RT Book, Section SR 00 A1 Casti, J. T1 On the theory of models and the modelling of natural phenomena. YR 1984 FD 1984-09 SP 73 OP 92 AB It is argued that a modelling relation in an encoding of a set of physical observables, characterising a natural system N, into an appropriate formal mathematical structure. The theorems of the formal structure are then decoded into true statements about N. Various system-theoretic concepts such as bifurcation, similarity, system analogy, reductionism, and complexity are then seen to be naturally expressed. A2 Bahrenberg, G. A2 Fischer, M. A2 Nijkamp, P. T2 On the theory of models and the modelling of natural phenomena. PB Gower SN 978-0566006852 AV Published LK https://pure.iiasa.ac.at/id/eprint/13686/