We prove formulas for the p-adic logarithm of quaternionic Darmon points on p-adic tori and modular abelian varieties over Q having purely multiplicative reduction at p. These formulas are amenable to explicit computations and are the first to treat Stark-Heegner type points on higher-dimensional abelian varieties.
In 1922, Mordell conjectured the striking statement that for a polynomial equation $f(x,y)=0$, if the topology of the set of complex number solutions is complicated enough, then the set of rational number solutions is finite. This was proved by Falti
ngs in 1983, and again by a different method by Vojta in 1991, but neither proof provided a way to provably find all the rational solutions, so the search for other proofs has continued. Recently, Lawrence and Venkatesh found a third proof, relying on variation in families of $p$-adic Galois representations; this is the subject of the present exposition.
If the $ell$-adic cohomology of a projective smooth variety, defined over a $frak{p}$-adic field $K$ with finite residue field $k$, is supported in codimension $ge 1$, then any model over the ring of integers of $K$ has a $k$-rational point. This sli
ghtly improves our earlier result math/0405318: we needed there the model to be regular (but then our result was more general: we obtained a congruence for the number of points, and $K$ could be local of characteristic $p>0$).
Let $F$ be a totally real field in which a prime number $p>2$ is inert. We continue the study of the (generalized) Goren--Oort strata on quaternionic Shimura varieties over finite extensions of $mathbb F_p$. We prove that, when the dimension of the q
uaternionic Shimura variety is even, the Tate conjecture for the special fiber of the quaternionic Shimura variety holds for the cuspidal $pi$-isotypical component, as long as the two unramified Satake parameters at $p$ are not differed by a root of unity.
We study the mod $p$-points of the Kisin-Pappas integral models of abelian type Shimura varieties with parahoric level structure. We show that if the group is quasi-split and unramified, then the mod $p$ isogeny classes are of the form predicted by t
he Langlands-Rapoport conjecture (c.f. Conjecture 9.2 of arXiv:math/0205022). We prove the same results for quasi-split and tamely ramified groups when their Shimura varieties are proper. The main innovation in this work is a global argument that allows us to reduce the conjecture to the case of a very special parahoric, which is handled in the appendix. This way we avoid the complicated local problem of understanding connected components of affine Deligne-Lusztig varieties for general parahoric subgroups. Along the way, we give a simple irreducibility criterion for Ekedahl-Oort and Kottwitz-Rapoport strata.
Let $k$ be a number field, let $X$ be a Kummer variety over $k$, and let $delta$ be an odd integer. In the spirit of a result by Yongqi Liang, we relate the arithmetic of rational points over finite extensions of $k$ to that of zero-cycles over $k$ f
or $X$. For example, we show that if the Brauer-Manin obstruction is the only obstruction to the existence of rational points on $X$ over all finite extensions of $k$, then the $2$-primary Brauer-Manin obstruction is the only obstruction to the existence of a zero-cycle of degree $delta$ on $X$ over $k$.