Logical Foundations of Multilevel Databases

International audienceIn this paper, we propose a formal model for multilevel databases. This model aims at being a generic model, that is it can be interpreted for any kind of database (relational, object-oriented...). Our model has three layers. The first layer corresponds to a model for a non-protected database. The second layer corresponds to a model for a multilevel database. In this second layer, we propose a list of theorems that must be respected in order to build a secure multilevel database. We also propose a new solution to manage cover stories without using the ambiguous technique of polyinstantiation. The third layer corresponds to a model for a MultiView database, that is, a database that provides at each security level a consistent view of the multilevel database. Finally, as an illustration, we interpret our 3-layer model in the case of an object-oriented database

The Contextual Database of the Generations and Gender Program

The increasing recognition that the study of human behaviors has to take into account the multiple contexts in which they occur has opened a promising research avenue in social sciences. It also presents new challenges, e.g., to complement micro-level surveys with the collection of meaningful contextual data within a common conceptual framework. The Contextual Database of the Generations and Gender Program aims at responding to the new data demands by providing a comparative collection of around 210 variables on a national and sub-national level, thus complementing the individual-level data collected in the Generations and Gender Survey.World, comparative analysis, data banks

ScratchMaths: evaluation report and executive summary

Since 2014, computing has been part of the primary curriculum. ‘Scratch’ is frequently used by schools, and the EEF funded this trial to test whether the platform could be used to improve pupils’ computational thinking skills, and whether this in turn could have a positive impact on Key Stage 2 maths attainment. Good computational thinking skills mean pupils can use problem solving methods that involve expressing problems and their solutions in ways that a computer could execute – for example, recognising patterns. Previous research has shown that pupils with better computational thinking skills do better in maths. The study found a positive impact on computational thinking skills at the end of Year 5 – particularly for pupils who have ever been eligible for free school meals. However, there was no evidence of an impact on Key Stage 2 maths attainment when pupils were tested at the end of Year 6. Many of the schools in the trial did not fully implement ScratchMaths, particularly in Year 6, where teachers expressed concerns about the pressure of Key Stage 2 SATs. But there was no evidence that schools which did implement the programme had better maths results. Schools may be interested in ScratchMaths as an affordable way to cover aspects of the primary computing curriculum in maths lessons without any adverse effect on core maths outcomes. This trial, however, did not provide evidence that ScratchMaths is an effective way to improve maths outcomes

The potential application of the blackboard model of problem solving to multidisciplinary design

The potential application of the blackboard model of problem solving to multidisciplinary design is discussed. Multidisciplinary design problems are complex, poorly structured, and lack a predetermined decision path from the initial starting point to the final solution. The final solution is achieved using data from different engineering disciplines. Ideally, for the final solution to be the optimum solution, there must be a significant amount of communication among the different disciplines plus intradisciplinary and interdisciplinary optimization. In reality, this is not what happens in today's sequential approach to multidisciplinary design. Therefore it is highly unlikely that the final solution is the true optimum solution from an interdisciplinary optimization standpoint. A multilevel decomposition approach is suggested as a technique to overcome the problems associated with the sequential approach, but no tool currently exists with which to fully implement this technique. A system based on the blackboard model of problem solving appears to be an ideal tool for implementing this technique because it offers an incremental problem solving approach that requires no a priori determined reasoning path. Thus it has the potential of finding a more optimum solution for the multidisciplinary design problems found in today's aerospace industries

Implementing Belief-Consistent Multilevel Secure Relational Data Model: Issues and Solutions

This paper summarizes our efforts in implementing a working multi-level secure database prototype. We have chosen Belief-Consistent Multilevel Secure Relational Data Model (BCMLS) as a basis for our prototype because of its comprehensive semantics for interpreting all stored information. While semantically superior to other models, this model has not been implemented as a working system before. Our prototype, which was created on an Informix database server with a PHP web client, enables insertion, deletion and update of multi-level data while addressing the underlying model complexities through a number of original solutions

Multilevel Hashing based Access Control for Authentication and Security in Relational Database Management System

The relational database is very widely used in these days and so as the relational database security is very vital to protect from different kinds of threats and attacks. The security of relational database is very important because now these days all data and information are stored in database by some form of database objects including user’s personal information like credit/debit card details, username, passwords etc. as well as confidential data of business organization and companies. Many researches are done in order to protect the relational database from these vulnerabilities but the methodologies of relational database security are not able to protect the relational database from all security issues. Authentication of users is an important issue in the database that is needed to be addressed most because it can give full access to the database objects. In this paper we present various security issues that can cause degradation in relational database security and we also identify various problems in the current database security policies. In this paper we propose the use of Multilevel Hashing based Access control mechanism for authentication and security in Relational database