Abstract This paper shows how safety and liveness properties are not necessarily preserved by different kinds of copies of computational artefacts and proposes procedures to preserve them, which are consistent with ethical analyses on software property rights infringement. Safety and liveness are second-order properties that are crucial in the definition of the formal ontology of computational artefacts. Software copies are analysed at the level of their formal models as exact, inexact and approximate copies, according to the taxonomy in [3]. First, it is explained how exact copies are the only kind of copies that preserve safety and liveness properties, and how inexact and approximate copies do not necessarily preserve them. Secondly, two model checking algorithms are proposed to verify whether inexact and approximate copies actually preserve safety and liveness properties. Essential properties of termination, correctness and complexity are proved for these algorithms. Finally, contraction and expansion algorithmic operations are defined, allowing for the automatic design of safety- and liveness-preserving approximate copies. As a conclusion, the relevance of the present logical analysis for the ongoing debates in miscomputation and computer ethics is highlighted.

Defining identity for entities is a longstanding logical problem in philosophy, and it has resurfaced in current investigations within the philosophy of technology. The problem has not yet been explored for the philosophy of information, and of Computer Science in particular. This paper provides a logical analysis of identity and copy for computational artefacts. Identity is here understood as the relation holding between an instance of a computational artefact and itself. By contrast, the copy relation holds between two distinct computational artefacts. We distinguish among exact, inexact and approximate copies. We use process algebra to provide suitable formal definitions of these relations, using in particular the notion of bisimulation to define identity and exact copies, and simulation for inexact and approximate copies. Equivalence is unproblematic for identical computational artefacts at each individual time and for inexact copies; we will examine to which extent the formal constraints on identity criteria discussed in the literature are satisfied by our approach. As for inexact and approximate copy, they are intended as a weakening of the identity relation in that equivalence and other constraints on identity are violated. The proposed approach also suggests a computable treatment of identity and copy checking.