Martingale characterizations of coherent acceptability measures

The coherent risk framework is linked to martingale valuation by adding hedgeinvariance as a fifth axiom, motivated by the concept of consistent hedging. The resulting subclass, called coherent pre-hedge (CoPr) measures, is characterized by a martingale condition on the test set that underlies a coherent measure. It is also made explicit how consistent hedging, optimal as well as non-optimal, transforms the test set of a given coherent measure into a martingale test set. These results are put in perspective of the fundamental theorems of asset pricing and the concept of valuation bounds

Free will, robots, and the axiom of choice

There are quite a number of similarities between the moral concept of choice and the mathematical axiom of choice. These similarities shed light on how to adapt law to solve cases that arise with the increasing “autonomy” of robots

Repairing Ontologies via Axiom Weakening.

Ontology engineering is a hard and error-prone task, in which small changes may lead to errors, or even produce an inconsistent ontology. As ontologies grow in size, the need for automated methods for repairing inconsistencies while preserving as much of the original knowledge as possible increases. Most previous approaches to this task are based on removing a few axioms from the ontology to regain consistency. We propose a new method based on weakening these axioms to make them less restrictive, employing the use of refinement operators. We introduce the theoretical framework for weakening DL ontologies, propose algorithms to repair ontologies based on the framework, and provide an analysis of the computational complexity. Through an empirical analysis made over real-life ontologies, we show that our approach preserves significantly more of the original knowledge of the ontology than removing axioms

A consistent multidimensional Pigou-Dalton transfer principle

The Pigou-Dalton principle demands that a regressive transfer decreases social welfare. In the unidimensional setting this principle is consistent, because regressivity in terms of attribute amounts and regressivity in terms of individual well-being coincide in the case of a single attribute. In the multidimensional setting, however, the relationship between the various attributes and well-being is complex. To formulate a multidimensional Pigou-Dalton transfer principle, a concept of wellbeing must therefore first be defined. We propose a version of the Pigou-Dalton principle that defines regressivity in terms of the individual well-being ranking that underlies the social ranking on which the principle is imposed. This well-being ranking (of attribute bundles) is induced from the social ranking over distributions in which all individuals have the same attribute bundle. It is shown that this new principle—the consistent Pigou-Dalton principle—imposes a quasi-linear structure on the well-being ranking. We discuss the implications of this result within the literature on multidimensional inequality measurement and within the literature on needs.Pigou-Dalton principle, Multidimensional inequality measurement, Majorization, Budget dominance, Needs, Weak equity axiom

Two Approaches to Ontology Aggregation Based on Axiom Weakening

Axiom weakening is a novel technique that allows for fine-grained repair of inconsistent ontologies. In a multi-agent setting, integrating ontologies corresponding to multiple agents may lead to inconsistencies. Such inconsistencies can be resolved after the integrated ontology has been built, or their generation can be prevented during ontology generation. We implement and compare these two approaches. First, we study how to repair an inconsistent ontology resulting from a voting-based aggregation of views of heterogeneous agents. Second, we prevent the generation of inconsistencies by letting the agents engage in a turn-based rational protocol about the axioms to be added to the integrated ontology. We instantiate the two approaches using real-world ontologies and compare them by measuring the levels of satisfaction of the agents w.r.t. the ontology obtained by the two procedures

A consistent multidimensional Pigou-Dalton transfer principle.

The Pigou-Dalton principle demands that a regressive transfer decreases social welfare. In the unidimensional setting this principle is consistent, because regressivity in terms of attribute amounts and regressivity in terms of individual well-being coincide in the case of a single attribute. In the multidimensional setting, however, the relationship between the various attributes and well-being is complex. To formulate a multidimensional Pigou-Dalton transfer principle, a concept of wellbeing must therefore first be defined. We propose a version of the Pigou-Dalton principle that defines regressivity in terms of the individual well-being ranking that underlies the social ranking on which the principle is imposed. This well-being ranking (of attribute bundles) is induced from the social ranking over distributions in which all individuals have the same attribute bundle. It is shown that this new principle—the consistent Pigou-Dalton principle—imposes a quasi-linear structure on the well-being ranking. We discuss the implications of this result within the literature on multidimensional inequality measurement and within the literature on needs.Pigou-Dalton principle; Multidimensional inequality measurement; Majorization; Budget dominance; Needs; Weak equity axiom;

The Complexity of Satisfiability for Sub-Boolean Fragments of ALC

The standard reasoning problem, concept satisfiability, in the basic description logic ALC is PSPACE-complete, and it is EXPTIME-complete in the presence of unrestricted axioms. Several fragments of ALC, notably logics in the FL, EL, and DL-Lite family, have an easier satisfiability problem; sometimes it is even tractable. All these fragments restrict the use of Boolean operators in one way or another. We look at systematic and more general restrictions of the Boolean operators and establish the complexity of the concept satisfiability problem in the presence of axioms. We separate tractable from intractable cases.Comment: 17 pages, accepted (in short version) to Description Logic Workshop 201