PL
The main aim of the paper is to revive Zdzisław Augustynek’s attempts to define the relation of genidentity. The text embraces the following issues: (i) a presentation of three axiomatic definitions of genidentity; (ii) a reconstruction of the definitions in question in the language of the predicate calculus; (iii) a supplementing the above reconstruction by appropriate proofs; (iv) an analysis of the selected methodological and ontological assumptions of the discussed systems; (v) a comparison of Augustynek’s systems with Eugeniusz Żabski’s proposal; (vi) an outline of the definition of a thing as an abstractum (equivalence class, invariant) over the set of all punctual events under a relation of genidentity.