Algebraic functional equation for big Galois representations over multiple $\mathbb{Z}_p$-extensions
Zeping Hao, Meng Fai Lim
TL;DR
The paper develops a unifying axiomatic framework for proving algebraic functional equations for big Galois representations over multi-$ abla Z_p$-extensions, encompassing Selmer groups and Nekovář Selmer complexes. It introduces a datum $(T, igl"{T_v}igr brace_{v|p})_{R,F}$ with conditions (C1)-(C4) and (R1)-(R2) and proves that the Greenberg Selmer groups and Selmer complexes satisfy a two-sided functional-equation-type relation, including a pseudo-isomorphism of torsion parts and equality of characteristic ideals under finite generation. The results unify and generalize numerous arithmetic cases (Hida families, Rankin–Selberg, triple products, half-ordinary deformations) and provide tools to realize algebraic functional equations beyond cyclotomic extensions, resolving prior gaps and extending Greenberg’s questions. Applications cover abelian varieties, modular forms, and their $p$-adic $L$-functions, offering a broad, multi-variable Iwasawa-theoretic perspective on algebraic functional equations.
Abstract
We present a general approach to establish algebraic functional equations for big Galois representations over multiple $\mathbb{Z}_p$-extensions. Our result is formulated in both Selmer group and Selmer complex settings, and encompasses a broad range of Iwasawa-theoretic scenarios. In particular, our result applies to the triple product of Hida families in both balanced and unbalanced cases, as well as the half-ordinary Rankin-Selberg universal deformations recently studied by the first named author and Loeffler. Our result also significantly generalizes many previously known cases of algebraic functional equations and answers a question of Greenberg.
