Determinant conjecture for twisted derivations when the conductor is 2rp2^r p

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Let K=Q(ζ)\mathbb{K}=\mathbb{Q}(\zeta) be the nnth cyclotomic number field with n=2rpn=2^r p, where r∈Nr\in\mathbb{N} and pp is an odd rational prime, and let OK=Z[ζ]O_{\mathbb{K}}=\mathbb{Z}[\zeta]. Let u,v∈U(n)u,v\in U(n) with u≠vu\ne v, and let σ,τ:OK→OK\sigma,\tau:O_{\mathbb{K}}\to O_{\mathbb{K}} satisfy σ(ζ)=ζu\sigma(\zeta)=\zeta^u and τ(ζ)=ζv\tau(\zeta)=\zeta^v. Write

β=∑i=02r−1(p−1)−1biζi∈OK,β(τ−σ)(ζ)=∑i=02r−1(p−1)−1(∑j=02r−1(p−1)−1aijbj)ζi,\beta=\sum_{i=0}^{2^{r-1}(p-1)-1}b_i\zeta^i\in O_{\mathbb{K}},\qquad \beta(\tau-\sigma)(\zeta)=\sum_{i=0}^{2^{r-1}(p-1)-1}\left(\sum_{j=0}^{2^{r-1}(p-1)-1}a_{ij}b_j\right)\zeta^i,

and let A=[aij]A=[a_{ij}]. Suppose v−u=2e1pe2mv-u=2^{e_1}p^{e_2}m, where mm is a positive integer, e1,e2e_1,e_2 are non-negative integers, and 2,p2,p do not divide mm. Determinant conjecture. The matrix AA is a 2r−1(p−1)×2r−1(p−1)2^{r-1}(p-1)\times 2^{r-1}(p-1) matrix with determinant ±22e1(p−1)\pm2^{2^{e_1}(p-1)} if 1≤e1≤r−11\le e_1\le r-1 and e2≥1e_2\ge1, determinant ±p2r−1\pm p^{2^{r-1}} if e1≥re_1\ge r and e2=0e_2=0, and determinant ±1\pm1 otherwise. The claim is intended to characterize the coefficient matrix governing inner (σ,τ)(\sigma,\tau)-derivations in this cyclotomic setting; the sign depends on the order in which the rows are formed, and the conjectural determinant underlies the subsequent criteria for inner and outer derivations.

References

Primary source

Praveen Manju and Rajendra Kumar Sharma, “Twisted Derivations in Algebraic Number Fields”, arXiv:2412.03507 (2026).

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