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Lifted Graphical Models: A Survey

arXiv.org Artificial Intelligence

This article presents a survey of work on lifted graphical models. We review a general form for a lifted graphical model, a par-factor graph, and show how a number of existing statistical relational representations map to this formalism. We discuss inference algorithms, including lifted inference algorithms, that efficiently compute the answers to probabilistic queries. We also review work in learning lifted graphical models from data. It is our belief that the need for statistical relational models (whether it goes by that name or another) will grow in the coming decades, as we are inundated with data which is a mix of structured and unstructured, with entities and relations extracted in a noisy manner from text, and with the need to reason effectively with this data. We hope that this synthesis of ideas from many different research groups will provide an accessible starting point for new researchers in this expanding field.


Prediction of peptide bonding affinity: kernel methods for nonlinear modeling

arXiv.org Machine Learning

Comparative Evaluation of Prediction Algorithms(COEPRA, http://www.coepra.org/) is a modeling competition organized to provide objective testing of various algorithms via the process of blind prediction for chemical, biological, and medical data. COEPRA's stated goals are to advance modeling algorithms and software as well as provide reference datasets to the research community. Transferable Atom Equivalent (TAE) RECON features are electron-density derived descriptors obtained by fragment reconstruction. MOE features are geometrical, structural, physiochemical and topological 2D descriptors.


Using Supervised Learning to Improve Monte Carlo Integral Estimation

arXiv.org Machine Learning

Monte Carlo (MC) techniques are often used to estimate integrals of a multivariate function using randomly generated samples of the function. In light of the increasing interest in uncertainty quantification and robust design applications in aerospace engineering, the calculation of expected values of such functions (e.g. performance measures) becomes important. However, MC techniques often suffer from high variance and slow convergence as the number of samples increases. In this paper we present Stacked Monte Carlo (StackMC), a new method for post-processing an existing set of MC samples to improve the associated integral estimate. StackMC is based on the supervised learning techniques of fitting functions and cross validation. It should reduce the variance of any type of Monte Carlo integral estimate (simple sampling, importance sampling, quasi-Monte Carlo, MCMC, etc.) without adding bias. We report on an extensive set of experiments confirming that the StackMC estimate of an integral is more accurate than both the associated unprocessed Monte Carlo estimate and an estimate based on a functional fit to the MC samples. These experiments run over a wide variety of integration spaces, numbers of sample points, dimensions, and fitting functions. In particular, we apply StackMC in estimating the expected value of the fuel burn metric of future commercial aircraft and in estimating sonic boom loudness measures. We compare the efficiency of StackMC with that of more standard methods and show that for negligible additional computational cost significant increases in accuracy are gained.


Promoting scientific thinking with robots

arXiv.org Artificial Intelligence

This article describes an exemplary robot exercise which was conducted in a class for mechatronics students. The goal of this exercise was to engage students in scientific thinking and reasoning, activities which do not always play an important role in their curriculum. The robotic platform presented here is simple in its construction and is customizable to the needs of the teacher. Therefore, it can be used for exercises in many different fields of science, not necessarily related to robotics. Here we present a situation where the robot is used like an alien creature from which we want to understand its behavior, resembling an ethological research activity. This robot exercise is suited for a wide range of courses, from general introduction to science, to hardware oriented lectures.


Biomimetic use of genetic algorithms

arXiv.org Artificial Intelligence

Abstract: Genetic algorithms are considered as an original way to solve problems, probably because of their generality and of their "blind" nature. But GAs are also unusual since the features of many implementations (among all that could be thought of) are principally led by the biological metaphor, while efficiency measurements intervene only afterwards. We propose here to examine the relevance of these biomimetic aspects, by pointing out some fundamental similarities and divergences between GAs and the genome of living beings shaped by natural selection. One of the main differences comes from the fact that GAs rely principally on the so-called implicit parallelism, while giving to the mutation/selection mechanism the second role. Such differences could suggest new ways of employing GAs on complex problems, using complex codings and starting from nearly homogeneous populations. In GAs, individuals are represented by their genome (most often a binary vector), and are evaluated so that only the best fitted ones have some chance to reproduce.


A Dynamical Systems Approach for Static Evaluation in Go

arXiv.org Artificial Intelligence

Abstract--In the paper arguments are given why the concept of static evaluation has the potential to be a useful extension to Monte Carlo tree search. A new concept of modeling static evaluation through a dynamical system is introduced and strengths and weaknesses are discussed. The general suitability of this approach is demonstrated. The concept of Monte-Carlo simulations applied to Go [1] combined with the UCT algorithm [2], [3], which is a tree search method based on Upper Confidence Bounds (UCB) (see e.g. The detailed tournament report [8] of the program MoGo playing against professional and amateur players reveals strengths and weaknesses of MoGo which are typical for programs that perform a Monte Carlo tree search (MCTS). Programs performing MCTS can utilize ever increasing computing power but in their pure form without extra Go knowledge the ratio log(increase in needed computing power) / (increase in strength) is too big to get to professional strength on large boards in the foreseeable future. Therefore in recent years Go knowledge has been incorporated either in form of heuristics, or pattern databases learned from professional games or from self-play. Although treesearch was naturally slowed down the playing strength increased further. With all of this tremendous progress of MCTS compared to the knowledge based era of computer Go summarized in [9], [10], [11], it needs good reasons to start work on a static evaluation function (SE) in Go. One indicator that more Go knowledge needs to be added is that, compared with human playing strength the playing level of current programs decreases as board size increases from 9 9 to 13 13 and then to 19 19. The principal difficulties of deriving knowledge and applying it become more relevant as knowledge is increasingly used in MCTS. Knowledge that is not 100% accurate reduces the scalability of the program when enough computing power is available for global search to replace increasingly the approximate Go knowledge which then becomes less useful or even less accurate than knowledge coming from search. It is difficult to combine knowledge on a high level if it comes from different sources, like from pattern and from local searches. It is one of the reasons of the originally surprising success of pure MCTS that it only uses knowledge from one source (statistics of simulations) without the need of merging different types of knowledge.


Toward Parts-Based Scene Understanding with Pixel-Support Parts-Sparse Pictorial Structures

arXiv.org Machine Learning

Scene understanding remains a significant challenge in the computer vision community. The visual psychophysics literature has demonstrated the importance of interdependence among parts of the scene. Yet, the majority of methods in computer vision remain local. Pictorial structures have arisen as a fundamental parts-based model for some vision problems, such as articulated object detection. However, the form of classical pictorial structures limits their applicability for global problems, such as semantic pixel labeling. In this paper, we propose an extension of the pictorial structures approach, called pixel-support parts-sparse pictorial structures, or PS3, to overcome this limitation. Our model extends the classical form in two ways: first, it defines parts directly based on pixel-support rather than in a parametric form, and second, it specifies a space of plausible parts-based scene models and permits one to be used for inference on any given image. PS3 makes strides toward unifying object-level and pixel-level modeling of scene elements. In this report, we implement the first half of our model and rely upon external knowledge to provide an initial graph structure for a given image. Our experimental results on benchmark datasets demonstrate the capability of this new parts-based view of scene modeling.


Self-Organizing Mixture Networks for Representation of Grayscale Digital Images

arXiv.org Artificial Intelligence

Self-Organizing Maps are commonly used for unsupervised learning purposes. This paper is dedicated to the certain modification of SOM called SOMN (Self-Organizing Mixture Networks) used as a mechanism for representing grayscale digital images. Any grayscale digital image regarded as a distribution function can be approximated by the corresponding Gaussian mixture. In this paper, the use of SOMN is proposed in order to obtain such approximations for input grayscale images in unsupervised manner.


Ontology Alignment at the Instance and Schema Level

arXiv.org Artificial Intelligence

We present PARIS, an approach for the automatic alignment of ontologies. PARIS aligns not only instances, but also relations and classes. Alignments at the instance-level cross-fertilize with alignments at the schema-level. Thereby, our system provides a truly holistic solution to the problem of ontology alignment. The heart of the approach is probabilistic. This allows PARIS to run without any parameter tuning. We demonstrate the efficiency of the algorithm and its precision through extensive experiments. In particular, we obtain a precision of around 90% in experiments with two of the world's largest ontologies.


A Machine Learning Perspective on Predictive Coding with PAQ

arXiv.org Machine Learning

PAQ8 is an open source lossless data compression algorithm that currently achieves the best compression rates on many benchmarks. This report presents a detailed description of PAQ8 from a statistical machine learning perspective. It shows that it is possible to understand some of the modules of PAQ8 and use this understanding to improve the method. However, intuitive statistical explanations of the behavior of other modules remain elusive. We hope the description in this report will be a starting point for discussions that will increase our understanding, lead to improvements to PAQ8, and facilitate a transfer of knowledge from PAQ8 to other machine learning methods, such a recurrent neural networks and stochastic memoizers. Finally, the report presents a broad range of new applications of PAQ to machine learning tasks including language modeling and adaptive text prediction, adaptive game playing, classification, and compression using features from the field of deep learning.