# Verified Software Competitions

## Introduction

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 or greater 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 not available any more from the website.

#### 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

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