Death and Suicide in Universal Artificial Intelligence

Reinforcement learning (RL) is a general paradigm for studying intelligent behaviour, with applications ranging from artificial intelligence to psychology and economics. AIXI is a universal solution to the RL problem; it can learn any computable environment. A technical subtlety of AIXI is that it is defined using a mixture over semimeasures that need not sum to 1, rather than over proper probability measures. In this work we argue that the shortfall of a semimeasure can naturally be interpreted as the agent's estimate of the probability of its death. We formally define death for generally intelligent agents like AIXI, and prove a number of related theorems about their behaviour. Notable discoveries include that agent behaviour can change radically under positive linear transformations of the reward signal (from suicidal to dogmatically self-preserving), and that the agent's posterior belief that it will survive increases over time.Comment: Conference: Artificial General Intelligence (AGI) 2016 13 pages, 2 figure

A flexible software architecture concept for the creation of accessible PDF documents

This paper presents a flexible software architecture concept that allows the automatic generation of fully accessible PDF documents originating from various authoring tools such as Adobe InDesign or Microsoft Word. The architecture can be extended to include any authoring tools capable of creating PDF documents. For each authoring tool, a software accessibility plug-in must be implemented which analyzes the logical structure of the document and creates an XML representation of it. This XML file is used in combination with an untagged non-accessible PDF to create an accessible PDF version of the document. The implemented accessibility plug-in prototype allows authors of documents to check for accessibility issues while creating their documents and add the additional semantic information needed to generate a fully accessible PDF document

Count-Based Exploration in Feature Space for Reinforcement Learning

We introduce a new count-based optimistic exploration algorithm for Reinforcement Learning (RL) that is feasible in environments with high-dimensional state-action spaces. The success of RL algorithms in these domains depends crucially on generalisation from limited training experience. Function approximation techniques enable RL agents to generalise in order to estimate the value of unvisited states, but at present few methods enable generalisation regarding uncertainty. This has prevented the combination of scalable RL algorithms with efficient exploration strategies that drive the agent to reduce its uncertainty. We present a new method for computing a generalised state visit-count, which allows the agent to estimate the uncertainty associated with any state. Our \phi-pseudocount achieves generalisation by exploiting same feature representation of the state space that is used for value function approximation. States that have less frequently observed features are deemed more uncertain. The \phi-Exploration-Bonus algorithm rewards the agent for exploring in feature space rather than in the untransformed state space. The method is simpler and less computationally expensive than some previous proposals, and achieves near state-of-the-art results on high-dimensional RL benchmarks.Comment: Conference: Twenty-sixth International Joint Conference on Artificial Intelligence (IJCAI-17), 8 pages, 1 figur

Developing a dataset of Linear Kinematic Features (LKFs) for the evaluation of small-scale sea ice deformation

The Arctic sea ice deforms constantly due to stresses imposed by winds, ocean currents and interaction with coastlines. The most dominant features produced by this deformation in the ice cover are leads and pressure ridges that are often referred to as Linear Kinematic Features (LKFs). With increasing resolution of classical (viscous-plastic) sea ice models, or using new rheological frameworks (e.g. Maxwell elasto-brittle), sea-ice models start to resolve this small-scale deformation. So far, scaling properties of sea-ice deformation are commonly used to evaluate the modelled LKFs, besides other measures like lead area density. These metrics evade the problem of detecting individual LKFs by taking statistics over continuous fields like sea ice deformation or concentration. This way, they can provide specific information, but lack a comprehensive description of LKFs. We detect individual LKFs in sea ice deformation fields from satellite observations with an object detection algorithm. Combining this information with the sea ice drift fields used to derive the deformation fields, the LKFs are tracked in time. In doing so, the spatial characteristics (density, length, orientation, intersection angle, curvature) as well as the temporal evolution can be extracted from the same data-set. This algorithm can be applied to modelled sea-ice deformation and drift to enable a consistent comparison and thorough evaluation of simulated sea-ice deformation. We present preliminary results of LKFs detected in the RGPS data set and give examples of possible applications

Scaling Properties of Arctic Sea Ice Deformation in a High-Resolution Viscous-Plastic Sea Ice Model and in Satellite Observations

Sea ice models with the traditional viscous-plastic (VP) rheology and very small horizontal grid spacing can resolve leads and deformation rates localized along Linear Kinematic Features (LKF). In a 1 km pan-Arctic sea ice-ocean simulation, the small-scale sea ice deformations are evaluated with a scaling analysis in relation to satellite observations of the Envisat Geophysical Processor System (EGPS) in the Central Arctic. A new coupled scaling analysis for data on Eulerian grids is used to determine the spatial and temporal scaling and the coupling between temporal and spatial scales. The spatial scaling of the modeled sea ice deformation implies multifractality. It is also coupled to temporal scales and varies realistically by region and season. The agreement of the spatial scaling with satellite observations challenges previous results with VP models at coarser resolution, which did not reproduce the observed scaling. The temporal scaling analysis shows that the VP model, as configured in this 1 km simulation, does not fully resolve the intermittency of sea ice deformation that is observed in satellite data

Selection of patients with germline MLH1 mutated Lynch syndrome by determination of MLH1 methylation and BRAF mutation

Lynch syndrome is one of the most common hereditary colorectal cancer (CRC) syndrome and is caused by germline mutations of MLH1, MSH2 and more rarely MSH6, PMS2, MLH3 genes. Whereas the absence of MSH2 protein is predictive of Lynch syndrome, it is not the case for the absence of MLH1 protein. The purpose of this study was to develop a sensitive and cost effective algorithm to select Lynch syndrome cases among patients with MLH1 immunohistochemical silencing. Eleven sporadic CRC and 16 Lynch syndrome cases with MLH1 protein abnormalities were selected. The BRAF c.1799T>A mutation (p.Val600Glu) was analyzed by direct sequencing after PCR amplification of exon 15. Methylation of MLH1 promoter was determined by Methylation-Sensitive Single-Strand Conformation Analysis. In patients with Lynch syndrome, there was no BRAF mutation and only one case showed MLH1 methylation (6%). In sporadic CRC, all cases were MLH1 methylated (100%) and 8 out of 11 cases carried the above BRAF mutation (73%) whereas only 3 cases were BRAF wild type (27%). We propose the following algorithm: (1) no further molecular analysis should be performed for CRC exhibiting MLH1 methylation and BRAF mutation, and these cases should be considered as sporadic CRC; (2) CRC with unmethylated MLH1 and negative for BRAF mutation should be considered as Lynch syndrome; and (3) only a small fraction of CRC with MLH1 promoter methylation but negative for BRAF mutation should be true Lynch syndrome patients. These potentially Lynch syndrome patients should be offered genetic counselling before searching for MLH1 gene mutation

On Martin-Löf convergence of Solomonoff’s mixture

We study the convergence of Solomonoff’s universal mixture on individual Martin-Löf random sequences. A new result is presented extending the work of Hutter and Muchnik (2004) by showing that there does not exist a universal mixture that converges on all Martin-Löf random sequences

Konsensdemokratie unter Druck? Politischer Protest in Österreich, 1975-2005

'Die vorliegende Studie untersucht das Ausmaß, die Aktionsform und die thematischen Schwerpunkte des politischen Protests in Österreich von 1975 bis 2005. Die Entwicklungen der 1990er Jahre und vor allem die Proteste gegen die Bildung der ÖVP-FPÖ-Regierung im Jahr 2000 wurden vielfach als Indikator für einen Wandel hin zu einer höheren Konfliktintensität der österreichischen Politik gesehen. Auf Basis einer systematischen Längsschnittuntersuchung weisen die Verfasser diese Interpretation zurück. Die Ergebnisse einer Inhaltsanalyse der Berichterstattung über Protestereignisse zeigen seit den 1990er Jahren ein leicht höheres Mobilisierungsniveau, jedoch keinen klaren Bruch mit stärker auf Konsens ausgerichteten Jahrzehnten. Noch immer ist unkonventionelles politisches Verhalten in Österreich deutlich geringer ausgeprägt als in vergleichbaren westeuropäischen Ländern und von einem gemäßigteren Aktionsrepertoire bestimmt. Diese empirischen Befunde werden mit dem spezifischen nationalen politischen Kontext erklärt.' (Autorenreferat)'In this article the authors analyse the extent, the form, and the thematic focus of political protest in Austria from 1975 to 2005. The developments of the 1990s and especially the protests against the formation of the ÖVP-FPÖ coalition government were understood to indicate a change towards a higher conflict intensity in Austrian politics. Based on findings of a systematic longitudinal analysis of political protest the authors dismiss such an interpretation. The results of a content analysis of the media coverage of protest events indicate a moderately increased level of mobilisation since the 1990s but no clear break with decades that were more consensus oriented. Unconventional political participation is still less frequent than in other West European countries.' (author's abstract)