I would like to thank the conveners of the experimentation session, R.Jacobsen, S.-K.Kim and R.Settles, for a well-organized session. I appreciate discussions with R.Settles, T.Hirose, C.Adolphsen, M.Yoshioka, S.Takeda, C.Damerell, D.Jackson, N.Khalatyan and K.Ishii. This work was supported in part by the JSPS Japanese-German Cooperative Program.