Unlikely intersections for algebraic curves in positive characteristic

Joint IAS/Princeton University Number Theory Seminar
Topic:Unlikely intersections for algebraic curves in positive characteristic
Speaker:David Masser
Affiliation:University of Basel
Date:Thursday, October 5
Time/Room:4:30pm - 5:30pm/Fine 214, Princeton University

In the last two decades there has been much study of what happens when an algebraic curve in \(n\)-space is intersected with two multiplicative relations
\[x_1^{a_1} \cdots x_n^{a_n} = x_1^{b_1} \cdots x_n^{b_n} = 1 \tag{\(\times\)}\]
for \((a_1, \ldots ,a_n),(b_1,\ldots, b_n)\) linearly independent in \({\bf Z}^n\). Usually the intersection with the union of all \((\times)\) is at most finite, at least in zero characteristic. This often becomes false in positive characteristic, and I gave in 2014 a substitute conjecture and proved it for \(n = 3\). I will describe all this together with more recent work with Dale Brownawell where we do the same for additive relations \((+)\); now an extra Frobenius structure has to be added, and there are no longer any direct analogues in zero characteristic.