A proof of the linear Arithmetic Fundamental Lemma for

Let $K/F$ be an unramified quadratic extension of a non-Archimedean local field. In a previous work [1], we proved a formula for the intersection number on Lubin–Tate spaces. The main result of this article is an algorithm for computation of this formula in certain special cases. As an application, we prove the linear Arithmetic Fundamental Lemma for $ \operatorname {{\mathrm {GL}}}_4$ with the unit element in the spherical Hecke Algebra.

Surjectivity of certain adjoint operators and applications

This paper is an extension and generalization of some previous works, such as the study of M. Benalili and A. Lansari. Indeed, these authors, in their work about the finite co-dimension ideals of Lie algebras of vector fields, restricted their study to fields $$X_0$$ X 0 of the form $$X_0=\sum _{i=1}^{n}( \alpha _i \cdot x_i+\beta _i\cdot x_i^{1+m_i}) \frac{\partial }{\partial x_i}$$ X 0 = ∑ i = 1 n ( α i · x i + β i · x i 1 + m i ) ∂ ∂ x i , where $$\alpha _i, \beta _i $$ α i , β i are positive and $$m_i$$ m i are even natural integers. We will first study the sub-algebra U of the Lie-Fréchet space E, containing vector fields of the form $$Y_0 = X_0^+ + X_0^- + Z_0$$ Y 0 = X 0 + + X 0 - + Z 0 , such as $$ X_0\left( x,y\right) =A\left( x,y\right) =\left( A^{-}\left( x \right) ,A^{+}\left( y\right) \right) $$ X 0 x , y = A x , y = A - x , A + y , with $$A^-$$ A - (respectively, $$ A^+ $$ A + ) a symmetric matrix having eigenvalues $$ \lambda < 0$$ λ < 0 (respectively, $$\lambda >0 $$ λ > 0 ) and $$Z_0$$ Z 0 are germs infinitely flat at the origin. This sub-algebra admits a hyperbolic structure for the diffeomorphism $$\psi _{t*}=(exp\cdot tY_0)_*$$ ψ t ∗ = ( e x p · t Y 0 ) ∗ . In a second step, we will show that the infinitesimal generator $$ad_{-X}$$ a d - X is an epimorphism of this admissible Lie sub-algebra U. We then deduce, by our fundamental lemma, that $$U=E$$ U = E .

RELATIVE UNITARY RZ-SPACES AND THE ARITHMETIC FUNDAMENTAL LEMMA

We prove a comparison isomorphism between certain moduli spaces of $p$ -divisible groups and strict ${\mathcal{O}}_{K}$ -modules (RZ-spaces). Both moduli problems are of PEL-type (polarization, endomorphism, level structure) and the difficulty lies in relating polarized $p$ -divisible groups and polarized strict ${\mathcal{O}}_{K}$ -modules. We use the theory of relative displays and frames, as developed by Ahsendorf, Lau and Zink, to translate this into a problem in linear algebra. As an application of these results, we verify new cases of the arithmetic fundamental lemma (AFL) of Wei Zhang: The comparison isomorphism yields an explicit description of certain cycles that play a role in the AFL. This allows, under certain conditions, to reduce the AFL identity in question to an AFL identity in lower dimension.