State Space Model (SSM)

A continuous or discrete linear dynamical system. Gemini uses Transformer attention; Mamba (next paper) uses SSMs as an alternative. Example: x_{t} = Ax_{t-1} + Bu_t.

A continuous-time dynamical system described by differential equations: dx/dt = Ax + Bu, y = Cx. In Mamba, this is discretised into a recurrence relation: x_t = Āx_{t-1} + B̄u_t, y_t = Cx_t. The state x summarises all information up to timestep t.