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A Metacognitive Classifier Using a Hybrid ACT-R/Leabra Architecture

AAAI Conferences

The major limitation to standard classification techniques is that the classifiers have to be trained on objects for which the ground truth, ACT-R contains a robust declarative memory module, which in terms of either a pre-assigned label or an error signal, is stores information as "chunks." A chunk in ACT-R may contain known. This limitation prevents the classifiers from dynamically any number of slots and values for those slots; slot values developing their own categories of classification based may be other chunks, numbers, strings, lists, or generally on information obtained from the environment. Previous attempts any data type allowed in Lisp (the base language for to overcome these limitations have been based on ACT-R). Retrieval from declarative memory is handled by a classical machine learning algorithms (Modayil and Kuipers request to the retrieval module; the request specifies the conditions 2007) (Kuipers et al. 2006). Here we present an alternative to be met in order for a chunk to be retrieved from approach to this problem, and develop the beginnings of declarative memory, and the module either returns a chunk a framework within which a classifier can evolve its own matching those specifications or generates a failure signal if representations based on dynamical information from the a retrieval cannot be made.


Context Transitions: User Identification and Comparison of Mobile Device Motion Data

AAAI Conferences

In this paper, we study a time-critical facet of context-awareness: context transitions, which we model as changes in specific context types over time, e.g., activity or location. We present results from a user-centred field study involving participant interviews and motion data capture from two mobile device sensors: the accelerometer and magnetic field sensor. The results show how the participants subjectively interpret their daily context transitions with variable granularity, and a comparison of these context transitions with mobile device motion data shows how the motion data poorly reflect the identified transitions. The results imply that care should be taken when representing and modelling users’ subjective interpretations of context, as well as the objective nature of context sensors. Furthermore, processing and usability trade-offs should be made if real-time on-device transition detection is to be implemented.


Continuous Occupancy Mapping with Integral Kernels

AAAI Conferences

We address the problem of building a continuous occupancy representation of the environment with ranging sensors. Observations from such sensors provide two types of information: a line segment or a beam indicating no returns along them (free-space); a point or return at the end of the segment representing an occupied surface. To model these two types of observations in a principled statistical manner, we propose a novel methodology based on integral kernels. We show that integral kernels can be directly incorporated into a Gaussian process classification (GPC) framework to provide a continuous non-parametric Bayesian estimation of occupancy. Directly handling line segment and point observations avoids the need to discretise segments into points, reducing the computational cost of GPC inference and learning. We present experiments on 2D and 3D datasets demonstrating the benefits of the approach.


Domain Independent Knowledge Base Population from Structured and Unstructured Data Sources

AAAI Conferences

In this paper we introduce a system that is designed to automatically populate a knowledge base from both structured and unstructured text given an ontology. Our system is designed as a modular end-to-end system that takes structured or unstructured data as input, extracts information, maps relevant information to an ontology, and finally disambiguates entities in the knowledge base. The novelty of our approach is that it is domain independent and can easily be adapted to new ontologies and domains. Unlike most knowledge base population systems, ours includes entity detection. This feature allows one to employ very complex ontologies that include events and the entities that are involved in the events.


The Problem of Premissary Relevance

AAAI Conferences

his paper focuses on the issue of premissary relevance, as a challenge faced in health promotion interventions. To promote attitude change and influence health behavior change, it is crucial that we use premises that are relevant on an individual level. Relevance in argumentation refers to both the fact that the premises have to do with the standpoint at issue and the fact that our interlocutors will accept them. We claim that autonomous argumentation systems hold the promise to enable proper argumentative exchanges that capture and addresses what matters to individuals. To do so, however, there is a need to better consider and operationalise theories of argumentation that enable a reconstruction of the different stages of argumentation. The theory of argumentation known as pragma-dialectics can offer a promising basis for the architecture of autonomous health promotion advisors.


Towards Robot Systems Architecture

AAAI Conferences

Just as special purpose computers and mainframes grew into the generalpurpose personal computers we use everyday, special purpose industrialrobots are evolving into more general purpose personal robots. Asrobots become more capable and universal, their applications are lesswell-defined or even unknown at design time. We will have to designrobots for classes of tasks rather than specific applications. Havingguidelines for how to best organize, interface, and implement robotsystems and reason about trade-offs, as we do in computerarchitecture, will become crucial for success. In this paper weintroduce and adapt some useful notions and principles from computerarchitecture to robot systems architecture. We argue that notions suchas locality of reference, balanced architectures, and boundedness (interms of IO, memory, and CPU) can be leveraged in robot systemsdesign, and in particular, in the design of distributed robot systems.



Automated Modelling and Solving in Constraint Programming

AAAI Conferences

Constraint programming can be divided very crudely into modeling and solving. Modeling defines the problem, in terms of variables that can take on different values, subject to restrictions (constraints) on which combinations of variables are allowed. Solving finds values for all the variables that simultaneously satisfy all the constraints. However, the impact of constraint programming has been constrained by a lack of "user-friendliness''. Constraint programming has a major "declarative" aspect, in that a problem model can be handed off for solution to a variety of standard solving methods. These methods are embedded in algorithms, libraries, or specialized constraint programming languages. To fully exploit this declarative opportunity however, we must provide more assistance and automation in the modeling process, as well as in the design of application-specific problem solvers. Automated modelling and solving in constraint programming presents a major challenge for the artificial intelligence community. Artificial intelligence, and in particular machine learning, is a natural field in which to explore opportunities for moving more of the burden of constraint programming from the user to the machine. This paper presents technical challenges in the areas of constraint model acquisition, formulation and reformulation, synthesis of filtering algorithms for global constraints, and automated solving. We also present the metrics by which success and progress can be measured.


From Tweets to Polls: Linking Text Sentiment to Public Opinion Time Series

AAAI Conferences

We connect measures of public opinion measured from polls with sentiment measured from text. We analyze several surveys on consumer confidence and political opinion over the 2008 to 2009 period, and find they correlate to sentiment word frequencies in contempora- neous Twitter messages. While our results vary across datasets, in several cases the correlations are as high as 80%, and capture important large-scale trends. The re- sults highlight the potential of text streams as a substi- tute and supplement for traditional polling. consumer confidence and political opinion, and can also pre- dict future movements in the polls. We find that temporal smoothing is a critically important issue to support a suc- cessful model.


Coping With Noise in a Real-World Weblog Crawler and Retrieval System

AAAI Conferences

In this paper we examine the effects of noise when creating a real-world weblog corpus for information retrieval. We focus on the DiffPost (Lee et al. 2008) approach to noise removal from blog pages, examining the difficulties encountered when crawling the blogosphere during the creation of a real-world corpus of blog pages. We introduce and evaluate a number of enhancements to the original DiffPost approach in order to increase the robustness of the algorithm. We then extend DiffPost by looking at the anchor-text to text ratio, and discover that the time-interval between crawls is more important to the successful application of noise-removal algorithms within the blog context, than any additional improvements to the removal algorithm itself.