Reseña: Comparison of two theorem provers: Isabelle/HOL and Coq

Se ha publicado un artículo de demostración asistida por ordenador titulado Comparison of two theorem provers: Isabelle/HOL and Coq.

Sus autores son

Su resumen es

The need for formal definition of the very basis of mathematics arose in the last century. The scale and complexity of mathematics, along with discovered paradoxes, revealed the danger of accumulating errors across theories. Although, according to Gödel’s incompleteness theorems, it is not possible to construct a single formal system which will describe all phenomena in the world, being complete and consistent at the same time, it gave rise to rather practical areas of logic, such as the theory of automated theorem proving. This is a set of techniques used to verify mathematical statements mechanically using logical reasoning. Moreover, it can be used to solve complex engineering problems as well, for instance, to prove the security properties of a software system or an algorithm. This paper compares two widespread tools for automated theorem proving, Isabelle/HOL and Coq, with respect to expressiveness, limitations and usability. For this reason, it firstly gives a brief introduction to the bases of formal systems and automated deduction theory, their main problems and challenges, and then provides detailed comparison of most notable features of the selected theorem provers with support of illustrative proof examples.

Reseña: A formal proof of the computation of Hermite normal form in a general setting

Se ha publicado un artículo de razonamiento formalizado en Isabelle/HOL sobre álgebra lineal titulado REGULAR-MT: A formal proof of the computation of Hermite normal form in a general setting.

Sus autores son Jose Divasón y Jesús Aransay (de la Universidad de la Rioja).

Su resumen es

In this work, we present a formal proof of an algorithm to compute the Hermite normal form of a matrix based on our existing framework for the formalisation, execution, and refinement of linear algebra algorithms in Isabelle/HOL. The Hermite normal form is a well-known canonical matrix analogue of reduced echelon form of matrices over fields, but involving matrices over more general rings, such as Bézout domains. We prove the correctness of this algorithm and formalise the uniqueness of the Hermite normal form of a matrix. The succinctness and clarity of the formalisation validate the usability of the framework.

El trabajo se presentará el 17 de septiembre en el AISC 2018 (13th International Conference on Artificial Intelligence and Symbolic Computation).

El código de las correspondientes teorías se encuentra aquí.

Reseña: Formalized linear algebra over elementary divisor rings in Coq

Se ha publicado un artículo de razonamiento formalizado en Coq sobre álgebra titulado Formalized linear algebra over elementary divisor rings in Coq.

Sus autores son

Su resumen es

This paper presents a Coq formalization of linear algebra over elementary divisor rings, that is, rings where every matrix is equivalent to a matrix in Smith normal form. The main results are the formalization that these rings support essential operations of linear algebra, the classification theorem of finitely presented modules over such rings and the uniqueness of the Smith normal form up to multiplication by units. We present formally verified algorithms computing this normal form on a variety of coefficient structures including Euclidean domains and constructive principal ideal domains. We also study different ways to extend Bézout domains in order to be able to compute the Smith normal form of matrices. The extensions we consider are: adequacy (i.e. the existence of a gdco operation), Krull dimension ≤1 and well-founded strict divisibility.

El trabajo se ha publicado en Logical Methods in Computer Science (Volume 12, Issue 2).

El código de las correspondientes teorías en Coq se encuentra aquí.

Reseña: Proving divide and conquer complexities in Isabelle/HOL

Se ha publicado un artículo de razonamiento formalizado en Isabelle/HOL sobre algorítmica titulado Proving divide and conquer complexities in Isabelle/HOL

Su autor es Manuel Eberl (de la Technische Universität München, Alemania).

Su resumen es

The Akra–Bazzi method, a generalisation of the well-known Master Theorem, is a useful tool for analysing the complexity of Divide & Conquer algorithms. This work describes a formalisation of the Akra–Bazzi method (as generalised by Leighton) in the interactive theorem prover Isabelle/HOL and the derivation of a generalised version of the Master Theorem from it. We also provide some automated proof methods that facilitate the application of this Master Theorem and allow mostly automatic verification of Θ-bounds for these Divide & Conquer recurrences. To our knowledge, this is the first formalisation of theorems for the analysis of such recurrences.

La versión final del trabajo se ha publicado en el Journal of Automated Reasoning.

El código de las correspondientes teorías en Isabelle/HOL se encuentra aquí.

Este artículo puede servir de lectura complementaria en los cursos de Razonamiento automático, Razonamiento asistido por ordenador y Lógica computacional y teoría de modelos.

Reseña: A decision procedure for univariate real polynomials in Isabelle/HOL

Se ha publicado un artículo de razonamiento formalizado en Isabelle sobre álgebra titulado A decision procedure for univariate real polynomials in Isabelle/HOL.

Su autor es Manuel Eberl (de la Technische Universität München, Alemania).

Su resumen es

Sturm sequences are a method for computing the number of real roots of a univariate real polynomial inside a given interval efficiently. In this paper, this fact and a number of methods to construct Sturm sequences efficiently have been formalised with the interactive theorem prover Isabelle/HOL. Building upon this, an Isabelle/HOL proof method was then implemented to prove interesting statements about the number of real roots of a univariate real polynomial and related properties such as non-negativity and monotonicity.

El trabajo se ha presentado en la CPP 2015 (The 4th ACM-SIGPLAN Conference on Certified Programs and Proofs).

El código de las correspondientes teorías en Isabelle/HOL se encuentra aquí.

Este artículo puede servir de lectura complementaria en los cursos de Razonamiento automático, Razonamiento asistido por ordenador y Lógica computacional y teoría de modelos.