A computer system and method for efficient storage and retrieval of data. The inventive computer system may comprise means for storing data, wherein data are allocated to predetermined categories that are components of at least one stored categorical structure forming an object model, wherein attributes that are inherited within the categorical structure are allocated to the categories; at least one inquiry unit for making queries relating to the stored data; and at least one inference unit used to evaluate declarative rules linking at least one of said categories and said attributes.