Wolfram Demonstrations Projecthttp://demonstrations.wolfram.com/An Open Resource of Interactive Mathematica VisualizationsCopyright 2009 Wolfram Demonstrations Project & ContributorsPaths of Balls Bouncing Off Pegshttp://demonstrations.wolfram.com/PathsOfBallsBouncingOffPegs/]]>http://demonstrations.wolfram.com/PathsOfBallsBouncingOffPegs/Proof of a Goal from a Hypothesishttp://demonstrations.wolfram.com/ProofOfAGoalFromAHypothesis/]]>http://demonstrations.wolfram.com/ProofOfAGoalFromAHypothesis/Substitution System Treeshttp://demonstrations.wolfram.com/SubstitutionSystemTrees/]]>http://demonstrations.wolfram.com/SubstitutionSystemTrees/