26. Lenses: where do they come from?
Statistics
Mean/Max/Min
Variance
n-Moment
Density
…
Machine
Learning
PCA/SVD
Autoencoders
Isomap/MDS/TS
NE
…
Geometry
Centrality
Curvature
Harmonic Cycles
…
29. Coordinate Invariance
1. Topology of shape doesn’t depend on the coordinates used to
describe the shape
1. Different feature sets can describe the same phenomena
1. While processing data, we frequently alter coordinates: scaling,
rotating, whitening
You want to study properties of your data that are invariant
under coordinate changes
31. Deformation Invariance
• Topological features don’t change when you stretch and distort the
data
Advantage: Makes problems easier
Noise resistance
Less pre-processing of data
Robust (stable) data
36. Compressed Representation
• Replace the metric space with a combinatorial summary: a simplicial
complex.
• Data becomes easier to manage, search, and query while
maintaining essential features.
• Leverages many known algorithms from graph theory, computational
topology, computational geometry.