Archive for September, 2008

iReMedI – Intelligent Retrieval from Medical Information

Effective encoding of information is one of the keys to qualitative problem solving. Our aim is to explore Knowledge Representation techniques that capture meaningful word associations occurring in documents. We have developed iReMedI, a TCBR-based problem solving system as a prototype to demonstrate our idea. For representation we have used a combination of NLP and graph based techniques which we call as Shallow Syntactic Triples, Dependency Parses and Semantic Word Chains. To test their effectiveness we have developed retrieval techniques based on PageRank, Shortest Distance and Spreading Activation methods. The various algorithms discussed in the paper and the comparative analysis of their results provides us with useful insight for creating an effective problem solving and reasoning system.

Read the paper:

iReMedI – Intelligent Retrieval from Medical Information

by Saurav Sahay, Bharat Ravisekar, Anu Venkatesh, Sundaresan Venkatasubramanian, Priyanka Prabhu, Ashwin Ram

9th European Conference on Case-Based Reasoning (ECCBR-08), Trier, Germany
www.cc.gatech.edu/faculty/ashwin/papers/er-08-05.pdf

Real-Time Plan Adaptation for Case-Based Planning in Real-Time Strategy Games

Case-based planning (CBP) is based on reusing past successful plans for solving new problems. CBP is particularly useful in environments where the large amount of time required to traverse extensive search spaces makes traditional planning techniques unsuitable. In particular, in real-time domains, past plans need to be retrieved and adapted in real time and efficient plan adaptation techniques are required.

We have developed real-time adaptation techniques for case-based planning and specifically applied them to the domain of real-time strategy games. In our framework, when a plan is retrieved, a plan dependency graph is inferred to capture the relations between actions in the plan suggested by that case. The case is then adapted in real-time using its plan dependency graph. This allows the system to create and adapt plans in an efficient and effective manner while performing the task.

Our techniques have been implemented in the Darmok system, designed to play WARGUS, a well-known real-time strategy game. We analyze our approach and prove that the complexity of the plan adaptation stage is polynomial in the size of the plan. We also provide bounds on the final size of the adapted plan under certain assumptions.

Read the paper:

Real-Time Plan Adaptation for Case-Based Planning in Real-Time Strategy Games

by Neha Sugandh, Santi Ontañón, Ashwin Ram

9th European Conference on Case-Based Reasoning (ECCBR-08), Trier, Germany, September 2008
www.cc.gatech.edu/faculty/ashwin/papers/er-08-06.pdf

Situation Assessment for Plan Retrieval in Real-Time Strategy Games

Case-Based Planning (CBP) is an effective technique for solving planning problems that has the potential to reduce the computational complexity of the generative planning approaches. However, the success of plan execution using CBP depends highly on the selection of a correct plan; especially when the case-base of plans is extensive.

In this paper we introduce the concept of a situation and explain a situation assessment algorithm which improves plan retrieval for CBP. We have applied situation assessment to our previous CBP system, Darmok, in the domain of real-time strategy games. During Darmok’s execution using situation assessment, the high-level representation of the game state i.e. situation is predicted using a decision tree based Situation-Classification model. Situation predicted is further used for the selection of relevant knowledge intensive features, which are derived from the basic representation of the game state, to compute the similarity of cases with the current problem. The feature selection performed here is knowledge-based and improves the performance of similarity measurements during plan retrieval. The instantiation of the situation assessment algorithm to Darmok gave us promising results for plan retrieval within the real-time constraints.

Read the paper:

Situation Assessment for Plan Retrieval in Real-Time Strategy Games

by Kinshuk Mishra, Santi Ontañón, Ashwin Ram

9th European Conference on Case-Based Reasoning (ECCBR-08), Trier, Germany, September 2008
www.cc.gatech.edu/faculty/ashwin/papers/er-08-07.pdf
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