An actuator is reduced in weight without impairing a walking assist function, and this reduces the inertial moment of a leg link. The higher-level cache may be inclusive with the lower-level cache and may update age data associated with the cache line, thus reducing the likelihood of eviction of the cache line. The receptor detects the position of incidence of the beam at the receptor. Updating is performed on the reconstructed prefix tables which are then reconverted into search tables to be inserted into the search data structure, for replacing or supplementing search tables that required updating. Progressive data representation, progressive transmission, and progressive model are thus three key elements that need to be integrated together. The composition is comprised of a cross-linked form of a water miscible polymer, and at least one phloroglucinol type compound selected from the group consisting of: phloroglucinol, a derivative of phloroglucinol, and a polymer synthetically prepared from phloroglucinol or a derivative of phloroglucinol.