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Francesco Sica

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Full Name: Francesco Sica

Open AccessArticle

A Proof of the Dimension Theorem for Vector Spaces

Francesco Sica

Annals of Communications in Mathematics 2025

8 (2)

299-302

DOI: https://doi.org/10.62072/acm.2025.080212

AbstractWe provide a proof of the theorem that, assuming Zorn’s lemma, two Hamel bases of a vector space have equal cardinality.
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Open AccessArticle

Subexponential Computation of Truncated Theta Series

Francesco Sica

Annals of Communications in Mathematics 2025

8 (3)

425-430

DOI: https://doi.org/10.62072/acm.2025.080309

ABSTRACT. We describe an algorithm to compute in $O(e^{c\sqrt{ k\log k}})$ binary operations, for some absolute constant $c>0$, expressions like $\sum_{1\leq n\leq 2^\alpha} e^{\frac{2\pi i n^2}{2^k}} n^a$ and $\sum_{\substack{1\leq n\leq 2^\alpha\\ 1\leq m\leq 2^\beta}} e^{\frac{2\pi i nm}{2^k}} n^a m^b$ where $\alpha,\beta= O(k)$ and $a,b$ are fixed (small) nonnegative integers. The error terms in these computations are $O(e^{-c k})$.
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