Technology
Adaptive Inference on General Graphical Models
Acar, Umut A., Ihler, Alexander T., Mettu, Ramgopal, Sumer, Ozgur
Many algorithms and applications involve repeatedly solving variations of the same inference problem; for example we may want to introduce new evidence to the model or perform updates to conditional dependencies. The goal of adaptive inference is to take advantage of what is preserved in the model and perform inference more rapidly than from scratch. In this paper, we describe techniques for adaptive inference on general graphs that support marginal computation and updates to the conditional probabilities and dependencies in logarithmic time. We give experimental results for an implementation of our algorithm, and demonstrate its potential performance benefit in the study of protein structure.
Critical behavior in a cross-situational lexicon learning scenario
Tilles, P. F. C., Fontanari, J. F.
The problem of early word-learning has been subject of philosophical controversy for centuries [1]. The always visionary Augustine argued that the child makes the connections between words and their referents by understanding the referential intentions of others, thus anticipating the modern theory of mind in about fifteen centuries [2]. In the 17th century, Locke's empiricism supported the associationist viewpoint, which contends that the mechanism of word learning is sensitivity to covariation, i.e., if two events occur at the same time, they become associated. Here we examine a radical offshoot of the associationist approach to lexicon acquisition termed crosssituational or observational learning [3], which asserts that the meaning of a word can be determined by looking for something in common across all observed uses of that word [4]. In other words, learning takes place through the statistical sampling of the contexts in which a word appears.
Sparse Prediction with the $k$-Support Norm
Argyriou, Andreas, Foygel, Rina, Srebro, Nathan
We derive a novel norm that corresponds to the tightest convex relaxation of sparsity combined with an $\ell_2$ penalty. We show that this new {\em $k$-support norm} provides a tighter relaxation than the elastic net and is thus a good replacement for the Lasso or the elastic net in sparse prediction problems. Through the study of the $k$-support norm, we also bound the looseness of the elastic net, thus shedding new light on it and providing justification for its use.
Uncertain and Approximative Knowledge Representation to Reasoning on Classification with a Fuzzy Networks Based System
The approach described here allows to use the fuzzy Object Based Representation of imprecise and uncertain knowledge. This representation has a great practical interest due to the possibility to realize reasoning on classification with a fuzzy semantic network based system. For instance, the distinction between necessary, possible and user classes allows to take into account exceptions that may appear on fuzzy knowledge-base and facilitates integration of user's Objects in the base. This approach describes the theoretical aspects of the architecture of the whole experimental A.I. system we built in order to provide effective on-line assistance to users of new technological systems: the understanding of "how it works" and "how to complete tasks" from queries in quite natural languages. In our model, procedural semantic networks are used to describe the knowledge of an "ideal" expert while fuzzy sets are used both to describe the approximative and uncertain knowledge of novice users in fuzzy semantic networks which intervene to match fuzzy labels of a query with categories from our "ideal" expert.
Preface
McCluskey, Thomas Leo (University of Huddersfield ) | Williams, Brian (Massachusetts Institute of Technology) | Silva, José Reinaldo (Universidade de São Paulo) | Bonet, Blai (Universidad Simón Bolívar)
From this excellent collection of papers, three for presentation at ICAPS 2012, the were selected for special recognition. ICAPS continues Nguyen, Vien Tran, Tran Cao Son and Enrico the traditional high standards of AIPS and ECP Pontelli were selected for Best Student Paper as an archival forum for new research in the Award. In addition to the oral presentation of these e 45 papers included in this volume, consisting papers, the technical program of this year's of 37 long papers and 8 short papers, are ICAPS conference includes invited talks by those selected for plenary presentation at three distinguished speakers: Robert O. Ambrose ICAPS 2012 from a total of 132 submissions. Topics under various constraints and assumptions, included real-time planning, planning in mixed to empirical evaluation of planning and discrete-continuous domains, planning for systems scheduling techniques in practical applications. Papers in the subareas of optimal planning, probabilistic were encouraged from a range of neighboring and non-deterministic planning, planning disciplines, including model-based and scheduling for transportation, robot path reasoning, hybrid systems, run-time verification, planning, and new developments in heuristics control and robotics.
A Planning Based Framework for Controlling Hybrid Systems
Löhr, Johannes (University of Freiburg) | Eyerich, Patrick (University of Freiburg) | Keller, Thomas (University of Freiburg) | Nebel, Bernhard (University of Freiburg)
The control of dynamic systems, which aims to minimize the deviation of state variables from reference values in a continuous state space, is a central domain of cybernetics and control theory. The objective of action planning is to find feasible state trajectories in a discrete state space from an initial state to a state satisfying the goal conditions, which in principle addresses the same issue on a more abstract level. We combine these approaches to switch between dynamic system characteristics on the fly, and to generate control input sequences that affect both discrete and continuous state variables. Our approach (called Domain Predictive Control) is applicable to hybrid systems with linear dynamics and discretizable inputs.
On Modeling the Tactical Planning of Oil Pipeline Networks
Ferber, Daniel Felix (Petrobras &ndash)
This paper aims at incorporating tactical aspects of oil pipeline networks to the supply chain planning model. The strategic design of supply chains is covered in literature by well understood and recurring patterns such as multi-commodity networks, dynamic parameters over time, capacity on facilities, transportation capacity or facilities with demand, production and inventory. We consider the following characteristics: capacity for in-transit inventory, transit time and flow reversal. Our objective is a better estimate for resources required by the network and therewith allow a more precise optimization of their use. All aspects are modeled to be efficiently solved by linear programming algorithms.
About Partial Order Reduction in Planning and Computer Aided Verification
Wehrle, Martin (University of Basel) | Helmert, Malte (University of Basel)
Partial order reduction is a state space pruning approach that has been originally introduced in computer aided verification. Recently, various partial order reduction techniques have also been proposed for planning. Despite very similar underlying ideas, the relevant literature from computer aided verification has hardly been analyzed in the planning area so far, and it is unclear how these techniques are formally related. We provide an analysis of existing partial order reduction techniques and their relationships. We show that recently proposed approaches in planning are instances of general partial order reduction approaches from computer aided verification. Our analysis reveals a hierarchy of dominance relationships and shows that there is still room for improvement for partial order reduction techniques in planning. Overall, we provide a first step towards a better understanding and a unifying theory of partial order reduction techniques from different areas.
Faster Bounded-Cost Search Using Inadmissible Estimates
Thayer, Jordan Tyler (University of New Hampshire) | Stern, Roni (Ben-Gurion University of the Negev) | Felner, Ariel (Ben-Gurion University of the Negev) | Ruml, Wheeler (University of New Hampshire)
Many important problems are too difficult to solve optimally. A traditional approach to such problems is bounded suboptimal search, which guarantees solution costs within a user-specified factor of optimal. Recently, a complementary approach has been proposed: bounded-cost search, where solution cost is required to be below a user-specified absolute bound. In this paper, we show how bounded-cost search can incorporate inadmissible estimates of solution cost and solution length. This information has previously been shown to improve bounded suboptimal search and, in an empirical evaluation over five benchmark domains, we find that our new algorithms surpass the state-of-the-art in bounded-cost search as well, particularly for domains where action costs differ.
Planning Via Random Walk-Driven Local Search
Xie, Fan (University of Alberta) | Nakhost, Hootan (University of Alberta) | Müller, Martin (University of Alberta)
The RW-LS planner Arvand-LS is described Most successful current satisficing planners combine several next, followed by a section about the generation and selection complementary search algorithms. Examples range from of harder problems from existing IPC domains for portfolio planners such as Fast Downward Stone Soup which scalable problem generators are available. The experimental (Helmert, Röger, and Karpas 2011) and loosely coupled parallel results for Arvand-LS show strong improvements planners such as ArvandHerd (Valenzano et al. 2011) to over the state of the art in both coverage and plan quality for systems which alternate several search strategies, such as FF hard problems from several IPC domains. The paper concludes (Hoffmann and Nebel 2001), FD (Helmert 2006), and ArvandHerd, with a discussion of possible future work, including and dual queue search algorithms as in LAMA perspectives for a portfolio system containing Arvand-LS. (Richter and Westphal 2010).