A redundant logic circuit detection method includes storing unit-logic-circuit information, waveform data and a limiting condition in a storage section. A kit and method of installation for a home owner or others with little installation experience can enhance a bathroom and can be assembled and installed in an easy, quick and secure manner. The acetabular cup is formed of a body having a sidewall defining a radius from a center point of the annular rim to the sidewall wherein the radius increases in length from the apex to said annular rim. The light emitted from the light emitting element is reflected by the air filter element or permeated to the air filter element, then forms an area of light attenuation where the light sensor is located. In one embodiment, the downward slope is between about 10 degrees and about 20 degrees.