Partially founded by UBACyT 20020090200116 and UBACyT 20020100200103.We present a formalization of Kanger’s types of rights in the context
of interacting two-party systems, such as contracts. We show that in this setting
basic rights such as claim, freedom, power and immunity can be expressed in
terms of (possibly negated) permissions and obligations over presence or absense
of actions, and that the set of atomic type rights is different from Kanger’s original
proposal.peer-reviewe