We study how the field of definition of a rational function changes under iteration. We provide a complete classification of polynomials with the property that the field of definition of one of their iterates drops in degree (over a given base field). We show with families of examples that this characterization does not hold for rational functions. Finally, we also classify fractional linear transformations with this property.
@article{MR4963751,
author = {Veneziano, Francesco and Vishkautsan, Solomon},
title = {The field of iterates of a rational function},
journal = {J. Th\'{e}or. Nombres Bordeaux},
fjournal = {Journal de Th\'{e}orie des Nombres de Bordeaux},
volume = {37},
year = {2025},
number = {2},
pages = {691--709},
issn = {1246-7405,2118-8572},
mrclass = {37P05 (11C08 11R04 37P15)},
mrnumber = {4963751},
doi = {10.5802/jtnb.1337},
url = {https://doi.org/10.5802/jtnb.1337},
eprint = {2404.04939},
eprinttype = {arxiv},
eprintclass = {math.NT}
}
2025. Classification of rational angles in plane lattices
II. Math. Ann., 393(3-4): 3713–3771. Roberto Dvornicich, Davide Lombardo, Francesco Veneziano, and Umberto Zannier.
This paper is a continuation of an earlier one, and completes a
classification of the configurations of points in a plane lattice that
determine angles that are rational multiples of \(\pi\). We give a complete and explicit
description of lattices according to which of these configurations can
be found among their points.
@article{MR5007552,
author = {Dvornicich, Roberto and Lombardo, Davide and Veneziano, Francesco and Zannier, Umberto},
title = {Classification of rational angles in plane lattices {II}},
journal = {Math. Ann.},
fjournal = {Mathematische Annalen},
volume = {393},
year = {2025},
number = {3-4},
pages = {3713--3771},
issn = {0025-5831,1432-1807},
mrclass = {11D61 (11H06 14G05 51M05)},
mrnumber = {5007552},
doi = {10.1007/s00208-025-03214-6},
url = {https://doi.org/10.1007/s00208-025-03214-6}
}
2022. Classification of rational angles in plane lattices. Bull. Amer. Math. Soc. (N.S.), 59(2): 191–226. Roberto Dvornicich, Francesco Veneziano, and Umberto Zannier.
This paper is concerned with configurations of points in a plane
lattice which determine angles that are rational multiples of
\(\pi\). We shall study
how many such angles may appear in a given lattice and in which
positions, allowing the lattice to vary arbitrarily. This classification
turns out to be much less simple than could be expected, leading even to
parametrizations involving rational points on certain algebraic curves
of positive genus.
@article{MR4390499,
author = {Dvornicich, Roberto and Veneziano, Francesco and Zannier, Umberto},
title = {Classification of rational angles in plane lattices},
year = {2022},
volume = {59},
number = {2},
pages = {191--226},
issn = {0273-0979},
mrclass = {11D61 (11G30 11H06 14G05 51M05)},
mrnumber = {4390499},
journal = {Bull. Amer. Math. Soc. (N.S.)},
fjournal = {American Mathematical Society. Bulletin. New Series},
eprint = {2005.13598},
eprinttype = {arxiv},
eprintclass = {math.NT},
doi = {10.1090/bull/1723},
url = {https://doi.org/10.1090/bull/1723}
}
2022. Finiteness and periodicity of continued fractions over
quadratic number fields. Bull. Soc. Math. France, 150(1): 77–109. Zuzana Masáková, Tomáš Vávra, and Francesco Veneziano.
In this paper we prove a periodicity theorem for certain continued
fractions with partial quotients in the ring of integers of a fixed
quadratic field. This theorem generalizes the classical theorem of
Lagrange to a large set of continued fraction expansions. As an
application we consider the \(\beta\)-continued fractions and show
that for any quadratic Perron number \(\beta\), the \(\beta\)-continued fraction expansion of
elements in \(\mathbb{Q}(\beta)\) is either finite
of eventually periodic. More in general we examine the finiteness and
periodicity of the \(\beta\)-continued
fractions for all quadratic integers \(\beta\), thus studying problems raised by
Rosen and Bernat.
@article{MR4440296,
author = {Mas\'{a}kov\'{a}, Zuzana and V\'{a}vra, Tom\'{a}\v{s} and Veneziano, Francesco},
title = {Finiteness and periodicity of continued fractions over
quadratic number fields},
journal = {Bull. Soc. Math. France},
fjournal = {Bulletin de la Soci\'{e}t\'{e} Math\'{e}matique de France},
volume = {150},
year = {2022},
number = {1},
pages = {77--109},
issn = {0037-9484},
mrclass = {11A55 (11J70 11K16)},
mrnumber = {4440296},
doi = {10.24033/bsmf.2845},
url = {https://doi.org/10.24033/bsmf.2845},
eprint = {1911.07670},
eprinttype = {arxiv},
eprintclass = {math.NT}
}
2022. On the integral values of a curious recurrence. Riv. Math. Univ. Parma (N.S.), 13(1): 1–18. Roberto Dvornicich, Francesco Veneziano, and Umberto Zannier.
We discuss an elementary problem, initially proposed for the Romanian
Mathematical Olympiad, which leads to interesting remarks of various
nature. We relate the problem to the theory of linear recurrence
sequences with non-constant coefficients and their \(p\)-adic behaviour. Our considerations can
be applied to a larger set of similarly-defined recurrences.
@article{MR4456578,
author = {Dvornicich, Roberto and Veneziano, Francesco and Zannier, Umberto},
title = {On the integral values of a curious recurrence},
journal = {Riv. Math. Univ. Parma (N.S.)},
fjournal = {Rivista di Matematica della Universit\`a di Parma. New Series. A
Journal of Pure and Applied Mathematics},
volume = {13},
year = {2022},
number = {1},
pages = {1--18},
issn = {0035-6298},
mrclass = {11B37 (11B83)},
mrnumber = {4456578},
url = {https://www.rivmat.unipr.it/vols/2022-13-1/01-dvornicich.html}
}
2022. Hyperelliptic continued fractions in the singular case of
genus zero. Atti Accad. Naz. Lincei Rend. Lincei Mat. Appl., 33(4): 795–832. Francesco Ballini and Francesco Veneziano.
It is possible to define a continued fraction expansion of elements
in a function field of a curve by expanding as a Laurent series in a
local parameter. Considering the square root of a polynomial \(\sqrt{D(t)}\) leads to an interesting
theory related to polynomial Pell equations. Unlike the classical Pell
equation, the corresponding polynomial equation is not always solvable
and its solvability is related to arithmetic conditions on the Jacobian
(or generalized Jacobian) of the curve defined by \(y^2=D(t)\). In this setting, it has been
shown by Zannier that the sequence of the degrees of the partial
quotients of the continued fraction expansion of \(\sqrt{D(t)}\) is always periodic, even when
the expansion itself is not. In this article we work out in detail the
case in which the curve \(y^2=D(t)\)
has genus 0, establishing explicit geometric conditions corresponding to
the appearance of partial quotients of certain degrees in the continued
fraction expansion. We also show that there are non-trivial polynomials
\(D(t)\) with non-periodic expansions
such that infinitely many partial quotients have degree greater than
one.
@article{MR4595292,
author = {Ballini, Francesco and Veneziano, Francesco},
title = {Hyperelliptic continued fractions in the singular case of
genus zero},
journal = {Atti Accad. Naz. Lincei Rend. Lincei Mat. Appl.},
fjournal = {Atti della Accademia Nazionale dei Lincei. Rendiconti Lincei. Matematica e Applicazioni},
volume = {33},
year = {2022},
number = {4},
pages = {795--832},
issn = {1120-6330,1720-0768},
mrclass = {11J70 (11A55 14H50 40A15)},
mrnumber = {4595292},
doi = {10.4171/rlm/989},
url = {https://doi.org/10.4171/rlm/989},
eprint = {2108.06560},
eprinttype = {arxiv},
eprintclass = {math.NT}
}
2021. Explicit height bounds for \(K\)-rational points on transverse
curves in powers of elliptic curves. Pacific J. Math., 315(2): 477–503. Francesco Veneziano and Evelina Viada.
Let \(C\) be an algebraic curve
embedded transversally in a power \(E^N\) of an elliptic curve \(E\) with complex multiplication. We produce
a good explicit bound for the height of all the algebraic points on
\(C\) contained in the union of all
proper algebraic subgroups of \(E^N\).
The method gives a totally explicit version of the Manin–Demjanenko
theorem in the elliptic case and complements previous results only
proved when \(E\) does not have complex
multiplication.
@article{MR4366750,
author = {Veneziano, Francesco and Viada, Evelina},
title = {Explicit height bounds for {$K$}-rational points on transverse
curves in powers of elliptic curves},
journal = {Pacific J. Math.},
fjournal = {Pacific Journal of Mathematics},
volume = {315},
year = {2021},
number = {2},
pages = {477--503},
issn = {0030-8730},
mrclass = {11G50 (14G40)},
mrnumber = {4366750},
mrreviewer = {Gabriel Andreas Dill},
doi = {10.2140/pjm.2021.315.477},
url = {https://doi.org/10.2140/pjm.2021.315.477},
eprint = {2006.02538},
eprinttype = {arxiv},
eprintclass = {math.NT}
}
2020. A note on the zeroes of the Fredholm series. Atti Accad. Naz. Lincei Rend. Lincei Mat. Appl., 31(4): 651–666. Umberto Zannier.
The issue had been raised whether the function \(z+z^2+\dotsb+z^{2^n}+\dotsb\), sometimes
called Fredholm series, has infinitely many zeroes in the unit
disk. We provide an affirmative answer, proving that in fact every
complex number occurs as a value infinitely many times, even restricting
the function to any open set meeting the unit circle.
@article{MR4215674,
author = {Zannier, Umberto},
title = {A note on the zeroes of the {Fredholm} series},
titleaddon = {With an appendix by Francesco Veneziano},
journal = {Atti Accad. Naz. Lincei Rend. Lincei Mat. Appl.},
fjournal = {Atti della Accademia Nazionale dei Lincei. Rendiconti Lincei. Matematica e Applicazioni},
volume = {31},
year = {2020},
number = {4},
pages = {651--666},
issn = {1120-6330},
mrclass = {30B10 (30B30)},
mrnumber = {4215674},
doi = {10.4171/rlm/909},
url = {https://doi.org/10.4171/rlm/909},
eprint = {2006.11922},
eprinttype = {arxiv},
eprintclass = {math.CV}
}
2019. An effective criterion for periodicity of \(\ell\)-adic continued fractions. Math. Comp., 88(318): 1851–1882. Laura Capuano, Francesco Veneziano, and Umberto Zannier.
The theory of continued fractions has been generalized to \(\ell\)-adic numbers by several
authors and presents many differences with respect to the real case. In
the present paper we investigate the expansion of rationals and
quadratic irrationals for the l-adic continued fractions introduced by
Ruban. In this case, rational numbers may have a periodic
non-terminating continued fraction expansion; moreover, for quadratic
irrational numbers, no analogue of Lagrange’s theorem holds. We give
general explicit criteria to establish the periodicity of the expansion
in both the rational and the quadratic case (for rationals, the
qualitative result is due to Laohakosol.
@article{MR3925488,
author = {Capuano, Laura and Veneziano, Francesco and Zannier, Umberto},
fjournal = {Mathematics of Computation},
issn = {0025-5718},
journal = {Math. Comp.},
mrclass = {11J70 (11D88 11Y16)},
mrnumber = {3925488},
mrreviewer = {Jeffrey O. Shallit},
number = {318},
pages = {1851--1882},
title = {An effective criterion for periodicity of {$\ell$}-adic continued fractions},
doi = {10.1090/mcom/3385},
url = {https://doi.org/10.1090/mcom/3385},
volume = {88},
year = {2019}
}
2019. The explicit Mordell conjecture for families of
curves. Forum Math. Sigma, 7: Paper No. e31, 62. Sara Checcoli, Francesco Veneziano, and Evelina Viada. With an appendix by M. Stoll.
In this article we prove the explicit Mordell Conjecture for large families of curves. In addition, we introduce a method, of easy application, to compute all rational points on curves of quite general shape and increasing genus. The method bases on some explicit and sharp estimates for the height of such rational points, and the bounds are small enough to successfully implement a computer search. As an evidence of the simplicity of its application, we present a variety of explicit examples and explain how to produce many others. In the appendix our method is compared in detail to the classical method of Manin-Demjanenko and the analysis of our explicit examples is carried to conclusion.
@article{MR4010563,
author = {Checcoli, Sara and Veneziano, Francesco and Viada, Evelina},
fjournal = {Forum of Mathematics. Sigma},
journal = {Forum Math. Sigma},
mrclass = {11G50 (11G30 11Y50 14G40)},
mrnumber = {4010563},
mrreviewer = {Robin de Jong},
pages = {Paper No. e31, 62},
eid = {e31},
pagetotal = {62},
title = {The explicit {Mordell} conjecture for families of curves},
note = {With an appendix by M. Stoll},
doi = {10.1017/fms.2019.20},
url = {https://doi.org/10.1017/fms.2019.20},
volume = {7},
year = {2019}
}
2018. Pisot unit generators in number fields. J. Symbolic Comput., 89: 94–108. TomášVávra and Francesco Veneziano.
Pisot numbers are real algebraic integers bigger than 1, whose other conjugates all have modulus smaller than 1. In this paper we deal with the algorithmic problem of finding the smallest Pisot unit generating a given number field. We first solve this problem in all real fields, then we consider the analogous problem involving the so called complex Pisot numbers and we solve it in all number fields that admit such a generator, in particular this includes all fields without CM.
@article{MR3804808,
author = {{V\'avra}, Tom{\'a}{\v s} and Veneziano, Francesco},
fjournal = {Journal of Symbolic Computation},
issn = {0747-7171},
journal = {J. Symbolic Comput.},
mrclass = {11K16},
mrnumber = {3804808},
mrreviewer = {Gerem\'{\i}as Polanco},
pages = {94--108},
title = {{Pisot} unit generators in number fields},
doi = {10.1016/j.jsc.2017.11.005},
url = {https://doi.org/10.1016/j.jsc.2017.11.005},
volume = {89},
year = {2018}
}
2017. On the explicit Torsion Anomalous Conjecture. Trans. Amer. Math. Soc., 369(9): 6465–6491. Sara Checcoli, Francesco Veneziano, and Evelina Viada.
The Torsion Anomalous Conjecture states that an irreducible variety
\(V\) embedded in a semi-abelian
variety contains only finitely many maximal \(V\)-torsion anomalous varieties. In this
paper we consider an irreducible variety embedded in a product of
elliptic curves. Our main result provides a totally explicit bound for
the Néron-Tate height of all maximal \(V\)-torsion anomalous points of relative
codimension one in the non-CM case, and an analogous effective result in
the CM case. As an application, we obtain the finiteness of such points.
In addition, we deduce some new explicit results in the context of the
effective Mordell-Lang Conjecture; in particular we bound the
Néron-Tate height of the rational points of an explicit
family of curves of increasing genus.
@article{MR3660229,
author = {Checcoli, Sara and Veneziano, Francesco and Viada, Evelina},
fjournal = {Transactions of the American Mathematical Society},
issn = {0002-9947},
journal = {Trans. Amer. Math. Soc.},
mrclass = {11G50 (11G05 14G40)},
mrnumber = {3660229},
mrreviewer = {Yu Yasufuku},
number = {9},
pages = {6465--6491},
title = {On the explicit Torsion Anomalous Conjecture},
doi = {10.1090/tran/6893},
url = {https://doi.org/10.1090/tran/6893},
volume = {369},
year = {2017}
}
2014. On torsion anomalous intersections. Atti Accad. Naz. Lincei Rend. Lincei Mat. Appl., 25(1): 1–36. Sara Checcoli, Francesco Veneziano, and Evelina Viada.
A deep conjecture on torsion anomalous varieties states that if \(V\) is a weak-transverse variety in an
abelian variety, then the complement \(V^{ta}\) of all \(V\)-torsion anomalous varieties is open and
dense in \(V\). We prove some cases of
this conjecture. We show that the \(V\)-torsion anomalous varieties of relative
codimension one are non-dense in any weak-transverse variety \(V\) embedded in a product of elliptic
curves with CM. We give explicit uniform bounds in the dependence on
\(V\). As an immediate consequence we
prove the conjecture for \(V\) of
codimension two in a product of CM elliptic curves. We also point out
some implications on the effective Mordell-Lang Conjecture.
@article{MR3180478,
author = {Checcoli, Sara and Veneziano, Francesco and Viada, Evelina},
fjournal = {Atti della Accademia Nazionale dei Lincei. Rendiconti Lincei. Matematica e Applicazioni},
issn = {1120-6330},
journal = {Atti Accad. Naz. Lincei Rend. Lincei Mat. Appl.},
mrclass = {11G50 (14G40)},
mrnumber = {3180478},
mrreviewer = {Dimitrios Poulakis},
number = {1},
pages = {1--36},
title = {On torsion anomalous intersections},
doi = {10.4171/RLM/666},
url = {https://doi.org/10.4171/RLM/666},
volume = {25},
year = {2014}
}
2012. A sharp Bogomolov-type bound. New York J. Math., 18: 891–910. Sara Checcoli, Francesco Veneziano, and Evelina Viada.
We prove a sharp lower bound for the essential minimum of a nontranslate variety in certain abelian varieties. This uses and generalises a result of Galateau. Our bound is a new step in the direction of an abelian analogue by David and Philippon of a toric conjecture of Amoroso and David and has applications in the framework of anomalous intersections.
@article{MR2991428,
author = {Checcoli, Sara and Veneziano, Francesco and Viada, Evelina},
fjournal = {New York Journal of Mathematics},
journal = {New York J. Math.},
mrclass = {11J95 (11G10 11G50)},
mrnumber = {2991428},
mrreviewer = {Aur{\'e}lien Galateau},
pages = {891--910},
title = {A sharp {Bogomolov}-type bound},
url = {http://nyjm.albany.edu:8000/j/2012/18_891.html},
volume = {18},
year = {2012}
}
2011. Quadratic Integral Solutions to Double Pell. Rend. Semin. Mat. Univ. Padova, 126: 47–61. Francesco Veneziano.
We study the quadratic integral points—that is, (\(S\)-)integral points defined over any
extension of degree two of the base field—on a curve defined in \(\mathbb{P}^3\) by a system of two Pell
equations. Such points belong to three families explicitly described, or
belong to a finite set whose cardinality may be explicitly bounded in
terms of the base field, the equations defining the curve and the set
\(S\). We exploit the peculiar geometry
of the curve to adapt the proof of a theorem of Vojta, which in this
case does not apply.
@article{MR2918198,
author = {Veneziano, Francesco},
fjournal = {Rendiconti del Seminario Matematico della Universit{\`a} di Padova. Mathematical Journal of the University of Padua},
isbn = {978-88-7784-335-7},
issn = {0041-8994},
journal = {Rend. Semin. Mat. Univ. Padova},
mrclass = {11D09},
mrnumber = {2918198},
mrreviewer = {Hizuru Yamagishi},
pages = {47--61},
title = {Quadratic Integral Solutions to Double {Pell} Equations},
doi = {10.4171/RSMUP/126-3},
url = {https://doi.org/10.4171/RSMUP/126-3},
volume = {126},
year = {2011}
}
Book Chapters
2019. Hyperelliptic Continued Fractions and Generalized
Jacobians. In Clemens Fuchs and Wüstholz Gisbert, editors, Arithmetic and Geometry: Ten Years in Alpbach, Annals of Mathematics Studies, pages 56–101. Princeton University Press, Princeton, NJ, edition. Laura Capuano, Peter Jossen, Christina Karolus, and Francesco Veneziano.
@incollection{AlpbachChapterCJKV,
author = {Capuano, Laura and Jossen, Peter and Karolus, Christina and Veneziano, Francesco},
title = {Hyperelliptic Continued Fractions and Generalized {Jacobians}},
subtitle = {Minicourse Given by {Umberto} {Zannier}},
booktitle = {Arithmetic and Geometry: Ten Years in Alpbach},
booktitleaddon = {AMS-202},
series = {Annals of Mathematics Studies},
number = {202},
editor = {Fuchs, Clemens and Gisbert, W{\"u}stholz},
type = {chapter},
chapter = {3},
pages = {56--101},
isbn = {9780691193786},
publisher = {Princeton University Press, Princeton, NJ},
year = {2019},
mrclass = {11G30 (11A55 14)},
mrnumber = {4353100},
doi = {https://doi.org/10.2307/j.ctvfrxrcd.6},
url = {http://www.jstor.org/stable/j.ctvfrxrcd.6}
}
Conference proceedings
August 2024. Learning to Play 7 Wonders Duel Without Human Supervision. In 2024 IEEE Conference on Games (CoG), pages 1–4. August. Giovanni Paolini, Lorenzo Moreschini, Francesco Veneziano, and Alessandro Iraci.
This paper introduces ZeusAI, an artificial intelligence system developed to play the board game 7 Wonders Duel. Inspired by the AlphaZero reinforcement learning algorithm, ZeusAI relies on a combination of Monte Carlo Tree Search and a Transformer Neural Network to learn the game without human supervision. ZeusAI competes at the level of top human players, develops both known and novel strategies, and allows us to test rule variants to improve the game’s balance. This work demonstrates how AI can help in understanding and enhancing board games.
@inproceedings{ProceedingsZeusAI,
author = {Paolini, Giovanni and Moreschini, Lorenzo and Veneziano, Francesco and Iraci, Alessandro},
booktitle = {2024 IEEE Conference on Games (CoG)},
title = {Learning to Play 7 Wonders Duel Without Human Supervision},
year = {2024},
month = aug,
volume = {},
number = {},
pages = {1--4},
eventtitle = {2024 IEEE Conference on Games},
eventdate = {2024-08-05},
venue = {Milano, Italy},
keywords = {Monte Carlo methods;Neural networks;Games;Reinforcement learning;Learning (artificial intelligence);Transformers;Artificial Intelligence;Reinforcement Learning;7 Wonders Duel;Board Game Strategy;Board Game Enhancement},
issn = {2325-4289},
doi = {10.1109/CoG60054.2024.10645555},
eprint = {2406.00741},
archiveprefix = {arXiv},
eprinttype = {arxiv},
primaryclass = {cs.AI},
eprintclass = {cs.AI}
}
2018. An effective criterion for periodicity of \(\ell\)-adic continued fractions. In Numeration 2018, pages 73–74. Francesco Veneziano.
@inproceedings{ProceedingsNumeration,
author = {Veneziano, Francesco},
title = {An effective criterion for periodicity of $\ell$-adic continued fractions},
booktitle = {Numeration 2018},
pages = {73--74},
year = {2018},
eventtitle = {Numeration 2018},
eventdate = {2018-05-22},
venue = {Universit{\'e} Paris Diderot},
url = {https://numeration2018.sciencesconf.org/data/pages/num18_abstracts.pdf}
}
2011. Punti interi quadratici su curve di genere 1 definite da una doppia
equazione di Pell. In Atti del XIX Congresso dell'Unione Matematica Italiana, page 946. Unione Matematica Italiana. Francesco Veneziano.
@inproceedings{ProceedingsUMI,
author = {Veneziano, Francesco},
title = {Punti interi quadratici su curve di genere 1 definite da una doppia equazione di {Pell}},
booktitle = {Atti del XIX Congresso dell'Unione Matematica Italiana},
pages = {946},
year = {2011},
eventtitle = {XIX Congresso dell'Unione Matematica Italiana},
eventdate = {2011-09-12},
organization = {Unione Matematica Italiana},
venue = {University of Bologna},
language = {Italian},
url = {http://umi.dm.unibo.it/umi/congressi/}
}
Preprints
2026. Achieving Expert-Level Performance in 7 Wonders Duel Through Deep Reinforcement Learning. Giovanni Paolini, Lorenzo Moreschini, Francesco Veneziano, and Alessandro Iraci.
2025. On the disk of convergence of algebraic power series. Francesco Veneziano and Umberto Zannier.
2025. \(p\)-adically convergent loci in
varieties arising from periodic continued fractions. Laura Capuano, Marzio Mula, Lea Terracini, and Francesco Veneziano.