Decoder. plain-English AI glossary

State Space Model

▲ Rising

Also called SSM

A sequence model that carries a compact running state, mixing RNN-like memory with parallel training.

Think of it like

A thermostat that tracks a single evolving reading over time instead of re-reading the whole day’s log.

Example

For very long sequences, an SSM keeps a fixed-size state so cost grows linearly, not quadratically like attention.

How it actually works

State space models process sequences through a linear dynamical system: a hidden state evolves step to step, summarizing history in fixed size. Cleverly, they can be computed either recurrently (cheap at inference) or as a convolution (parallel at training), sidestepping the RNN’s training bottleneck. Their linear scaling with length makes them attractive for very long contexts where attention gets expensive.

For product teams

A promising challenger to attention for very long inputs, with cheaper scaling.

For engineers

A linear-recurrence sequence model with a fixed-size state, computable as convolution for parallel training.

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