evolution equations enjoying specific regularizing effects. More precisely, for a given index $\frac {1}{2} \leq \mu <1$, we deduce sufficient geometric conditions on control subsets to ensure the null-controllability of evolution equations enjoying regularizing effects in the symmetric Gelfand–Shilov space $S^{\mu }_{\mu }(\mathbb {R}^{n})$. These results apply in particular to derive the null-controllability in any positive time for evolution equations associated to certain classes of hypoelliptic non-self-adjoint quadratic operators, or to fractional harmonic oscillators.

Soit $G$ un groupe algébrique réductif sur la clôture algébrique d’un corps fini $\mathbb{F}_q$ et défini sur ce dernier. L’existence du support unipotent d’un caractère irréductible du groupe fini $G(\mathbb{F}_q)$, ou d’un faisceau caractère de $G$, a été établie dans différents cas par Lusztig, Geck et Malle, et le second auteur. Dans le présent article, nous démontrons que toute classe unipotente sur laquelle la restriction du caractère ou du faisceau caractère donné est non nulle est contenue l’adhérence de Zariski du support unipotent de ce dernier. Pour établir ce résultat, nous étudions certaines représentations des groupes de Weyl, dites “bien supportées”.

Let $G$ be a reductive algebraic group over the algebraic closure of a finite field $\mathbb{F}_q$, and defined over the latter. The existence of a unipotent support for an irreducible character of the finite group $G(\mathbb{F}_q)$, or for a character sheaf on $G$, has been established in several cases by Lusztig, Geck and Malle, and the second author. In this paper, we prove that any unipotent class on which the restriction of the given character or character sheaf does not vanish is contained in the Zariski closure of its unipotent support. In order to establish this result, we study some representations of Weyl groups, which are called ‘well supported’.

Using a connected sum construction, we prove the existence of complete non-compact embedded constant-mean-curvature-1 surfaces in hyperbolic 3-space with finitely many ends and non-trivial topology. These surfaces are obtained by desingularizing finitely many mutually tangent horospheres.

AMS 2000 Mathematics subject classification: Primary 53A10; 53A35

We consider the Klein–Gordon equation on asymptotically anti-de-Sitter spacetimes subject to Neumann or Robin (or Dirichlet) boundary conditions and prove propagation of singularities along generalized broken bicharacteristics. The result is formulated in terms of conormal regularity relative to a twisted Sobolev space. We use this to show the uniqueness, modulo regularizing terms, of parametrices with prescribed $\text{b}$-wavefront set. Furthermore, in the context of quantum fields, we show a similar result for two-point functions satisfying a holographic Hadamard condition on the $\text{b}$-wavefront set.

On calcule les restrictions aux points fixes de deux bases de la cohomologie équivariante des tours de Bott, et on précise la structure multiplicative de ces algèbres de cohomologie. En s’aidant du travail de Duan, on en déduit une méthode de calcul des constantes de structure de la cohomologie équivariante des variétés de drapeaux (calcul de Schubert équivariant).

‘Equivariant cohomology of Bott towers and equivariant Schubert calculus’. We calculate the restrictions to fixed points of two bases of the equivariant cohomology of Bott towers, and we describe the multiplicative structure of these cohomology algebras. We build on the work of Duan to give a method to calculate the structure constants of the equivariant cohomology of the flag varieties (equivariant Schubert calculus).

Given a separable Banach space E, we construct an extremely non-complex Banach space (i.e. a space satisfying that ‖ Id + T2 ‖ = 1 + ‖ T2 ‖ for every bounded linear operator T on it) whose dual contains E* as an L-summand. We also study surjective isometries on extremely non-complex Banach spaces and construct an example of a real Banach space whose group of surjective isometries reduces to ±Id, but the group of surjective isometries of its dual contains the group of isometries of a separable infinite-dimensional Hilbert space as a subgroup.

We construct local and global metaplectic double covers of odd general spin groups, using the cover of Matsumoto of spin groups. Following Kazhdan and Patterson, a local exceptional representation is the unique irreducible quotient of a principal series representation, induced from a certain exceptional character. The global exceptional representation is obtained as the multi-residue of an Eisenstein series: it is an automorphic representation, and it decomposes as the restricted tensor product of local exceptional representations. As in the case of the small representation of $\mathit{SO}_{2n+1}$ of Bump, Friedberg, and Ginzburg, exceptional representations enjoy the vanishing of a large class of twisted Jacquet modules (locally), or Fourier coefficients (globally). Consequently they are useful in many settings, including lifting problems and Rankin–Selberg integrals. We describe one application, to a calculation of a co-period integral.

Linear differential algebraic groups (LDAGs) measure differential algebraic dependencies among solutions of linear differential and difference equations with parameters, for which LDAGs are Galois groups. Differential representation theory is a key to developing algorithms computing these groups. In the rational representation theory of algebraic groups, one starts with and tori to develop the rest of the theory. In this paper, we give an explicit description of differential representations of tori and differential extensions of irreducible representation of . In these extensions, the two irreducible representations can be non-isomorphic. This is in contrast to differential representations of tori, which turn out to be direct sums of isotypic representations.

We show that a twisted Hilbert space with an unconditional basis is isomorphic to a Hilbert space.

AMS 2000 Mathematics subject classification: Primary 46B10. Secondary 46C15

We consider valued fields with a value-preserving automorphism and improve on model-theoretic results by Bélair, Macintyre and Scanlon on these objects by dropping assumptions on the residue difference field. In the equicharacteristic 0 case we describe the induced structure on the value group and the residue difference field.

Let $\mathcal{L}^{S}\left (s,\pi ,{\mathfrak{st}}\right )$ be a partial $\mathcal{L}$-function of degree $7$ of a cuspidal automorphic representation $\pi $ of the exceptional group $G_2$. In this paper we construct a Rankin–Selberg integral for representations having a certain Fourier coefficient.

Using the $\ell $-invariant constructed in our previous paper we prove a Mazur–Tate–Teitelbaum-style formula for derivatives of $p$-adic $L$-functions of modular forms at trivial zeros. The novelty of this result is to cover the near-central point case. In the central point case our formula coincides with the Mazur–Tate–Teitelbaum conjecture proved by Greenberg and Stevens and by Kato, Kurihara and Tsuji at the end of the 1990s.

We provide a class of separable II1 factors $M$ whose central sequence algebra is not the ‘tail’ algebra associated with any decreasing sequence of von Neumann subalgebras of $M$. This settles a question of McDuff [On residual sequences in a II1 factor, J. Lond. Math. Soc. (2) (1971), 273–280].

in this article we compare different conditions on abelian schemes with real multiplication which occur in the integral models of the hilbert–blumenthal shimura variety considered by rapoport, deligne, pappas and kottwitz. we show that the models studied by deligne/pappas and kottwitz are isomorphic over $\mathrm{spec}\mathbb{z}_{(p)}$. we also examine the associated local models and prove that they are equal.