Workshop on Verification and Theorem Proving for Continuous Systems (NetCA Workshop 2005)

Oxford, UK, 26 August 200

Automated theorem proving for mathematics : real analysis in PVS

Computer Algebra Systems (CASs), such as Maple and Mathematica, are now widely used in both industry and education. In many areas of mathematics they perform well. However, many well-established methods in mathematics, such as definite integration via the fundamental theorem of calculus, rely on analytic side conditions which CASs in general do not support. This thesis presents our work with automatic, formal mathematics using the theorem prover PVS. Based on an existing real analysis library for PVS, we have implemented transcendental functions such as exp, cos, sin, tan and their inverses, and we have provided strategies to prove that a function is continuous at a given point. In general, this is undecidable, but using certain restrictions we can still provide proofs for a large collection of functions. Similarly, we can prove that a function has a limit at a point. We illustrate how the extended library may be used with Maple to provide correct results where Maple's are incorrect. We present a case study of definite integration in the CASs axiom. Maple, Mathematica and Matlab. The case study clearly shows that apart from axiom the systems do not fully check the necessary conditions for the definite integral to exist, thus giving results varying from plain incorrect to correct, even if the latter is difficult to detect without manipulating the result. The extension and correction of the PVS library consists of around 1000 theorems proven by around 18000 PVS proof commands. We also have a test suite of 88 lemmas for the automatic checks for continuity and existence of limits. Thus we have devised and tested automatic computational logic support for the use of formal mathematics in applications, particularly computer algebra

Applications of real number theorem proving in PVS

This work is supported by funding from the EPSRC under grants EP/H500162, EP/F02309X and GR/S31242Real number theorem proving has many uses, particularly for verification of safety critical systems and systems for which design errors may be costly. We discuss a chain of developments building on real number theorem proving in PVS. This leads from the verification of aspects of an air traffic control system, through work on the integration of computer algebra and automated theorem proving to a new tool, NRV, first presented here that builds on the capabilities of Maple and PVS to provide a verified and automatic analysis of Nichols plots. This automates a standard technique used by control engineers and greatly improves assurance compared with the traditional method of visual inspection of the Nichols plots.Publisher PDFPeer reviewe

Hidden verification for computational mathematics

AbstractWe present hidden verification as a means to make the power of computational logic available to users of computer algebra systems while shielding them from its complexity. We have implemented in PVS a library of facts about elementary and transcendental functions, and automatic procedures to attempt proofs of continuity, convergence and differentiability for functions in this class. These are called directly from Maple by a simple pipe-lined interface. Hence we are able to support the analysis of differential equations in Maple by direct calls to PVS for: result refinement and verification, discharge of verification conditions, harnesses to ensure more reliable differential equation solvers, and verifiable look-up tables

Workshop on Verification and Theorem Proving for Continuous Systems (NetCA Workshop 2005)

Abstract: The UK Network in Computer Algebra (NETCA) organised a workshop on various aspects of continuous systems verification, mainly with the focus on theorem proving. The workshop provides a forum for work in progress on new and emerging areas to be presented and discussed, and experiences to be shared. Contents Pag