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A Happening-Based Encoding for Nonlinear PDDL+ Planning

AAAI Conferences

Hybrid planning with nonlinear continuous change is a significant challenge for existing planners. Prior works limit their scope to linear change or base their formalisms in model checking frameworkswith inherent limitations. We address nonlinear PDDL+ planning with anew encoding in first order logic over real valued functions. Our planner, PluReal, translates PDDL+ to this logical encoding and applies the dReal Satisfiability Modulo Theories (SMT) solver to construct plans. Unlike prior work that uses dReal in the hybrid system model checking tradition, PluReal is based in the planning as satisfiability (SAT) heritage. Adopting the SAT approach helps lift several unnatural restrictions that are imposed by the translation through hybrid systems and leads to improved scalability even without SMT solver variable selection heuristics.


Policy Communication for Coordination with Unknown Teammates

AAAI Conferences

Within multiagent teams research, existing approaches commonly assume agents have perfect knowledge regarding the decision process guiding their teammates' actions. More recently, ad hoc teamwork was introduced to address situations where an agent must coordinate with a variety of potential teammates, including teammates with unknown behavior. This paper examines the communication of intentions for enhanced coordination between such agents. The proposed decision-theoretic approach examines the uncertainty within a model of an unfamiliar teammate, identifying policy information valuable to the collaborative effort. We characterize this capability through theoretical analysis of the computational requirements as well as empirical evaluation of a communicative agent coordinating with an unknown teammate in a variation of the multiagent pursuit domain.


Automatic Extraction of Events-Based Conditional Commonsense Knowledge

AAAI Conferences

Reasoning with commonsense knowledge plays an important role in various NLU tasks. Often the commonsense knowledge is needed to be extracted separately. In this paper we present our work of automatically extracting a certain type of commonsense knowledge. The knowledge resembles the kind that humans have about the events and the entities that participate in those events. One example of such knowledge is that "IF A bullying B causes T rescued Z THEN (possibly) Z = B ''. We call this knowledge an event-based conditional commonsense. Our approach involves semantic parsing of natural language sentences by using the Knowledge Parser (K-Parser) and extracting the knowledge, if found. We extracted about 19000 instances of such knowledge from the Open American National Corpus.


Extending Biology Models with Deep NLP over Scientific Articles

AAAI Conferences

This paper describes R3 (Reading, Reasoning, and Reporting), our system for deep language understanding and model management for the biomedical domain. Starting from a base BioPAX model, we learn extensions to it by reading biomedical research articles from PubMed Central. We describe the particular issues for text understanding in this domain and how we use pre- and post-analysis reasoning to bridge the differences in how knowledge is packaged in a text and in a biomedical database. We close with brief description of our first year results, where R3 was faster than all other reported systems, reading 1,000 articles in 15 minutes.


Modeling Trust Evaluating Agents: Towards a Comprehensive Trust Management for Multi-agent Systems

AAAI Conferences

In multiagent systems, if interactions are based on trust, trustworthy trustees will have a greater impact on the results of interactions. Consequently, building a high trust may be an advantage for rational trustees. This work describes a trust establishment model that goes beyond trust evaluation to outline actions to direct trustees (instead of trusters). The model uses the number of transactions performed by trusters. A trustee will adjust its performance, depending on the average number of transactions carried out by that truster, relative to the mean number of transactions performed by all trusters interacting with this trustee. The proposed model does not depend on direct feedback, nor does it rely on current reputation of trustees in the community. Simulation results indicate that trustees empowered with the proposed model can be selected more by trusters.


Predicting 30-Day Risk and Cost of "All-Cause" Hospital Readmissions

AAAI Conferences

The hospital readmission rate of patients within 30 days after discharge is broadly accepted as a healthcare quality measure and cost driver in the United States. The ability to estimate hospitalization costs alongside 30 day risk-stratification for such readmissions provides additional benefit for accountable care, now a global issue and foundation for the U.S.~government mandate under the Affordable Care Act. Recent data mining efforts either predict healthcare costs or risk of hospital readmission, but not both. In this paper we present a dual predictive modeling effort that utilizes healthcare data to predict the risk and cost of any hospital readmission (``all-cause''). For this purpose, we explore machine learning algorithms to do accurate predictions of healthcare costs and risk of 30-day readmission.Results on risk prediction for ``all-cause'' readmission compared to the standardized readmission tool (LACE) are promising, and the proposed techniques for cost prediction consistently outperform baseline models and demonstrate substantially lower mean absolute error (MAE).


Combining Multiple Concurrent Physiological Streams to Assessing Patients Condition

AAAI Conferences

Multiple concurrent physiological streams generated by various medical devices play important roles in patient condition assessment. However, these physiological streams needto be analyzed together and output in real-time for preciseand timely controlling and management, which poses a non-trivial challenge to existing methods. This paper presents ourresearch on real-time assessing based on this kind of data.To address this problem, we first extract sketches from original data with the help of adaptive sampling and wave splittingalgorithm, then define scalable operators on sketches and propose MUNCA (MUlti-dimensional Nearest Center Analysis)to combine these multiple concurrent data together for anal-ysis. Experiments on real data demonstrate the effectiveness and efficiency of the proposed method.


Learning Constraints and Optimization Criteria

AAAI Conferences

While there exist several approaches in the constraint programming community to learn a constraint theory, few of them have considered the learning of constraint optimization problems.To alleviate this situation, we introduce an initial approach to learning first-order weighted MAX-SAT theories. It employs inductive logic programming techniques to learn a set of first-order clauses and then uses preference learning techniques to learn the weights of the clauses.In order to learn these weighted clauses, the clausal optimization system uses examples of possible worlds and a set of preferences that state which examples are preferred over other ones.The technique is also empirically evaluated on a number of examples.These experiments show that the system is capable of learning clauses and weights that accurately capture underlying models.


Compact CFR

AAAI Conferences

This paper describes a collection of ideas that allow large games of imperfect information to be solved with counterfactual regret minimization (CFR) using little memory. We replace the regret matching component of CFR with a simple approach known as "follow-the-leader." This helps us quantize the regret values computed in CFR to a single byte. We also investigate not maintaining the accumulated strategy, which saves additional memory. Ultimately, our collection of techniques allows CFR to be run with only 1/16 of the memory required by classic approaches. We present experimental results on poker.


Constrained Sampling and Counting: Universal Hashing Meets SAT Solving

AAAI Conferences

Constrained sampling and counting are two fundamental problems in artificial intelligence with a diverse range of applications, spanning probabilistic reasoning and planning to constrained-random verification. While the theory of these problems was thoroughly investigated in the 1980s, prior work either did not scale to industrial size instances or gave up correctness guarantees to achieve scalability. Recently, we proposed a novel approach that combines universal hashing and SAT solving and scales to formulas with hundreds of thousands of variables without giving up correctness guarantees. This paper provides an overview of the key ingredients of the approach and discusses challenges that need to be overcome to handle larger real-world instances.