15 research outputs found
Rational motivic path spaces and Kim's relative unipotent section conjecture
We initiate a study of path spaces in the nascent context of "motivic dga's",
under development in doctoral work by Gabriella Guzman. This enables us to
reconstruct the unipotent fundamental group of a pointed scheme from the
associated augmented motivic dga, and provides us with a factorization of Kim's
relative unipotent section conjecture into several smaller conjectures with a
homotopical flavor. Based on a conversation with Joseph Ayoub, we prove that
the path spaces of the punctured projective line over a number field are
concentrated in degree zero with respect to Levine's t-structure for mixed Tate
motives. This constitutes a step in the direction of Kim's conjecture.Comment: Minor corrections, details added, and major improvements to
exposition throughout. 52 page
A non-abelian conjecture of Tate-Shafarevich type for hyperbolic curves
We state a conjectural criterion for identifying global integral points on a
hyperbolic curve over in terms of Selmer schemes inside
non-abelian cohomology functors with coefficients in -unipotent
fundamental groups. For and the
complement of the origin in semi-stable elliptic curves of rank 0, we compute
the local image of global Selmer schemes, which then allows us to numerically
confirm our conjecture in a wide range of cases.Comment: Improvements to the exposition and numerous minor corrections
throughou
: Towards the Chabauty-Kim method in higher dimensions
If Z is an open subscheme of Spec ZZ, X is a sufficiently nice Z-model of a
smooth curve over QQ, and p is a closed point of Z, the Chabauty-Kim method
leads to the construction of locally analytic functions on X(ZZ_p) which vanish
on X(Z); we call such functions "Kim functions". At least in broad outline, the
method generalizes readily to higher dimensions. In fact, in some sense, the
surface M_{0,5} should be easier than the previously studied curve M_{0,4}
since its points are closely related to those of M_{0,4}, yet they face a
further condition to integrality. This is mirrored by a certain "weight
advantage" we encounter, because of which, M_{0,5} possesses new Kim functions
not coming from M_{0,4}. Here we focus on the case "ZZ[1/6] in half-weight 4",
where we provide a first nontrivial example of a Kim function on a surface.
Central to our approach to Chabauty-Kim theory (as developed in works by S.
Wewers, D. Corwin, and the first author) is the possibility of separating the
geometric part of the computation from its arithmetic context. However, we find
that in this case the geometric step grows beyond the bounds of standard
algorithms running on current computers. Therefore, some ingenuity is needed to
solve this seemingly straightforward problem, and our new Kim function is huge.Comment: Minor correction