Intrinsic dimension M satisfies 0 ≤ M ≤ N
Image: Alice im Miniland, CC BY-SA 4.0, via Wikimedia Commons
Intrinsic dimension M satisfies 0 ≤ M ≤ N
The intrinsic dimension of a dataset is a measure of its complexity, indicating the minimal number of variables needed to represent it. This concept helps in understanding the underlying structure of data and signals.
Example
A dataset with 100 variables might have an intrinsic dimension of 10, meaning it can be effectively represented with just 10 variables.
Understanding intrinsic dimension helps in efficient data compression and analysis, reducing computational costs and improving clarity.
random projection to O(log n/ε²) dimensions preserves pairwise distances within 1±ε
Random projection reduces dimensionality while preserving pairwise distances within ε² due to the Johnson-Lindenstrauss lemma
the Johnson-Lindenstrauss lemma says
Random projection reduces dimensionality while approximately preserving pairwise distances
Manifold hypothesis
High-dimensional data lies on lower-dimensional manifolds
the curse of dimensionality makes nearest neighbor search unreliable
High dimensionality dilutes data density, making nearest neighbors less distinct and search unreliable
Dimensionality reduction
Dimensionality reduction transforms high-dimensional data into low-dimensional space while preserving meaningful properties
cosine similarity works better than Euclidean distance in high dimensions
Cosine similarity measures orientation, not magnitude, making it more robust to irrelevant dimensions in high-dimensional spaces
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