Necklace ring
In mathematics, the necklace ring is a ring introduced by Metropolis and Rota (1983).
Definition
If A is a commutative ring then the necklace ring over A consists of all infinite sequences (a1,a2,...) of elements of A. Addition in the necklace ring is given by pointwise addition of sequences. Multiplication is given by a sort of arithmetic convolution: the product of (a1,a2,...) and (b1,b2,...) has components
![\displaystyle c_n=\sum_{[i,j]=n}(i,j)a_ib_j](/2012-wikipedia_en_all_nopic_01_2012/I/56be1d94a985313784f4347245338393.png)
where [i,j] is the least common multiple of i and j, and (i,j) is their highest common factor.
See also
References
- Hazewinkel, Michiel (2009). "Witt vectors. I.". Handbook of Algebra. 6. Elsevier/North-Holland. pp. 319–472. arXiv:0804.3888. ISBN 978-0444532572. MR2553661.
- Metropolis, N.; Rota, Gian-Carlo (1983). "Witt vectors and the algebra of necklaces". Advances in Mathematics 50 (2): 95–125. doi:10.1016/0001-8708(83)90035-X. MR723197.