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In this chapter we overview the main structures of epistemic and doxastic logic. We start by discussing the most celebrated models for epistemic logic, i.e., epistemic Kripke structures. These structures provide a very intuitive interpretation of the accessibility relation, based on the notion of information. This also naturally extends to the multi-agent case. Based on Kripke models, we then look at systems that add a temporal or a computational component, and those that provide a ‘grounded’ semantics for knowledge. We also pay special attention to ‘non-standard semantics’ for knowledge and belief, i.e., semantics that are not based on an underlying relation on the sets of states. In particular, we discuss here neighbourhood semantics and topological semantics. In all of these approaches, we can clearly point at streams of results that are inspired by work by Johan van Benthem. We are extremely pleased and honoured to be part of this book dedicated to his work and influences.

Background: Q fever is a zoonosis caused by Coxiella burnetii, a Gram negative bacterium present worldwide. Small ruminants are considered the main reservoirs for infection of humans. This study aimed to estimate the extent of C. burnetii infection among sheep and goats in part of The Gambia. Methodology/Principal Findings: This survey was carried out from March to May 2012 at two areas in The Gambia. The first area comprised a cluster of seven rural villages situated 5–15 km west of Farafenni as well as the local abattoir. A second sampling was done at the central abattoir in Abuko (30 km from the capital, Banjul) in the Western Region. Serum samples were obtained from 490 goats and 398 sheep. In addition, 67 milk samples were obtained from lactating dams. Sera were tested with a Q fever ELISA kit. C. burnetii DNA was extracted from milk samples and then detected using a specific quantitative multiplex PCR assay, targeting the IS1111a element. A multivariable mixed logistic regression model was used to examine the relationship between seropositivity and explanatory variables. An overall seroprevalence of 21.6% was found. Goats had a significantly higher seroprevalence than sheep, respectively 24.2% and 18.5%. Seropositive animals were significantly older than seronegative animals. Animals from the villages had a significantly lower seroprevalence than animals from the central abattoir (15.1% versus 29.1%). C. burnetii DNA was detected in 2 out of 67 milk samples, whereas 8 samples gave a doubtful result. Conclusion/Significance: A substantial C. burnetii seroprevalence in sheep and goats in The Gambia was demonstrated. People living in close proximity to small ruminants are exposed to C. burnetii. Q fever should be considered as a possible cause of acute febrile illness in humans in The Gambia. Future studies should include a simultaneous assessment of veterinary and human serology, and include aetiology of febrile illness in local clinics.

Q fever is a disease of humans, caused by Coxiella burnetii, and a large range of animals can be infected. This paper presents a review of the epidemiology of Q fever in humans and farm animals between 1982 and 2010, using case studies from four European countries (Bulgaria, France, Germany and the Netherlands). The Netherlands had a large outbreak between 2007 and 2010, and the other countries a history of Q fever and Q fever research. Within all four countries, the serological prevalence of C. burnetii infection and reported incidence of Q fever varies broadly in both farm animals and humans. Proximity to farm animals and contact with infected animals or their birth products have been identified as the most important risk factors for human disease. Intrinsic farm factors, such as production systems and management, influence the number of outbreaks in an area. A number of disease control options have been used in these four countries, including measures to increase diagnostic accuracy and general awareness, and actions to reduce spillover (of infection from farm animals to humans) and human exposure. This study highlights gaps in knowledge, and future research needs.

An analysis of 3,264 notifications for acute Q fever show that the patients were mostly men, smokers and persons aged 40–60 years. Pneumonia was the most common clinical presentation in >60% of patients. Fewer than 5% of the notified patients were working in the agriculture sector or meat-processing industry, including abattoirs. The outbreaks in the Netherlands can therefore not be explained by occupational exposure. To estimate the number of infections, including those that remain asymptomatic, notification rates were compared with seroconversion rates in blood donors from whom serial samples were available. This resulted in a ratio of one Q fever notification to 12.6 incident infections of Coxiella burnetii. Control measures during the epidemic in the Netherlands primarily focused on dairy goat farms. However, in many other countries, outbreaks have been associated with non-dairy sheep and the Netherlands has many more sheep than goats. Modelling of numbers of Q fever cases based on residential addresses and population size produced smooth incidence maps that clearly showed Q fever hotspots around infected dairy goat farms but not around infected meat sheep farms. An analysis of datasets on vegetation, land use, soil characteristics, and weather conditions in 5 km areas around infected farms suggest that intensive goat and sheep husbandry should be avoided in areas that are characterized by a combination of arable land with deep groundwater and little vegetation. Awareness of Q fever among patients and doctors can influence health seeking behaviour, laboratory testing practices, and the number of notifications. However, analysis of unbiased serological data from pregnant women in the high incidence area confirmed that presence of antibodies against C. burnetii is related to proximity to infected dairy goat farms. In a retrospective analysis the presence of antibodies against C. burnetii was not significantly associated with preterm delivery, low birth weight, or several other adverse outcome measures. This is in contrast to previous reports from the international literature. In a follow-up study of 686 patients with acute Q fever, 11 cases of chronic Q fever were identified based on serological profile, PCR results, and clinical presentation. In a comparison of various serological algorithms, IgG phase I titre ≥1:1,024 at 6 months had the most favourable sensitivity and positive predictive value for the detection of chronic Q fever. However, the diagnosis of chronic Q fever must be based primarily on clinical grounds. In the aftermath of the epidemic, with a seroprevalence >12% in the most affected area in the south of the country, questions remain about the follow-up of acute Q fever patients, screening of groups at risk for chronic Q fever, screening of donors of blood and tissue, and human vaccination.

Large outbreaks of Q fever in the Netherlands from 2007 to 2009 were monitored using notification data of acute clinical Q fever. However, the notification system provides no information on infections that remain subclinical or for which no medical attention is sought. The present study was carried out immediately after the peak of the 2009 outbreak to estimate the ratio between Coxiella burnetii infections and Q fever notifications. In 23 postcode areas in the high-incidence area, notification rates were compared with seroconversion rates in blood donors from whom serial samples were available. This resulted in a ratio of one Q fever notification to 12.6 incident infections of C. burnetii. This ratio is time and place specific and is based on a small number of seroconversions, but is the best available factor for estimating the total number of infections. In addition, as subclinical C. burnetii infection may lead to chronic Q fever, the ratio can be used to estimate the expected number of chronic Q fever patients in the coming years and as input for cost–benefit analyses of screening options.

We develop a formal model of opinion polls in elections and study how they influence the voting behaviour of the participating agents, and thereby election outcomes. This approach is particularly relevant to the study of collective decision making by means of voting in multiagent systems, where it is reasonable to assume that we can precisely model the amount of information available to agents and where agents can be expected to follow relatively simple rules when adjusting their behaviour in response to polls. We analyse two settings, one where a single agent strategises in view of a single poll, and one where multiple agents repeatedly update their voting intentions in view of a sequence of polls. In the single-poll setting we vary the amount of information a poll provides and examine, for different voting rules, when an agent starts and stops having an incentive to manipulate the election. In the repeated-poll setting, using both analytical and experimental methods, we study how the properties of different voting rules are affected under different sets of assumptions on how agents will respond to poll information. Together, our results clarify under which circumstances sharing information via opinion polls can improve the quality of election outcomes and under which circumstances it may have negative effects, due to the increased opportunities for manipulation it provides.

BACKGROUND: Q fever is an occupational risk for veterinarians, however little is known about the risk for veterinary medicine students. This study aimed to assess the seroprevalence of Coxiella burnetii among veterinary medicine students and to identify associated risk factors. METHODS: A cross-sectional study with questionnaire and blood sample collection was performed among all veterinary medicine students studying in The Netherlands in 2006. Serum samples (n = 674), representative of all study years and study directions, were analyzed for C. burnetii IgG and IgM phase I and II antibodies with an immunofluorescence assay (IFA). Seropositivity was defined as IgG phase I and/or II titer of 1:32 and above. RESULTS: Of the veterinary medicine students 126 (18.7%) had IgG antibodies against C. burnetii. Seropositivity associated risk factors identified were the study direction 'farm animals' (Odds Ratio (OR) 3.27 [95% CI 2.14-5.02]), advanced year of study (OR year 6: 2.31 [1.22-4.39] OR year 3-5 1.83 [1.07-3.10]) having had a zoonosis during the study (OR 1.74 [1.07-2.82]) and ever lived on a ruminant farm (OR 2.73 [1.59-4.67]). Stratified analysis revealed study direction 'farm animals' to be a study-related risk factor apart from ever living on a farm. In addition we identified a clear dose-response relation for the number of years lived on a farm with C. burnetii seropositivity. CONCLUSIONS: C. burnetii seroprevalence is considerable among veterinary medicine students and study related risk factors were identified. This indicates Q fever as an occupational risk for veterinary medicine students.

The growing number of logics has lead to the question: How do we compare two formalisms? A natural answer is: We can compare their expressive power and computational properties. There is, however, another way of comparing logics that has attracted attention recently, namely in terms of representational succinctness, i.e., we can ask whether one of the logics allows for a more "economical" encoding of information than the other. Using extended-syntax trees that correspond to game trees for the Addler-Immerman games, we prove that two well-known abbreviations in multimodal logic lead to an exponential increase in succinctness.

Following the emergence of a novel strain of influenza A(H1N1) in Mexico and the United States in April 2009, its epidemiology in Europe during the summer was limited to sporadic and localised outbreaks. Only the United Kingdom experienced widespread transmission declining with school holidays in late July. Using statistical modelling where applicable we explored the following causes that could explain this surprising difference in transmission dynamics: extinction by chance, differences in the susceptibility profile, age distribution of the imported cases, differences in contact patterns, mitigation strategies, school holidays and weather patterns. No single factor was able to explain the differences sufficiently. Hence an additive mixed model was used to model the country-specific weekly estimates of the effective reproductive number using the extinction probability, school holidays and weather patterns as explanatory variables. The average extinction probability, its trend and the trend in absolute humidity were found to be significantly negatively correlated with the effective reproduction number - although they could only explain about 3% of the variability in the model. By comparing the initial epidemiology of influenza A (H1N1) across different European countries, our analysis was able to uncover a possible role for the timing of importations (extinction probability), mixing patterns and the absolute humidity as underlying factors. However, much uncertainty remains. With better information on the role of these epidemiological factors, the control of influenza could be improved. UK Medical Research Council for Centre funding;European PCRD 7 (Flumodcont); Institute for the Promotion of Innovation by Science and Technology in Flanders (IWT), project number 060081 and by the IAP research network nr P6/03 of the Belgian Government (Belgian Science Policy)

We study a particular multiagent resource allocation problem with indivisible, but sharable resources. In our model, the utility of an agent for using a bundle of resources is the difference between the valuation of that bundle and a congestion cost (or delay), a figure formed by adding up the individual congestion costs of each resource in the bundle. The valuation and the delay can be agent-dependent. When the agents that share a resource also share the resource's control, the current users of a resource will require some compensation when a new agent wants to use the resource. We study the existence of distributed protocols that lead to a social optimum. Depending on constraints on the valuation functions (mainly modularity), on the delay functions (e.g., convexity), and the structural complexity of the deals between agents, we prove either the existence of some sequences of deals or the convergence of all sequences of deals to a social optimum. When the agents do not have joint control over the resources (i.e., they can use any resource they want), we study the existence of pure Nash equilibria. We provide results for modular valuation functions and relate them to results from the literature on congestion games.

The paper applies modal logic to formalize fragments of argumentation theory. Such formalization allows to import, for free, a wealth of new notions (e.g., argument equivalence), new techniques (e.g., calculi, model-checking games, bisimulation games), and results (e.g., completeness of calculi, adequacy of games, complexity of model-checking) from logic to argumentation.

Aggregating the judgments of a group of agents regarding a set of interdependent propositions can lead to inconsistent outcomes. One of the parameters involved is the agenda, the set of propositions on which agents are asked to express an opinion. We introduce the problem of checking the safety of the agenda: for a given agenda, can we guarantee that judgment aggregation will never produce an inconsistent outcome for any aggregation procedure satisfying a given set of axioms? We prove several characterisation results, establishing necessary and sufficient conditions for the safety of the agenda for different combinations of the most important axioms proposed in the literature, and we analyse the computational complexity of checking whether a given agenda satisfies these conditions.

The paper studies the interrelationships between the social-theoretic problems of preference and judgment aggregation from the perspective of formal logic. The result of the paper is twofold. On the one hand, preference aggregation on total preorders is proven equivalent to the aggregation of specific types of judgments. On the other hand, judgment aggregation on propositional logic is proven equivalent to the aggregation of specific types of preferences. This shows how the aggregation of preferences and judgments can be viewed, in fact, as the two faces of a same coin.

An important drawback to the popular Belief, Desire, and Intentions (BDI) paradigm is that such systems include no element of learning from experience. In particular, the so-called context conditions of plans, on which the whole model relies for plan selection, are restricted to be boolean formulas that are to be specified at design/implementation time. To address these limitations, we propose a novel BDI programming framework that, by suitably modeling context conditions as decision trees, allows agents to learn the probability of success for plans based on previous execution experiences. By using a probabilistic plan selection function, the agents can balance exploration and exploitation of their plans. We develop and empirically investigate two extreme approaches to learning the new context conditions and show that both can be advantageous in certain situations. Finally, we propose a generalization of the probabilistic plan selection function that yields a middle-ground between the two extreme approaches, and which we thus argue is the most flexible and simple approach.

In the multi-agent systems community, dependence theory and game theory are often presented as two alternative perspectives on the analysis of social interaction. Up till now no research has been done relating these two approaches. The unification presented provides dependence theory with the sort of mathematical foundations which still lacks, and shows how game theory can incorporate dependence-theoretic considerations in a fully formal manner.

We present a logical setting that incorporates a belief-revision mechanism within Dynamic-Epistemic logic. As the "static" basis for belief revision, we use epistemic plausibility models, together with a modal language based on two epistemic operators: a "knowledge" modality K (the standard S5, fully introspective, notion), and a "safe belief" modality ("weak", non-negatively-introspective, notion, capturing a version of Lehrer's "indefeasible knowledge"). To deal with "dynamic" belief revision, we introduce action plausibility models, representing various types of "doxastic events". Action models "act" on state models via a modified update product operation: the "Action- Priority" Update. This is the natural dynamic generalization of AGM revision, giving priority to the incoming information (i.e. to "actions") over prior beliefs. We completely axiomatize this logic, and show how our update mechanism can "simulate", in a uniform manner, many different belief-revision policies.

Hans van Ditmarsch and Barteld Kooi (2008). Semantic results for ontic and epistemic change. In: G. Bonanno, W. van der Hoek and M. Wooldridge (editors). Logic and the Foundations of Game and Decision Theory (LOFT 7). Texts in Logic and Games 3, pp. 87-117, Amsterdam University Press, Amsterdam.

Natuurontwikkeling is een instrument dat al geruime tijd wordt toegepast binnen het Nederlandse natuurbeleid. De resultaten zijn echter nogal wisselend en er bestaat een groeiende behoefte aan een adequate wijze van monitoring en evaluatie. In opdracht van LNV directie Kennis en DLG is daarom door Alterra een monitoringssystematiek uitgewerkt.

In Molden, David (Ed.). Water for food, water for life: a Comprehensive Assessment of Water Management in Agriculture. London, UK: Earthscan; Colombo, Sri Lanka: International Water Management Institute (IWMI).