We present some improvements of our integral elimination algorithm. A new division algorithm for integral monomials is presented. A surprising simultaneous reduction of an expression by a set of integral polynomials is introduced. Logarithm expressions are added to our integral setting. Finally, previously unhandled examples are presented.

Summary Two essential problems in computer algebra, namely polynomial factorization and polynomial greatest common divisor computation, can be efficiently solved thanks to multiple polynomial evaluations in two variables using modular arithmetic. In this article, we focus on the efficient computation of such polynomial evaluations on one single CPU core. We first show how to leverage SIMD (single instruction, multiple data) computing for modular arithmetic on AVX2 and AVX‐512 units, using both intrinsics and OpenMP compiler directives. Then we manage to increase the operational intensity and to exploit instruction‐level parallelism in order to increase the compute efficiency of these polynomial evaluations. All this results in the end to performance gains up to about 5x on AVX2 and 10x on AVX‐512.

In this paper, we provide a differential algebra algorithm for integrating fractions of differential polynomials. It is not restricted to differential fractions that are the derivatives of other differential fractions. The algorithm leads to new techniques for representing differential fractions, which may help converting differential equations to integral equations (as for example used in parameter estimation).

We present two new algorithms based on Lie symmetries that respectively allow to semi-rectify algebraic systems and reduce the number of parameters on which the steady points of a differential system depend. These algorithms facilitate the qualitative analysis of algebraic and differential systems. They are designed with a strong view towards applications, such as modeling in biology. Their implementation, already available in our MABSys package, is of polynomial time complexity in the input size.

Given a regular chain T, we aim at finding an efficient way for computing a system of generators of Sat(T), the saturated ideal of T. A natural idea is to test whether the equality {T}=Sat(T) holds, that is, whether T generates its saturated ideal. By generalizing the notion of primitivity from univariate polynomials to regular chains, we establish a necessary and sufficient condition, together with a Grobner basis free algorithm, for testing this equality. Our experimental results illustrate the efficiency of this approach in practice.

We propose a new algorithm for converting a characteristic set of a prime differential ideal from one ranking into another. This differential algebra algorithm computes characteristic sets by change of ranking (ordering) for prime ideals. It identifies the purely algebraic subproblems which arise during differential computations and solves them algebraically. There are two improvements w.r.t. other approaches: formerly unsolved problems could be carried out; it is conceptually simple. Different variants are implemented.

In this paper, we give three theoretical and practical contributions for solving polynomial ODE or PDE systems. The first one is practical: an algorithm which improves the purely algebraic part of Rosenfeld—Gröbner (the polynomial ODE or PDE systems simplifier which is the core of the Maple 5.5 diffalg package). It is a variant of lextriangular but does not need any Gröbner basis computation. The second one is theoretical: a characterization of the output of Rosenfeld—Gröbner and a clarification of the existing relationship between algebraic and differential characteristic sets. The third one is theoretical as well as practical: an algorithm to compute canonical representatives of differential polynomials modulo regular differential ideals without any use of Gröbner bases. This algorithm simplifies the theory (somehow a “pedagogic” contribution) but permits us also to perform easily linear algebra over the base field in the factor differential ring defined by a regular differential ideal.