Joint IAS/Princeton University Number Theory Seminar
Unlikely intersections for algebraic curves in positive characteristic
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.