A method includes providing a plurality of sampling rules. For the strangers who are users of the social network and not related to each other, information spreading probabilities based on features, information reach, and information spreading probabilities based on a wait time are computed. Based on the output of the radiation receiver, the tester measures the opacity of the sample. A large number of base stations are each allocated a few MHz portion of a 900 MHz bandwidth of the millimeter wave trunk line. The information relating to the object relative to the display may be provided by correlating the amount of detected light from the plurality of light sensors to the information relating to the object. In the optical recording disk, a playback signal is stabilized by setting the level ratio of an AC component of a sum signal to a DC component of the sum signal in a plurality of spots to be equal to or smaller than a predetermined value.