EN
This paper examines heterogeneous nature of interaction space in mixed reality systems, i.e systems that merge everyday, real spaces and virtual worlds, to produce new kind of environments, where physical and digital objects can interact in real time. Hybrid reality systems, in this paper, are analyzed in a theoretical framework provided by a new paradigm in human-computer interaction research, which is called 'Ubicomp - ubiquitous computing'. One of the main goals of Ubicomp is to investigate, both theoretically and practically, the possibility of 'seamless integration between real and virtual domains'. After analyzing this project the author tries to point out how the concept of hybridity is defined, and to what general strategies of designing interaction it may lead to.