Extraction method of $\gamma$ from semi-inclusive b ---> D s decays

We propose a new method to extract a CP angle $\gamma$ from semi-inclusive two-body nonleptonic decays, b ---> D^0(\bar{D}^0) s and b ---> D_{CP} s. This method is free from the unknown long distance strong interaction effects and gives theoretically cleaner signal than the similar method using exclusive nonleptonic decays, B ---> D K. We can determine $\gamma$ with 4-$\sigma$ accuracy for 40^o < \gamma < 160^o.