## Exam - Start: **Karhunen-Loeve-Transformation (PCA)** - Basis rotation / Decomposition of the covariance matrix - Dimension Reduction by removing small eigenvalues (variances) - Requires a Euclidean space - **Edit distances** - Some data has no Euclidean space - Expensive, use GEMINI - Prune data and then compute the distance - Levenshtein distance - Computation - Dynamic programming - What metrics work? --> Additive metrics (comparable to Markov property; the way we got to the result does not matter) - Indexing using M-Trees - **M-Trees** - Idea - Spherical geometry using the Triangle Inequality - Explain pruning criterion