A Quanti-Qualitative Approach to Alexander’s Harmony-Seeking Computations

Harmony-seeking computations, as proposed by Christopher Alexander, offer a way to tackle complexity. Smart, free agents, facing uncertainty, look for order in a context powered by fifteen attractors, or patterns. Harmony-seeking would then be a relatively guided path across those idealized patterns, towards wholeness and beauty. However, individuals acting to change the city must combine circumstances imposed by external and inner urban forces with personal interpretations of one or more of those patterns that could change all the time. Moreover, each action is intertwined with others, in an unpredictable outcome. This article explores the possibility of bringing together urban inner and outer forces and ingenious individuals’ actions of city change by hypothesizing: (a) wholeness as a structural attribute defined as spatial centrality; (b) beauty as meaning attached to places, evolving either from historic accumulation or individual assignment; (c) order as every meaningful approximation between them; (d) a disaggregated description of the urban organism, based on multi-layered graphs, in which would be possible to record both morphological and territorial characteristics (form, transport, infrastructure) and semantic attributes (land uses, public image, remote associations, symbolic relationships); and (e) a set of spatial differentiation measures, mostly based on centrality, potentially able to depict wholeness (by measuring the effect of each component on all others) and beauty (by measuring urban robustness derived from any selected set of components). A multilayer graph-based approach to spatial differentiation algorithms provides a framework for the description, analysis, and performance evaluation of every component, as well as the whole system, both through quantitative and qualitative representation.