Definition
Plain language
A sequence model that maintains a fixed-size running memory rather than attending to every previous token.
As stated in the literature
A class of sequence models that maintain a fixed-dimensional recurrent state, including Mamba and S4 variants, offering constant memory per step.
Also called: state-space models, SSM, state-space
Why it matters: Constant-memory recurrence offers a path to much longer effective contexts than attention can affordably handle, though typically at some quality cost on short tasks.
For example, a Mamba layer keeps a small hidden vector that gets updated as each new token arrives, with no need to look back at every prior token.
Heard on the show
“New model families — hybrid state-space models, multimodal models that mix text and images in weird ways.”Episode 027 — When AI Agents Build the Serving Stack: A Bet on Bespoke Infrastructure