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- Levi Lelis, Jörg Sander
- 2009 Ninth IEEE International Conference on Data…
- 2009

Most of the effort in the semi-supervised clustering literature was devoted to variations of the K-means algorithm. In this paper we show how background knowledge can be used to bias a partitional density-based clustering algorithm. Our work describes how labeled objects can be used to help the algorithm detecting suitable density parameters for the… (More)

Korf, Reid, and Edelkamp launched a line of research aimed at predicting how many nodes IDA* will expand with a given cost bound. This paper advances this line of research in three ways. First, we identify a source of prediction error that has hitherto been overlooked. We call it the “discretization effect”. Second, we disprove the intuitively appealing… (More)

- Levi Lelis, Sandra Zilles, Robert C. Holte
- AAAI
- 2012

Korf, Reid and Edelkamp initiated a line of research for developing methods (KRE and later CDP) that predict the number of nodes expanded by IDA* for a given start state and cost bound. Independent of that, Chen developed a method (SS) that can also be used to predict the number of nodes expanded by IDA*. In this paper we advance these prediction methods.… (More)

- Willian M. P. Reis, Levi Lelis, Ya'akov Gal
- 2015 IEEE Conference on Computational…
- 2015

One of the major challenges in procedural content generation in computer games is to automatically evaluate whether the generated content has good quality. In this paper we describe a system which uses human computation to evaluate small portions of levels generated by an existing system for the game of Infinite Mario Bros. Several such evaluated portions… (More)

- Levi Lelis, Sandra Zilles, Robert C. Holte
- Artif. Intell.
- 2013

Article history: Received 24 November 2011 Received in revised form 13 December 2012 Accepted 12 January 2013 Available online 16 January 2013

- Levi Lelis, Lars Otten, Rina Dechter
- IJCAI
- 2013

This paper provides algorithms for predicting the size of the Expanded Search Tree (EST ) of Depthfirst Branch and Bound algorithms (DFBnB) for optimization tasks. The prediction algorithm is implemented and evaluated in the context of solving combinatorial optimization problems over graphical models such as Bayesian and Markov networks. Our methods extend… (More)

- Levi Lelis, Roni Stern, Ariel Felner, Sandra Zilles, Robert C. Holte
- ICAPS
- 2012

Optimal planning and heuristic search systems solve state-space search problems by finding a least-cost path from start to goal. As a byproduct of having an optimal path they also determine the optimal solution cost. In this paper we focus on the problem of determining the optimal solution cost for a state-space search problem directly, i.e., without… (More)

- Levi Lelis, Roni Stern, Shahab Jabbari Arfaee
- SOCS
- 2011

Classical heuristic search algorithms find the solution cost of a problem while finding the path from the start state to a goal state. However, there are applications in which finding the path is not needed. In this paper we propose an algorithm that accurately and efficiently predicts the solution cost of a problem without finding the actual solution. We… (More)

- Levi Lelis, Sandra Zilles, Robert C. Holte
- AAMAS
- 2013

Traditional heuristic search algorithms use the ranking of states that a heuristic function provides to guide the search. In this paper—with the objective of improving suboptimality and runtime of search algorithms when only weak heuristics are available—we present Stratified Tree Search (STS), a suboptimal heuristic search algorithm that uses a heuristic… (More)

- Jordan Tyler Thayer, Roni Stern, Levi Lelis
- SOCS
- 2012

Heuristic search is a general problem solving technique. While most evaluations of heuristic search focus on the speed of search, there are relatively few techniques for predicting when search will end. This paper provides a study of progress estimating techniques for optimal, suboptimal, and bounded suboptimal heuristic search algorithms. We examine two… (More)