“…Pair, select or engage with device by: → stitching [54,129] → pinching [190,192,238,243] → synchronous tapping [280] → vision-based handshake [360] → pointing [259,349] → finger postures [141] → painting on surfaces [370] Pair, select or engage with device by: → touching the surface [293] → knocking or tapping [103,280] → tapping appliance [372] → taking picture to recognize device [299] → roll-and-pointing [61] → hold-and-flipping [54] → pitching-to-open [54] Pair or engage with device by: → bumping [127] → synchronous gestures [272] → stacking [61] → snapping a picture pair [60] → shaking [131,211] → placing down device [143,270,360] → recognizing motion correlation [359] Pair or engage with device by: → bending [61] → using sandwich structure [61] → stretching [61] Pair or engage with device by: → approaching [12,203] → turning body towards [12,107,205,369] → detecting presence of person [12,30,145,369] → detect groups…”