Mapping accessibility in Belgium: a tool for land-use and transport planning?

This paper compares the spatial structure of car accessibility to towns and to railway stations during peak and off-peak hours in Belgium for the country’s 2616 municipalities. A clustering method is applied. It is shown that in a highly urbanised country, the situation is far from being spatially equitable in terms of accessibility, and some areas are more favoured than others. Congestion increases spatial inequalities, differently according to absolute or relative measures of change. By means of examples, this paper shows that even simple accessibility indicators could be useful to support decisions taken by planners and politicians (e.g. as regards the development of residential, industrial and business park areas). Maps indicate the spatial inequalities in terms of accessibility to urban centres and transport nodes, and the impact of congestion on these inequalities. The absolute and relative time losses due to congestion affect different areas in different ways. The location of new developments further increases the congestion problem and the spatial disparities. This paper also insists on the caution that should be adopted when measuring and interpreting “accessibility”, its measurements, its inputs, its temporal changes in absolute and relative terms as well as the need for spatially disaggregated data.     

Cognitive bubbles

Smith et al. (Econometrica 56(5):1119, 1988) reported large bubbles and crashes in experimental asset markets, a result that has been replicated many times. Here we test whether the occurrence of bubbles depends on the experimental subjects’ cognitive sophistication. In a two-part experiment, we first run a battery of tests to assess the subjects’ cognitive sophistication and classify them into low or high levels. We then invite them separately to two asset market experiments populated only by subjects with either low or high cognitive sophistication. We observe classic bubble and crash patterns in markets populated by subjects with low levels of cognitive sophistication. Yet, no bubbles or crashes are observed with our sophisticated subjects, indicating that cognitive sophistication of the experimental market participants has a strong impact on price efficiency.     

IMPERFECTLY INFORMED VOTERS AND STRATEGIC EXTREMISM

We analyze a two‐candidate Downsian model considering that voters use shortcuts (e.g., interest‐group/media endorsements) to infer candidates' policy platforms. That is, voters do not observe candidates' exact platforms but only which candidate offers the more leftist/rightist platform (relative positions). In equilibrium, candidates' behavior tends to maximum extremism, but it may converge or diverge depending on how voters behave when indifferent policywise between the candidates. When the tie‐breaking rule used by the voters is sufficiently fair, candidates converge to the extreme preferred by the median voter, but when it strongly favors a certain candidate, each candidate specializes in a different extreme.     

HOW DO SPATIAL SPILLOVERS DIFFUSE IN SCIENCE–INDUSTRY INTERACTIONS? THE CASE OF FRENCH BIOTECH SECTOR

The objective of this article is to study the interactions that exist between public research and private research in the French biotechnology sector. These interactions are observable at a double level. On the one hand, public research can influence private research, and conversely. Researchers of these two spheres develop important relations of cooperation. We then seek to identify these mutual influences and to measure their spatial dimension. Using asymptotic least squares method, we show that spillovers can diffuse through cooperation in upstream and downstream phases of the innovation process. On the other hand, spillovers resulting from public or private research, when measured by an external stock of knowledge, would be located, in so far as they exist.     

Time-Varying Leverage and Basel III: A Look at Canadian Evidence

Why did the conventional leverage indicators not pick up any meaningful signal of the mounting systemic risk before the subprime crisis? They remained almost unchanged in recent decades, whereas the banking landscape underwent a tremendous metamorphosis. Market-oriented banking is characterized by a new type of systemic risk, a risk which essentially evolves off the radar screen, i.e., off-balance sheet (OBS) (Calmès and Théoret Journal of Banking and Finance 34 (7): 1719–1728, 2010, 2011). In this article, we argue that the standard leverage indicators are not fitted to capture this kind of new banking risk. We introduce a new empirical framework which enables us to exploit the cyclical properties of elasticity leverage measures, while at the same time controlling for the noisy information they usually deliver. In a nutshell, thanks to the Kalman filter, we are able to compute optimal levels of bank leverage. This methodology delivers cyclical, forward-looking measures signalling systemic risk bubbles years before their burst. By properly accounting for all activities, including market-oriented banking, these time-varying leverage measures tend to systemically capture regulatory capital arbitrage and the OBS risk it entails.     

Consistent risk management: Three models outlined

This article introduces three models on how to understand the demand for consistent risk management. The first model, which accords with traditional risk analysis, is called the Standard Model. In this model, the decisive criterion of whether or not to accept a risk is if the total benefit exceeds the total cost. Since this model cannot protect the individual from unfair risk exposure two more models are outlined. The arguments in the Model of Inviolable Rights and in the Model of Procedural Justice evolve around the separateness of individuals, rights and fair risk taking. It is argued that risk management needs to acknowledge a variety of morally salient factors to avoid exposing people unfairly to risks.     

Solvable local and stochastic volatility models: supersymmetric methods in option pricing

In this paper we provide an extensive classification of one- and two-dimensional diffusion processes which admit an exact solution to the Kolmogorov (and hence Black–Scholes) equation (in terms of hypergeometric functions). By identifying the one-dimensional solvable processes with the class of integrable superpotentials introduced recently in supersymmetric quantum mechanics, we obtain new analytical solutions. In particular, by applying supersymmetric transformations on a known solvable diffusion process (such as the Natanzon process for which the solution is given by a hypergeometric function), we obtain a hierarchy of new solutions. These solutions are given by a sum of hypergeometric functions, generalizing the results obtained in a paper by Albanese et al. (Albanese, C., Campolieti, G., Carr, P. and Lipton, A., Black–Scholes goes hypergeometric. Risk Mag., 2001, 14, 99–103). For two-dimensional processes, more precisely stochastic volatility models, the classification is achieved for a specific class called gauge-free models including the Heston model, the 3?/?2-model and the geometric Brownian model. We then present a new exact stochastic volatility model belonging to this class.     

Portfolio optimization under model uncertainty and BSDE games

We consider robust optimal portfolio problems for markets modeled by (possibly non-Markovian) Itô–Lévy processes. Mathematically, the situation can be described as a stochastic differential game, where one of the players (the agent) is trying to find the portfolio that maximizes the utility of her terminal wealth, while the other player (“the market”) is controlling some of the unknown parameters of the market (e.g., the underlying probability measure, representing a model uncertainty problem) and is trying to minimize this maximal utility of the agent. This leads to a worst case scenario control problem for the agent. In the Markovian case, such problems can be studied using the Hamilton–Jacobi–Bellman–Isaacs (HJBI) equation, but these methods do not work in the non-Markovian case. We approach the problem by transforming it into a stochastic differential game for backward stochastic differential equations (a BSDE game). Using comparison theorems for BSDEs with jumps we arrive at criteria for the solution of such games in the form of a kind of non-Markovian analogue of the HJBI equation. The results are illustrated by examples.