A sequence generation model is being trained to maximize the objective function $U(\mathbf{x}, \mathbf{y}; \theta) = \sum_{t=1}^{T} A(\mathbf{x}, y_t, \mathbf{y}_{<t}) \log \pi_\theta(y_t|\mathbf{x}, \mathbf{y}_{<t})$. The training goal is to specifically penalize the model for using repetitive phrasing. Which of the following strategies for designing the weighting function $A(\cdot)$ would best accomplish this?

Analysis of a Simplified Objective Function

Debugging Model Behavior via the Objective Function