@article {IOPORT.05920424, author = {Cenk, Murat and \"Ozbudak, Ferruh}, title = {Multiplication of polynomials modulo $x^{n}$.}, year = {2011}, journal = {Theoretical Computer Science}, volume = {412}, number = {29}, issn = {0304-3975}, pages = {3451-3462}, publisher = {Elsevier Science Publishers, Amsterdam}, doi = {10.1016/j.tcs.2011.02.031}, abstract = {Summary: Let $n,\ell $ be positive integers with $\ell \leq 2n - 1$. Let $\cal R$ be an arbitrary nontrivial ring, not necessarily commutative and not necessarily having a multiplicative identity, and let $\cal R[x]$ be the polynomial ring over $\cal R$. In this paper, we give improved upper bounds on the minimum number of multiplications needed to multiply two arbitrary polynomials of degree at most $(n - 1)$ modulo $x^{n}$ over $\cal R$. Moreover, we introduce a new complexity notion, the minimum number of multiplications needed to multiply two arbitrary polynomials of degree at most $(n - 1)$ modulo $x^{\ell }$ over $\cal R$. This new complexity notion provides improved bounds on the minimum number of multiplications needed to multiply two arbitrary polynomials of degree at most $(n - 1)$ modulo $x^{n}$ over $\cal R$.}, identifier = {05920424}, }