Regulatory networks seen as asynchronous automata: A logical description

The aim of this paper is to provide a compact answer to the questions: why treat complex biological systems in logical terms? how can one do it conveniently? Our initial description (Thomas, R. J. theor. Biol. 1973, 42, 563) is what we now call the “naive” logical description. After recalling the essential elements of this asynchronous description, the present paper introduces the use of logical variables with more than two values the notion of logical parameters the logical identification of all steady states of the differential description the notion of “characteristic” state of feedback loops a compact matricial presentation This is an essentially methodological paper. More extended developments including concrete biological examples will be found elsewhere (Thomas & D'Ari, 1990).