N. T. Le and N. Pinkwart. Can Soft Computing Techniques Enhance the Error Diagnosis Accuracy for Intelligent Tutors? Proceedings of the 11th International Conference on Intelligent Tutoring Systems (ITS), Springer Verlag, issue 7315, 2012. N. T. Le and N. Pinkwart. INCOM: A Web-based Homework Coaching System For Logic Programming. Proceedings of the IADIS International Conference on Cognition and Exploratory Learning in Digital Age (CELDA), International Association for Development of the Information Society, 2011. N. T. Le and N. Pinkwart. Adding Weights to Constraints in Intelligent Tutoring Systems: Does it Improve the Error Diagnosis? Proceedings of the 6th European Conference On Technology Enhanced Learning (ECTEL), Springer Verlag, issue 6964, 2011. N. T. Le and N. Pinkwart. Enhancing The Error Diagnosis Capability For Constraint-based Tutoring Systems. Proceedings of the 15th International Conference on Artificial Intelligence in Education (AIED), Springer Verlag, issue 6738, 2011. N. T. Le and N. Pinkwart. Analysis of Learning Curves for Weighted Constraint-Based Tutoring Systems. Proceedings of the IADIS International Conference on Cognition and Exploratory Learning in Digital Age (CELDA), International Association for Development of the Information Society, 2010. N. T. Le, W. Menzel, and N. Pinkwart. Considering Ill-Definedness Of Problem Tasks Under The Aspect Of Solution Space. Proceedings of the 23st International Conference of the Florida Artificial Intelligence Research Society (FLAIRS), AAAI, 2010. N. T. Le, W. Menzel, and N. Pinkwart. Evaluation of a Constraint-Based Homework Assistance System for Logic Programming. Proceedings of the 17th International Conference on Computers in Education (ICCE), Asia-Pacific Society for Computers in Education, 2009.