Model Architectures
Normalizing flows
Transform a simple distribution into a complex data distribution through a sequence of invertible mappings with tractable Jacobians.
Mental model
A reversible deformation of probability space: data can map to noise and noise can map back to data.
Data flow
- Data sample
- Invertible transformations
- Simple latent distribution
- Exact change-of-variables likelihood
- Reverse transforms for sampling
How it trains
Maximum likelihood is optimized exactly under architectural constraints that make inversion and the Jacobian determinant tractable.
How inference runs
Density evaluation runs data toward the latent; generation samples the base distribution and applies every transform in reverse.
Strengths
- Exact likelihood under the model
- Invertible encoding and generation
- Useful when density estimation is itself important
Trade-offs
- Invertibility constrains network design
- High-dimensional media can require deep, memory-heavy flows
- Likelihood does not necessarily track perceived sample quality
Use it when
- Exact density or reversible transforms are requirements
- The domain fits available invertible architectures
- You will evaluate both likelihood and task utility
Avoid or challenge it when
- Only perceptual generation quality matters
- Architectural flexibility is more important than exact likelihood
- A simpler discriminative uncertainty method is sufficient
Illustrative published families
- • Real NVP
- • Glow-style image flows
Commonly combines with
Variational inferenceHybrid latent-variable models