Distribution of a particle's position in the ASEP with the {alternating} initial condition

In this paper we give the distribution of the position of the particle in the asymmetric simple exclusion process (ASEP) with the alternating initial condition. That is, we find $\mathbb{P}(X_m(t)\le x)$ where $X_m(t)$ is the position of the particle at time $t$ which was at $m=2k-1,k\in \mathbb{Z}$ at $t=0.$ As in the ASEP with the step initial condition, there arises a new combinatorial identity for the alternating initial condition, and this identity relates the integrand to a determinantal form together with an extra product.