Government
Computational Logic Foundations of KGP Agents
Kakas, Antonis, Mancarella, Paolo, Sadri, Fariba, Stathis, Kostas, Toni, Francesca
This paper presents the computational logic foundations of a model of agency called the KGP (Knowledge, Goals and Plan model. This model allows the specification of heterogeneous agents that can interact with each other, and can exhibit both proactive and reactive behaviour allowing them to function in dynamic environments by adjusting their goals and plans when changes happen in such environments. KGP provides a highly modular agent architecture that integrates a collection of reasoning and physical capabilities, synthesised within transitions that update the agents state in response to reasoning, sensing and acting. Transitions are orchestrated by cycle theories that specify the order in which transitions are executed while taking into account the dynamic context and agent preferences, as well as selection operators for providing inputs to transitions.
A Heuristic Search Approach to Planning with Continuous Resources in Stochastic Domains
Meuleau, Nicolas, Benazera, Emmanuel, Brafman, Ronen I., Hansen, Eric A., Mausam, null
We consider the problem of optimal planning in stochastic domains with resource constraints, where the resources are continuous and the choice of action at each step depends on resource availability. We introduce the HAO* algorithm, a generalization of the AO* algorithm that performs search in a hybrid state space that is modeled using both discrete and continuous state variables, where the continuous variables represent monotonic resources. Like other heuristic search algorithms, HAO* leverages knowledge of the start state and an admissible heuristic to focus computational effort on those parts of the state space that could be reached from the start state by following an optimal policy. We show that this approach is especially effective when resource constraints limit how much of the state space is reachable. Experimental results demonstrate its effectiveness in the domain that motivates our research: automated planning for planetary exploration rovers.
The Eighth International Workshop on Planning and Scheduling for Space (IWPSS)
Morris, Robert (NASA Ames Research Center) | Chien, Steve A. (Jet Propulsion Laboratory)
The two invited talks illustrated used NASA's Deep Space Habitat both the diverse applications of planning (DSH), an analog spacecraft habitat, for and scheduling technologies for the simulation, and a number of scenarios space, as well as the degree to which covering a range of activities these technologies have been successfully were applied. Scheduling for Space (IWPSS) focuses infused into space systems. In addition to the two full days of he Workshop on Planning and on the technical challenges Chien from JPL presented a talk titled technical talks, there were demonstrations and opportunities facing the AI planning "Using Space, Air, Marine, and Ground of six planning and scheduling and scheduling community when Assets for Disaster Response and Environmental systems in various stages of deployment. He described Copies of papers and slides are space-based applications, from mission how space, air, Inin-situ, and marine available at robotics.estec.esa.int/IWoperations to autonomy in space exploration assets have been integrated into sensor PSS. There have been webs to enable detection, tracking, The next IWPSS workshop will be eight workshops in the series. At this and response to a wide range of terrestrial held in 2015 at a location to be determined.
Virtual Humans for Learning
Swartout, William (University of Southern California) | Artstein, Ron (University of Southern California) | Forbell, Eric (University of Southern California) | Foutz, Susan (Independent Consultant) | Lane, H. Chad (University of Southern California) | Lange, Belinda (University of Southern California) | Morie, Jacquelyn Ford (All These Worlds, LLC) | Rizzo, Albert Skip (University of Southern California) | Traum, David (University of Southern California)
Virtual humans are computer-generated characters designed to look and behave like real people. Studies have shown that virtual humans can mimic many of the social effects that one finds in human-human interactions such as creating rapport, and people respond to virtual humans in ways that are similar to how they respond to real people. We believe that virtual humans represent a new metaphor for interacting with computers, one in which working with a computer becomes much like interacting with a person and this can bring social elements to the interaction that are not easily supported with conventional interfaces. We present two systems that embody these ideas. The first, the Twins are virtual docents in the Museum of Science, Boston, designed to engage visitors and raise their awareness and knowledge of science. The second SimCoach, uses an empathetic virtual human to provide veterans and their families with information about PTSD and depression.
Belief Revision in Structured Probabilistic Argumentation
Shakarian, Paulo, Simari, Gerardo I., Falappa, Marcelo A.
In real-world applications, knowledge bases consisting of all the information at hand for a specific domain, along with the current state of affairs, are bound to contain contradictory data coming from different sources, as well as data with varying degrees of uncertainty attached. Likewise, an important aspect of the effort associated with maintaining knowledge bases is deciding what information is no longer useful; pieces of information (such as intelligence reports) may be outdated, may come from sources that have recently been discovered to be of low quality, or abundant evidence may be available that contradicts them. In this paper, we propose a probabilistic structured argumentation framework that arises from the extension of Presumptive Defeasible Logic Programming (PreDeLP) with probabilistic models, and argue that this formalism is capable of addressing the basic issues of handling contradictory and uncertain data. Then, to address the last issue, we focus on the study of non-prioritized belief revision operations over probabilistic PreDeLP programs. We propose a set of rationality postulates -- based on well-known ones developed for classical knowledge bases -- that characterize how such operations should behave, and study a class of operators along with theoretical relationships with the proposed postulates, including a representation theorem stating the equivalence between this class and the class of operators characterized by the postulates.
Reasoning about Independence in Probabilistic Models of Relational Data
Maier, Marc, Marazopoulou, Katerina, Jensen, David
We extend the theory of d-separation to cases in which data instances are not independent and identically distributed. We show that applying the rules of d-separation directly to the structure of probabilistic models of relational data inaccurately infers conditional independence. We introduce relational d-separation, a theory for deriving conditional independence facts from relational models. We provide a new representation, the abstract ground graph, that enables a sound, complete, and computationally efficient method for answering d-separation queries about relational models, and we present empirical results that demonstrate effectiveness.
Reasoning With Neural Tensor Networks for Knowledge Base Completion
Socher, Richard, Chen, Danqi, Manning, Christopher D., Ng, Andrew
A common problem in knowledge representation and related fields is reasoning over a large joint knowledge graph, represented as triples of a relation between two entities. The goal of this paper is to develop a more powerful neural network model suitable for inference over these relationships. Previous models suffer from weak interaction between entities or simple linear projection of the vector space. We address these problems by introducing a neural tensor network (NTN) model which allow the entities and relations to interact multiplicatively. Additionally, we observe that such knowledge base models can be further improved by representing each entity as the average of vectors for the words in the entity name, giving an additional dimension of similarity by which entities can share statistical strength. We assess the model by considering the problem of predicting additional true relations between entities given a partial knowledge base. Our model outperforms previous models and can classify unseen relationships in WordNet and FreeBase with an accuracy of 86.2% and 90.0%, respectively.
Tracking Time-varying Graphical Structure
Kummerfeld, Erich, Danks, David
Structure learning algorithms for graphical models have focused almost exclusively on stable environments in which the underlying generative process does not change; that is, they assume that the generating model is globally stationary. In real-world environments, however, such changes often occur without warning or signal. Real-world data often come from generating models that are only locally stationary. In this paper, we present LoSST, a novel, heuristic structure learning algorithm that tracks changes in graphical model structure or parameters in a dynamic, real-time manner. We show by simulation that the algorithm performs comparably to batch-mode learning when the generating graphical structure is globally stationary, and significantly better when it is only locally stationary.