Some conservative stopping rules for the operational testing of
Bev Littlewood, Peter Popov, Lorenzo Strigini, Nick Shryane
Modelling the effects of combining
Analyses of Software Failure Data (2007)
Sarah Brocklehurst, Karama Kanoun, Jean-Claude Laprie, Bev Littlewood, Sylvain Metge, Peter Mellor, ...
In this paper we present and analyse a new set of software failure data which shows the failure behaviour, over a period of four years, of a single-user work station which was installed at the City...
Bev Littlewood, Peter Popov, Lorenzo Strigini, Nick Shryane
Modelling the effects of combining
The limits to the reliability that can be claimed for a design-diverse faulttolerant system are mainly determined by the dependence that must be expected in the failure behaviours of the different...
Phyllis Frankl, Cis Dept, Dick Hamlet, Bev Littlewood, Lorenzo Strigini
Testing methods are compared in a model where program failures are detected and the software changed to eliminate them. The question considered is whether it is better to use tests that seek out...
Intended Recipients: Public distribution Confidentiality: Cleared for publication (2007)
Contact Lorenzo Strigini, Document Location, Lorenzo Strigini's Macintosh, Bev Littlewood, Lorenzo Strigini
Title of Document: A discussion of practices for enhancing diversity in software designs
Recent models for the failure behaviour of systems involving redundancy and diversity have shown that common mode failures can be accounted for in terms of the variability of the failure probability...
Some conservative stopping rules for the operational testing of
Newcastle-upon-Tyne NE1 7RU (2007)
Bev Littlewood, Sarah Brocklehurst, Norman Fenton, Peter Mellor, David Wright, John Dobson, ...
Ideally, a measure of the security of a system should capture quantitatively the intuitive notion of `the ability of the system to resist attack'. That is, it should be operational, reflecting...
software reliability model (2007)
May Barghout, Bev Littlewood, Abdalla Abdel-ghaly
A non-parametric order statistics
Ross Anderson, James Backhouse, Ewart Carson, Patrik O’brian Holt, Roland Ibbett, Ray Ison, ...
Contact email address: confidential AT nhs.it.info (replace “ AT “ by “@”) Extracted from the online dossier at
Redundancy and Diversity in Security (2004)
Bev Littlewood, Lorenzo Strigini
Abstract. Redundancy and diversity are commonly applied principles for fault tolerance against accidental faults. Their use in security, which is attracting increasing interest, is less general and...
Redundancy and Diversity in Security (2004)
Bev Littlewood, Lorenzo Strigini
Abstract. Redundancy and diversity are commonly applied principles for fault tolerance against accidental faults. Their use in security, which is attracting increasing interest, is less general and...
Assessing the Reliability of Diverse Fault-Tolerant Software-based Systems (2002)
Bev Littlewood, Peter Popov, Lorenzo Strigini
Design diversity between redundant channels is a way of improving the dependability of software-based systems, but it does not alleviate the difficulties of dependability assessment. Assuming failure...
Design Diversity: an Update from Research on Reliability Modelling (2001)
Bev Littlewood, Peter Popov, Lorenzo Strigini
Diversity between redundant subsystems is, in various forms, a common design approach for improving system dependability. Its value in the case of software-based systems is still controversial. This...
Modelling Software Design Diversity - a Review (2001)
Bev Littlewood, Peter Popov, Lorenzo Strigini
Design diversity has been used for many years now as a means of achieving a degree of fault tolerance in software-based systems. Whilst there is clear evidence that the approach can be expected to...
Software reliability and dependability: a roadmap (2000)
Bev Littlewood, Lorenzo Strigini
Software's increasing role creates both requirements for being able to trust it more than before, and for more people to know how much they can trust their software. A sound engineering approach...
The Use of Proof in Diversity Arguments,” in (2000)
The limits to the reliability that can be claimed for a design-diverse faulttolerant system are mainly determined by the dependence that must be expected in the failure behaviours of the different...
The Problems of Assessing Software Reliability ...When you really need to depend on it (2000)
This paper looks at the ways in which the reliability of software can be assessed and predicted. It shows that the levels of reliability that can be claimed with scientific justification are...
Software reliability and dependability: a roadmap (2000)
Bev Littlewood, Lorenzo Strigini
Shifting the focus from software reliability to user-centred measures of dependability in complete software-based systems. Influencing design practice to facilitate dependability assessment....
Peter Popov, Lorenzo Strigini, Bev Littlewood
the same title, PP_DD_TR-06_v1.0) Fault tolerant systems based on the use of software design diversity may be able to achieve high levels of reliability more cost-effectively than other approaches,...
Assessment of the Reliability of Fault-Tolerant Software: a Bayesian Approach (2000)
Bev Littlewood, Peter Popov, Lorenzo Strigini
Fault tolerant systems based on the use of software design diversity may be able to achieve high levels of reliability more cost-effectively than other approaches, such as heroic debugging. Earlier...
N-Version Design Versus One Good Version (2000)
Bev Littlewood, Peter Popov, Lorenzo Strigini
Software Diversity as a way of achieving high reliability of software Software diversity has long been seen as way of achieving higher reliability of software than is attainable by a single software...
The Use of Proof in Diversity Arguments,” in (2000)
The limits to the reliability that can be claimed for a design-diverse faulttolerant system are mainly determined by the dependence that must be expected in the failure behaviours of the different...
Software reliability and dependability: a roadmap (2000)
Bev Littlewood, Lorenzo Strigini
Software's increasing role creates both requirements for being able to trust it more than before, and for more people to know how much they can trust their software. A sound engineering approach...
Bev Littlewood, Peter Popov, Lorenzo Strigini
It has been argued that functional diversity might be a plausible means of claiming independence of failures between two versions of a system. We present a model of functional diversity, in the...
Bev Littlewood, Lorenzo Strigini, David Wright
Abstract We report here on a continuation of work on the Bayesian Belief Network (BBN) model described in [Fenton, Littlewood et al. 1998]. As explained in the previous deliverable, our model...
Evaluating Testing Methods by Delivered Reliability (1998)
Phyllis Frankl, Cis Dept, Dick Hamlet, Bev Littlewood, Lorenzo Strigini
There are two main goals in testing software: (1) To achieve adequate quality (debug testing); the objective is to probe the software for defects so that these can be removed. (2) To assess existing...
Assessing dependability of safety critical systems using diverse evidence (1998)
Norman Fenton, Bev Littlewood, Martin Neil, Lorenzo Strigini, Alistair Sutcliffe, David Wright
Version 2.1
Some Conservative Stopping Rules for the Operational Testing of Safetycritical Software (1997)
: Operational testing, which aims to generate sequences of test cases with the same statistical properties as those that would be experienced in real operational use, can be used to obtain...
Some Conservative Stopping Rules for the Operational Testing of Safety-critical Software (1997)
Operational testing, which aims to generate sequences of test cases with the same statistical properties as those that would be experienced in real operational use, can be used to obtain quantitative...
Applying Bayesian Belief Networks to Systems Dependability Assessment (1996)
Martin Neil, Bev Littlewood, Norman Fenton
The dependability of technological systems is a growing social concern. Increasingly computer based systems are developed that carry the potential of increasing catastrophic consequences from single...
On Measurement of Operational Security (1994)
S. Brocklehurst, T. Olovsson, B. Littlewood, E. Jonsson, Sarah Brocklehurst, Bev Littlewood
Ideally, a measure of the security of a system should capture quantitatively the intuitive notion of `the ability of the system to resist attack'. That is, it should be operational, reflecting...
Towards Operational Measures of Computer Security (1993)
Bev Littlewood, Sarah Brocklehurst, Norman Fenton, Peter Mellor, David Wright, John Dobson, ...
Ideally, a measure of the security of a system should capture quantitatively the intuitive notion of ‘the ability of the system to resist attack’. That is, it should be operational, reflecting...
Validation of ultrahigh dependability for software-based systems (1993)
Bev Littlewood, Lorenzo Strigini
Modern society depends on computers for a number of critical tasks in which failure can have very high costs. As a consequence, high levels of dependability (reliability, safety, etc.) are required...
The CSR approach to software reliability prediction (1992)
S. Brocklehurst, B. Littlewood, Sarah Brocklehurst, Bev Littlewood
A plethora of software reliability models have been developed over the years but, in spite of extravagant claims for their efficacy, none can be trusted to give accurate results in all circumstances....
Limits to Evaluation of Software Dependability (1991)
inherent uncertainty It has been said that the term software engineering is an aspiration not a description. We would like to be able to claim that we engineer software, in the same sense that we...
Towards Operational Measures of Computer Security (1991)
Bev Littlewood, Sarah Brocklehurst, Norman Fenton, Peter Mellor, Stella Page, David Wright, ...
Ideally, a measure of the security of a system should capture quantitatively the intuitive notion of `the ability of the system to resist attack'. That is, it should be operational, reflecting...
Recalibrating Software Reliability Models (1990)
Sarah Brocklehurst, P Y Chan, Bev Littlewood, John Snell
In spite of much research effort, there is no universally applicable software reliability growth model which can be trusted to give accurate predictions of reliability in all circumstances. Worse, we...
Recalibrating Software Reliability Models (1990)
Sarah Brocklehurst, P. Y. Chan, Bev Littlewood, John Snell
Abstract-In spite of much research effort, there is no universally applicable software reliability growth model which can be trusted to give accurate predictions of reliability in all circumstances....