## Tohoku Mathematical Journal

### On a certain nilpotent extension over $\boldsymbol{Q}$ of degree 64 and the 4-th multiple residue symbol

Fumiya Amano

#### Abstract

In this paper, we introduce the 4-th multiple residue symbol $[p_1,p_2,p_3,p_4]$ for certain four prime numbers $p_i$'s, which extends the Legendre symbol $\big(\frac{p_1}{p_2}\big)$ and the Rédei triple symbol $[p_1,p_2,p_3]$ in a natural manner. For this we construct concretely a certain nilpotent extension $K$ over $\boldsymbol{Q}$ of degree 64, where ramified prime numbers are $p_1, p_2$ and $p_3$, such that the symbol $[p_1,p_2,p_3,p_4]$ describes the decomposition law of $p_4$ in the extension $K/\boldsymbol{Q}$. We then establish the relation of our symbol $[p_1,p_2,p_3,p_4]$ and the 4-th arithmetic Milnor invariant $\mu_2(1234)$ (an arithmetic analogue of the 4-th order linking number) by showing $[p_1,p_2,p_3,p_4] = (-1)^{\mu_2(1234)}$.

#### Article information

Source
Tohoku Math. J. (2), Volume 66, Number 4 (2014), 501-522.

Dates
First available in Project Euclid: 21 May 2015

https://projecteuclid.org/euclid.tmj/1432229194

Digital Object Identifier
doi:10.2748/tmj/1432229194

Mathematical Reviews number (MathSciNet)
MR3350281

Zentralblatt MATH identifier
06431044

Subjects
Primary: 11A15: Power residues, reciprocity
Secondary: 11R32: Galois theory 57M27: Invariants of knots and 3-manifolds

#### Citation

Amano, Fumiya. On a certain nilpotent extension over $\boldsymbol{Q}$ of degree 64 and the 4-th multiple residue symbol. Tohoku Math. J. (2) 66 (2014), no. 4, 501--522. doi:10.2748/tmj/1432229194. https://projecteuclid.org/euclid.tmj/1432229194

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