Layerwise symbolic knowledge extraction from deep neural networks

We examine the feasibility of rule extraction as a method of explanation for neural networks with an emphasis on deep neural networks. This is done by establishing a framework for neural-symbolic computing which gives precise meaning to notions such as fidelity, neural encoding, and rule extraction. Using this framework, we establish semantic and syntactic relationships between different classes of neural networks and different logical systems. This shows that there is nothing inherently different about the computations done by deep neural networks and logical systems. We use this to argue that complexity is the primary difference between neural and symbolic approaches. We develop a measure of complexity and two different rule extraction algorithms using M-of- N rules. The first extraction algorithm is a fast decompositional algorithm for Deep Belief Networks that builds on the optimal confidence extraction algorithm. The second algorithm is a parallel search for optimal M-of-N rules that implements a hyperparameter that controls the complexity of the extracted rules. We apply this algorithm to a variety of deep networks and find that although differences in architecture, dataset, and learning algorithm influence the complexity of extracted rules, generally only the final softmax layer can be represented simply and accurately with M-of-N rules. We conclude by experimenting with the combination of rule extraction from the final layer and importance methods to visualize the inputs to the final layer

Lessons Learned from Applying Formal Specification in Industry

this paper, we report on the lessons learned during a study of one such change on the software development process at British Aerospace Systems and Equipment Ltd. (BASE) in the UK. At BASE, there was interest in developing a security-critical system to levels of assurance at which the use of formal specification for modelling the security policy was mandated. The purpose of our study was to provide evidence on the effect of introducing a modest amount of formal specification into an existing development process applied to this system. Note that the study was not an attempt to prove the costeffectiveness or technical value of formal meth1 ods generally. Also, our aim was to introduce a relatively minor "delta" to the development process, so there was no stress on formal proof, our use of a specification language being largely for system and software modelling. The study itself consisted of the parallel development of a system component known as a trusted gateway by two separate teams of engineers. One team employed the conventional BASE development methodology using structured analysis with CASE tool support (referred to as the conventional path below). The other team followed the same design process, but used formal specification wherever it was felt appropriate (referred to as the formal pat

Carbon cloth stimulates direct interspecies electron transfer in syntrophic co-cultures

This study investigated the possibility that the electrical conductivity of carbon cloth accelerates direct interspecies electron transfer (DIET) in co-cultures. Carbon cloth accelerated metabolism of DIET co-cultures (Geobacter metallireducens-Geobacter sulfurreducens and G. metallireducens-Methanosarcina barkeri) but did not promote metabolism of co-cultures performing interspecies H-2 transfer (Desulfovibrio vulgaris-G. sulfurreducens). On the other hand, DIET co-cultures were not stimulated by poorly conductive cotton cloth. Mutant strains lacking electrically conductive pili, or pili-associated cytochromes participated in DIET only in the presence of carbon cloth. In co-cultures promoted by carbon cloth, cells were primarily associated with the cloth although the syntrophic partners were too far apart for cell-to-cell biological electrical connections to be feasible. Carbon cloth seemingly mediated interspecies electron transfer between the distant syntrophic partners. These results suggest that the ability of carbon cloth to accelerate DIET should be considered in anaerobic digester designs that incorporate carbon cloth. (C) 2014 Elsevier Ltd. All rights reserved.This study investigated the possibility that the electrical conductivity of carbon cloth accelerates direct interspecies electron transfer (DIET) in co-cultures. Carbon cloth accelerated metabolism of DIET co-cultures (Geobacter metallireducens-Geobacter sulfurreducens and G. metallireducens-Methanosarcina barkeri) but did not promote metabolism of co-cultures performing interspecies H-2 transfer (Desulfovibrio vulgaris-G. sulfurreducens). On the other hand, DIET co-cultures were not stimulated by poorly conductive cotton cloth. Mutant strains lacking electrically conductive pili, or pili-associated cytochromes participated in DIET only in the presence of carbon cloth. In co-cultures promoted by carbon cloth, cells were primarily associated with the cloth although the syntrophic partners were too far apart for cell-to-cell biological electrical connections to be feasible. Carbon cloth seemingly mediated interspecies electron transfer between the distant syntrophic partners. These results suggest that the ability of carbon cloth to accelerate DIET should be considered in anaerobic digester designs that incorporate carbon cloth. (C) 2014 Elsevier Ltd. All rights reserved

First energy-loss-straggling experiments with relativistic heavy ions in solids

First energy-loss-straggling measurements performed at the high-momentum-resolution magnetic spectrometer FRS with bare and highly-charged _8O, _5_4Xe, _7_9Au and _9_2U ions with specific kinetic energies (700... 1000) MeV/u are reported. The results are in good agreement with excact calculations recently reported by Lindhard and Soerensen and reveal systematic deviations from the well-known relativistic Bohr formula, which was obtained within the framework of the first-order Born approximation. (orig.)Available from TIB Hannover: RO 801(96-28) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman