Givental's conjecture for the projective line

Let $G(\{x_k\},\{y_k\})$ be the generating function associated with the tau-functions, and let $P(\lambda\Delta_{+},\{x_k\},\{y_k\})$ be the formal power series defined by

$$G(\{x_k\},\{y_k\})=P(\lambda\Delta_{+},\{x_k\},\{y_k\})\,\tau(\lambda\Delta_{+},\{x_k+y_k\})\,\tau(\lambda\Delta_{+},\{x_k-y_k\}).$$

Here $\lambda\Delta_{+}$ is the parameter appearing in the tau-functions, and $\{T_k^+\}$ denotes the relevant specialization of the variables.

Givental's conjecture. The generating function $G(\{T_k^+\},\{0\})$ is equal to one, or equivalently

$$P(\lambda\Delta_{+},\{T_k^+\},\{0\})=\frac{1}{\tau(\lambda\Delta_{+},\{T_k^+\})^2}.$$

This is Givental's conjecture for the Gromov–Witten theory of $\mathbf{P}^1$, expressed through the generating function and the associated tau-function. The supplied source gives no evidence that the conjecture has been resolved.