Eisenstein sum

Not to be confused with Eisenstein series.

In mathematics, an Eisenstein sum is a finite sum depending on a finite field and related to a Gauss sum. Eisenstein sums were introduced by Eisenstein in 1848, named "Eisenstein sums" by Stickelberger in 1890, and rediscovered by Yamamoto in 1985, who called them relative Gauss sums.

Definition

The Eisenstein sum is given by

$E(\chi ,\alpha )=\sum _{Tr_{F/K}t=\alpha }\chi (t)$

where F is a finite extension of the finite field K, and χ is a character of the multiplicative group of F, and α is an element of K.

Bibliography

• Berndt, Bruce C.; Evans, Ronald J. (1979), "Sums of Gauss, Eisenstein, Jacobi, Jacobsthal, and Brewer", Illinois Journal of Mathematics, 23 (3): 374–437, doi:10.1215/ijm/1256048104, ISSN 0019-2082, MR 0537798, Zbl 0393.12029
• Eisenstein, Gotthold (1848), "Zur Theorie der quadratischen Zerfällung der Primzahlen 8n + 3,7n + 2 und 7n + 4", Journal für die Reine und Angewandte Mathematik, 37: 97–126, ISSN 0075-4102
• Lemmermeyer, Franz (2000), Reciprocity laws, Springer Monographs in Mathematics, Berlin, New York: Springer-Verlag, ISBN 978-3-540-66957-9, MR 1761696, Zbl 0949.11002
• Lidl, Rudolf; Niederreiter, Harald (1997), Finite fields, Encyclopedia of Mathematics and Its Applications, vol. 20 (2nd ed.), Cambridge University Press, ISBN 0-521-39231-4, Zbl 0866.11069
• Stickelberger, Ludwig (1890), "Ueber eine Verallgemeinerung der Kreistheilung", Mathematische Annalen, 37 (3): 321–367, doi:10.1007/bf01721360, JFM 22.0100.01, MR 1510649, S2CID 121239748
• Yamamoto, K. (1985), "On congruences arising from relative Gauss sums", Number theory and combinatorics. Japan 1984 (Tokyo, Okayama and Kyoto, 1984), Singapore: World Sci. Publishing, pp. 423–446, MR 0827799, Zbl 0634.12017