In the independent model, we introduce observation variables (e.g., x ′ t and x ′′ t ) and parameters (e.g., ϕ ′ k and ϕ ′′ k ) for each information.
x ′ t and ϕ ′ k are introduced for the surface form of aligned words, and x ′′ t and ϕ ′′ k for the POS of aligned words.