FLINT is a C library concerned mainly with efficient arithmetic in basic rings like $\mathbb{Q}[x]$, used in SageMath, Oscar, and elsewhere. We give a brief introduction to FLINT and discuss its current strengths and weaknesses for high performance algebraic computing. We will also present the upcoming FLINT 3.0 release. Notable changes include a new vectorized small-prime FFT, a C implementation of generic rings, and merging with the Arb, Calcium and Antic libraries.

For decades, Libre software has had a deep and fruitful relationship with research, as tool, outcome, or object of study. Painting an exhaustive landscape in a few tens of minutes will be a task for historians, especially so since the needs and practices greatly vary from one field to the other. In this talk, we will simply highlight some fundamental trends -- typology of software, development and funding models -- from a personal perspective, with the aim to trigger experience sharing among participants.

We introduce a new lattice basis reduction algorithm with approximation guarantees analogous to the LLL algorithm and practical performance that far exceeds the current state of the art. We achieve these results by iteratively applying precision management techniques within a recursive algorithm structure and show the stability of this approach. We analyze the asymptotic behavior of our algorithm, and show that the heuristic running time is $O(n^{\omega}(C+n)^{1+\varepsilon})$ for lattices of dimension $n$, $\omega\in (2,3]$ bounding the cost of size reduction, matrix multiplication, and QR factorization, and $C$ bounding the log of the condition number of the input basis $B$. This yields a running time of $O\left(n^\omega (p + n)^{1 + \varepsilon}\right)$ for precision $p = O(\log \|B\|_{max})$ in common applications. Our algorithm is fully practical, and we have published our implementation. We experimentally validate our heuristic, give extensive benchmarks against numerous classes of cryptographic lattices, and show that our algorithm significantly outperforms existing implementations.

The Cado-NFS software was used in the latest computational records for integer factoring and the computation of discrete logarithms in finite fields. Beyond that, it is also a rather versatile piece of software whose building blocks can be used in many similar computations. This talk will describe both the general context of the Number Field Sieve as well as the specifics of the Cado-NFS implementation, and highlight to which extent it can be used as a research platform for the investigation of variations of this algorithm for other purposes.

First released in 1988, CoCoA is a special-purpose system for doing Computations in Commutative Algebra. It is freely available under GPL, and offers CoCoALib, the C++ library, which is the mathematical heart; a computation server; and CoCoA-5, the interactive system.
CoCoA is optimized for working with multivariate polynomials, their ideals and modules, and operations on these objects. Other special strengths of CoCoA include polynomial factorization, exact linear algebra, Hilbert functions, zero-dimensional schemes, and toric ideals. CoCoALib also offers some facilities for exploring the world of approximate algebra (real roots of polynomials, twin-float arithmetic, approximate border bases, ..).
CoCoA-5 provides its own programming language which places great emphasis on being easy and natural to use (dynamically typed) for mathematicians. It can also be used as an interactive interface for other libraries (includes libnormaliz, Frobby, MathSAT, ..).
CoCoALib was designed to be an open source library: we focus on clear and comprehensible code, also providing quite good run-time performance. The inheritance mechanism of C++ plays a crucial role, especially in the challenge of reconciling the traditionally conflicting goals of mathematical abstraction and efficiency.

In this talk, I'll introduce the number theory module of Oscar, starting from the basics like number fields, ring of integers and ideals to class groups, class fields, Galois theory and Galois cohomology.

The LiePRing Package of GAP gives access to the classification by O'Brien and Vaughan-Lee (2005) of p-groups and nilpotent Lie rings of order dividing $p^7$ for all primes $p>5$. More precisely, it contains parametrised presentations for the considered Lie rings, it provides some methods to compute with these Lie rings and it gives access to an implementation by de Graaf of the Lazard correspondence that determines the associated p-group for a Lie ring in the database. The talk gives an overview on all of this and exhibits some open problems and desiderata.

The computer algebra system Macaulay2 (M2) was initially designed to appeal to commutative algebraists and algebraic geometers. In its more than 30 years of existence M2 attracted mathematicians and computer scientists coming from many neighboring areas. Many of them have appetite for resource-intensive casework of various kinds: one typical use case for M2 is to search for examples or counterexamples over large families of mathematical objects.
Among many developments in the recent years, the support for parallel computation has been introduced both in the kernel of M2 and in the top-level interpreted language. We will showcase several examples and discuss the M2 future regarding distributed and high-performance computing.

Proofs of Retrievability are protocols which allow a Client to store data remotely and to efficiently ensure, via audits, that the entirety of that data is still intact. Dynamic Proofs of Retrievability (DPoR) also support efficient retrieval and update of any small portion of the data. We propose a novel protocol for arbitrary outsourced data storage that achieves both low remote storage size and audit complexity. A key ingredient, that can be also of intrinsic interest, reduces to efficiently evaluating a secret polynomial at given public points, when the (encrypted) polynomial is stored on an untrusted Server. The Server performs the evaluations and also returns associated certificates. A Client can check that the evaluations are correct using the certificates and some pre-computed keys, more efficiently than re-evaluating the polynomial. Our protocols support two important features: the polynomial itself can be encrypted on the Server, and it can be dynamically updated by changing individual coefficients cheaply without redoing the entire setup. We present in this talk some implementations of these methods, using linearly homomorphic encryption and pairings, and show good performance for polynomial evaluations with millions of coefficients, and efficient distant (e.g. transatlantic) DPoR with terabytes of data.

Crouzeix’s conjecture is among the most intriguing developments in matrix theory in recent years. Made in 2004 by Michel Crouzeix, it postulates that, for any polynomial \(p\) and any matrix A , \(\|p(A)\| \le 2 \max\{|p(z)|: z \in W(A)\}\), where the norm is the 2-norm and \( W(A) \) is the field of values (numerical range) of \(A\), that is the set of points attained by \( v^*Av \) for some vector \(v\) of unit length. Crouzeix proved in 2007 that the inequality above holds if \(2\) is replaced by \(11.08\), and in 2016 this was greatly improved by Palencia, replacing \( 2 \) by \( 1+\sqrt{2} \). Furthermore, it is known that the conjecture holds in a number of special cases. We use nonsmooth optimization to investigate the conjecture numerically by locally minimizing the “Crouzeix ratio”, defined as the quotient with numerator the right-hand side and denominator the left-hand side of the conjectured inequality. We use Chebfun to compute the boundary of the fields of values and BFGS for the optimization, computing the Crouzeix ratio at billions of data points. We also present local nonsmooth variational analysis of the Crouzeix ratio at conjectured global minimizers. All our results strongly support the truth of Crouzeix’s conjecture.

Since forcing everyone to switch to elliptic curve cryptography, computational number theorists have spun out of control and now feel entitled to dump their crazy sh..eaves on the world.
It started with the Supersingular Isogeny Diffie-Hellman key exchange (SIDH/SIKE), a monstrosity birthed from the minds of two deranged mathematicians in UWaterloo. With a laughable pretense of post-quantum security, they tried to compel engineers all over the world to learn about isogenies of elliptic curves over finite fields and walks in Ramanujan graphs. Luckily, after 10 years of toil, their foolish plan was foiled last summer... by more number theorists using even crazier tools!
You would think people had learned their lesson and stopped listening to these mad wannabe cryptographers, right? Wrong! They're coming back, with a new end-of-the-world device named SQIsign. They blabber about an esoteric connection they call "The Deuring Correspondence", some sort bridge between supersingular isogenies and ideals of maximal orders of quaternion algebras. They want you to believe your smartwatch will be running their amateurish 55Klocs C code in a few years from now. And who's to stop them? No one! They get even invited to YOUR conference!
In this talk I will reveal leaked documents exposing their evil conspiracy. I will guide you through the incomprehensible intricacies of the Deuring correspondence and its dark ritual named KLPT. I will describe the challenges one has to face to put into code these madmen and women's hallucinated plan that no God-fearing computer algebra system would ever dare implement. These crooks must be stopped, and we need your help!

The DifferentialAlgebra project, lead by François Boulier, aims at providing BLAD, a C library dedicated to Ritt and Kolchin differential algebra, and BMI, a library providing interface packages for various scientific computing software such as Maple, Sagemath, Python / Sympy... Recent functionalities will be presented through several applications of differential algebra technics (quasi-equilibrium approximation, fraction decoupling, ...). URL: https://codeberg.org/francois.boulier/DifferentialAlgebra

In a parametric ODE model, a parameter is called structurally identifiable if its value can be uniquely determined from the input-output data, assuming the absence of noise and sufficiently exciting inputs. This identifiability property is a natural prerequisite for practical parameter estimation, and, therefore, it is an important step in the experimental design process. The problem of assessing identifiability has been studied since the 70-s and several approaches, all relying at least partially on computer algebra, have been proposed. At the moment there are at least a dozen software tools to assess different types of structural identifiability. I will talk about three of them in the development of which I have been involved: SIAN written in Maple, web-based Structural Identifiability Analyzer, and StructuralIdentifiability.jl. I will describe the algorithms and design decisions behind these tools, current challenges and future plans, and some experience of interactions with the end users who are typically far outside of the computer algebra community.

The solution of sparse systems of linear equations is a key computational kernel in scientific computing. It often represents the most time, memory and energy consuming part of the whole numerical simulation process. Therefore, it is critical to design efficient sparse solvers. In this talk, we focus on sparse direct solvers, which are well-known for their numerical robustness and accuracy. We present recent key features of sparse direct solvers that enable to efficiently solve large real and complex systems, and that have led to a strong gain of interest of these methods in many applications. We also illustrate how today challenges related to heterogeneity of computers, energy control, mixed-precision arithmetics, new models and applications, motivate new research in the field of sparse direct solvers. We finally mention how the sparse direct solver MUMPS is supported by research and industrial collaborations.