An autoregressive model generates a sequence token by token. In a standard implementation, the query vector at position i (q_i) computes attention over the key-value pairs from all preceding positions, from 1 to i. Consider a modified implementation where the query q_i is restricted to attend only to the key-value pairs from the very first position (k_1, v_1) and its own current position (k_i, v_i). How does the computational cost of calculating the attention output for a singl