<p>Syftet med den här uppsatsen är att undersöka om det finns en så kallad “vänstervridning” i Sveriges televisions nyhetsprogram. Det vill säga en favorisering av vänstern gentemot högern. Detta genom att undersöka nyhetsrapporteringen, i Rapport och Aktuellt, av i förväg valda ämnen.</p>

Syftet med den här uppsatsen är att undersöka om det finns en så kallad “vänstervridning” i Sveriges televisions nyhetsprogram. Det vill säga en favorisering av vänstern gentemot högern. Detta genom att undersöka nyhetsrapporteringen, i Rapport och Aktuellt, av i förväg valda ämnen.

Requirements engineering (RE) is a well-established practice that is also emphasized in safety standards such as IEC 61508 and ISO 26262. Safety standards advocate a particularly stringent RE where requirements must be structured in an hierarchical manner in accordance with the system architecture; at each level, requirements must be allocated to heterogeneous (SW, HW, mechanical, electrical, etc.) architecture elements and trace links must be established between requirements. In contrast to the stringent RE in safety standards, according to previous studies, RE in industry is in general of poor quality. Considering a typical RE tool, other than basic impact analysis, the tool neither gives feedback nor guides a user  when specifying, allocating, and structuring requirements. In practice, for industry to comply with the stringent RE in safety standards, better support for RE is needed, not only from tools, but also from principles and methods. Therefore, a foundation is presented consisting of an underlying theory for specifying heterogeneous systems and complementary principles and methods to specifically support the stringent RE in safety standards. This foundation is indeed suitable as a base for implementing guidance- and feedback-driven tool support for such stringent RE; however, the fact is that the proposed theory, principles, and methods provide essential support  regardless if tools are used or not. The underlying theory is a formal compositional contracts theory for heterogeneous systems. This contracts theory embodies the essential RE property of separating requirements on a system from assumptions on its environment. Moreover, the contracts theory formalizes the stringent RE effort of structuring requirements hierarchically with respect to the system architecture. Thus, the proposed principles and methods for supporting the stringent RE in safety standards are well-rooted in formal concepts and conditions, and are thus, theoretically sound. Not only that, but the foundation is indeed also tailored to be enforced by both existing and new tools considering that the support is based on precise mathematical expressions that can be interpreted unambiguously by machines. Enforcing the foundation in a tool entails support that guides and gives feedback when specifying heterogeneous systems in general, and safety-critical ones in particular. / Kravhantering är en väletablerad praxis som ocksåbetonas i säkerhetsstandarder såsom IEC 61508 och ISO 26262. Säkerhetsstandarder förespråkar en särskilt noggrann kravhantering där krav skall struktureras på ett hierarkiskt sätt i enlighet med systemarkitekturen; på varje nivå så skall krav allokeras till heterogena (SW, HW, mekaniska, elektriska, etc.) arkitekturelement och spårlänkar skall upprättas mellan kraven. I motsats till den noggranna kravhanteringen i säkerhetsstandarder så är kravhantering i industrin av allmänt dålig kvalitet enligt tidigare studier. Ett typisk kravverktyg ger inte mycket mer stöd än grundläggande konsekvensanalyser, d.v.s.\ verktyget ger varken återkoppling eller vägledning för att formulera, allokera, och strukturera krav. Bättre stöd behövs för att industrin i praktiken skall kunna förverkliga den noggranna kravhanteringen i säkerhetsstandarder -- inte bara stöd från verktyg, men också från kravhanteringsprinciper och metoder. Därför presenteras ett fundament bestående av en underliggande teori för specifiering av heterogena system, samt kompletterande principer och metoder för att stödja den noggranna kravhanteringen i säkerhetsstandarder. Detta fundament är lämplig som en bas för att kunna implementera verktyg som ger återkoppling och vägledning för kravhantering; likväl så ger den föreslagna teorin, principerna och metoderna essentiellt stöd oavsett om verktyg används eller inte. Den underliggande teorin är en kompositionell och formell kontraktsteori för heterogena system. Denna kontraktsteori ger konkret form åt den centrala kravhanteringsegenskapen att separera kraven på ett system från antaganden på dess omgivning. Dessutom så formaliserar kontraksteorin den noggranna uppgiften att hierarkiskt strukturera krav i enlighet med systemarkitekturen. Således så är de föreslagna principerna och metoderna för att stödja den noggranna kravhanteringen i säkerhetsstandarder välförankrade i formella begrepp och villkor och är därmed också teoretiskt sunda. Det erbjudna stödet är dessutom välanpassat för att kunna verkställas av såväl befintliga som nyaverktyg med tanke på att stödet är grundat på exakta matematiska uttryck som kan tolkas entydigt av maskiner. Verkställandet av fundamentet av ett verktyg medför stöd i form av vägledning och återkoppling vid specifiering av heterogena system i allmänhet, och säkerhetskritiska sådana i synnerhet. / <p>QC 20160909</p> / ESPRESSO

Given a formal model of the behavior of a system, an objective and some notion of control the goal of controller synthesis is to construct a (finite-state) controller that ensures that the system always satisfies the objective. Often, the controller can base its decisions only on limited observations of the system. This notion of limited observability induces a partial-information game between the controller and the uncontrollable part of the system. A successful controller then realizes an observation-based strategy that enforces the objective. In this thesis we consider the controller synthesis problem in the linear-time setting where the behavior of the system is given as a nondeterministic, labeled transitions system A, where the controller can only partially observe and control the behavior of A. The goal of the thesis is to develop a compositional approach for constructing controllers, suitable to treat conjunctive cascades of linear-time objectives P_1, P_2, ..., P_k in an online manner. We iteratively construct a controller C_1 for system A enforcing P_1, then a controller C_2 enforcing P_2 for the parallel composition of the first controller with the system, and so on. It is crucial for this approach that each controller C_i enforces P_i in a most general manner, being as permissive as possible. Otherwise, behavior that is needed to enforce subsequent objectives could be prematurely removed. Standard notions of strategies and controllers only allow the most general treatment for the limited class of safety objectives. We introduce a novel concept of most general strategies and controllers suited for the compositional treatment of objectives beyond safety. We demonstrate the existence of most general controllers for all enforceable, observation-based omega-regular objectives and provide algorithms for the construction of such most general controllers, with specialized variants for the subclass of safety and co-safety objectives. We furthermore adapt and apply our general framework for the compositional synthesis of most general controllers to the setting of exogenous coordination in the context of the channel-based coordination language Reo and the constraint automata framework and report on our implementation in the verification toolset Vereofy. The construction of most general controllers in Vereofy for omega-regular objectives relies on our tool ltl2dstar for generating deterministic omega-automata from Linear Temporal Logic (LTL) formulas. We introduce a generic improvement for exploiting insensitiveness to stuttering during the determinization construction and evaluate its effectiveness in practice. We further investigate the performance of recently proposed variants of Safra\'s determinization construction in practice.

Given a formal model of the behavior of a system, an objective and some notion of control the goal of controller synthesis is to construct a (finite-state) controller that ensures that the system always satisfies the objective. Often, the controller can base its decisions only on limited observations of the system. This notion of limited observability induces a partial-information game between the controller and the uncontrollable part of the system. A successful controller then realizes an observation-based strategy that enforces the objective. In this thesis we consider the controller synthesis problem in the linear-time setting where the behavior of the system is given as a nondeterministic, labeled transitions system A, where the controller can only partially observe and control the behavior of A. The goal of the thesis is to develop a compositional approach for constructing controllers, suitable to treat conjunctive cascades of linear-time objectives P_1, P_2, ..., P_k in an online manner. We iteratively construct a controller C_1 for system A enforcing P_1, then a controller C_2 enforcing P_2 for the parallel composition of the first controller with the system, and so on. It is crucial for this approach that each controller C_i enforces P_i in a most general manner, being as permissive as possible. Otherwise, behavior that is needed to enforce subsequent objectives could be prematurely removed. Standard notions of strategies and controllers only allow the most general treatment for the limited class of safety objectives. We introduce a novel concept of most general strategies and controllers suited for the compositional treatment of objectives beyond safety. We demonstrate the existence of most general controllers for all enforceable, observation-based omega-regular objectives and provide algorithms for the construction of such most general controllers, with specialized variants for the subclass of safety and co-safety objectives. We furthermore adapt and apply our general framework for the compositional synthesis of most general controllers to the setting of exogenous coordination in the context of the channel-based coordination language Reo and the constraint automata framework and report on our implementation in the verification toolset Vereofy. The construction of most general controllers in Vereofy for omega-regular objectives relies on our tool ltl2dstar for generating deterministic omega-automata from Linear Temporal Logic (LTL) formulas. We introduce a generic improvement for exploiting insensitiveness to stuttering during the determinization construction and evaluate its effectiveness in practice. We further investigate the performance of recently proposed variants of Safra\'s determinization construction in practice.