Tool-supported invariant-based programming

The development of correct programs is a core problem in computer science. Although formal verification methods for establishing correctness with mathematical rigor are available, programmers often find these difficult to put into practice. One hurdle is deriving the loop invariants and proving that the code maintains them. So called correct-by-construction methods aim to alleviate this issue by integrating verification into the programming workflow. Invariant-based programming is a practical correct-by-construction method in which the programmer first establishes the invariant structure, and then incrementally extends the program in steps of adding code and proving after each addition that the code is consistent with the invariants. In this way, the program is kept internally consistent throughout its development, and the construction of the correctness arguments (proofs) becomes an integral part of the programming workflow. A characteristic of the approach is that programs are described as invariant diagrams, a graphical notation similar to the state charts familiar to programmers. Invariant-based programming is a new method that has not been evaluated in large scale studies yet. The most important prerequisite for feasibility on a larger scale is a high degree of automation. The goal of the Socos project has been to build tools to assist the construction and verification of programs using the method. This thesis describes the implementation and evaluation of a prototype tool in the context of the Socos project. The tool supports the drawing of the diagrams, automatic derivation and discharging of verification conditions, and interactive proofs. It is used to develop programs that are correct by construction. The tool consists of a diagrammatic environment connected to a verification condition generator and an existing state-of-the-art theorem prover. Its core is a semantics for translating diagrams into verification conditions, which are sent to the underlying theorem prover. We describe a concrete method for 1) deriving sufficient conditions for total correctness of an invariant diagram; 2) sending the conditions to the theorem prover for simplification; and 3) reporting the results of the simplification to the programmer in a way that is consistent with the invariantbased programming workflow and that allows errors in the program specification to be efficiently detected. The tool uses an efficient automatic proof strategy to prove as many conditions as possible automatically and lets the remaining conditions be proved interactively. The tool is based on the verification system PVS and i uses the SMT (Satisfiability Modulo Theories) solver Yices as a catch-all decision procedure. Conditions that were not discharged automatically may be proved interactively using the PVS proof assistant. The programming workflow is very similar to the process by which a mathematical theory is developed inside a computer supported theorem prover environment such as PVS. The programmer reduces a large verification problem with the aid of the tool into a set of smaller problems (lemmas), and he can substantially improve the degree of proof automation by developing specialized background theories and proof strategies to support the specification and verification of a specific class of programs. We demonstrate this workflow by describing in detail the construction of a verified sorting algorithm. Tool-supported verification often has little to no presence in computer science (CS) curricula. Furthermore, program verification is frequently introduced as an advanced and purely theoretical topic that is not connected to the workflow taught in the early and practically oriented programming courses. Our hypothesis is that verification could be introduced early in the CS education, and that verification tools could be used in the classroom to support the teaching of formal methods. A prototype of Socos has been used in a course at Åbo Akademi University targeted at first and second year undergraduate students. We evaluate the use of Socos in the course as part of a case study carried out in 2007.

L'Indicateur des locations : guides des locataires : publication spéciale des annonces de ventes d'immeubles, renseignements et avis divers ...

1862/07/15 (N1)-1862/07/30.

L'Indicateur des locations : guides des locataires : publication spéciale des annonces de ventes d'immeubles, renseignements et avis divers ...

1862/08/01 (N2)-1862/08/15.

L'Indicateur des locations : guides des locataires : publication spéciale des annonces de ventes d'immeubles, renseignements et avis divers ...

Etat de collection : juillet 1862 (n° 1-30). août 1862 (n° 2-15)

Indicent reporting in shipping. Experiences and best practices for the Baltic Sea

Incident and near miss reporting is one of the proactive tools of safety management. By analyzing incidents and near misses and by corrective actions, severe accidents can potentially be avoided. Near miss and incident reporting is widely used in many riskprone industries such as aviation or chemical industry. In shipping incident and near miss reporting is required by the mandatory safety management system International Safety Management Code (ISM Code). However, in several studies the conclusion has been that incidents are reported poorly in the shipping industry. The aim of this report is to highlight the best practices for incident reporting in shipping and to support the shipping industry in the better utilization of incident reporting information. The study consists of three parts: 1) voluntary, shared reporting systems in shipping (international experiences), 2) interview study at four shipping companies in Sweden and in Finland (best practices), 3) expert workshop on incident reporting (problems and solutions). Preconditions for a functional reporting system are an existing no blame culture, commitment of the top management, feedback, good communication, training and an easy-to-use system. Although preconditions are met, problems can still appear, for example due to psychological, interpersonal or nationality-related reasons. In order to keep the reporting system functioning, the shipping company must be committed to maintain and develop the system and to tackle the problems. The whole reporting process from compiling, handling and analyzing a report, creating corrective actions and implementing them has to be handled properly in order to gain benefits from the reporting system. In addition to avoiding accidents, the functional reporting system can also offer other benefits by increasing safety awareness, by improving the overall safety and working conditions onboard, by enhancing team work and communication onboard and between ships and the land-based organization of shipping companies. Voluntary shared reporting systems are supported in the shipping industry in principle, but their development in the Baltic Sea is still in its infancy and the potential benefits of sharing the reports have not been realized. On the basis of this study we recommend that a common reporting system be developed for the Baltic Sea area which all the ships operating in the area could use regardless of their flag. Such a wider system could prevent some of the problems related to the current national systems. There would be more incident cases available in the database and this would support anonymity and thus encourage shipping companies to report to a shared database more frequently. A shared reporting system would contribute to the sharing of experiences and to the wider use of incident information in the shipping industry.

Fraud detection in the banking sector : a multi-agent approach

Fraud is an increasing phenomenon as shown in many surveys carried out by leading international consulting companies in the last years. Despite the evolution of electronic payments and hacking techniques there is still a strong human component in fraud schemes. Conflict of interest in particular is the main contributing factor to the success of internal fraud. In such cases anomaly detection tools are not always the best instruments, since the fraud schemes are based on faking documents in a context dominated by lack of controls, and the perpetrators are those ones who should control possible irregularities. In the banking sector audit team experts can count only on their experience, whistle blowing and the reports sent by their inspectors. The Fraud Interactive Decision Expert System (FIDES), which is the core of this research, is a multi-agent system built to support auditors in evaluating suspicious behaviours and to speed up the evaluation process in order to detect or prevent fraud schemes. The system combines Think-map, Delphi method and Attack trees and it has been built around audit team experts and their needs. The output of FIDES is an attack tree, a tree-based diagram to ”systematically categorize the different ways in which a system can be attacked”. Once the attack tree is built, auditors can choose the path they perceive as more suitable and decide whether or not to start the investigation. The system is meant for use in the future to retrieve old cases in order to match them with new ones and find similarities. The retrieving features of the system will be useful to simplify the risk management phase, since similar countermeasures adopted for past cases might be useful for present ones. Even though FIDES has been built with the banking sector in mind, it can be applied in all those organisations, like insurance companies or public organizations, where anti-fraud activity is based on a central anti-fraud unit and a reporting system.

Avaliação de microcalcificações mamárias de acordo com as classificações do Breast Imaging Reporting and Data System (BI-RADS TM) e de Le Gal

OBJETIVO: avaliar a acurácia da mamografia para o diagnóstico de microcalcificações mamárias suspeitas, com as classificações do Breast Imaging Reporting and Data System (BI-RADS TM) e Le Gal em comparação com o resultado histopatológico utilizado como padrão-ouro. MÉTODOS: foram selecionados dos arquivos dos blocos cirúrgicos, 130 casos operados com mamografias contendo somente microcalcificações mamárias, inicialmente classificadas como suspeitas sem lesões detectáveis ao exame clínico. Estas foram reclassificadas por dois examinadores, utilizando as classificações de Le Gal e BI-RADS TM, obtendo-se diagnóstico de consenso. As biópsias foram revistas por dois patologistas e foi obtido diagnóstico de consenso. A leitura das mamografias e a revisão das lâminas foram feitas em duplo-cego. As análises estatísticas utilizadas neste estudo foram o teste do chi2, o modelo Fleiss quadrático para VPP e o programa Epi-Info 6.0. RESULTADOS: a correlação entre a análise histopatológica e mamográfica, usando BI-RADS TM e Le Gal, mostrou a mesma sensibilidade de 96,4%, especificidade de 55,9 e 30,3%, valor preditivo positivo (VPP) de 37,5% e 27,5% e acurácia de 64,6 e 44,6%, respectivamente. Quando discriminamos por categorias de BI-RADS TM, obtivemos VPPs: categoria 2, 0%; categoria 3, 1,8%; categoria 4, 31,6% e categoria 5, 60%. Os VPPs pela classificação de Le Gal foram: categoria 2, 3,1%; categoria 3, 18,1 %; categoria 4, 26,4%; categoria 5, 66,7% e não classificável, 5,2%. CONCLUSÕES: observou-se uma maior precisão com a classificação de BI-RADS TM, porém não se conseguiu reduzir a ambigüidade na avaliação das microcalcificações mamárias.

Our publication fund - what have we learnt?

Presentation at the Nordic Perspectives on Open Access and Open Science seminar, Helsinki, October 15, 2013

Harmonization of Environmental Costs and Investments Reporting

The objective of this Master’s Thesis is to examine the current state of environmental costs and investments reporting at Stora Enso in the Business Area of Printing and Reading. Differences and the factors causing the differences in environmental costs and investments reporting are examined in order to further harmonize the reporting between the mills. Research method is a case study, which comprises 11 paper mills. Environmental costs are studied from year 2012 and environmental investments from year 2011 or from 2012 depending on the mill. The results show that there are two types of differences such as actual and harmonisable affecting to environmental costs reporting. Actual differences result from factors such as location and technical features of the mill. Harmonisable differences represent differences, which distort the actual differences. Factors that cause harmonisable differences are identification and traceability of environmental costs as well as interpretation of the instructions. Estimation of the environmental share of indirect environmental investments causes differences between the mills in environmental investments reporting, as it has to be done case-by-case judgments. A further research could consider a detailed examination of the data registering process in order to further improve traceability of environmental costs. Furthermore, identification and reporting of potential savings could be studied from environmental point of view as resource efficiency is an increasing interest.

Data management as a part of performance management: Case study about production reporting development project

Because of the increased availability of different kind of business intelligence technologies and tools it can be easy to fall in illusion that new technologies will automatically solve the problems of data management and reporting of the company. The management is not only about management of technology but also the management of processes and people. This thesis is focusing more into traditional data management and performance management of production processes which both can be seen as a requirement for long lasting development. Also some of the operative BI solutions are considered in the ideal state of reporting system. The objectives of this study are to examine what requirements effective performance management of production processes have for data management and reporting of the company and to see how they are effecting on the efficiency of it. The research is executed as a theoretical literary research about the subjects and as a qualitative case study about reporting development project of Finnsugar Ltd. The case study is examined through theoretical frameworks and by the active participant observation. To get a better picture about the ideal state of reporting system simple investment calculations are performed. According to the results of the research, requirements for effective performance management of production processes are automation in the collection of data, integration of operative databases, usage of efficient data management technologies like ETL (Extract, Transform, Load) processes, data warehouse (DW) and Online Analytical Processing (OLAP) and efficient management of processes, data and roles.