I think we should literally stop calling every linear model as an SSM. Mamba2: Sₜ = αₜSₜ₋₁ + kₜvₜᵀ GDN: Sₜ = αₜ(I − βₜkₜkₜᵀ)Sₜ₋₁ + βₜkₜvₜᵀ GDN-2: Sₜ = (I − kₜ(bₜ⊙kₜ)ᵀ)DₜSₜ₋₁ + kₜ(wₜ⊙vₜ)ᵀ GDN family is a gradient step on a local regression loss, not a discretized ODE. Umbrella term should be "linear RNNs", with SSMs as one sub-family.