fe. Althoughthose legal concepts are abstract in the sense that there always exist possibilities to interpret them in various ways, lawyers seem to understand themas real things at least in their "legal reality". For instance, Japanese Civil Codesinclude a notion of falsity that meansa false declaration of intention. In spite of ractness, well-trained lawyers can judge that one legal act involves the falsity and that the others do not. Fromthis point of view, it seems natural to consider that each legal act has its legal identity. Since the standard first order logic (FOL,for short) is foundedon the assumption that every object treated within the logic has its identity, it seems natural to develop a wayof representing the legal acts as first-order terms denoting individual objects. However,they are highly related each other at their conceptual level. For instance, a person fills the role of agent in a contract. Thus the two concepts "person" and "contract"...