method and apparatus are provided for use in a frame - based semantic network wherein at least one specialization slot - control frame defining a specialized behavior is linked to a base slot - control frame defining a global behavior in a hierarchical data structure . slot behavior is attached to an occurrence of the slot in any other frame such that the slot and its behaviors are inherited to related frames as a unit . all specialized behaviors are compiled into a compact internal format and stored in a reserved space in the slot - control frame . the method and apparatus have particular utility in knowledge - based or expert systems .