Traditionally, the determination of phase diagrams has followed the inductive paradigm, where experimental observations provide the phase boundaries in more or less detail and phenomenological and semi-phenomenological models are employed to interpolate between the experimental data points, and by extrapolation to predict the shape of the phase boundaries in experimentally inaccessible regions. Over the past fifteen years, a new methodology has been developing, the aim of which is the prediction, determination and validation of phase diagrams in chemical systems without any recourse to experimental information. The foundation stone of this deductive approach is the global study of the energy landscape of the chemical system. In this study, we present an application of this approach to the prediction of the low-temperature part of the phase diagram of the quasi-ternary semiconductors (Al, Ga, In)As.