2. Unsupervised learning 2.1. Gaussian mixture models 2.1.2. Variational Bayesian Gaussian Mixture 2.2.1. Introduction2.2.3. Locally Linear Embedding2.2.5. Hessian Eigenmapping2.2.7. Local Tangent Space Alignment2.2.9. t-distributed Stochastic Neighbor Embedding (t-SNE) 2.3. Clustering 2.3.3. Affinity Propagation2.3.5. Spectral clustering2.3.7. DBSCAN2.3.9. Birch 2.4. Biclustering 2.4.2. Spectral Biclustering 2.5. Decomposing signals in components (matrix factorization problems) 2.5.2. Truncated singular value decomposition and latent semantic analysis2.5.5. Independent component analysis (ICA)2.5.7. Latent Dirichlet Allocation (LDA) 2.6.1. Empirical covariance2.6.3. Sparse inverse covariance 2.7. Novelty and Outlier Detection 2.7.2. Novelty Detection2.7.4. Novelty detection with Local Outlier Factor 2.8.1. Density Estimation: Histograms