Luhmann likens the operation of autopoiesis (the filtering and processing of information from the environment) to a program, making a series of logical distinctions (in German, "Unterscheidungen"). Here, Luhmann refers to the British mathematician G. Spencer-Brown's logic of distinctions that Maturana and Varela had earlier identified as a model for the functioning of any cognitive process. The supreme criterion guiding the "self-creation" of any given system is a defining binary code. This binary code is not to be confused with the computers operation: Luhmann (following Spencer-Brown and Gregory Bateson) assumes that auto-referential systems are continuously confronted with the dilemma of disintegration/continuation. This dilemma is framed with an ever-changing set of available choices; every one of those potential choices can be the system's selection or not (a binary state, selected/rejected). The influence of Spencer-Brown's book, "Laws of Form", on Luhmann can hardly be overestimated.