Verified Software Competitions


Several software verification competitions have been organized last years, with different objectives and modalities. Some problems from these competitions have been selected and solved using the B method. For each of these problems, are provided:

  • a B model archive, containing the B models, the proof files (saved demonstration), the added mathematical rules (to be used during interactive proof)
  • a report:
    • explaining how the problem was tackled (possibly with several options), how the proof was conducted,
    • providing project metrics per component
    • showing the generated source code when executed
  • source code, generated by Atelier B from B models and handwritten for others files.

These projects should be replayed with Atelier B 4.1.0 with the parameters below. Copy the two lines, select your Atelier B project, open contextual menu, select « properties » then « resources file », paste the two lines at the end of the file, press « OK ».


VSTTE 2010

The VSTTE 2010 conference was organized August 16-19, 2010 in Edinburgh, Scotland (website). Problems are available here.

Problem 1: Sum and maximum

« Given an N-element array of natural numbers, write a program to compute the sum and the maximum of the elements in the array. »

Report     B Projet Archive     Source code

Problem 2: Inverting an injection

« Invert an injective array A on N elements in the subrange from 0 to N-1, i.e. the output array B must be such that B[A[i]] = i for 0 ≤ i ˂ N. You can assume that A is surjective. »

Report     B Projet Archive     Source code

Problem 3: Searching a Linked List

« Given a linked list representation of a list of integers, find the index of the first element that is equal to 0. »

Report     B Projet Archive     Source code

Problem 4: N-Queens

« Write a program to place N queens on an N*N chess board so that no queen can capture another one with a legal move. »

Report     B Projet Archive     Rodin Project Archive

VSTTE 2011

The COST IC701 Verification Competition 2011 was organized at the occasion of the conference on Formal Verification of Object-Oriented Software, held in 5-7 October, 2011, at Turin, Italy (website). Problems are available here.

Challenge 3: Two equal elements

« Given an integer array A of length n+2 with n>=2. It is known that at least two values stored in the array appear twice (i.e., there are at least two duplets). Implement and verify a program finding such two values. You may assume that the array contains values between 0 and n-1.« 

 Report        B Projet Archive     Source code

VSTTE 2012

The VSTTE 2012 conference was organized January 28-29, 2012 in Philadelphia, USA (website). Problems are available here.

Problem 1: Two-way sort

« We want to sort an array of Boolean values (assuming false < true) using only swaps. »

Report        B Projet Archive     Source code

Problem 3: Ring Buffer

« We want to implement a queue data structure using a ring buffer. »

Report        B Projet Archive     Source code