kile under kde4 has automated spelling checking
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{
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\begin{abstract}
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%This chapter describes using diagrams to represent propositional logic.
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Propositial Logic Diagrams (PLD) have been designed to provide an intuitive method for visualising and manipulating
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Propositional Logic Diagrams (PLD) have been designed to provide an intuitive method for visualising and manipulating
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a specific sub-set of logic equations, to express fault modes in Mechanical and Electronic Systems.
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PLDs are a variant of constraint diagrams. Contours used to express
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sets represent failure modes and the Symptomatically merged groups
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@ -15,7 +15,7 @@ PLD Diagrams can also be used to model the structure of software
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and the flow of data through a computer program.
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This type of diagram can therefore
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integrate logical models from mechanical, electronic and software domains.
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Nearly all modern safety critical systems involve these three disiplines.
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Nearly all modern safety critical systems involve these three disciplines.
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%
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It is intended to be used for analysis of automated safety critical systems.
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Many types of safety critical systems now legally
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@ -35,7 +35,7 @@ for the analysis of safety critical software and hardware systems.
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}
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{
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\section{Intrduction}
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Propositial Logic Diagrams (PLD) have been designed to provide an intuitive method for visualising and manipulating
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Propositional Logic Diagrams (PLD) have been designed to provide an intuitive method for visualising and manipulating
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a specific sub-set of logic equations, to express fault modes in Mechanical and Electronic Systems.
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PLDs are a variant of constraint diagrams. Contours used to express
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sets represent failure modes and the Symptomatically merged groups
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@ -47,7 +47,7 @@ PLD Diagrams can also be used to model the structure of software
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and the flow of data through a computer program.
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This type of diagram can therefore
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integrate logical models from mechanical, electronic and software domains.
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Nearly all modern safety critical systems involve these three disiplines.
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Nearly all modern safety critical systems involve these three disciplines.
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%
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It is intended to be used for analysis of automated safety critical systems.
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Many types of safety critical systems now legally
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@ -86,7 +86,7 @@ for the analysis of safety critical software and hardware systems.
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}
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Propositional Logic Diagrams (PLDs) have been created
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to collect and simplfy fault~modes in safety critical systems undergoing
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to collect and simplify fault~modes in safety critical systems undergoing
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static analysis.%\cite{sccs}\cite{en61508}.
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%
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This type of analysis treats failure modes within a system as logical
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@ -96,7 +96,7 @@ within these systems, and aids the collection of
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common failure symptoms.
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%
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Contrasting this to looking at many propositional logic equations directly
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in a text editor or spreadsheet, a visual method is percieved as being more intuitive.
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in a text editor or spreadsheet, a visual method is perceived as being more intuitive.
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%Traditional set theory is often represented by Euler\cite{euler} or Spider\cite{spider}
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@ -166,7 +166,7 @@ can by occupied by `test points'.
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The `test points' may be joined by joining lines.
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A group of `test points' connected by joining lines
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is defined as a `test point disjunction' or Spider.
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Spiders may be labeled.
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Spiders may be labelled.
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%To differentiate these from common Euler diagram notation (normally used to represent set theory)
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%the curves are drawn using dotted and dashed lines.
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@ -218,7 +218,7 @@ $$ \mathbb{R}^{2} - \; \bigcup_{\hat{c} \in \hat{C}(\hat{d})}\hat{c}$$
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{
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\definition
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{
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Let d be a PLD and $ \mathcal{X} \subseteq \hat{C}(\hat{d})$ a set of countours.
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Let d be a PLD and $ \mathcal{X} \subseteq \hat{C}(\hat{d})$ a set of contours.
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If the set
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$$ \hat{z} = \bigcap_{c \in \mathcal{X}}
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{interior}
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@ -252,7 +252,7 @@ Each test point can be associated with the set of contours that enclose it.
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{
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\definition{ $ \mathcal{Z}_{d}:T(d)\rightarrow \mathcal{C}$ is a function
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associating a testpoint with a set of contours in the plane. This corresponds to the interior of the contours defining the zone.
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associating a test-point with a set of contours in the plane. This corresponds to the interior of the contours defining the zone.
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}
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}
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@ -834,7 +834,7 @@ at the module level have the same symptoms.
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The act of collecting common symptoms by joining lines is seen as intuitive.
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Syntax checking (looking for contradictions and tautologies), as well as detecting
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errors of ommission are automated in the FMMD tool.
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errors of omission are automated in the FMMD tool.
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\section{Double Simultaneous Fault Modelling}
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@ -845,7 +845,7 @@ that not only single component failure modes must be considered in
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analysis, but that the possibility of two component failing
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simultaneously must be considered.
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EN298 states that if a burner controller is in `lock out' (i.e. has detected a fault
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and has ordered a shutdown) a secondary fault cannot be allowed to put the equipement under control (the burner) into a dangerous state.
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and has ordered a shutdown) a secondary fault cannot be allowed to put the equipment under control (the burner) into a dangerous state.
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To cover this rigorously, we are bound to consider more than one fault being active at a time.
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\paragraph{Covering Double faults in a PLD Diagram}
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Because we are allowed to repeat contours in a PLD diagram,
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