Selected Publications

In this page you will find a list of selected papers I have co-authored and co-edited. All papers are freely available for download. The images in the co-edited publication section link to the AAAI website with all papers I have co-edited freely available for download. See my Google Scholar profile for more information on my publications.

Co-Edited Publications

Conference and Journal Publications

Program Synthesis with Best-First Bottom-Up Search
Saqib Ameen and Levi Lelis
Journal of Artificial Intelligence Research (JAIR), 2023.

Choosing Well Your Opponents: How to Guide the Synthesis of Programmatic Strategies
Rubens Moraes, David Aleixo, Lucas Ferreira, and Levi Lelis
In the Proceedings of the International Joint Conference on Artificial Intelligence (IJCAI), 2023.

Levin Tree Search with Context Models (Distinguished Paper Award)
Laurent Orseau, Marcus Hutter, and Levi Lelis
In the Proceedings of the International Joint Conference on Artificial Intelligence (IJCAI), 2023.

Can You Improve My Code? Optimizing Programs with Local Search
Fatemeh Abdollahi, Saqib Ameen, Matthew Taylor, and Levi Lelis
In the Proceedings of the International Joint Conference on Artificial Intelligence (IJCAI), 2023.

Show Me the Way! Bilevel Search for Synthesizing Programmatic Strategies
David Aleixo and Levi Lelis
In the Proceedings of the Conference on Artificial Intelligence (AAAI), 2023.

What can we Learn Even From the Weakest? Learning Sketches for Programmatic Strategies
Leandro Medeiros, David Aleixo, and Levi Lelis
In the Proceedings of the Conference on Artificial Intelligence (AAAI), 2022.

Learning Curricula for Humans: An Empirical Study with Puzzles from The Witness.
Levi Lelis, Joao Nova, Eugene Chen, Nathan Sturtevant, Carrie Demmans Epp, and Michael Bowling
In the Proceedings of the International Joint Conference on Artificial Intelligence (IJCAI), 2022.

Asymmetric Action Abstractions for Planning in Real-Times Strategy Games
Rubens Moraes, Mario Nascimento, and Levi Lelis
Journal of Artificial Intelligence Research (JAIR), 2022.

Controlling Perceived Emotion in Symbolic Music Generation with Monte Carlo Tree Search
Lucas Ferreira, Lili Mou, Jim Whitehead, and Levi Lelis
In the Proceedings of the AAAI Conference on AI and Interactive Digital Entertainment (AIIDE), 2022.

Portability and Explainability of Synthesized Formula-based Heuristics.
Vadim Bulitko, Shuwei Wang, Justin Stevens, and Levi Lelis
In the Proceedings of the Symposium on Combinatorial Search (SoCS), 2022.

Teaching People by Justifying Tree Search Decisions: An Empirical Study in Curling
Cleyton Silva, Michael Bowling, and Levi Lelis
Journal of Artificial Intelligence Research (JAIR) - Research Note, 2021.

Policy-Guided Heuristic Search with Guarantees
Laurent Orseau and Levi Lelis
In the Proceedings of the Conference on Artificial Intelligence (AAAI), 2021.

Programmatic Strategies for Real-Time Strategy Games
Julian Mariño, Rubens Moraes, Tassiana Oliveira, Claudio Toledo, and Levi Lelis
In the Proceedings of the Conference on Artificial Intelligence (AAAI), 2021.

Improving the Performance-Compatibility Tradeoff with Personalized Objective Functions
Jonathan Martinez, Kobi Gal, Ece Kamar, and Levi Lelis
In the Proceedings of the Conference on Artificial Intelligence (AAAI), 2021.

Birds in Boots: Learning to Play Angry Birds with Policy-Guided Search
Lucas Pereira, Luiz Chaimowicz, and Levi Lelis
In the Proceedings of the AAAI Conference on AI and Interactive Digital Entertainment (AIIDE), 2021.

Marginal Utility for Planning in Continuous or Large Discrete Action Spaces
Zaheen Ahmad, Levi Lelis, and Michael Bowling
In the Proceedings of the Conference on Neural Information Processing Systems (NeurIPS), 2020.

Planning Algorithms for Zero-Sum Games with Exponential Action Spaces: A Unifying Perspective. [video]
Levi Lelis.
In the Proceedings of the International Joint Conference on Artificial Intelligence - Survey Track (IJCAI), 2020.

Computer-Generated Music for Tabletop Role-Playing Games [video]
Lucas Ferreira, Levi Lelis, and Jim Whitehead
In the Proceedings of the AAAI Conference on AI and Interactive Digital Entertainment (AIIDE), 2020.

Procedural Generation of Initial States of Sokoban.
Damaris Bento, Andre G. Pereira, and Levi Lelis.
In the Proceedings of the International Joint Conference on Artificial Intelligence, (IJCAI) 2019.

Iterative Budgeted Exponential Search.
Malte Helmert, Tor Lattimore, Levi Lelis, Laurent Orseau, and Nathan Sturtevant.
In the Proceedings of the International Joint Conference on Artificial Intelligence, (IJCAI) 2019.

Evolving Action Abstractions for Real-Time Planning in Extensive-Form Games
Julian Marino, Rubens O. Moraes, Claudio Toledo, and Levi Lelis
In the Proceedings of the Conference on Artificial Intelligence (AAAI), 2019.

Be Inaccurate but don't be Indecisive: How Error Distribution Can Affect User Experience
Rafael Padovani, Lucas N. Ferreira, and Levi Lelis.
In the Proceedings of the Conference on Artificial Intelligence (AAAI), 2019.

Strategy Generation for Multiunit Real-Time Games via Voting
Cleyton Silva, Rubens Moraes, Levi Lelis, and Ya'akov (Kobi) Gal
IEEE Transactions on Games, 2019.

Single-Agent Policy Tree Search with Guarantees
Laurent Orseau, Levi Lelis, Tor Lattimore, and Theophane Weber
In the Proceedings of the Conference on Neural Information Processing Systems (NeurIPS), 2018.

Asymmetric Action Abstractions for Multi-Unit Control in Adversarial Real-Time Games
Rubens O. Moraes and Levi Lelis
In the Proceedings of the Conference on Artificial Intelligence (AAAI), 2018.

Action Abstractions for Combinatorial Multi-Armed Bandit Tree Search [video]
Rubens O. Moraes, Julian Marino, Levi Lelis, and Mario Nascimento
In the Proceedings of the AAAI Conference on AI and Interactive Digital Entertainment (AIIDE), 2018.

Nested-Greedy Search for Adversarial Real-Time Games [video].
Rubens O. Moraes, Julian Marino, and Levi Lelis
In the Proceedings of the AAAI Conference on AI and Interactive Digital Entertainment (AIIDE), 2018.

Procedural Generation of Game Maps with Human-in-the-Loop Algorithms
Levi Lelis, Willian Reis, and Ya'akov (Kobi) Gal
IEEE Transactions on Games, 2018.

The First MicroRTS Artificial Intelligence Competition
Santiago Ontanon, Nicolas Barriga, Cleyton Silva, Rubens Moraes, and Levi Lelis
AI Magazine 2018.

Stratified Strategy Selection for Unit Control in Real-Time Strategy Games.
Levi Lelis.
In the Proceedings of the International Joint Conference on Artificial Intelligence (IJCAI) 2017.

On Creating Complementary Pattern Databases.
Santiago Franco, Alvaro Torralba, Levi Lelis, and Mike Barley.
In the Proceedings of the International Joint Conference on Artificial Intelligence (IJCAI) 2017.

Bardo: Emotion-based Music Recommendation for Tabletop Role-Playing Games.
Rafael Padovani, Lucas N. Ferreira, and Levi Lelis.
In the Proceedings of the AAAI Conference on AI and Interactive Digital Entertainment (AIIDE), 2017.

Understanding Mario: An Evaluation of Design Metrics For Platformers.
Adam Summerville, Julian Marino, Sam Snodgrass, Santiago Ontanon and Levi Lelis.
In Proceedings of the International Conference on the Foundations of Digital Games (FDG) 2017.

Mixed-Initiative Tool to Speed Up Content Creation in Physics-Based Games
Cesar R. F. G. Campos, Walter de O. Sa, Joao Marcos G. Teixeira, and Levi Lelis.
In Proceedings of the SBGames 2017.

A Computational Model based on Symmetry for Generating Visually Pleasing Maps of Platform Games.
Julian Marino and Levi Lelis.
In the Proceedings of the AAAI Conference on AI and Interactive Digital Entertainment (AIIDE), 2016.

Learning to Speed Up Evolutionary Content Generation in Physics-based Puzzle Games.
Leonardo Pereira, Claudio Toledo, Lucas Ferreira, and Levi Lelis.
In the Proceedings of the IEEE International Conference on Tools with Artificial Intelligence (ICTAI), 2016.

Searching with a Corrupted Heuristic.
Levi Lelis, Rick Valenzano, Gabriel Nazar, and Roni Stern.
In the Proceedings of the Symposium on Combinatorial Search (SoCS), 2016.

Heuristic Subset Selection in Classical Planning.
Levi Lelis, Santiago Franco, Marvin Abisrror, Mike Barley, Sandra Zilles, and Robert Holte.
In the Proceedings of the International Joint Conference on Artificial Intelligence (IJCAI) 2016.

What's Hot in Heuristic Search? (Invited Extended Abstract)
Roni Stern and Levi Lelis
In the Proceedings of the Conference on Artificial Intelligence (AAAI) 2016.

Predicting Optimal Solution Costs with Bidirectional Stratified Sampling in Regular Search Spaces.
Levi Lelis, Roni Stern, Shahab Jabbari Arfaee, Sandra Zilles, Ariel Felner, and Robert C. Holte.
Artificial Intelligence, 2016.

An Empirical Evaluation of Evaluation Metrics of Procedurally Generated Mario Levels.
Julian Marino, Willian Reis, and Levi Lelis.
In the Proceedings of the AAAI Conference on AI and Interactive Digital Entertainment (AIIDE), 2015.

Human Computation for Procedural Content Generation in Platform Games.
Willian Reis, Levi Lelis, and Ya'akov (Kobi) Gal.
In the Proceedings of the Conference on Computational Intelligence and Games (CIG), 2015.

Feature Selection as State-Space Search: An Empirical Study in Clustering Problems.
Julian Marino and Levi Lelis.
In the Proceedings of the Symposium on Combinatorial Search (SoCS), 2015.

Caching in Context-Minimal OR Spaces.
Rina Dechter, Levi Lelis, and Lars Otten.
In the Proceedings of the Symposium on Combinatorial Search (SoCS), 2015.

Stratified Sampling for Even Workload Partitioning Applied to Single Source Shortest Path Algorithm.
Jeeva Paudel, Levi Lelis, and Jose Nelson Amaral.
In the Proceedings of the Annual International Conf. on Computer Science and Software Engineering (CASCON). 2015.

Stratified Sampling for Even Workload Partitioning Applied to IDA* and Delaunay Algorithms.
Jeeva Paudel, Levi Lelis, and Jose Nelson Amaral.
In the Proceedings of the International Parallel & Distributed Processing Symposium (IPDPS), 2015.

Predicting optimal solution cost with conditional probabilities.
Levi Lelis, Roni Stern, Ariel Felner, Sandra Zilles, and Robert C. Holte.
Annals of Mathematics and Artificial Intelligence, 2014.
[publisher's website for this paper].

Estimating Search Tree Size with Duplicate Detection.
Levi Lelis, Roni Stern, and Nathan Sturtevant.
In the Proceedings of the Symposium on Combinatorial Search (SoCS), 2014.

Memory-Efficient Tree Size Prediction for Depth-First Search in Graphical Models.
Levi Lelis, Lars Otten, and Rina Dechter.
In the Proceedings of the International Conference on Principles and Practice of Constraint Programming (CP), 2014.

Cluster-and-Conquer: a Paradigm for Solving State-Space Problems.
Levi Lelis.
PhD Dissertation, University of Alberta, 2013.

Active Stratified Sampling with Clustering-Based Type Systems for Predicting the Search Tree Size of Problems with Real-Valued Heuristics.
Levi Lelis.
In the Proceedings of the Symposium on Combinatorial Search (SoCS), 2013.

Predicting the Size of Depth-First Branch and Bound Search Trees.
Levi Lelis, Lars Otten, and Rina Dechter.
In the Proceedings of the International Joint Conference on Artificial Intelligence (IJCAI) 2013.

Predicting the Size of IDA*'s Search Tree.
Levi Lelis, Sandra Zilles, and Robert C. Holte.
Artificial Intelligence, 2013.

Stratified Tree Search: A Novel Suboptimal Heuristic Search Algorithm.
Levi Lelis, Sandra Zilles, and Robert C. Holte.
In the Proceedings of the Conference on Autonomous Agents and Multiagent Systems (AAMAS) 2013.

Fast and Accurate Predictions of IDA*'s Performance.
Levi Lelis, Sandra Zilles, and Robert C. Holte.
In the Proceedings of the Conference on Artificial Intelligence (AAAI) 2012.

Predicting Optimal Solution Cost with Bidirectional Stratified Sampling.
Levi Lelis, Roni Stern, Ariel Felner, Sandra Zilles, and Robert C. Holte.
In the Proceedings of the International Conference on Automated Planning and Scheduling (ICAPS) 2012.

Learning Heuristic Functions Faster by Using Predicted Solution Costs.
Levi Lelis, Shahab Jabbari Arfaee, Sandra Zilles, and Robert C. Holte.
In the Proceedings of the Symposium on Combinatorial Search (SoCS), 2012.

Are We There Yet? -- Estimating Search Progress.
Jordan Thayer, Roni Stern, and Levi Lelis.
In the Proceedings of the Symposium on Combinatorial Search (SoCS), 2012.

Predicting Solution Cost with Conditional Probabilities.
Levi Lelis, Roni Stern, and Shahab Jabbari Arfaee.
In the Proceedings of the Symposium on Combinatorial Search (SoCS), 2011.

Improved Prediction of IDA*'s Performance via e-Truncation.
Levi Lelis, Sandra Zilles, and Robert C. Holte.
In the Proceedings of the Symposium on Combinatorial Search (SoCS), 2011.

Time Complexity of Iterative-Deepening A*: The Informativeness Pathology (Abstract).
Levi Lelis, Sandra Zilles, and Robert C. Holte.
In AAAI Student Abstract and Poster Section 2011.

Semi-supervised density-based clustering.
Levi Lelis and Joerg Sander.
In the IEEE Proceedings of the International Conference of Data Mining (ICDM) 2009.