Flatness in the totally even two-dimensional rational case

Determine whether the unframed universal deformation ring \(R_{\bar\rho}\) is flat over \(W(k)\) when \(K=\mathbb Q\), \(n=2\), the residual representation is continuous and absolutely irreducible over a finite field of characteristic \(2\), and complex conjugation acts trivially, \(\bar\rho(c)=I_2\).

Background

The proposed modified dimension conjecture predicts flatness when ρˉ(c)≠I2\bar\rho(c)\ne I_2, but the paper explicitly leaves open whether flatness should also be expected in the totally even case ρˉ(c)=I2\bar\rho(c)=I_2.

The paper gives an example over Q\mathbb Q with trivial residual complex conjugation for which the universal deformation ring is not a complete intersection. That example does not resolve the separate question of flatness.

References

We do not know whether one should expect R_{\bar\rho} to be flat over W(k) in this case.

— On the dimension conjecture for global Galois deformation rings in characteristic two  (2610.21298 - Luo, 15 Oct 2026) in Remark following Conjecture~\ref{conj:two-dimensional-Q}, Section 7 (Further remarks)