Analysing orchestrations with risk profiles and angel-daemon games

In this paper game theory is used to analyse the effect of a number of service failures during the execution of a grid orchestration. A service failure may be catastrophic in that it causes an entire orchestration to fail. Alternatively, a grid manager may utilise alternative services in the case of failure, allowing an orchestration to recover, A risk profile provides a means of modelling situations in a way that is neither overly optimistic nor overly pessimistic. Risk profiles are analysed using angel and daemon games. A risk profile can be assigned a valuation through an analysis of the structure of its associated Nash equilibria. Some structural properties of valuation functions, that show their validity as a measure for risk, are given. Two main cases are considered, the assessment of Orc expressions and the arrangement of a meeting using reputations.

Uncertainty in the Cloud: An Angel-Daemon Approach to Modelling Performance

Uncertainty profiles are used to study the effects of contention within cloud and service-based environments. An uncertainty profile provides a qualitative description of an environment whose quality of service (QoS) may fluctuate unpredictably. Uncertain environments are modelled by strategic games with two agents; a daemon is used to represent overload and high resource contention; an angel is used to represent an idealised resource allocation situation with no underlying contention. Assessments of uncertainty profiles are useful in two ways: firstly, they provide a broad understanding of how environmental stress can effect an application’s performance (and reliability); secondly, they allow the effects of introducing redundancy into a computation to be assessed

‘The Violence of History: Rosa Chacel’s Memorias de Leticia Valle’

Leticia Valle, the eleven-year-old narrator and protagonist of Rosa Chacel’s 1945 novel Memorias de Leticia Valle seduces and destroys her history teacher, Daniel. Here, I argue that Daniel represents traditionalist, right-wing interpretations of Spanish history while also recalling the importance of the colonial wars in Morocco in the build up to the Civil War, and the Nationalists’ use of Moroccan conscripts and recruits within the peninsula. Written at a time when history was being used to justify an armed rebellion, a civil war, and the imposition of a brutal dictatorship, Chacel’s novel depends on ellipses and absence to question historiographical principles. Furthermore, it combines continued reference to Spanish history with the use of violent and militant language. The most devastating conflict of all is between Leticia and Daniel: she silences and dehumanizes him, though she is not able to fully explain what happened. Writing from Switzerland, Chacel’s narrator takes possession of Spanish history at a time when dissent within Spain was being silenced by the Francoist regime.